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MHI Copy 3 DEPARTMENT OF THE ARMY FIELD MANUAL LIGHT ANTIAIRCRAFT ARTILLERY (AUT T jIC WEAPONS) DEPARTMENT OF THE ARMY · JULY 1956

LIGHT ANTIAIRCRAFT ARTILLERY · 2016. 4. 22. · *fm 44-2 field manual 1 department of the army no. 44-2 j washington 25, d.c., 12 july 1956 light antiaircraft artillery (automatic

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Page 1: LIGHT ANTIAIRCRAFT ARTILLERY · 2016. 4. 22. · *fm 44-2 field manual 1 department of the army no. 44-2 j washington 25, d.c., 12 july 1956 light antiaircraft artillery (automatic

MHICopy 3

DEPARTMENT OF THE ARMY FIELD MANUAL

LIGHTANTIAIRCRAFT

ARTILLERY(AUT T jIC WEAPONS)

DEPARTMENT OF THE ARMY · JULY 1956

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*FM 44-2FIELD MANUAL 1 DEPARTMENT OF THE ARMYNo. 44-2 J WASHINGTON 25, D.C., 12 July 1956

LIGHT ANTIAIRCRAFT ARTILLERY(AUTOMATIC WEAPONS)

Paragraph PagePART ONE. ORGANIZATION AND

TACTICSCHAPTER 1. INTRODUCTION -------- 1, 2 3

2. ORGANIZATIONSection I. Missions ------------------ 3-5 4

II. Battalion ----------------- 6-18 5III. Battery, -. ................. 19-25 14

CHAPTER 3. CHARACTERISTICS OFEQUIPMENT ---------- 26-32 17

4. RECONNAISSANCE, SE-LECTION, AND OCCU-PATION OF POSITION

Section I. Antiaircraft defense ------ 33-35 25II. Surface mission ----------- 36-39 30

CHAPTER 5. COMMUNICATIONS .---- 40-46 356. OBSERVATION AND

EARLY WARNING ---- 47-49 477. SECURITY AND PRO-

TECTION ------------- 50-52 508. LOGISTICS.

Section I. Supply and evacuation ---- - 53-56 58II. Transportation ------- 57, 58 60

III. Messing -__-- 59, 60 61

*This manual supersedes FM 44-2, 24 August 1950,including C 1, 26 November 1952.

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Paragraph Page

PART Two. GUNNERY AND FIRECONTROL DEVICES

CHAPTER 9. ANTIAIRCRAFT ARTIL-LERY (AUTOMATICWEAPONS) GUNNERYPROBLEM

Section I. Introduction -------- __---- 61, 62 63II. Elements of data __--......63-67 64

III. Solution of the problem- - .. 68-70 73IV. General application and anal-

ysis of problem ---------- 71-73 77CHAPTER 10. TRACER OBSERVATION_ 74-82 85

11. SPEED RING SIGHTS --- 83-88 10412. COMPUTING SIGHTS --- 89-93 12013. ANTIAIRCRAFT ARTIL-

LERY (AUTOMATICWEAPONS) SURFACEFIRING

Section I. General .----------------- 94-96 146II. Direct fire --------------- __ 97, 98 148

III. Indirect fire ---------------- 99-109 154APPENDIX I. REFERENCES ----------------- 174

II. ANTIAIRCRAFT ARTILLERY(AUTOMATIC WEAPONS)TRAINING AIDS ----------- 177

III. MATHEMATICAL ANALYSISOF LEAD ------------------- 184

IV. GLOSSARY OF ANTIAIRCRAFTARTILLERY (AUTOMATICWEAPONS) SYMBOLS ANDTERMS --------------------- 194

INDEX ---------------------------------- 198

2

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PART ONEORGANIZATION AND TACTICS

CHAPTER 1INTRODUCTION

1. Purpose and ScopeThis manual is for the use of battalion commanders

and staff, battery commanders, platoon leaders, andfire unit leaders of AAA (AW) (antiaircraft artilleryautomatic weapons). It covers the organization,reconnaissance, selection, and occupation of posi-tions, communications, observation and early warn-ing, security, logistics, gunnery, and fire controlsighting devices of antiaircraft artillery automaticweapons -batteries and battalions. Part one includesbattalion organization and tactics. Part two in-cludes antiaircraft and surface gunnery techniquesand fire control devices. Fundamental tacticalemployment principles of antiaircraft artillery auto-matic weapons units are contained in FM 44-1.

2. ReferencesFor a list of references containing material supple-

menting this manual, see appendix I.

3

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CHAPTER 2ORGANIZATION

Section I. MISSIONS

3. General MissionThe mission of AAA (AW) is to attack and destroy

enemy targets in the air, on land, and on water.This mission is divided into air defense and surfacemissions. Force commanders assign missions toAAA (AW) units. A commander may decide to useall or any part of his AAA (AW) against ground orwater targets while there is a threat of air attack if heconsiders that these targets offer a greater threat tothe successful accomplishment of his mission than anair attack. Antiaircraft artillery automatic weaponsare disposed and emplaced to best execute theassigned mission, air or surface defense. Whenpractical, the weapons are sited to permit attack ontargets other than those included in the assignedmission.

4. Air Defense MissionThe mission of AAA (AW) in defense against air

attack is to attack all forms of enemy aircraft andmissiles, to destroy them, to nullify their effective-ness, or to force them to abandon their mission.Automatic weapons are employed in the zone ofinterior, communications zone, and combat zone.It is the responsibility of the battalion commander

4

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in a one-battalion defense, or higher unit commanderin a multiple battalion defense, to design the entiredefense and designate position areas to be occupiedby the fire units. A discussion of AAA (AW)defense designing is contained in FM 44-1.

5. Surface MissionThe mission of AAA (AW), when employed in

defense against surface attack, is to give fire supportto other arms; to neutralize or destroy targets whichare most dangerous to the supported arm by provid-ing or reinforcing field artillery fires, and by attack-ing and destroying targets of opportunity on land orwater. Details of employment in a surface missionare covered in chapter 4.

Section II. BATTALION

6. Antiaircraft Artillery Automatic Weapons BattalionThe battalion is the basic tactical and administra-

tive unit. It is composed of a headquarters andheadquarters battery and four firing batteries. Seeappropriate TOE (tables of organization and equip-ment) for specific organization and equipment.

7. Battalion Commandera. The battalion commander is responsible for all

battalion activities. He is responsible for the tacticaland technical employment of his unit and its combateffectiveness, its training, administration, discipline,supply and maintenance of equipment, and the well-being and morale of its personnel. He exercisescommand by making decisions and issuing orders tobattery commanders, and supervises the activities of

S

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the unit by means of reports and frequent personalvisits and inspections covering all phases of activityengaged in by elements of his command.

b. In accordance with assigned missions and ordersof higher authority, the battalion commander willprepare and execute standing operating proceduresfor the unit. He must:

(1) Keep himself and his subordinates informedof friendly and enemy situations for bothground and air.

(2) Maintain communications and liaison withadjacent and supported units and insureproper functioning of those communicationsnets required for the tactical success of theunit.

(3) Coordinate the AAAIS (antiaircraft artilleryinformation service) within the unit andinsure its proper functioning in accordancewith current instructions from higher head-quarters.

(4) Make certain the commissioned officersassigned to duty as AAOO (antiaircraftartillery operations officer) are qualified forthat position.

8. Battalion Staffa. A battalion staff is provided to assist the com-

mander in the exercise of his command, in unit train-ing, and in forming and executing a plan for combat.The staff secures and furnishes required information,prepares details of plans and orders, transmits ordersto subordinate commanders when necessary, andprovides staff supervision over all activities of thebattalion.

6

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b. Figure 1 shows the organization of the AAA(AW) battalion staff. For detailed study of staffdoctrine, procedures, and duties, see FM 101-5.Specific duties applicable to AAA (AW) battalionstaff officers are in the following paragraphs. Com-mon responsibilities of the head of each staff sectioninclude:

(1) Organization and supervision of the section.(2) Training personnel in section duties.(3) Maintaining such records, charts, or maps

as required by specific duties, including prep-aration of appropriate portions of the unitreport.

(4) Informing other staff members and batterycommanders of pertinent information re-ceived.

(5) Advising the commander on technical as-pects of the staff position.

(6) Serving as AAOO when required.

9. Executive Officer

The executive officer is second in command of thebattalion, acting as the principal assistant and ad-visor to the commander. His duties correspond tothose of chief of staff and/or deputy commander of adivision or higher. In general, his job is to relieve thecommander of detailed supervision of administrationand operations, enabling the commander to devotehimself to command functions. The executive officermust be prepared to assume command of the bat-talion at all times by keeping fully informed of thesituation. His duties are to-

a. Supervise the battalion staff activities.

7

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BATTALIONCOMMANDER

EXECUTIVEOFFICER

PERS 0 ASST ASSTS t S4

STRY COMMO O LN MTR 0 CHCMDR (WO)

Figure 1. Organization of the battalion staff.

b. Supervise the establishment and operation ofthe command post.

c. Coordinate battalion security measures.d. Supervise the compilation of required reports,

such as the unit journal and command report.e. Supervise the establishment and operation of

the battalion AAOC..f. Coordinate and supervise the displacement and

movement of the unit.g. Supervise the installation and operation of the

AAAIS, and communication nets required for tacticalsuccess of the unit.

10. SiThe S1, as battalion adjutant, plans, coordinates,

and supervises administrative and personnel func-

8

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tions of the battalion. A personnel officer is hisassistant.

a. Administrative duties of the S1 are to---(1) Process official correspondence.(2) Supervise publication, distribution, and

authentication of all orders, except combatorders.

(3) Maintain the records of the battalion.b. Personnel duties of the S1 are to-

(1) Prepare strength records and reports.(2) Requisition and process personnel replace-

ments.(3) Supervise discipline and legal activities in-

cluding the processing of court-martialcases.

(4) Handle the administration of civilian em-ployees, civil affairs, and prisoners of war.

(5) Supervise and record the classification,assignment, promotion, pay, allotments,transfers, casualties, and separation ofpersonnel.

(6) Supervise morale activities, including postalfacilities, awards and decorations, leavesand passes, recreation and exchange fa-cilities, and religious and welfare matters.

(7) Maintain the unit journal and other recordsnot assigned to other staff sections.

(8) Handle personal effects with the assistanceof the summary court officer.

(9) Supervise administrative procedures.(10) Handle internal arrangement of battalion

headquarters.

9

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11. S2The S2 is the battalion intelligence officer. He

collects, evaluates, interprets, and disseminates allcombat information ano. intelligence received atbattalion headquarters. In addition, his dutiesare to-

a. Supervise the installation and operation of theAAAIS.

b. Coordinate intelligence training.c. Coordinate all means of gathering information

pertaining to the enemy situation, both air andground, from all sources.

d. Make sure that this information is processed,evaluated, interpreted, and disseminated reliablyand efficiently.

e. Make sure that a comprehensive system ofrecognition and identification of friendly aircraft isestablished. This system must provide for maximumexploitation of visual means and proper employmentof electronic means. Limitations imposed by thehuman element must be minimized.

f. Requisition and distribute maps.

12. S3The S3 is the battalion operations and training

officer. He has one officer assistant. The principleduties of the S3 are to-

a. Prepare plans for and supervise the organiza-tion, training, movement, and combat operation ofthe battalion.

b. Assist in the preparation and issuance of opera-tions orders and instructions.

c. Assist in the establishment and operation ofthe AAOC.

10

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d. Keep up-to-date information of the operatingstatus of materiel, training, weapon locations,and missions.

e. Make sure that all commissioned and enlistedpersonnel assigned duties in the AAOC are competentand well trained.

f. Make sure that the means of tactical battalioncontrol are adequate and that-

(1) A complete but brief SOP (standing operat-ing procedure) for engagement control andtarget selection is provided for each fireunit leader and that fire unit personnel arewell versed in its contents.

(2) A list of instructions for implementation ofthe fire unit SOP is composed for the useof the AAOO.

g. Make certain that means of communicationprovided for the control of battalion elements isreliable, rapid, and within tactical requirements.

h. Coordinate liaison activity, TIE (troop informa-tion and education) functions, use of training facili-ties, and the analysis of defenses.

13. S4The S4 is the battalion supply officer and super-

vises the operation of supply, evacuation, trans-portation, and maintenance. He has one warrantofficer assistant. Principle duties of the S4 are to-

a. Requisition and distribute all supplies.b. Supervise food service.c. Coordinate the planning, supervision, and

allocation of ammunition supply operations andcritical supplies with the S3.

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d. Coordinate administrative orders and motormovements with S3.

e. Keep current information for the battalioncommander on the status of supply, propertyaccounting procedures and records, and organiza-tional maintenance of equipment.

f. Collect and process salvage.

14. Communication OfficerThe battalion communication officer, under super-

vision of the S3, supervises the installation andoperation of the communication nets that areneeded to meet the tactical and administrativerequirements of the battalion. Specific dutiesare to-

a. Organize and operate the battalion com-munication center.

b. Advise the battalion commander and staff on allmatters of communications, to include communi-cation training and the status of communicationsupply and maintenance.

c. Maintain communication with the staff of thenext higher, lower, adjacent, and supported unitsas directed by higher headquarters.

d. Install and maintain those means of com-munications used in the operation of the AAOCand AAAIS.

15. Motor OfficerThe motor officer, under S4 supervision, advises

the commander and staff on motor maintenanceand transportation. He supervises the operationand maintenance of battalion wheel and trackvehicles and trains his personnel.

12

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16. ChaplainThe chaplain advises the commander and staff on

moral and religious matters in the battalion. Heconducts religious services, advises personnel onspiritual matters, ministers to sick and wounded,and corresponds with relatives of sick, wounded,and deceased personnel. He does not performoperational duties such as AAOO.

17. Liaison OfficerThe liaison officer is the personal representative of

the battalion commander, acting as a link betweenthe battalion headquarters and the headquarters towhich he reports. Functioning under the super-vision of the S3, he makes sure that the tactics,techniques, and employment of the unit he repre-sents are understood by the commander of theorganization to which he is detailed.

18. Radar Warrant OfficerThe radar warrant officer is a special staff officer

and normally works under the supervision of the S2.The duties of the radar officer are to-

a. Advise the commander and staff on the statusof radar equipment issued to the battalion.

b. Supervise movement and siting of the surveil-lance radar.

c. Supervise operation and maintenance of radarequipment.

d. Supervise preparation of cover and clutterdiagrams.

e. Assist in the establishment of the AAAIS and airwarning nets.

13

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Section III. BATTERY

19. Headquarters BatteryHeadquarters battery furnishes the necessary per-

sonnel and equipment to assist the battalion infunctions of command, control, reconnaissance, com-munication, intelligence, logistics, and administra-tion. See appropriate TOE for organization.

20. Headquarters Battery CommanderThe headquarters battery commander commands

headquarters battery and acts as headquarters com-mandant. He is responsible for the supply, mess,quarters, pay, conduct, training, health, and moraleof his unit personnel. As headquarters commandant,he is responsible for:

a. Organization and security of the battalioncommand post.

b. Physical movement of battalion headquarters.c. Supervision of mess and transportation facilities

for battalion headquarters.

21. Automatic Weapons BatteryThe automatic weapons battery consists of a

battery headquarters and two platoons of eight fireunits each. An automatic weapons fire unit is con-sidered to be one weapons mount. The platoon hasfour multiple gun motor carriage M16A1's and four40-mm gun motor carriage M42's in self-propelledunits; four multiple machinegun trailer mount M55'splus four 40-mm gun on carriage M2A3's in mobileunits. The airborne automatic weapons batteryconsists of a battery headquarters and three platoonsof six fire units each. The airborne platoon has fourM55's plus two M42's.

14

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22. Battery CommanderThe AAA (AW) battery commander is responsible

for all activities of the battery, including administra-tion, training, and tactical employment. His spe-cific duties are to-

a. Accomplish the combat mission of the battery.b. Carry out training schedules, supervise actual

instruction, and maintain proper discipline.c. Keep battery records, supply and maintain

clothing and equipment, and supervise food service.

23. Battery Executive OfficerThe battery executive officer assists and advises

the battery commander, and makes sure that hispolicies are carried out. He is second in commandof the battery and normally acts as battery liaisonofficer in surface or AA (antiaircraft) missions withinfantry, armor, or field artillery units.

24. Platoon Leaders and Assistant Platoon LeadersThese officers are responsible to the battery com-

mander for training personnel of their platoon, thetactical employment of the platoon, and the admin-istration of the platoon in the field.

25. Fire Unit LeaderThe fire unit leader is directly subordinate to the

platoon leader. He supervises target selection andexercises engagement control of his fire unit. Hisresponsibilities and functions are to-

a. Train his crew in service of the piece.b. Train his crew in the SOP for engagement con-

trol and target selection.

15

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c. Understand the application of such basic tacti-cal principles as:

(1) The value of primary and secondary sectorsof fire.

(2) The necessity for overlapping adjacent pri-mary sectors of fire.

(3) The greater threat to the vital area of anincoming target than an outgoing target inthe primary sector of fire.

(4) The rule for engaging an incoming target inthe secondary sector before an outgoingtarget in the primary sector of fire.

(5) The necessity for engaging a target at maxi-mum effective range to produce maximumeffective fire.

(6) The importance of smooth and rapid targettransfer during a multiple target raid.

(7) The importance of maximum use of visualaircraft recognition means because of limita-tions of available fire control equipment.

d. Inform his crew of the limited engagement timeavailable and the importance of communications.

16

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CHAPTER 3CHARACTERISTICS OF EQUIPMENT

26. Generala. Antiaircraft artillery automatic weapons use a

projectile which must hit the enemy aircraft, or sur-face target, to be effective. The 40-mm gun uses ashell with a supersensitive fuze which bursts on con-tact. If no contact is made as the tracer burns out,the relay ignition charge is ignited detonating thebursting charge of the shell. The caliber .50 ma-chinegun uses API (armor-piercing incendiary) am-munition with and without tracer.

b. Automatic weapons have a flexibility that en-ables them to track aircraft at a high angular rateand shift quickly from one target to another. Thesefactors, plus a high rate of fire, make automaticweapons highly effective against low-flying aircraftat short ranges.

c. The M42 and M16A1, self-propelled AAA (AW),because of their greater mobility, are desirable foruse with combat forces.

27. Ammunitiona. Types. The principal types of ammunition for

the caliber .50 machinegun are API and API-T(armor-piercing incendiary tracer). The 40-mm gunuses high explosive and armor-piercing tracer shot.The tracer element of the caliber .50 ammunitionburns out at ranges of 1,850 or 2,450 yards, depend-ing on the type. The 40-mm high explosive shell

388163 0--56 2 17

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destroys itself at the tracer burn-out point varyingfrom 3,500 to 5,500 yards, depending on the type.

b. Uses. The various types of ammunition areused as follows:

(1) Caliber .50 API-T and API ammunition and40-mm high explosive shells are used againstpersonnel and light materiel.

(2) Caliber .50 API, API-T, and 40-mm armor-piercing ammunition are used against lightlyarmored vehicles, concrete shelters, andsimilar targets.

(3) The tracer element of the caliber .50 and40-mm ammunition are used primarily forobservation of fire.

(4) All types of automatic weapons ammunitionmay be employed against aerial targets.

28. Range Capabilitiesa. Extreme Deterrent Range. The extreme deter-

rent range is the tracer burn-out range of automaticweapons projectiles. At this range, the fire is in-accurate but, if delivered with maximum density,may cause enemy aircraft to take evasive action,break formation, and even abandon their mission.Extreme deterrent ranges of automatic weapons are:

(1) Caliber .50 machineguns: 1,800 to 2,450yards.

(2) 40-mm gun: 3,500 to 5,500 yards.b. Effective Hitting Range. Effective hitting range

is the maximum distance within which hits may beexpected. It depends on tracer observation, but inaddition, is determined by the type of sighting de-vice, lead tolerance, angle of approach, and the aver-age state of training of personnel. The averageeffective hitting ranges are:

18

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(1) Caliber .50 machinegun: 800 yards.(2) 40-mm gun: 1,800 yards.

c. Minimum Midpoint Tracking Range. This isthe shortest midpoint range at which the weapon cantrack a target. It depends on target speed and themaximum tracking rate of the gun mount. Thecaliber .50 machinegun turret mount can track a600-mile-per-hour target at a midpoint range of 300yards. The M42 can track a 600-mile-per-hourtarget at approximately 420 yards midpoint range.

29. Weaponsa. 40-mm Gun. The 40-mm gun may be either

fully automatic or semiautomatic; it can delivershort bursts at a rate of 120 rounds per minute. Itis air-cooled and, if fired at maximum rate, will over-heat after about 100 rounds are fired. Firing mustbe suspended and the barrel changed when it is over-heated. The horizontal range for antiaircraft tacti-cal planning is 1,800 yards.

b. Caliber .50 Machinegun. The individual caliber.50 machinegun fires at a rate of 400 to 600 roundsper minute. Although the effective range is de-pendent upon the gunner's depth perception andtraining, a horizontal range of 800 yards is used fortactical planning purposes. The standard mountfor the caliber .50 machinegun is an electrically op-erated, quadruple gun mount. These quadruplemounts can be traversed and elevated at rates of 80 °

per second by a single operator.

30. Self-Propelled Carriagesa. The twin 40-mm gun motor carriage M42 (fig.

2) has two 40-mm guns mounted coaxially on a fulltrack vehicle.

19

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b. The multiple gun motor carriage M16A1 (fig.3) is a quadruple machinegun mount (M45) installedin a half track vehicle.

31. Towed Mounts and Carriagesa. 40-mm Gun on Carriage M2A3 (fig. 4). The

40-mm gun on carriage M2A3 is used in mobileunits. The time required to emplace the carriagefrom traveling position and commence firing (utiliz-ing the primary means of on-carriage fire control) is1 to 2 minutes.

b. Multiple Machinegun Trailer Mount M55 (fig.5). The multiple machinegun trailer mount is usedin mobile and airborne units. The mount may betowed for short distances but is generally transportedin a 2X-ton truck, or loaded without disassembly inconventional type troop carriers. The mount mustbe emplaced before firing, the time for emplacementrequiring 1 to 2 minutes. The turret in the trailermount is the M45.

32. Fire Control Devicesa. 40-mm Speed Ring Sights (fig. 32). The 40-mm

gun has two metal speed ring sights used as secondarymeans of fire control.

b. M18 Reflex Speed Ring Sight (fig. 33). TheM45 caliber .50 multiple machinegun utilizes theM18 speed ring sight as the only means of firecontrol.

c. Computing Sights M38 and M19A1 (figs. 43 and44). The computing sight is the primary means offire control on the 40-mm gun.

20

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1j

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a

E6

5~ s_

21

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-4

* _ D ~~~~~~~~~sTo

i;

22~~~~~~~~~~~~~~~I-

22

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Io~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

th0

p,

Q9;s

9-uz

23

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-i,

Figure 6. Multiple machinegun trailer mount M55.

24

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CHAPTER 4

RECONNAISSANCE, SELECTION, ANDOCCUPATION OF POSITION

Section I. ANTIAIRCRAFT DEFENSE

33. GeneralSince the AAA (AW) battalion may be given a

variety of missions, for example, air defense, surface,or modifications of these two missions, it is necessaryto develop separate procedures for reconnaissance,selection, and occupation of positions to accomplisheach type of mission.

34. Reconnaissance'a. General. The purpose of reconnaissance is to

obtain accurate information concerning terrain onwhich personnel, vehicles, and weapons will be

operating. The two general classifications of recon-naissance are route and position. Position recon-naissance establishes actual positions on the groundfor location of weapons, vehicles, and commandposts. Route reconnaissance is the selection' ofroutes suitable for moving personnel and equipmentto and from selected positions.

b. Types of Reconnaissance.(1) A2ap reconnaissance. A map reconnaissance

is generally used as a basis for planning aground or aerial reconnaissance. Higherheadquarters normally makes this type of

25

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reconnaissance. Lower headquarters, iftime is available, makes a more detailedground reconnaissance. In a rapidly mov-ing situation, however, there may be littletime available for reconnaissance other thanby map.

(2) Aerial reconnaissance. This type of recon-naissance may be used preceding, simul-taneously with, or in place of, a groundreconnaissance. Aerial reconnaissance isspeedier than ground reconnaissance butit does not provide as detailed informationas ground reconnaissance.

(3) Ground reconnaissance. There is no sub-stitute for ground reconnaissance, whichprovides a detailed examination of theterrain.

c. Time Available. Since time available for re-connaissance may often be very limited, each com-mander must anticipate possible displacements andperform a continuous progressive reconnaissance andstudy of the terrain. Whenever possible, com-manders must allow enough time for subordinatesto complete their reconnaissance during daylighthours.

d. Battalion Reconnaissance. Since AAA (AW)batteries and platoons often operate in fluid situa-tions and are separated by considerable distances,the battalion commander can rarely perform a groundreconnaissance of all fire unit positions. When timeis limited, the battalion commander will decentralizereconnaissance to subordinates and will later con-solidate and organize as time permits. When timedoes permit, however, the following steps, subject to

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variations as the situation demands, are performed.He-

(1) Makes a map reconnaissance to locate allelements.

(2) Decides the exact time for start of troopmovements.

(3) Decides when and how to make groundreconnaissance and who will accompanyhim.

(4) Issues warning orders to subordinates cover-ing-

(a) Enemy and friendly situation.(b) Troop movements desired.(c) Time and place for issue of further orders.(d) Probable route of reconnaissance party.

(5) Performs reconnaissance, and verifies-(a) Sites for AAAIS surveillance radar and

visual observer posts.(b) Location of battalion AAOC.(c) Position of headquarters battery service

elements.(d) Routes to positions.(e) The location of each battery headquarters

and as many fire unit positions as timewill allow.

(6) Returns to assembly point and issues ordersto subordinates for occupation of positions.

e. Battery Reconnaissance.(1) Adequate time. If the battalion commander

makes a complete reconnaissance of all fireunit positions, the battery commander willbe responsible for the details of occupationand make arrangements for having his fireunits directed to positions. If, however,

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the battalion commander does not make aground reconnaissance, the battery com-mander will make a ground reconnaissancebased on the battalion commander's mapreconnaissance. This will determine-

(a) Routes to all positions.(b) Position of each weapon.(c) Alternate positions and dummy positions.(d) Exact location of battery command post,

bivouac area, and truck park.(e) Sectors of fire for each fire unit.

(2) Procedure. Before departing, the batterycommander briefs his executive officer onorders of the battalion commander. If thebattery commander is to return before theelements of the battery start moving, theexecutive officer is informed of the probabletime the battery commander will returnfrom the reconnaissance. If elements ofthe battery start moving before the batterycommander completes his reconnaissance,the executive is given the time of movementfrom the assembly area, the route, andspecial instructions concerning the march.

(3) Limited time. The battery commander mayhave his firing units so widely separatedthat time is not available to make a groundreconnaissance of all his unit positions.In this case, the platoon leaders and NCO(noncommissioned officers) must performthe reconnaissance. The battery com-mander will consolidate the unit positionsif and when time is available.

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f. Platoon Reconnaissance. When enough time isavailable, the platoon leaders accompany the batterycommander on reconnaissance to coordinate sectorsof fire. When time is limited, the platoon leaderswith the fire unit leaders perform the reconnaissanceand select positions in accordance with orders fromthe battery commander. In fast-moving situations,the platoon leader may designate the positions andgeneral layout of the fire units, while the actualground reconnaissance is made by the fire unitleaders just prior to moving into their positions.

35. Selection and Occupationa. Sectors of Fire and Observation.

(1) Each automatic weapons fire unit is assigneda primary and secondary sector of fire.All fire unit crews maintain constant vigi-lance in their primary sectors of fire, regard-less of the sector in which the weapons areactually engaged.

(2) Since target selection and engagement con-trol depend upon visual means, the siteswhich are selected for the weapons mustprovide for maximum observation and unobstructed sectors of fire. Adjacent 40-mmfire units must be sited within 100 to 900yards of each other. Caliber .50 weaponsare sited within mutual support distancesof 100 to 400 yards. The limitation im-posed by tracer observation requires thatfire units be sited at least 100 yards apart.To provide the required concentration offire against aerial targets and insure cover-

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age of the dead area of adjacent weapons,40-mm fire units must be sited not fartherthan 900 yards apart.

b. Level Ground. The ground for emplacing auto-matic weapons should be within 2° of level. Ifnecessary, the selected location should be leveledwithin tolerance using tools available.

c. Cover. Immediately after a position has beenselected and occupied and the fire unit is preparedto engage the enemy, cover is provided for protec-tion of personnel and materiel. Fox holes or slittrenches are dug by all personnel.

d. Occupation. Actual occupation of a position isdirected and supervised by the fire unit leader.Timely arrival and prompt readiness for fire are theprimary considerations. Weapons are emplaced firstand then, as time permits, the positions are improvedby fortification and construction of alternate posi-tions. Dummy positions are constructed as directedby higher headquarters.

Section II. SURFACE MISSION

36. Generala. The methods outlined in this section apply to

all types of surface employment, whether in closesupport of infantry in offense or defense, in defenseagainst mechanized, airborne, guerilla, or infiltrationattacks, or in engagement of naval targets.

b. Since infantry and armored divisions have anorganic AAA (AW) battalion assigned, the divisioncommander may designate the mission of this bat-talion as that of close support of infantry elements,in part or in whole. This AAA (AW) battalion con-

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tains self-propelled weapons, and as such is capableof diversified uses in the close support role. Althoughthe towed 40-mm gun may be used in a surface role,it is limited by its lack of mobility and the lengthof time needed to emplace it.

37. Command, Control, and Coordinationa. When AAA (AW) units are assigned surface

missions, they are normally attached to supportedunits. Antiaircraft artillery automatic weaponscommanders serve as special staff officers of the com-mander of the supported unit and advise these com-manders on the employment of AAA (AW). Anti-aircraft artillery automatic weapons platoon commandposts are located at or near the command post of thesupported unit. The normal role of automaticweapons battery and platoon commanders is to directthe operations of their units. Battery and platoonexecutives serve as liaison officers with supportedunits. Liaison is also established with each com-mitted rifle company. The AAA (AW) unit com-mander provides a noncommissioned officer assistedby a radio operator to advise the rifle companycommander of the capabilities of AAA (AW) and toact as a forward observer.

b. Some of the automatic weapons attached forclose support are given interdiction, harassing, orneutralization fire missions. Other automatic weap-ons may augment the infantry heavy weapons byoverhead fire, and fire through gaps in the friendlylines. Regardless of what mission is given, the sup-port fires must be carefully prepared and coordinatedwith the plans of the attack or defense of the infantryor armor unit commander.

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38. Reconnaissance and Plansa. The automatic weapons platoon leader is re-

sponsible for performing the ground reconnaissancein the surface mission. After being briefed by theinfantry battalion commander as to the general planof action, the amount of fire support desired, theexact location of friendly units and of known andprobable enemy targets such as direct fire weaponsand observation posts, and after studying the mapcarefully, the platoon leader makes a personal groundreconnaissance, attempting to gain the followinginformation:

(1) Primary and secondary firing positions foreach weapon.

(2) Routes to primary and alternate positions.(3) Location of new firing positions to be used

in case of lateral, forward, or rear displace-ments.

(4) Routes to displacement positions.(5) Location of ammunition vehicle parks and

routes of supply.(6) Platoon observation posts.(7) Positions for reinforcement of the main bat-

tle position in the event of an envelopmentor penetration.

(8) Key points in the battalion area essential tothe defense of the area.

(9) Likely avenues of approach of hostileforces.

b. The automatic weapons employment plan forsupport of infantry or armor will be coordinated withthe infantry or armor commander and should include:

(1) Initial positions from which supporting firesare to be delivered. Positions will be in

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the same general area with the organicinfantry support weapons, as far forwardas is consistent with the tactical situation,and with adequate cover.

(2) Plans and routes of displacement.(a) Weapons will be displaced by echelon,

with one-half the weapons in each echelon,if possible.

(b) Select routes affording the most rapiddisplacement, in order to supply con-tinuous fire support.

(3) Ammunition supply points and protectedroutes.

(a) Estimate the amount of ammunitionneeded at the initial position, and dumpthat amount on the ground and replenishsupplies so that weapons may displacewith full basic loads.

(b) Select covered ammunition supply routesand instruct ammunition truck drivers onammunition resupply procedure.

39. Selection and Occupation of Positionsa. The principal factor affecting the selection of

positions in a surface role is complete integrationwith the supported unit's Fire Support Plan. Posi-tions selected for a surface role should-

(1) Assist in the protection of vital terrainfeatures.

(2) Retain essential observation to front andflanks.

(3) Deny the enemy close observation into thebattle position.

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(4) I/ocate positions so as not to interfere withfields of fire of weapons located in the rear.

(5) Take maximum advantage of natural coverand concealment.

(6) Site caliber .50 weapons within 1,000 yardsof possible target and 40-mm weapons within1,500 yards of possible target.

(7) Provide mutual support with infantryweapons and have safety zones to protectagainst firing into friendly positions.

(8) For naval targets, be as close to water levelas possible to take advantage of the flattrajectory.

b. When reconnaissance and selection of positionshas been accomplished and the plan of action ap-proved by the infantry or armor commander, theautomatic weapons are moved to the selected posi-tions. This move must be coordinated with sup-ported units so that motor columns will not interferewith foot troop or tank movements. The moveshould be made at night, if possible, but in any case,with maximum cover and concealment.

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CHAPTER 5COMMUNICATIONS

40. GeneralAntiaircraft artillery automatic weapons com-

munications include all means employed to transmitinformation, intelligence, commands, orders of anoperational control nature, and the means to estab-lish liaison with other units. Due to the importanceof communication to effective operation, every personinvolved must be thoroughly grounded in com-munication operation and maintenance. This isespecially true in the case of the AAA (AW) unitswhich are sometimes widely dispersed or isolated.Primary and alternate means of communicationmust be provided and available for immediate useby all elements of the command. The basic meansof communication available to the automatic weap-ons units include radio, wire, and messenger. Wireis considered to be the more desirable means ofcommunication due to its greater degree of depend-ability. Maximum use should be made of thismeans during static situations. Frequent movementand wide dispersion will often dictate the use ofradio as the means of communication to be employed.The use of radio in the initial stages of an operation,in rapidly moving situations, and in amphibiousoperations will be essential. In many situations,wire and radio will be integrated.

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41. Radioa. The capabilities and limitations of radio equip-

ment must be thoroughly understood by all antiair-craft artillery officers and considered by a commanderwhen plans for radio communications are made.

(1) Capabilities.(a) Radio sets are readily portable, may be

placed in operation quickly, and may beoperated from moving vehicles.

(b) No physical circuit is required betweenstations.

(c) Radio is a readily available means of longrange communication.

(2) Limitations.(a) Radio equipment is complex and fragile.

It requires constant maintenance andintelligent care.

(b) Operating and maintenance personnelrequires specialized individual training.

(c) Radio messages are easily intercepted bythe enemy. Necessary cryptography de-lays transmission.

(d) Radio is subject to enemy jamming andaffords the enemy means of locatingtransmitters, and thereby, commandposts and other installations.

b. In radio nets which supplement wire nets,operators listen on assigned frequencies and do nottransmit unless instructed to do so. In other radionets, operation is normally continuous unless other-wise prescribed.

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42. WireWire communication equipment provided by TOE

is sufficient to install essential command linesbetween command posts. Additional wire to installother wire nets must be drawn from the appropriatesignal supply agency when required. The extent towhich wire communication is installed is governedby the tactical mission of the unit. The wire com-munication net of a unit employed in a static situa-tion should be as complete and extensive as timeand material permit. The wire communication netof a unit employed in a moving situation, wherefrequent changes of position are involved, will belimited.

a. Capabilities.(1) Wire is flexible, reliable, and less subject to

mechanical and electronic failure thanradio.

(2) Wire requires a somewhat lesser degree oftechnical skill to install and maintainthan radio.

(3) Wire communications are less easily inter-cepted than radio.

b. Limitations.(1) Wire requires considerable time, labor,

material, and equipment to install, operate,and maintain.

(2) Wire is subject to failure due to vulnerabilityof long wire lines to bombing, artillery fire,enemy patrols, and damage by vehicles.

43. Radiotelephone Procedurea. Radiotelephone procedure is covered in ACP

125. All officers and enlisted men should be thor-

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oughly familiar with proper radiotelephone procedureand comply strictly with instructions contained inthat publication.

b. Unnecessary and improper transmissions mustbe avoided in order to prevent the enemy from ob-.taining information which may reveal the tacticaldisposition, strength, or movement of friendly forces.Effective transmission security requires constantsupervision by the commander and a high state oftraining on the part of personnel using communica-tion nets.

44. Communication Nets, GeneralCommunication nets required for an AAA (AW)

defense include the following:a. Early Warning Net. This is a one-way wire or

radio net (or both) between the AA teller (a memberof the AA liaison party) in the Air Force Agency andthe early warning plotter at the AAOC. In the fieldarmy, the primary AAOC in the area usually estab-lishes this net.

b. Air Force Liaison Net. This is a two-way wireor radio net (or both) which connects the AA liaisonofficer in the Air Force Agency with the AA defensecommander's representative in the AAOC.

c. Observation Post Net. This is the net establishedfor the transmission of information from the AAAvisual observation posts to the elements of the AAdefense. Due to the complexity of this net, it israrely practical to use wire. This is a two-way netbetween the observation posts and the NCS (netcontrol station) at the AAOC and a one-way net be-tween the observation posts and all other elementsof the defense.

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OPERATES FROM TO FROM COIRMAnOWITH AAOC AOC AAOC OPS IF DEFENSE TO MIGHER

OPERATIONAL CONTROL RADAR rI INTELLIGENCE REPORTING

O S-

(44TRYS PER N T P

(2 PLATS PER BTRY)

(4 PER PLAT) P

OP'S ORGANIC TO AW(4 PER PLAT)

Figure 6. AAA bn (AW) (Mbl), radio nets under seniorAAOC.

d. Radar Reporting Net. This is a two-way wireor radio net (or both) over which radars operating ina surveillance role within the AA defense transmitdata to the AAOC.

e. Intelligence Net. This is a one-way wire orradio net (or both) over which the AAOC dissemi-nates intelligence to the elements of the defense andother interested agencies.

f. Operational Control Net. This is a two-waywire or radio net (or both) over which the AA de-fense commander, or his representative from theAAOC, exercises operational control over the ele-ments of the AA defense.

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g. Command Net. This is a two-way wire or radionet (or both) over which all elements of command forwhich other nets are not established, including ad-ministration, are transmitted. This net is normallyestablished from the administrative headquarters ofthe AA commander and not from the AAOC.

45. Radio Netsa. Mobile Battalion, Under Senior AAOC (fig. 6).

(1) Higher headquarters command net (AM).The battalion operates a radio set in theAM (amplitude modulated) command netof the next higher headquarters. This netmay be a voice or CW (continuous wave)net and is used for command and adminis-trative purposes. This station operates ona frequency assigned by the higher head-quarters concerned.

(2) Battalion command net (AM). The battal-ion command net includes a station at thebattalion headquarters and one at each ofthe firing batteries. The radio at the bat-talion headquarters is the NCS for this net.

(3) Intelligence net (AM). The battalion oper-ations center, each firing battery, and eachautomatic weapons platoon operate a radioreceiver, AN/GRR-5, in this net.

(4) Radar reporting net (AM). The battalionsurveillance radar is-connected to the seniorAAOC by a two-way radio over which in-formation concerning radar pick-ups istransmitted to the AAOC and over whichthe AAOC passes special instructions to thesurveillance radars.

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(5) Observation post net (AM). The battalionoperations center, each of the firing bat-teries, and each fire unit operate a radioreceiver, AN/GRR-5, in this net to receiveOP information direct from the OP.

(6) Operational control net (AM). The bat-talion operations center, each firing battery,and each of the automatic weapons pla-toons operate a two-way radio in this netproviding direct communications betweenthese elements and the AAOC.

b. Self-propelled Battalion, Under Senior AAOC(fig. 7).

(1) Higher headquarters command net (AM).

p

A (ASPB--4 TEAMS) no C IA

A PN/SS BN CD NE10 T(W)

(2 PLATS PER TRT)

(4-PER PLAT) P . T(

(4-PER PLATI

Figure 7. Self-propelled battalion antiaircraft mission, undersenior AAOC.

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The battalion operates a radio set in thecommand net of the next higher headquar-ters. This net may be a voice or CW netand is used for command and administra-tive purposes. This station operates on afrequency assigned by the higher head-quarters concerned.

(2) Battalion command net (FM). The FM(frequency modulated) battalion commandnet includes at least one station at the bat-talion headquarters and one at each of thefiring batteries. This net may includevarious staff officers of the battalion.

(3) Battery command net (FM). The batterycommand net consists of at least one sta-tion at the battery headquarters and oneat each automatic weapons platoon head-quarters.

(4) Platoon command net (FM). The platooncommand net consists of a radio set at theplatoon headquarters and one at each fireunit. (When available frequencies do notpermit operation of separate platoon com-mand nets, these nets may be combinedwith the battery command net and alloperate on the same frequency.)

(5) Intelligence net (AM). The battalion opera-tions center and each firing battery operatea radio receiver in this net.

(6) Radar reporting net (AM). The battalionsurveillance radar is connected to the seniorAAOC by a two-way radio over whichinformation concerning pick-ups is trans-mitted to the AAOC and over which the

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AAOC passes special instructions, as neces-sary to the surveillance radar.

(7) Observation post net (AM). The battalionoperations center and each fire unit operatea radio receiver in this net to receive OPinformation direct from the OP

(8) Operational control net (AM). The battalionoperations center, each firing battery, andeach automatic weapons platoon head-quarters operate a two-way radio in thisnet providing direct communication be-tween these elements and the AAOC.

c. Divisional-Antiaircraft Artillery AutomaticWeapons Battalion. The FM radio equipment of theAA (AW) battalion organic to the division will be

ARTT 4 04* INTEL

C AD t . NOS L A H

aircraft mission radio nets.

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I (4 PER PLA TO.o ) (4 pER WPL& N) O

~~~~I ~ PLAWTOON CO .ANDp fII FIRE DIRECTION NOT

P INF BN K"

P 8AS IO O IICOMp TCO

1F REITN.

s- c .o GRE i i(W"IEN SMN OP'S ARE ED} 40' K A. SRI ErR! co

MA I__TELLISESCE N, T- - AS LAO TO RECA CO

Fi/ture 9. Self-propelled battalion (Infantry Division) surfacemission radio nets.

of the same general type as that used within thedivision. When establishing an AA defense, thedivisional unit will establish essentially the samefacilities for communication as those required forAAOC operation at higher echelons (fig. 8). Whenassigned close support missions, divisional units willgenerally establish communication nets as indicatedin figure 9.

d. Communication with Other Combat Arms. WhenAAA (AW) units are assigned missions which requireclose liaison with other combat arms, such as closesupport missions, radio communication becomes avital problem. If available radio sets are of thesame general type, with overlapping channels, as-signment of operating frequencies in the overlap

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band will permit communications between the AAA(AW) unit and the supported unit. If radio sets ofthe units concerned are not of the same general type,it will be necessary to effect a temporary trade ofradio sets between units so that each unit has therequired number of radio sets.

46. Wire NetsFigure 10 shows a type wire net for an AAA bat-

talion (AW), nondivisional, in an AA role. Figure11 shows a type wire net for a divisional type AAAbattalion (AW) in a ground support role. Becauseof the limited amount of wire and wire equipmentavailable, every effort must be made by all com-manders to conserve wire. The need for wire com-munication to each installation must be carefully

AAOG aAOA

,:O~. AND rCo ST RRIP

ST, T ...

STRIP NAL

IE R CLIC TO C I N

I(4 PR PLTOON) (4 KIER PLTOON)

Figure 10. AAA Bn. (AW) wire nets, AA mission, underSenior AAOC.

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considered. Command posts are located as near aspossible to subordinate units in order to reduce thelength of wire circuits. When no provision is madefor wire communication personnel within the battery,personnel from the fire units must- be trained toestablish, operate, and maintain wire communicationas well as radio communication.

Ex R THER BTRYS IDENT

AS RE IRED

(4 PER PLATOON) (4 PER PLATOON) (4 PER PLATOON) (4 PER PLATOON)

Figure t1. AAA Bn (AW) wire nets, surface mission (Div).

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CHAPTER 6

OBSERVATION AND EARLY WARNING

47. Warning SystemAdequate early warning information of the ap-

proach of aircraft is a prime requirement for theeffective employment of AAA (AW). Adequateearly warning will provide enough time for thepersonnel and equipment of the unit to be in therequired condition of readiness to engage a hostileaircraft at the maximum effective range of theweapon.

a. Conditions of Air Defense Warning. The con-dition of air defense warning is announced to thesenior AAOC by the air defense commander. Theconditions of warning are:

(1) Warning Red. Hostile air attack imminent.(2) Warning Yellow. Hostile air attack prob-

able.(3) Warning White. Attack by hostile aircraft

improbable.

b. Conditions of Readiness. The condition ofreadiness will be directed by the AAOC, but anyfire unit may assume a higher condition of readinessif conditions warrant. All units in forward areasnormally maintain one of the following conditions ofreadiness:

(1) Battle stations. With a Warning Red, all

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equipment is fully manned ready for im-mediate effective delivery of fire.

(2) Standby. With a Warning Yellow, weaponsare partially manned, communication netsand command posts fully manned. Fireunits are prepared to assume battle stationswithin a time limit prescribed by theAAOC.

(3) Secure. With a Warning White, commandposts and communications are partiallymanned, surveillance and guard personnelare on duty. with all other personnel readyto assume battle stations within a timelimit prescribed by the AAOC.

c. Action Status. Action status is the degree of en-gagement control imposed by the air defense com-mander through the AAOC on fire units in air de-fense. The terms are:

(1) Guns Free. Fire at any aircraft not identi-fied as friendly.

(2) Guns Tight. Fire only at aircraft identifiedas hostile.

(3) Hold Fire. Do not open fire. Cease fire.

48. Functions of AAOC and AAAISAntiaircraft artillery information service properly

employed, will furnish information on the activityof aircraft within a limited zone of surveillance.The AAAIS is not capable of providing warningearly enough to eliminate the necessity for maintain-ing a constant condition of alert on the weapons.For detailed coverage of the AAOC and AAAIS inthe zone of interior, communications zone, and com-bat zone, see FM 44-1 and FM 44-8.

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49. Aircraft IdentificationA comprehensive means of positive recognition

and identification of aircraft is essential. Decisionsas to conditions of readiness (secure, standby, andbattle stations) must be based upon timely and ac-curate information as to the friendly or hostile natureof aircraft which have been detected. For detailedcoverage of recognition and identification, see FM30-30.

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CHAPTER 7

SECURITY AND PROTECTION

50. GeneralAll AAA (AW) commanders must consider local

defense capabilities while selecting fire unit positionsand command posts. Automatic weapons positionsare often widely separated and isolated, making itvitally important to establish effective local securityfor each position.

51. Passive DefenseA passive defense is designed without the expecta-

tion of taking the initiative or utilizing actionweapons. It is based on concealment, dispersion,deception, and protection.

a. Cover and Concealment. The mission and timelimitation with automatic weapons may restrict theamount of cover and concealment used. Time per-mitting, slit trenches, fortifications, shelters, and dug-outs should be constructed (FM 5-15).

b. Dispersion. With automatic weapons dispersedin an antiaircraft defense, the problem of localsecurity is increased. However, if the mission isprimarily ground defense, the fire units should beconcentrated in one locality to provide for moreeffective local security. Local security must be co-ordinated with adjacent or defended units.

c. Alternate and Dummy Positions. When aprimary unit position becomes untenable or unsuit-

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able for further occupation, the unit should be movedto an alternate position. Subject to the direction ofhigher headquarters, dummy positions may be pre-pared to deceive the enemy. Dummy positions arelaid out a safe distance from all friendly troops andinstallations, and partially concealed to make themmore realistic.

d. Blackout and Night Movement. Blackout dis-cipline should be strictly enforced with all units incombat. An installation may be concealed duringthe day, but revealed at night because of the slightestlight showing. Entrances to command post tents orshelters must have light locks and be checked fre-quently for light leaks. When a unit moves, it shouldbe done at night with blackout lights.

e. Radio Silence. Radio silence is imposed to denythe enemy the opportunity of traffic analysis. Move-ments of units can be traced by listening to trans-missions, even though the messages may be valueless.Communication during radio silence may be carriedon by wire, messenger, or visual means.

f. Warning Signals. In combat, observation teamswarn of enemy attack. Warning signals should bestandardized so they may be understood by allfriendly units. Different signals should be devisedto indicate each type of attack.

g. Defilade. To hinder enemy observation, andprovide protection of materiel and personnel, posi-tions of AAA (AW) in a ground role should be placedso as to be shielded from direct fire of enemy artillery.

52. Local Securitya. General. Local security is provided by the

effective use of personnel and materiel available to a

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unit. It includes all the measures necessary for pro-tection against local attack. Local security plansand procedures must be closely coordinated withsupported and adjacent units and conform with thearea defense plan and area damage control plan.

b. Type of Attack. Antiaircraft units may expectany of the following types of attack:

(1) Infiltration.(2) General breakthrough.(3) Reconnaissance in force.(4) Mechanized thrust.(5) Parachutist.(6) Glider.(7) Guerilla.

c. Selection of Position. In selecting the AAposition, the following factors are considered inattaining local security:

(1) Fields of fire for ground targets.(2) Routes of approach to and from the position.(3) Observation.(4) Tactical advantage of ground.(5) Camouflage.

d. Organization of Position. The defended areashould be kept as small as possible, with the primaryarmament and available equipment within the per-imeter defense. Machineguns and rifles are sited toform bands of interlocking fire around the perimeterto prevent enemy penetration.

e. Materiel. Weapons and equipment normallycontained within an automatic weapons unit willbe used for local security as follows:

(1) Machineguns. Machineguns are the pri-mary ground defense weapons. They are

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sited for interlocking, grazing fire throughunobstructed fire lanes which are preparedon the far side of the wire or other obstacles.Multiple machine guns should be firedtwo barrels at a time only, and in shortbursts, to prevent overheating. Alternatemachinegun positions should be prepared.

(2) 40-mm guns. The 40-mm gun, utilizinghigh explosive ammunition, is particularlyvaluable against enemy personnel in woodedor underbrush areas where air bursts canbe obtained.

(3) Hand grenades. The added value of handgrenades is that they do not reveal thefriendly position to the enemy.

(4) Mines and booby traps. Mines and boobytraps, in addition to being effective inafflicting casualties on the enemy, alsoserve as warning devices. Mines must belaid in bands far enough outside the de-fended area to minimize the danger ofinjuring friendly personnel. Before minesare laid, clearance must be obtained fromthe engineer of the headquarters to whichthe automatic weapons unit is attachedand also from adjacent units. See FM20-32 for mine laying information.

(5) Barbed wire. Wire delays the enemy andprovides a warning to the defended area.Wire should be strung from 50 to 100yards from equipment. Noise-making de-vices may be attached to the wire. Detailson wire obstacle construction are containedin FM 5-15.

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(6) Individual arms. Wire and other obstaclesshould be covered by rifle, carbine, andmachine gun fire from foxhole positions..Small arms positions should provide flank-ing and crossfire. Riflemen should beplaced where they can provide protectionfor machineguns.

(7) Rocket launchers. Rocket launchers arelocated to cover probable avenues of ap-proach in forward areas to provide for anti-mechanized defense. Launchers with super-sensitive detonating ammunition areeffective against enemy personnel.

(8) Rifle grenades. Rifle grenades provide alonger range effect against enemy person-nel and lightly armored vehicles than doordinary hand grenades.

f.'Standing Operating Procedure. An SOP forlocal security is necessary for every unit. It mustbe coordinated with adjacent higher, and lower units,and be thoroughly understood by every individual.It will include:

(1) A plan for establishing and executing imme-diate local security upon occupation ofposition.

(2) A system of marking restricted areas, in-cluding mines and booby traps.

(3) The procedure for submitting mine andbooby trap reports.

(4) Alert signals.(5) The organization of a mobile reserve to

support units needing aid.(6) A system of challenges, passwords, and

replies.

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(7) An alert plan for manning primary equip-ment for ground defense.

(8) The establishment of ground observationand listening posts.

(9) Priorities for opening fire on ground targets.(10) A plan for individual weapon ammunition

supply and reserve.(11) A plan for defense against CBR attack.

g. The Local Security Plan. The local securityplan must be simple and flexible. It makes provisionfor establishing:

(1) An all-around perimeter defense.(2) Sites for weapons.(3) Sectors of fire for all weapons.(4) Guards and listening posts.(5) Guard details and orders.(6) Booby trap and mine locations.(7) Alert stations of personnel.(8) Procedure in the event of perimeter pene-

tration.(9) Location of obstacles.(10) Location of sleeping stations.(11) Location and type of foxholes.(12) Restricted areas.(13) Night movement regulations.(14) Firing lane preparation.(15) Methods of communication.(16) CBR defense.(17) Chronological order of work to be done.

h. Conduct of Defense. In most cases AAA (AW)fire units are isolated and therefore must defendthemselves. This presents a special problem be-cause manpower is limited. At least one man mustbe on the alert at all times. When an infiltration

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v\\ \

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\\ \I5

Figure 12. Perimeter defense in daytime.

becomes likely, men located on the perimeter remainalert and must conduct the defense with handgrenades until the enemy is definitely located orpenetrates the perimeter. Ordinarily primary weap-ons do not fire until grenades and small arms failto halt the penetration. If units are close enoughtogether, supporting and flanking fire should beplanned (fig. 12). At night when there is a threatof ground attack, weapons on the outer gun ring ofthe defense should be moved in and placed on the500-yard ring. Positions should then be organizedas strong points for local security (fig. 13).

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N'

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, \,\.A \\ ' A"

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Figure 13. Perimeter defense at night.

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CHAPTER 8

LOGISTICS

Secion 1. SUPPLY AND EVACUATION53. General-Classes of Supply

a. General. General supply procedures and defi-nitions are contained in FM 100-10 and FM 101-10.

b. Class I (Rations). Class I supplies consist ofthose articles which are consumed by personnel oranimals at an approximately uniform rate, regardlessof local changes in combat or terrain conditions.Rations are picked up daily by the battalion supplysection. Issue is based on the daily battalion con-solidated report of actual strength.

c. Class II (Supplies and Equipment Prescribedby TOE or TA). Battalion supply consolidatesclass II supply requisitions and forwards themthrough appropriate supply channels.

d. Class III (Petroleum Products). These suppliesconsist of fuels and lubricants used for all purposesexcept the operation of aircraft and flame throwers.Class III supplies are characterized by reasonablyuniform demands, as in the case of class I supplies.They are, however, subject to sudden peak loadsbased on the tactical situation; they present atonnage, transportation, and control problem. Solidfuels are the responsibility of the engineers. Quarter-master handles all other class III items.

e. Class IV (Miscellaneous Unclassified Articles).Class IV supplies are those for which allowances are

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not prescribed or are not otherwise classified. Thesesupplies are issued by item; automatic supply israre except in the case of certain medical items.

f. Class V (Ammunition). Class V supply in-cludes both ordnance and chemical ammunitionitems. Flamethrower fuel and those demolitionsand explosives which are closely allied with engineeractivities are included in class V supply.

54. Supply Agenciesa. Antiaircraft artillery automatic weapons bat-

talions have the necessary personnel and trans-portation to draw and deliver all classes of supply.Antiaircraft artillery groups do not function as asupply agency except for allocating critical suppliesor ammunition.

b. Requisitions for supplies are submitted bybatteries to the battalion supply officer, who con-solidates and forwards them through appropriatesupply channels.

c. When requisitioned supplies become available,the battalion is notified. Instructions concerningdrawing and distributing supplies are normallypublished by higher headquarters. The battalionsupply section issues and the batteries pick up theavailable supplies.

d. When AAA (AW) batteries are attached toother units, they will be supplied by the unit towhich they are attached.

55. Airborne Suppliesa. The organic tactical loads of airborne units

include an initial supply, or basic load, of ammuni-tion. All other supplies carried by the airborne unit

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are limited and will last for a short time only. Per-sonnel must be trained to conserve all supplies,particularly during the earlier stages of a missionwhen resupply is very difficult.

b. Supply of airborne units follows normal pro-cedures, except that supplies for the airborne aretransported by air until ground units have effected ajunction with airborne troops.

56. Medical Agencies and Evacuationa. For complete information on evacuation and

medical agencies, see FM 100-10, FM 8-5, and FM8-10.

b. The AAA (AW) battalion may or may not haveattached medical personnel depending on the assign-ment, mission, and tactical situation. The medical de-tachment is an integral part of the battalion, at-tached for command, administration, and supply.Personnel of the detachment establish an aid stationat battalion headquarters, with an aid man attachedto each battery or platoon for first aid. Casualtiesare evacuated through the battalion or nearest aidstation and from there as directed by higher head-quarters.

Section II. TRANSPORTATION

57. Organic TransportationThe current TOE shows the transportation avail-

able to each type of unit. Mobile units normallyhave adequate transportation to move all equipmentand personnel at the same time. Because of thelimited number of cargo trucks in the self-propelledbattalion, their allocation for use requires careful

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planning. The airborne battalion has the greatestproblem because of limited organic transportation.

58. Mobility and Securitya. The mobility of an AAA (AW) unit depends

largely on carefully prepared loading plans. In self-propelled and airborne units, each weapons mountmust carry its own personnel and allied equipment.Platoon, battery, and battalion headquarters musthave stringent loading plans because of the limitednumber of vehicles available.

b. During all motor movements, convoys should beprotected against enemy air and guerilla attacks.By interspersing self-propelled weapons and manningother organizational weapons along the march col-umn, a convoy will be assured of maximum protec-tion against surprise attack.

c. Detailed information applicable to maintenance,operation, and security of motor transportation isfound in FM 25-10.

Section III. MESSING

59. ResponsibilityDue to the widely scattered positions of automatic

weapons in a normal antiaircraft mission, the prob-lem of messing becomes an acute one. The solutionof the problem rests with the commanding officer.

60. Combat MessingWhen a fire unit is located near another installa-

tion, arrangements should be made to have the anti-aircraft troops mess with that installation. If noinstallation is nearby, food must be prepared by thebattery or battalion mess and transported in insu-

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lated containers to the gun positions or prepared atthe fire unit; there are so many disadvantages to thelast arrangement, however, that every effort shouldbe made to have personnel mess with an adjacentinstallation.

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PART TWOGUNNERY AND FIRE CONTROL DEVICES

- CHAPTER 9ANTIAIRCRAFT ARTILLERY (AUTOMATIC

WEAPONS) GUNNERY PROBLEM

Section I. INTRODUCTION

61. Generala. A knowledge of the basic AAA (AW) gunnery

problem is essential for a study of the sighting devicesused with AAA (AW). Since these sighting devicesare utilized on highly mobile weapons, and sincethese weapons are used in the defense of low-flying,bard hitting enemy aircraft, they are not expectedto have round-for-round accuracy. Rather, theaccuracy depends on the skill, speed, and knowledgeof personnel operating them. It is therefore neces-sary, in training these personnel, to have a thoroughunderstanding of the working parts of these devices,and the role those parts have in the overall solutionof the gunnery problem.

b. Basically, the LAAA (AW) gunnery problem isto locate a point in space ahead of a target and tohit it. LAA (AW) sighting devices attempt to solvethe problem with fixed assumptions. It is assumed,first, that the target is flying a straight course duringengagement. Second, the target is assumed to beflying at a constant speed. These assumptions arelogical due to the short engagement ranges of under2,000 yards and the inability of modern high-speedtargets to maneuver within a very short period of

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time. The third assumption is that the closest thetarget will come to the gun during its flight is afixed distance or a fixed midpoint slant range. Asexplained in appendix III, variations in range effectthe problem of correct lead very slightly short of1,500 yards slant range.

62. Slant Plane ConceptTo facilitate the understanding of the AAA (AW)

problem and the sighting devices used in the solution,a geometric approach has been developed. This isknown as the slant plane concept. The future posi-tion of the target is located by reducing the probleminto one imaginary tilted surface, or slant plane,containing the firing weapon, the present positionof the target, and future position of the target. Inthis mathematical solution, the weapon and targetpositions are reduced to points. (In the practicalsolution and analysis of the problem, the pointrepresenting the target reverts to its original shape,allowing for a small margin for error.) The slantplane concept is a simplified approach to the gun-nery problem which places the single lead angle inan imaginary plane surface. With this accomplished,it remains only to apply superelevation. In anti-aircraft automatic weapons this is a very smallfactor because of the high muzzle velocity and shorteffective range of the weapon.

Section II. ELEMENTS OF DATA

63. GeneralTo present this gunnery problem, it is necessary

to name and define certain geometric plane surfaces,points, lines, and angles used in the problem.

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64. Planesa. General. By definition, a geometric plane is an

imaginary flat surface of infinite dimensions, and isestablished among other conditions, by a straightline and a point not on that line, or by three pointsnot in a straight line.

b. Slant Plane. The slant plane is that geometricplane established by the target course line and thepintle center of the gun. The target course line forpractical purposes is a straight line established byextending the longitudinal axis of the target fuselageto infinity. The pintle center of the gun is thatpoint around which the gun bore moves laterallyand vertically. As long as the target course linedoes not pass through the pintle center of the gun,a geometric plane surface exists and is called theslant plane (fig. 14).

c. Horizontal Plane. The horizontal plane is thatplane established by the pintle center of the gun andall imaginary points at that same elevation, dis-regarding the curvature of the earth (fig. 14).

65. Points (fig. 15)a. G. Point G is the gun and is defined as the

pintle center of the gun.b. To (T sub o). Point To is the present position

(observed position) of the target and is defined asthe location of center of mass of the target themoment a round is assumed to be fired.

c. T, (T sub p). Point T, is the future position(predicted position) and is defined as the point onthe course line where the assumed round, if correctlyaimed, will intersect the center of mass of the target.

d. Tm (T sub m). Point Tm is midpoint and is

388163 0-56 5 65

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defined as that point on the course line at minimumslant range from the gun.

66. Lines (fig. 15)a. Do (D sub o). The line Do is present slant

range and is defined as the straight line distance inyards between the gun and the present position.

b. D, (D sub p). The line D, is future slant rangeand is defined as the straight line distance in yardsbetween the gun and the future position.

c. Dm (D sub m). The line Dm is midpoint slantrange and is defined as the straight line distance inyards between the gun and midpoint.

d. Target Course Lines (fig. 16). In any discussionof AA (AW) gunnery, the attitude of the targetcourse line in space is of prime importance. Todescribe these different attitudes, target courses arenamed according to the altitude from the horizontalplane and the direction of flight in respect to the gun.Every target course will be described by two words;one describing altitude and the other describingdirection.

(1) Level. A level course is formed by a targetflying at a constant altitude.

(2) Climbing. A climbing course is formed by atarget flying at increasing altitude.

(3) Diving. A diving course is formed by a tar-get flying at decreasing altitude.

(4) Incoming. An incoming course is formed bythe target flying toward a vertical lineerected through the pintle center of the gun,perpendicular to the horizontal plane.

(5) Outgoing. An outgoing course is formed by atarget flying directly away from a vertical

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line erected through the pintle center of thegun, perpendicular to the hori7ontal plane.

(6) Crossing. A crossing course is formed whenthe target course line does not pass directlyover the gun.

(7) Directly-at-the-gun. A directly-at-the-guncourse is formed when the target is flyingdirectly toward the pintle center of the gun.

e. By combining the above names, any course canbe described; for example, "Incoming Diving","Crossing Level", "Climbing Outgoing" or "DivingDirectly-at-the-gun."

f. Every target course line can be divided, for gun-nery purposes, into two portions called legs. Theapproaching leg is that portion of the target courseline along which the target is flying toward midpoint.The receding leg is that portion of the target courseline along which the target is flying away from mid-point.

g. Vt, (V small t sub p). The line Vt, is targettravel distance and is defined as the straight line dis-tance in yards from the present position to the futureposition of the target. The letter V is the targetspeed (velocity) in yards per second along the courseline. The letter t is the time of flight in seconds of theprojectile assumed to be fired. The subscript pdesignates future position. Vt,, then, has the valuein yards of the speed of the target (in yards persecond) multiplied by the time of flight of theprojectile (in seconds) from the gun to the futureposition.

67. Angles (fig. 15)a. Eo (E sub o). The angle E, is present angular

height and is defined as the vertical angle between

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the line of present slant range and the horizontalplane.

b. E, (E sub p). The angle E, is future angularheight and is defined as the vertical angle betweenthe line of future slant range and the horizontal plane.

c. Em (E sub m). The angle Em is midpoint angu-lar height and is defined as the vertical angle betweenthe line of midpoint slant range and the horizontalplane.

d. E, (E sub s). The angle E, is slant plane angu-lar height and is defined as the vertical angle betweenthe slant plane and horizontal plane measured per-pendicular to their line of intersection.

e. Angular Height Variations.(1) ES, the slant plane angular height, cannot

vary with any single target course line,because the position of one course line isfixed in space, just as the gun is at a fixedpoint.

(2) Eo and EP, present angular height and futureangular height, will both change in value assuccessive rounds are assumed to be firedalong a target course line, provided thattarget course line does not lie in the-hori-zontal plane. On level courses, Eo and E,increase to midpoint and decrease there-after. On climbing and diving courses theyincrease to a point other than midpointwhere angular height to that point is equalto slant plane angular height and decreasethereafter. This point is located on theapproaching leg of a diving course and onthe receding leg of a climbing course.

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f. d, (Phi sub s). The angle b, is superelevationand is defined as the vertical angle required to elevatethe gun bore above the line of future slant range, inorder to overcome the effect of curvature of trajectorycaused by gravity. This angle varies inversely withthe elevation of the gun bore and directly with rangeto the target (future slant range).

g. 0 (Phi). The angle 0 is quadrant elevation andis defined as the vertical angle between the axis ofthe gun bore and the horizontal plane.

h. a (Alpha). The angle a is the angle of approachand is defined as the angle formed by To, T,, and Gwith the apex at T,. This angle increases along agiven course line as successive rounds are assumedto be fired and it varies, theoretically, from 0° to1800. It always lies in the slant plane.

i. LR (L sub R). The angle LR is the required leadangle and is defined as the mathematically correctlead angle between the lines of present slant rangeand future slant range. This is a slant plane angle.

j. La (L sub G). The angle La is the generatedlead angle and is defined as the angle between thetracker's line of sight and the axis of the gun bore(disregarding superelevation). The tracker's line ofsight is a line projected from the tracker's eyethrough, or along, a sighting device. The axis ofthe gun bore (disregarding superelevation) is animaginary line along which the axis of the gun borewould lie if the angle of superelevation were not setin. The generated lead angle and required leadangle are two distinctly separate angles. Therequired lead is a mathematically correct lead. Thegenerated lead is the lead which actually exists on

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the gun. The problem, therefore, is to make thegenerated lead coincide with the required lead.

Section III. SOLUTION OF THE PROBLEM

68. GeneralWith certain mathematically fixed points, lines,

and angles established in and between the slant andhorizontal planes, the AAA (AW) gunnery problemcan now be solved. In conjunction with the mathe-matical solution to the problem, the practical andmechanical solution must also be explained. Theproblem of obtaining a hit is reduced to two basicrequirements, line and lead. A set of four conditionsor steps called links of the gunnery chain exist which,if collectively satisfied, will accomplish the tworequirements.

69. Gunnery Chaina. Link I. To establish and maintain the tracker's

line of sight on center of mass of the target. Thetracker's line of sight has been defined as a line fromthe tracker's eye through, or along, a sighting device.Link I, then, is to make the tracker's line of sight liealong the line of Do, present slant range.

b. Link II. To establish the axis of the gun bore(disregarding superelevation) in the slant plane.With antiaircraft artillery automatic weapons, super-elevation is mechanically applied. It is thereforenecessary to stipulate, in academic definitions, thatthe angular height of the axis of the gun bore doesnot contain additional angle of superelevation.

c. Link III. To establish the correct amount oflead. This is to make the generated lead angle,LG, equal to the required lead angle, LR, or, having

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established links I and II, to make the axis of thegun bore (disregarding superelevation), lie along theline of future slant range, D,.

d. Link IV. To establish the correct amount ofsuperelevation. With the axis of the gun bore (dis-regarding superelevation) lying along D,, the laststep to obtain a hit is to elevate the gun bore a smallamount necessary to overcome curvature of trajec-tory caused by gravity.

70. Requirements for a Hita. General. It can be seen that the men who aim

and fire the gun would have little time to establisheach link of the gunnery chain separately. Theirimmediate problem, while firing, is therefore reducedto two requirements for a hit. These are line andlead.

b. Line. This requirement is satisfied if the pro-jectile is made to intersect the target course linewithin tolerance. In the line tolerance, a margin forerror is introduced by the fact that the projectileneed not intersect the narrow line of the projectedlongitudinal axis of the target fuselage in order tobe effective. Intersecting the bottom or top of thefuselage is a hit. By definition, the line tolerance isone-half the angle subtended at the gun by thediameter of the fuselage of the target. The amountof this line tolerance increases with the diameter ofthe target fuselage and decreases with increasingrange (D,) to the target (fig. 17).

c. Lead. This requirement is satisfied, after lineis obtained, when the projectile is made to intersectthe target.

(1) Lead tolerance. Again, a margin for error is

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0. SLANT-PLANE VIEW, CROSSING COURSE.

INCOMING COURSE

CROSSING COURSES

DI AMETER OF FUSELAGE

LINE TOLERANCE

G b. CROSS- SECTIONAL VIEW.Figure 17. Line tolerance.

introduced. The projectile need not hit thecenter of mass of the target to be effective.An intersection with the nose or tail is

classified as a hit. By definition, the leadtolerance is one-half the angle subtended atthe gun by the length of the target fuselage.The amount of this lead tolerance increaseswith the length of the target fuselage, de-

creases with greater range (Dp) to the tar-get, and increases with the sine of the angleof approach to minimum slant range anddecreases thereafter (fig. 18 and app. III).

(2) Mathematical solution ql lead angles. Tofully understand the lead problem, it is

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LEADTOLERANCE

LRT

Figure 18. Lead tolerance.

necessary to have a working knowledge oftrigonometry. In figure 15, the trianglesin the slant plane are formed by the gun(G), the target's present position (To),future position (T,), and midpoint (Tm).These points are mathematically locatedwhen a target is flying a certain courseand a particular round is assumed to befired. The mathematical problem is todetermine the magnitude of the angle LR,the lead angle required to hit the target.By applying the law of sines to the triangle

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GToT,, the following proportion is found:sin LR sin a

Vt, DVSolving the proportion for sin LR, the result

i VtpXsin ais: sin L= sin a Since antiaircraft

automatic weapons have a high muzzlevelocity, and are effective at short ranges,t, may be considered a function of Dr, per-mitting the combination of values for t,

and D, into the factor tp or the rangeDp

factor. Thus, the required lead equation

emerges in its final form: sin LR=(V) (P )(sin a). It can be seen by a completemathematical analysis of this equation(app. III) that the amount of the requiredlead angle will increase with the speed ofthe target and the angle of approach tominimum range, but will change veryslightly with range variations within effec-tive ranges of antiaircraft automaticweapons.

Section IV. GENERAL APPLICATION ANDANALYSIS OF PROBLEM

71. GeneralWith a knowledge of the mathematical solution to

the gunnery problem, the officer supervising firingpractice can analyze errors, and apply corrections infiring, by utilizing the links of the gunnery chain.In the critique of a particular firing course, each

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round must be sensed for line and lead. It is pos-sible to do this through tracer observation, which isexplained in chapter 10. The officer conductingthe critique will then have line information; whethereach round is High, Low, or On line within the toler-ance, and lead information; whether each round isAstern, Ahead, or On in lead within tolerance. Withthis information recorded, the officer conducting thecritique can analyze the problem with the tools athand, the links of the gunnery chain, applying themfirst to line, then to lead.

72. LineThe supervising officer must realize that line shots

must be obtained before corrections for lead (by theman on the gun) can be made. This is emphasizedin Tracer Observation (ch. 10). He must alsorealize that obtaining line shots is as difficult, ifnot more so, than establishing correct lead, becauseof the smaller line tolerance provided by the shape ofthe target. The average AAA (AW) target fuselageis approximately 2 yards wide, or about 1 yardeither way from the center. This 1 yard producesthe line tolerance and, at a range of 1,000 yards fromthe gun, would subtend 1 mil, a very small margin forerror. In addition, the line requirement must besatisfied, on crossing courses, by manipulating threelinks of the gunnery chain.

a. Link I. The tracker's line of sight must bekept on the target, and if possible the center of mass,at all times. The sighting device uses this line asthe basic reference for its solution to the problem.Since automatic tracking devices are not available toAAA (AW), the physical and mental skills of the gun

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crew must be highly developed. Constant trackingpractice is just as important to AAA (AW) accuracyas physical training is to the athlete. Techniques oftracking must be thoroughly covered in AA (NW)training, and even a highly trained tracker mustcontinue practicing daily to maintain tracking skill.

b. Link II. Point the axis of the gun bore (dis-regarding superelevation) ahead of the target alongthe target course line. With the tracker's line ofsight established, the axis of the gun bore (disre-garding superelevation) is moved separately fromthe tracker's line of sight until it lies ahead of thetarget, pointing at the target course line, or lying inthe slant plane. This operation is accomplished bymanipulating the sighting device, or by the trackercarrying the target at a certain attitude in his sight-ing device. It again requires physical skill andtechnique. If link II is in error only a mil or twothe round fired will be off line. The combinederrors in link I and link II must be no greater than aaverage of 1 mil in one direction in order to obtain aline shot.

c. Link III. Since this link considers only theangular displacement between the tracker's line ofsight and the axis of the gun bore (disregarding super-elevation), an error in this link would merely placethe round at some other point along the course line.Link III has no bearing on the line requirement.

d. Link IV. Superelevation in light AA (AW) isestablished automatically by mechanical linkagesand cams when elevating or depressing the gun tube,or by setting it into the sighting device during orien-tation. This link, however, is critical to the linerequirement on crossing courses. With links I and II

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established correctly, an error in superelevation ofone or two mils will cause the projectile to passabove or below the target. Again, the combinederrors in links I, II, and IV on crossing courses mustbe no greater than the average 1 mil in one directionin order to obtain a line shot. For incoming or out-going courses, link IV will have no bearing on linebecause the angle of superelevation will be in theslant plane; E,=90°.

e. Application.(1) In summarizing the role of the links of the

gunnery chain, links I, II, and IV establishthe line requirement for crossing courses.If all of these links are satisfied within theline tolerance, line shots will result. How-ever, it is possible for a link to be establishedincorrectly and be compensated for by errorsin the opposite direction in the remaininglinks, resulting in line shots. The factremains, however, that there can be no hitswithout line shots.

(2) On the firing range the supervising officerwill set up a system for determining firingerrors and correcting them after eachweapon fires a course. For line performance,the tracers must be observed from a posi-tion in the immediate vicinity of the firingweapon. Sensings for line will be recordedby the observer, and a critique procedureformulated. A suggested procedure is asfollows:

(a) Fire and observe the results.(b) Question the gun crew. What did each

crew member do during the firing?

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(c) Analyze the facts obtained in the first twosteps, and take positive corrective action.

(3) With a thorough knowledge of how the sight-ing device solves the problem, the gunnerytroubles for any given firing course cangenerally be diagnosed by observation andquestions. Each sighting device has alever, knob, or handwheel, or the operatoris provided with a rule or procedure ofengagement, designed to permit properadjustments for line performance. Men onthe gun will seldom be able to diagnose theerrors they have made. The observer(critiquing officer) behind the gun willexperience difficulty in attributing the errorsto any one individual, but he may be ableto determine the cause of error by analyzingthe links of the gunnery chain and therebymake accurate corrections in gunneryprocedure.

73. LeadTargets normally engaged by AAA (AW) average

16 yards in length or about 8 yards either way fromcenter of mass. This 8 yards provides the averagelead tolerance which, at a midpoint slant range of1,000 yards from the gun is 8 mils, a greater marginfor error than in the line requirement. However,the problem of satisfying the lead requirement de-pends on at least two links of the gunnery chain.For incoming and outgoing courses, three links areinvolved.

a. Link I. Just as in the solution of line, thetracker's line of sight is the basic reference line in

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the lead solution. Again, the tracker's line of sightmust be kept as close to center of mass of the targetas possible. Tracking the nose of the target, forinstance, would allow no margin for error in frontof the target. It follows, then, that training oftrackers is just as important in the lead requirementas in establishing line.

b. Link II. Link II is of no importance to leadsince it is strictly a step in placing the axis of thegun bore (disregarding superelevation) in the slantplane.

c. Link III. In order to establish the correctlead, it is necessary to make the lead angle generatedon the gun equal to the mathematically correctrequired lead angle, within tolerance. Since AAA(AW) sighting devices are constructed with theassumption that the target is at a constant or fixedslant range, the error provided by this assumptioncauses rounds fired at extreme ranges to pass asternof the target (app. III). However, this error isabsorbed by the lead tolerance within effective rangesof the weapon. The fact that the sight is producingcorrect lead within tolerance is called a flythrough.The AA (AW) sighting device is producing satis-factory lead results when one or two flythroughs ona firing course are obtained. Flythrough timeinterval is the total time during which fiythroughsoccur during any one firing course. It must beunderstood, however, that these sighting devices donot automatically produce correct leads or fly-throughs. Their accuracy depends on the skill ofthe sight operator in estimating the correct lead.Again, human skill and training are essential.

d. Link IV. Since superelevation is a vertical

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angle, it is of significance to the lead requirementonly if a target is flying an incoming or outgoingcourse, or if the slant plane angular height is 90° .

Normally, errors in superelevation are easily absorbedin the lead tolerance. However, when added toother errors produced by links I and III, the super-elevation error might cause the lead to be too greator too small.

e. Application.(1) Summarizing the role of each link of the

gunnery chain in establishing the lead re-quirement, links I and III are contributingfactors for all courses, with link IV playinga small part during incoming and outgoingcourses. If all these links are collectivelysatisfied within the lead tolerance, a hitwill result, assuming correct line. How-ever, errors in individual links may add toeach other to produce too great or too smalla lead, or may offset each other andproduce hits.

(2) On the firing range, just as in line perform-ance, the supervising officer will set up asystem for determining errors in lead andcorrecting them on the spot. For lead in-formation, the tracers must be observedfrom a downcourse position, at a prescribeddistance from the firing gun (ch. 10). Aftereach course, sensings for lead are com-municated to the officer conducting thecritique at the gun. The same proceduresuggested for line can be used.

(3) Similar to line, each sighting device has alever, knob, handwheel, or the operator

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has a procedure of engagement designed topermit proper adjustmenthof lead perform-ance. The operator of the sighting device,in observing tracers will, if line shots occur,be able to make lead adjustments, but willseldom be able to diagnose all the errorsmade. The officer conducting the critiquewill also experience difficulty in attributingthe error to any one individual. How-ever, he may be able to determine the causeby applying the links of the gunnery chainin analyzing the lead problem and improvethe lead performance of the crew.

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CHAPTER 10

TRACER OBSERVATION

74. GeneralEvery round of ammunition fired by AAA (AW)

cannot be expected to hit an aerial target. It istherefore necessary to make adjustments duringfiring. In order to do this, the operator of thesighting device must know the location of the pro-jectile with respect to the target. Tracer ammuni-tion will provide this essential information. How-ever, the operator must be trained to sense tracerscorrectly in order to make the adjustments that arerequired to produce a hit. One of the most importantduties is that of training gun crews to produce accu-rate fire. It is essential to understand tracerobservation thoroughly in order to train gun crewsproperly.

75. Basic Principlesa. Superimpose Tracer and Target. In order for

the observer to adjust fire, he must compare therange from the gun to the tracer with the range fromthe gun to the target. This will give him thedirection of a lead error, if one exists. If the rangesare short enough, the observer can determine adifference between the two ranges by using normalstereoscopic vision. However, stereoscopic visionbreaks down at a maximum range of about 500 yards.

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Since targets are normally fired on at ranges greaterthan 500 yards, stereoscopic vision cannot be used.Instead, the observer must use the principle ofsuperimposition. This means that the observeralines the tracer with, or superimposes it upon thetarget, in order to compare ranges to tracer and totarget (fig. 19). Thus, lead can be judged. Becauseof the common tendency for gun crews and observersto attempt to judge lead without having the tracerand target alined, this first basic principle of tracerobservation must be stressed. Do not judge forlead until the tracer is alined with the target.

b. Localize Vision. In figure 19, the tracer hasbeen depicted as a single spot in the sky movingdirectly away from the observer's eye. However,in actual practice, the tracer will not appear as afixed spot but rather as a curved path (fig. 20).This apparent curvature of the tracer path is calledthe illusion of curvature. It is an illusion becausethe curve does not actually occur. When a roundis fired, it actually moves in a straight line awayfrom the gun, except for the slight curvature oftrajectory caused by the pull of gravity. Yet thetracer does appear to curve, and the point of maxi-mum apparent curvature is called the tracer hump.This illusion of the tracer curvature is caused by theobserver focusing his attention oa a moving referencepoint, the target. At a certain instant, the eye of theobserver is tricked into making him think the targethas stopped in the sky, and the tracer is moving pastthe target instead of the target moving through thetracer path. This is a fascinating phenomenon tomost observers, and there is a resulting tendency for

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TRACER HUMP

APPARENT TRACER PATH

Figure 20. Illusion of curvature.

the observers to use this illusion for judging lead.However, tracers should never be observed near thetracer hump because it does not present factual leadinformation to the observer at the gun. Nor canthe observer judge line performance by observingthe tracer in the vicinity of the tracer hump. Inorder to obtain the desired information at the gun,the observer must focus his attention on the im-mediate vicinity of the target, as if looking througha telescope with a restricted field of view (fig. 21).Although the observer will see the curvature and thetracer hump in the actual field of vision, he mustignore them completely. From this analysis, thesecond basic principle of tracer observation isderived: Localize vision to the immediate vicinity ofthe target.

c. Read Tracer Passing Target from Nose to Tail.The target actually crosses the tracer path only

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once; it enters the path nose first and leaves thepath tail last. Because of the illusion of curvature,the observer at the gun will see this passage whenthe tracer appears to pass by the target in a nose-to-tail direction. Under certain circumstances, thetracer will appear to pass by the target in a tail-to-nose direction (a, fig. 22). For example, on incomingcourses the observer at the gun will sometimes seethe tracer pass by the target twice; first in a tail-to-nose-direction, then in a nose-to-tail direction.

VISION AND ATTENTION FOCUSEDHERE.

Figure 21. Localize vision.

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TRACER

SILHOUETTEDECLIPSED

OBSERVER'Sa. \ CONE OF

SIGHT

LEAD X' EYE

G

b.Figure £2. False picture.

Many observers make a tracer sensing in the firstinstance. This is wrong, because the tracer is notactually in the immediate vicinity of the target, butis somewhere short of the target (b, fig. 22). There-fore, the third basic principle of tracer observation is:Read the tracer only when it is passing the target in anose-to-tail direction.

76. Observation at the Gun, Crossing Coursea. Line Information. The following are sensings

for line information used by observers:(1) HIGH. The tracer sensing called HIGH

is illustrated in a, figure 23. By applyingthe test of superimposition to this picture,

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it follows that lead information cannot beobtained. Hence, the projectile simplypasses above the target as the target passesthe tracer path.

(2) LOW. The sensing called LOW is illus-trated in c, figure 23. As in the case withthe HIGH tracer, this LOW tracer cannotprovide lead information to the observer atthe gun. The observer knows only thatthe tracer passes below the target as thetarget passes the tracer path.

(3) ON. The sensing called ON, as illustratedin b and d, figure 23, is made when a lineshot occurs. A line shot occurs when thetracer pierces the cone of sight. The coneof sight is a rough cone with the apex atthe observer's eye, having a cross sectionshaped as the contour of the outline of thetarget and extending to infinity.

b. Lead Information. The following are sensingsfor lead information used by observers:

(1) AHEAD (b, fig. 23). Line shots will pro-vide lead information at the gun becauseof the principle of superimposition. Whenthe tracer pierces the cone of sight at agreater range than that of the target, thetracer is eclipsed by the target during thepassage of the target through the tracerpath. The tracer reaches the target courseline in front of the nose of the target andis therefore AHEAD.

(2) ASTERN (d, fig. 23). When the tracerpierces the cone of sight at a range lessthan that to the target, the tracer is sil-

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houetted against the target during the pas-sage of the target through the tracer path.The target crosses the point of intersectionof the tracer path and target course line inadvance of the projectile. When the noseof the target arrives at that point, thetracer will be silhouetted against the targetuntil the tail or rear edge of the targetclears that point. The tracer will thenreach the point of intersection, passing tothe rear of the target and is thereforeASTERN.

a. noGH b. ONLINE, ECLIPSE, AICAD

C. LOW d. aVLINE, SILHOUETTE, A$SER

Figure 23. Line and lead sensinge, crossing course.

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a. LEFT C. AHEAD

b. RIGHT d. ASTERN

Figure 24. Line and lead, incoming course.

77. Observation at the Gun, Incoming Counea. Line Information. The following are sensings

for line information.

(1) LEFT. In a, figure 24, the observer knowsthat the tracer has passed to his left of thetarget and that no lead sensing can bemade. It is therefore sensed as LEFT.

(2) RIGHT. In b, figure 24, the observer

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knows that the tracer has passed to hisright of the target and that again no leadsensing can be made. It is therefore sensedas RIGHT.

b. Lead Information. The following are sensingsfor lead information used by observers:

(1) AHEAD. In c, figure 24, the tracer haspierced the cone of sight at a greater rangethan that of the target because the traceris eclipsed by the target. When the pro-jectile crossed the target course line, it wasin front of the nose of the target. Ittherefore had too much lead.

(2) ASTERN. In d, figure 24, the tracer issilhouetted against the target and thereforehas too little lead.

78. Observation at the Gun, Outgoing CourseFigure 25 illustrates tracer sensings of LEFT,

RIGHT, AHEAD, and ASTERN for an outgoingcourse. Notice that the tracer is always read in anose-to-tail direction.

79. Observation at the Gun, Nonlevel Crossing CoursesTracers fired at targets which are climbing or div-

ing will produce the same picture to the observer asthose for level courses (fig. 26). Merely tilt figure23 to the desired angle of dive or climb of the targetand the tracer still follows the target course line ina nose-to-tail direction. However, if the climb ordive becomes very steep, the sensings for line changefrom HIGH or LOW to LEFT or RIGHT (fig. 27).

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a. LEFT c. AHEAD

b. RIGHT d. ASTERN

Figure 25. Line and lead, outgoing course.

80. Observation at the Gun, Directly-at-the-Gun CourseTracer sensings for this type of course include line

terminology only, since the required lead to hit thetarget is zero. There is no lateral or vertical move-ment of the target to the observer's eye. Therefore,the tracers are sensed as either HIGH, LOW,RIGHT, LEFT, or appropriate combinations of thesefour. Figure 28 shows three different tracer pictures

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A, 0.Sigh | ~~~~~b .HEAD

Figure 26. Line and lead, non-level course.

for a directly-at-the-gun course. Because the gunhas had super-elevation applied to it, the tracer ap-pears to climb from bottom to top of the picture,passing through the cone of sight, and then appears todrop from top to bottom of the picture. This drop orcurve of the tracer is caused by the actual curvature oftrajectory and is not an illusion. Whenever possible,the tracer should be read as it appears to drop fromtop to bottom of the picture, because this dropnormally starts at a range slightly less than therange to the target. Reading the tracer from top tobottom, then, satisfies the basic principles of readingfrom nose to tail and in the immediate vicinity ofthe target.

81. Downcourse Observationa. How to Observe.

(1) As long as an observer at the gun can seethe target and the tracer, sensings for linecan be made. In combat, tracer observa-tions for both line and lead will be madeonly by observers at the gun. However,during the training phase, a gun crew can

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profit from lead information obtained fromnonline shots. Observers at the gun cannotprovide lead information on nonline shots.There is a location known as the "down-

RIGH T

Figure 27. Line sensings, steep diving course.

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0 to Z

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course observation station" where an ob-server can obtain lead information. Thedowncourse observer is placed in the slantplane, a computed distance (b below) fromthe firing gun, in the direction of targetflight. The observation station is locatedleft of the gun for a right to left course,right of the gun for a left to rightcourse, and to the rear of the gun foran incoming course. In a, figure 29 isshown the position of the downcourse ob-server, who is placed in the slant plane andthe computed distance, b yards, to the rightof the gun for the left to right course.

(2) From the downcourse station, the observersees a unique view of the tracer hump. Inb, figure 29, is shown the target on theapproaching leg and the appearance of thetracer hump. The observer determines alead sensing by noting the position of thehump in relation to the target. An imagi-nary line is projected from the hump, per-pendicular to the imaginary target courseline. If the intersection of this perpendic-ular line with the course line is anywhereon the target, the lead is correct and thesensing is ON (d, fig. 29). Likewise, if theperpendicular line intersects the course linein front of or behind the target, the sensingsare AHEAD or ASTERN, respectively(b and c, fig. 29). It can be seen that, eventhough the projectile is off line, a lead sens-ing can still be made.

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-\\

b yd WCW//a DOW*COUflSE

G IOSSERVER

a. DOWNCOURSE STATION b. LEAD TOO GREAT

OA'

ASTERN

c LEAD TOO SMALL d. LEAD CORRECT

Figure 29. Downcourse observation.

b. Douncourse Distance. The distance of thedowncourse observer to the firing gun is vital to theaccuracy of the lead sensings. Th.e equation usedto solve for the downcourse distance, b, is:Where

b=distance from gun to downcourse stationV=speed of the target in yards per second

Dm=slant range to midpoint500=a constant factor

b VXDm500

To illustrate the above equation, the solution for the

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downcourse observer distance for a target traveling200 miles per hour, at a midpoint range of 600 yards,is as follows:

b=1OOX600-120 yards500

The downcourse observer would be stationed 120yards from the firing gun.

c. Tolerance. The downcourse observer, in thecase above, need not be stationed exactly 120 yardsfrom the firing gun for sufficient accuracy of obser-vation. There is a tolerance in this distance whichmay be convenient in observing for several guns onthe firing line. This tolerance is :±Y b, or in thecase above, ±30 yards. This means that the down-course observer can be placed anywhere from 90 to150 yards from the firing gun, and still be reasonablyaccurate. If a firing line contained 5 guns 15 yardsapart, a single downcourse observer stationed 120yards from the center gun could observe for all 5guns with reasonable accuracy (fig. 30). It must beemphasized that the downcourse observer can obtainlead sensings for only one gun at a time.

82. Limiting Factorsa. Visibility Conditions. Tracer observation is an

efficient method for determining relative ranges be-tween the tracer, or projectile, and target when thebackground of the target is a deep blue sky thatreveals the contrasting tracer. But when the skybecomes hazy so as to reflect sunlight into the ob-server's eyes, the observer cannot clearly distinguishthe tracer in the equally bright sky. In combat,when the observer is watching the tracers of one gun,

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several other guns may open fire on the same target,which would cause confusion. Visibility conditionsaffect tracer observation greatly. Variable densitygoggles may help to improve the visibility of tracerswhen the sky is hazy.

b. Target Speed. The observer will see the tracerin the immediate vicinity of a target that is 16 yardslong and traveling at 400 miles per hour for only8/100 second. If it is a line shot, the observer atthe gun must see, in that very brief period of time,whether the tracer is silhouetted against, or eclipsedby, the target, in order to obtain a lead sensing. Ifan observer so much as blinks his eyes he may lose avalid sensing.

c. Range to Target. The brilliance of the tracerdiminishes as the range from the gun to tracer andtarget increases. Tracer observation, for lead infor-mation at the gun, is limited to ranges of about 1,500yards. Line information, however, is obtainable aslong as tracer and target are visible.

d. Time Delay. Because of the time of flight ofthe projectile from the gun to the immediate vicinityof the target, the information obtained from a sensingis always delayed. In view of the fact that the targetwill be in the effective field of fire for only a fewseconds, this delay is critical.

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CHAPTER 11

SPEED RING SIGHTS

83. Basic Principles of Constructiona. Speed ring sights are the simplest but the least

accurate of AAA (AW) fire control devices. Theyare designed on the principle of similar triangles. Asmall triangle within the mechanism is similar to theslant plane triangle in space, GToTp (fig. 31). Thebasic speed ring sight has a rear peep element repre-sented by the point G and a series of concentriccircles as a front element, the center or hub of whichrepresents the point T,. The point To is representedat a point on one of the outer concentric circles wherethe center of mass of the target is carried whiletracking. The concentric circles are called speedrings, and the points representing the slant planepoints G, T,, and T, are given the symbols G', To',and T,' (G prime, T sub o prime, and T sub p prime).

b. The radius of the individual speed rings de-pends upon the designer's conception of range (Dp)to the target, the distance the rings are placed fromthe rear peep sight, and the speed of the target whicha particular speed ring must represent.

c. A speed ring sight is constructed by attachinga metal rod to the gun rigidly so that it is parallel tothe axis of the gun bore. At the rear end of this rod,a small metal ring or peep sight is attached; at thefront end attach a series of concentric metal rings,with the plane surface formed by those rings fixed

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To TP

To'

G AND G'Figure 31. Principle of similar triangles.

perpendicular to the rod and to the axis of the gunbore. The size or radius of each speed ring must bemathematically fixed, with each ring representinga different speed of the target in miles per hour.Most speed rings are in increments of 100 miles perhour; one ring representing 100 miles per hour,

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another representing 200 miles per hour, etc. Theradius of a speed ring may be determined as follows:With:

T , 'Tp'=radius of speed ringV=speed of target in yards per secondt,= time of flight of projectile

G'Tp'=distance, in yards, between peepsight and speed ring

D,--=slant range to the future position.

The rate between corresponding sides of similartriangles may be expressed:

AIT, lT_ G' Tot VtPG Tp'Vt= -- Dor To'T--DVt, DP DP

To solve for the radius of a 100-mile-per-hour speedring, the speed must be expressed in yards per second(50). Dp is fixed at 1,000 yards for all speed ringsights because it is an average range to targets forantiaircraft artillery automatic weapons. Assumethat the distance between the peep sight and speedring is 0.5 yard, an arbitrary distance that will makethe sighting device small enough to handle. Thefactor tp, which depends on Dp (1,000 yards), is then1.23 seconds, assuming the sight to be mounted on a40-mm gun. The equation then becomes:

T,'T,' (Radius)= 5 0 X 12 3 X0 0.03 yards or 1.1

inches

84. Speed Ring Sight with Computing Sight M38a. Front Sight. The speed ring sight used as an

auxiliary to the computing sight M38 on the twin

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40-mm gun has eight speed rings (figs. 32 and 59).The eight speed rings represent the required lead,at a midpoint range of 1,000 yards, for a targettraveling 25, 100, 200, 300, 400, 500, 600 or 700miles per hour, respectively. This sight has eightclock-hour wires which serve to hold the sighttogether and also aid the tracker.

n Photograph

Figure 83. Reflex sight M18.

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400 MPH MIRROR

200 UPH I MAGNIIFYIN200 MPH . . .. LENS

100 MPH

EYE

.1C.E IEFLECTORREnCLE IMAGE Schematic

Figure 33. Continued.

b. Rear Sight. The rear sight is a circular peepsight. For orientation, the rear sight can be adjustedvertically by loosening the two clamp nuts on therear sight bracket and sliding the sight up or down.Lateral adjustment is made by loosening the clampnut on the stem of the rear sight and sliding thepeep sight left or right.

85. Reflex Sight M18a. Description. The M18 reflex sight (fig. 33) on

the multiple caliber .50 machinegun mount, consistsof a mounting bracket, sight assembly, and a housingassembly. The sight assembly contains the opticalsystem of the reflex sight, while the housing assembly

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provides artificial illumination when desired. Thehousing assembly can be raised by pulling out on thehousing knob and rotating it 900. In the up posi-tion, the housing assembly will allow daylight toenter the optical system of the sight assembly. Thelight rays, either from a natural or artificial source,pass through the sight assembly window. Thediffused light, falling on a metal reticle, passesthrough the etched pattern, is deviated 900 by amirror, and is focused at infinity by a double-lensobjective in the objective assembly. The image ofthe reticle from the objective assembly strikes thereflector which is held at an angle of 45 ° . Thisreflector is a chemically treated glass plate whichacts as both a mirror and a window. To the trackerthe image appears out in space at the same rangeas the target. This image has 4 speed rings and 3dots. The speed rings represent midpoint leads at1,000 yards range for targets traveling 100, 200,300, and 400 miles per hour. The lower dot is thehub or center of the speed ring reticle. The upperdot is used during orientation to establish super-elevation and is approximately 10 mils from the dotat the hub. The dot located midway between thehub and the upper dot is used to vary superelevationin surface firing and represents approximately 5 milsof superelevation. For orientation, the sight isadjusted vertically by loosening the elevation clampnut and turning the elevation adjusting screw,moving the image of the reticle up or down. Forlateral adjustments, loosen the azimuth clamp nutand turn the azimuth adjusting screw, moving theimage of the reticle left or right.

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b. Operation. The tracker sights at the targetthrough the reflector and at the same time, sees theimage of the reticle mirrored from the reflector. Hethen moves the mount in azimuth and elevationuntil the image of the reticle is properly superim-posed on the target. The image of the reticle passesdown to the magnifying lens, which converges thelight rays of the reticle image to a point G' betweenthe lens and the reflector. The reticle image thendiverges to the reflector, thence, to the tracker'seye. The reticle image can be said to create a conewith the base at the center of the lens, and thevertex at the point of convergence between the lensand the reflector. As the range to the target isincreased, the diameter of the reticle image appearsto increase proportionally although the actual sizeof the reticle remains constant. Thus it is seen thatthe speed ring always subtends the same lead angles,regardless of range to the target. The point To'is the point on the objective assembly correspondingto the tracking point. T,' is the geometric centerof the objective assembly. Point G' is the pointof convergence of the reticle image. The positionof the tracker's eye does not affect the gunneryproblem. The only requirement is that the trackerlook into the reflector in such a manner that thereticle image is reflected back to the eye, and atthe same time, the target is visible through thereflector.

86. Gunnery Chaina. Link I. The tracker's line of sight is estab-

lished when the tracker alines the sights on thetarget (fig. 34). This requirement is not exacting

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Figure 34. Link I.

since the other links of the gunnery chain willposition the target at one specific spot in the sights.

b. Link II. The tracker keeps the nose of thetarget pointing toward the hub of the sight. Thiswill establish the axis of the gun bore (disregardingsuperelevation) in the slant plane. The trackervisualizes the slant plane by extending the fuselageof the target to form the target course line, thenpositions the target in the sight in such a mannerthat the target course line passes through the centerof the sight. In figure 34, the slant plane is abovethe hub of the sight. The axis of the gun bore isrepresented by the sight reference axis Therefore,

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the axis of the gun bore (disregarding superelevation)is not in the slant plane, and the sight must beelevated until the hub lies on the target course line(fig. 35). When a tracker is tracking properly alonga target course, the target on a level crossing coursewill appear to be climbing toward the hub of thesight on the approaching leg, will appear to levelout at midpoint, and will appear to be diving towardthe hub on the receding leg. This appearance ofthe target rotating about the hub of a sight is calledimage spin and makes the establishment of link IIa continuous operation. An aid to the establish-ment of link II is supplied to the tracker in the formof clock-hour wires radiating from the hub of somespeed ring sights. These clock-hour wires assistthe tracker in pointing the nose of the target towardthe hub of the sight.

Figure 35. Link II.

388163 0-56-8 113

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c. Link III. The tracker makes the generatedlead equal to the required lead or establishes the cor-rect amount of lead (fig. 36). For any one targetcourse, the required lead angle is constantly changingbecause the angle of approach and, to a lesser degree,the range to the target are constantly changing.When the tracker, utilizing a speed ring sight, carriesthe target on one speed ring the entire length of thecourse, the lead being generated is constant. Assum-ing the speed ring on which the target is trackedrepresents the correct speed of the target, the gen-erated lead would equal the required lead only whenT, is in the vicinity of midpoint. To satisfy linkIII, the tracker must be able to estimate the speedof the target correctly. If the tracker should over-estimate the speed of the target, the result would bethe firing of an entire course with all rounds goingahead. To eliminate this possibility, the rule is forthe tracker to adjust the sight picture so that thecenter of mass of the target will lie under a speedring representing three-fourths of the estimatedtarget speed (fig. 37). Using this rule, the tracker isgiven a leeway in target speed estimation, and will beassured of an effective flythrough. The factor ofthr'ee-fourths speed is used merely because it is easilyhandled mathematically. A factor such as one-half,although easily handled mathematically, will produceflythroughs at a point beyond the maximum effectivehitting range of the automatic weapons. The factorof three-fourths speed, then, gives the greatest assur-ance of at least one effective flythrough under combatconditions.

d. Link IV. Superelevation is set into speed ringsights during orientation and is a fixed value. In

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Figure 37. Link III, X speed. Estimated target speed =400

mph.

every case the orienting point will be above the hubof the sight. The sight pictures, during orientation,will vary as depicted in figure 38, and should beproperly established by use of orientation adjust-ments on each sight. The first step in the orientationof any speed ring sight is to boresight the gun tubeon the orienting point.

(1) Reflex sight M18 (fig. 33)). The upper dotshould lie on the orienting point, thusestablishing approximately 10 mils of super-elevation. The dot midway between thehub of the sight and the upper dot is usedonly as a guide to permit the tracker in

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n*.

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surface firing to set in any amount of super-elevation from 0 to 10 mils by estimatingfrom a 5 mil dot.

(2) Speed ring auxiliary to computing sight M88(figs. S3 and 59). The peep sight is adjustedso that the tracker's line of sight, passingthrough the center of the peep sight to theorienting point, intersects an imaginarypoint two-thirds of the distance from thehub of the sight to the 25 mile per hourspeed ring, in the 12 o'clock direction.This sight picture will establish approxi-mately 10 mils superelevation.

87. Adjustments for a Hita. General. Speed ring gunnery does not neces-

sarily depend upon tracer observation. If thetracker establishes the 4 links of the gunnery chainas prescribed, flythroughs will be obtained. If, how-ever, the tracker is able to make a positive tracersensing, a correction should be made under certaincircumstances.

b. Line. If the tracers appear high, low, left, orright, depending upon the type of course, the trackershould adjust the fire. For line adjustment, merelymove the hub of the sight. On crossing courses,move the hub to the right or left, depending on thecorrection needed. The basic rule is: Move the hubof the sight in the direction you desire the rounds to go.

c. Lead. Because of smoke, dust, or vibration ofthe gun, the tracker will rarely be able to obtainaccurate lead sensings, and should therefore concen-trate on tracking the center of mass of the target onthe speed ring that represents three-quarters esti-

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mated speed, in order to obtain two flythroughs. Ifthe tracker does make a lead sensing, an adjustmentshould be made only if the sensing indicates a hope-less case. A hopeless case is an astern far out on theapproaching leg, an ahead in the immediate vicinityof midpoint, and an ahead anywhere on the recedingleg of a course. These are hopeless cases because,if the firing were continued in that manner, no fly-throughs could possibly occur. For a properlytracked course, tracers should appear ahead far outon the approaching leg, astern in the vicinity of mid-point, and ahead far out on the receding leg. Thus,even a properly tracked course has a hopeless caseon the receding leg. To correct for a hopeless case,select a larger or smaller speed ring (at least a 100-mile-per-hour difference).

88. Speed Ring Sight Engagement Rulesa. Assuming the speed ring sight is properly

oriented, the following rules for engagement willbring hits during all types of courses except one:

(1) Point the nose of the target toward the hubof the sight at all times.

(2) Track the center of mass of the target onthe speed ring representing three-quartersestimated target speed.

(3) Keep firing.b. The one exception to the rules is during a

directly-at-the-gun course. In that course, the ruleis to hold the hub of the sight on the nose of thetarget and keep firing.

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CHAPTER 12

COMPUTING SIGHTS

89. Basic Principles of Constructiona. Computing sights are the primary means of

fire control on the twin 40-mm gun motor carriageM42 and the 40-mm gun MiAl on carriage M2A3.Computing sights are designed, as in the case ofspeed ring sights, to use the relationship betweensimilar triangles (fig. 39). The sight produces asmall triangle, G'To'T/', which the lead setter andgun pointer attempt to position similar to the slantplane triangle, GToT,.

b. To produce a basic computing sight, as illus-trated in figure 39, fasten a rod to the gun in sucha manner that it will always be parallel to the axisof the gun bore (disregarding superelevation). Atpoint G', fasten a second rod by a universal pivot,and along that rod attach a reflex sight in such amanner that it is parallel to the second rod at alltimes. Hence a gun pointer would have his tracker'sline of sight displaced as the rod moves. Next,connect the two rods by a lead rack gear (repre-sented in fig. 39 as To'T,') with one end attachedto the first rod at Tp' by means of a circular gear.This circular gear is arranged in such a manner asto allow the lead rack gear to be moved verticallyabout Tv'. The lead rack is attached to the rodholding the reflex sight at Tp' by means of the leadrack stud. Any movement of the rack will causethe tracker's line of sight to move an equal amount.

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As the gear is turned, it causes the lead rack to bedisplaced a linear distance along the line To'Tn',changing the generated lead angle. Also, in orderto have the sight triangle similar to and alined withthe slant plane triangle, the lead rack must be ableto rotate about the rod G' T','; hence, there is a needfor the pivotal motion around the vertical axisthrough T,'. In order to protect the lead rack andother mechanisms of the sight from the elements,these mechanisms are enclosed in a metal case calledthe computing box. With the computing box cover-ing the lead rack and other mechanisms, the leadsetter can no longer see the essential parts for ad-justment of the sight triangle. Therefore, computingsights have external indicators to show the positionof the lead rack and the amount of displacement ofthe lead rack stud from T,'.

c. The first indicator is the target course arrow.The target course arrow is mounted outside thecomputing box on a bail shaped like a pail handle.The arrow is fixed to the bail in such a manner thatit is always parallel to the lead rack. Therefore,when the lead setter adjusts the arrow parallel tothe target course line, the lead rack will also beparallel to the same target course line. The secondindicator is the speed knob, which is located outsidethe computing box. By setting a speed on the speedknobs, the lead setter causes the gear at T,' torotate. The rotation of this gear causes the leadrack to be displaced a linear distance, which inturn, causes T,' to move away from T,', establishinga generated lead angle. By observing the speedknob, the lead setter knows the magnitude of thegenerated lead. In order to make the sight triangle

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similar to the large slant plane triangle in space,two adjustments by the lead setter are necessary.First, the target course arrow must be positionedwith the head of the arrow pointed in the directionof flight of the target, and parallel to the targetcourse line, placing the lead rack in the slant plane.Second, full estimated speed of the target is set onthe speed knob.

d. Computing sights are designed for a fixedrange. This is illustrated by the following equa-tion, which is solved for the length of the lead rack(To'T,') for a target speed of 400 miles per hour:

To'T,'_ G'Tp' To'Tp' _G'T,'Vt, D, o200 t, D,

To substitute a value for t,, it is necessary to knowD,. For all computing sights used on 40-mm guns,this range is 900 yards. The sights, therefore, con-sider all targets to be at a range (D,) of 900 yards,regardless of the true range. In the equation it canbe seen that G'T,' must also be established arbitrar-ily by the designer. For the M38 sight, this distanceis 0.216 yard. The t, of a 40-mm projectile for 900yards is 1.09 seconds. The equation then becomes:

To'T,' 0.216200.1.09 900

With only one unknown, the solution of the equationis: TT,' .218.0.216is: T'T,'=218 900 2o 0.0524 yard or 1.88 inches.

The range factor in computing sights is held con-stant; yet this is not critical to the solution of thelead problem because of the method used by thelead setter to adjust for lead.

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e. In the M38 or M19A1 computing sight triangle,there is only one rod instead of two as in the basicsight discussed above. This rod is called the swivelshaft. G' is still the pivot of this rod; however,To,' is not the lead rack stud but is actually the stemball located directly beneath the lead rack stud onthe bottom of the vertical slide. Therefore, To'T,'is a line parallel to the lead rack, passing through thecenter of the stem ball. T,' is the point where thisline intersects the vertical axis of the lead rack.

f. If there are two adjustments on the computingsight which affect the final position of the gun bore.The first is performed with the speed knobs. Turningthe speed knobs in one direction causes the lead rackto move a linear distance, moving T,' from T/'.Turning the speed knobs in the other direction causesthe lead rack to move in the opposite direction,moving T,' toward T,'. Assume a left to rightcrossing level course, with the gun pointer tracking thecenter of mass of the target; if the speed knob wereturned to increase speed, the lead rack would movethe sight off the target to the left in the direction ofthe tail, causing the gun pointer to track faster toget his sight on center of mass of the target; there-fore moving the muzzle of the gun to the right aheadof the target, thus increasing lead. The secondadjustment affecting the final position of the gunbore is with the arrow positioning mechanism. Byturning the computing box positionihg handwheel,the computing box is rotated about its vertical axis,thus repositioning the target course arrow and the leadrack. The lead rack stud moves with the lead rackand is a fixed distance from T,' if the speed setting isnot changed. Since the lead rack stud moves, the

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sight moves off the center of mass of the target.This forces the gun pointer to reposition the sight onthe center of mass of the target, and in doing so,reposition the gun bore. Any movement of the bailwill affect the final position of the gun bore in thesame manner. If the arrow is positioned verticallyby moving the bail, the lead rack will be repositionedalso. The motion of the lead rack causes the sightto move, thus throwing it off target, and causes thegun pointer to reposition the gun bore while he movesthe sight back on center of mass of the target.

g. When the lead setter initially positions thetarget course arrow parallel to the target course line,the arrow remains parallel to the target course line,even though the gun bore may move through 3600of traverse. As the gun traverses, the azimuth gearmechanism sends, by means of a flexible cable,equal but opposite rotation to the computing boxpositioning mechanism. This rotation positions thecourse arrow and lead rack, keeping them parallelto the target course line. This system of cable andgearing is called the course memory feature. Theresult of this feature is to automatically change thegenerated lead angle according to the constant changeof the angle of approach along the target course line.

90. Solution of the Gunnery Chaina. Link I. To establish the tracker's line of sight,

the gun pointer places the intersection of the crosshairs on the center of mass of the target, and main-tains that alinement. As with all on-carriage sights,the maintenance of that alinement is extremely im-portant, but very difficult because of distractionssuch as the explosion and recoil of the gun, and smoke

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from the hot tube. With computing sights there isthe added distraction of the sight moving off thecenter of mass of the target due to line and lead cor-rections made by the lead setter. The gun pointer,then, must be highly trained if the most effective useof the computing sight is to be obtained.

b. Link II. To place the axis of the gun bore(disregarding superelevation) in the slant plane, therule is: Adjust the target course arrow. The axis ofthe gun bore (without superelevation) will always bein the slant plane when the line T' T,' is in the slantplane. With the gun pointer establishing the track-er's line of sight on center of mass of the target, theline To'Tp' will be in the slant plane if the targetcourse arrow is pointed in the direction of flight ofthe target, and is parallel to the target course line.The target course arrow is positioned by adjustingthe computing box positioning handwheel and thebail. Once established for any one course line,link II will be maintained by the operation ofthe course memory feature, keeping the line To'T,'in the slant plane. The one exception is for a targetflying directly at the gun. In this case, set the speedknobs at zero, ignore the target course arrow, trackthe nose of the target, and fire.

c. Link III. To establish the correct lead, adjustthe speed setting. The rule is: Set the speed dial toreadfull estimated speed of the target. The lead setter,when positive lead sensings are made, changes thespeed setting by adjusting the speed knobs, whichmoves the reflex sight from the center of mass of thetarget. When the gun pointer reestablishes thereticle image of the sight on center of mass of the

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target, the gun bore is moved farther ahead or closerto the target, increasing or decreasing the value ofthe generated lead. The value of the generated leadangle will vary by the operation of the course memoryfeature according to changes in the angle of approach.The exception to the rule is for a target flyingdirectly at the gun. In this case, set the speed knobsat zero, ignore the target course arrow, point at thenose of the target, and fire.

d. Link IV. The computing sight mechanicallysolves for, and produces, a variable amount of super.-elevation by a camming mechanism attached to theelevating mechanism of the gun bore. This super-elevation varies, from maximum with the gun boreat +9 mils elevation, to zero when the gun bore iselevated to 900. The origin of superelevation in thecomputing sight is the offset distance of the stemball below the computer support trunnion axis (fig.40). This offset distance subtends the angleformed by the line G'T,' and a line parallel to theaxis of the gun bore, passing through the verticalpivot box of the swivel shaft. At +9 mils elevationof the gun bore, this offset distance subtends 9 mils.As the gun bore elevates, the parallel link keeps thecomputing box level at all elevations of the gun bore,which causes a relative rotation of the stem ball. Asthe stem ball rotates about the computer supporttrunnion axis, the offset distance remains verticaland, as a result, the angle it subtends becomessmaller. With the gun bore elevated to 900, theoffset distance becomes parallel with the axis of thegun bore, hence the superelevation angle becomeszero mils.

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COMPUTER SUPPORT-TRUNNION

\ PARALLEL WITHVERTICAL PX~\ ~)S JAXIS OF GUN BORE

PARALLEL TO~~SW IVTEM TRACKEWRS LINE

SHAFT BALL OF SIGHTEp. ' SPEED SETTING ZERO

COMPUTER SUPPORT TRUNNIONPARALLEL WITHAXIS OF GUN BORE

\PARALLEL WITH TRACKERS,LINE OF SIGHT

VERTICAL STEM BALLPIVOT \

SWIVEL SHAFT

SPEECOMPUTER UETTINGPPOR ZERO

TRUNNION

AXIS OF GUN BORE AND TRACKER'Si LINE OF SIGHT. PARALLEL

STEMBALL

VERTICALPIVOT

Ep 900SPEED' SETTING-ZERO

Figure 40. Superelevation mechanism, M38 computing sight.

12B

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91. Computing Sight M38.a. Description (fig. 43). The M38 computing

sight is the primary means of fire control on thetwin 40-mm gun motor carriage M42. It consistsof a computing box, two speed knobs with two speedscales graduated from 0 to 700 miles per hour oneach knob, a target course arrow mounted on topof a bail, a computing box positioning handwheel,and a main support bar for housing a steel bandused to transmit lateral motion to the gun pointer'sreflex sight M24C. The reflex sight M24C is similarin operation to the M18 reflex sight, and has a lightwindow, reticle and mirror, magnifying lens, andcoated glass reflector (fig. 41).

b. Operaiton (fig. 42).(1) Target course arrow.

(a) When the lead setter turns the computingbox positioning handwheel, gear (1) ro-tates and supplies one input to the dif-ferential. The second input comes fromthe azimuth gear mechanism, along a flex-ible shaft, to worm gear (2). The twoinputs are added algebraically, through aseries of gears and shafts to gear (8),turning the azimuth base ring gear (9)which is the lower base of the computingbox. When gear (9) turns, the entirecomputing box turns, thus positioningthe target course arrow and lead rackhorizontally.

(b) For hasty dive or climb adjustments, thelead setter grips the bail and positionsthe course arrow vertically. The rota-

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tion of the bail turns the dive and climbscales (11), and the hub (10) which, bydirect connection, turns gear (12) andlead rack guide (13), thus positioninglead rack (14) vertically parallel to thetarget course line.

(2) Speed. When the lead setter turns thespeed knobs, shafts (A) are rotated. Yoke(B) directly connects shafts (A). Thisrotation turns gear (C) which moves leadrack (14) along guide (13), thus positioningthe lead rack pivot (D). The movementof lead rack pivot (D) is converted tolateral and vertical components. The lat-eral component causes movement of guide(E) along slide (F), thus moving guide(H) which laterally positions the stemball. The vertical component causes move-ment of the stem (G) along guide (H),thus vertically positioning the stem ball.

(3) Differential action. As the lead setterpositions the lead rack for climb or diveangles, the lead rack (14) would movearound gear (C), if gear (C) were stationary.The result would be a new speed settingon the speed knobs and the lead rack pivot(D) would change position. To preventthis from happening, a differential actiontakes place. The lead rack (14) revolvesas a result of a vertical movement of thebail. Between one speed knob and thebail there is a friction pad (15) keyed tothe knob and forced against the bail bysprings; when the bail revolves, the speed

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knobs move with the bail because the fric-tion of the pad is greater than the com-bined inertia of the speed knobs, gear(C), and lead rack (14). Thus, gear (C)and lead rack (14) remain meshed withoutchange, leaving the readings on the speedknobs unchanged. When the lead setterturns the speed knobs to change the speedsetting, the friction of the pad is not greatenough to overcome the inertia of the arrowpositioning mechanism; therefore, the padrotates with the knob. The bail, however,remains stationary and no change in theposition of the arrow occurs.

c. Transmission of Motion to Reflex Sight (fig. 43).(1) Lateral motion. A steel band is used to

transmit lateral motion to the reflex sightM24C. This band runs through the sightmechanism beginning and ending at thevertical pivot box. The steel band runsaround two pulley wheels, one of which isconnected to the reflex sight. The otherpulley wheel, located in the vertical pivotbox, receives motion from the swivel shaftand stem ball (fig. 43) when the lead rack ismoved laterally. The band transmits thismotion in equal amounts to the reflex sight.In order to prevent a lag in the transmissionof motion, tension is placed on the steelband by means of an adjustable bearingroller mounted on springs. The band runsaround the bearing roller. An adjustmentmoving the roller forward or backward willdecrease or increase the tension on the steel

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band. Tension on the steel band shouldbe checked periodically. To make thischeck:

(a) Aline the sight on an object at a knowndistance.

(b) Make a vertical chalk mark on this objectcoinciding with the vertical reticle of thereflex sight.

(c) Grasp the reflex sight, pull it laterally ina counter clockwise direction at least 10° ,then release the sight.

(d) With proper tension on the steel band,the vertical reticle will return to within5 mils of its original position.

(e) If the tolerance is exceeded, adjust thetension on the steel band in the adjust-ment box on the left side of the mainsupport bar, and repeat the check.

(2) Vertical motion. Vertical movement of thelead rack is transmitted to the stem ball,swivel shaft, and vertical pivot box. Thevertical pivot box is mounted on the rightside of the main support bracket andfastened to the main support box. Move-ment of the vertical pivot box rotates themain support bar inside the main supportbracket, positioning the reflex sightvertically.

d. Computing Boz Leveling. Before the computingsight can solve the gunnery problem accurately, thecomputing box must be level with the mount withinthe entire elevation limits of the gun tube. Thereis a tolerance in this requirement of i 2 mils from 0°

through 45 ° elevation, and ± 4 mils from 45 ° to 750

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elevation. To check and adjust the level of thecomputing box:

(1) Lock the turret in azimuth so that no move-ment of the gun will be possible during theleveling procedure.

(2) Place a gunner's quadrant on the quadrantseat of the gun trunnion. Center the quad-rant bubble and record the reading.

(3) Place the gunner's quadrant on the com-puting box quadrant seat. Elevate the gunbore to 0° , 15° , 300, 450, 600, and 750 inturn, and center the quadrant level bubblerecording the quadrant reading at each testposition. Approach each test position ofthe gun tube from the same direction toeliminate backlash errors.

(4) If any of the readings obtained in step (3)above exceed the reading obtained in step(2) above by as much as the specifiedtolerance, the computing box must be ad-justed. To adjust the computing box:

(a) Bring the gun bore up to 00 elevation.(b) With the quadrant on the computing box

quadrant seat, and the reading obtainedin step (2) above on the quadrant, centerthe bubble of the quadrant by adjustingthe parallel link.

(c) Elevate the gun bore to 15° , 300° , 45° , 60° ,and 75° , in turn, and record the readingof the gunner's quadrant at each test posi-tion after centering the quadrant bubbleby manipulating the quadrant arm. Anydeviations from level at all test positionsshould be within the specified tolerance.

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If not, an error in procedure is evident.Repeat the procedure until the level iswithin tolerance at all test positions.

e. Initial Insertion oJ Superelevation. The stemball must be offset to subtend 9 mils measured fromthe vertical pivot of the swivel shaft, with the gunbore at + 9 mils elevation. This adjustment shouldbe made periodically to insure the correct stem balloffset distance; however, it need not be done eachtime the weapon is oriented. This distance ischecked and adjusted by the following procedure:

(1) Lock the turret in azimuth.(2) Place the gunner's quadrant on the quadrant

seat of the left gun trunnion, center thequadrant bubble, and record the reading.

(3) Add 9 mils to the setting on the quadrant,place the quadrant on the machined quad-rant seat on the breech casing, and elevatethe gun until the quadrant bubble is centered.

(4) Again set the quadrant at the trunnion levelreading obtained in step (2), above andplace it on the vertical pivot box quadrantseat.

(5) Zero the speed setting on the speed knobs.(6) Remove the protective bag at the base of

the computing box, loosen the clamp screwon the stem ball, and turn the stem balluntil the bubble is centered in the quadrant.

(7) Tighten the stem ball clamp screw, and re-place the protective bag.

f. Orientation Procedure.(1) Bore sight the gun on the orienting point

(preferably 1,500 yards away).(2) Set the target course arrow parallel to the

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axis of the gun bore, with the head of thearrow pointed toward the breech (azimuthscale on the base of the computing boxshould read minus 1,600 mils).

(3) Place the target course arrow at an angle ofdive of 50° . (On older sight models, withthe BS mark at 17 mph, place the targetcourse arrow at maximum dive.)

(4) Set the speed knobs to the reading markedBS.

(5) Adjust the reflex sight M24C in azimuth byturning the screw of the worm gear in thereflex sight support cap until the verticalreticle is on the orienting point.

(6) Adjust the reflex sight in elevation by loosen-ing the clamp screw located on the sightsupport housing, then turning the screw ofthe worm gear located above the clampscrew on the sight housing. The worm gearmoves along a gear rack to produce a ver-tical motion. When the horizontal reticlein the reflex sight is on the orienting point,tighten the clamp screws.

(7) Return the target course arrow and speedknob to standby settings.

g. Design. The M38 computing sight requiresspecial adjustments in order to compensate for super-elevation while orienting. Steps (2) and (3) in fabove will aline the lead rack in such a position thatwhen step (4) is completed, the lead rack has movedvertically, moving the reflex sight up the approximateamount of superelevation. This procedure effec-tively compensates for superelevation and producesthe same result as though the stem ball had been

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adjusted in order to eliminate and reinsert super-elevation for each orientation.

92. Computing Sight M19A1The M19A1 computing sight (fig. 44) is the pri-

mary means of fire control on the 40-mm gun MlA1on carriage M2A3. It solves the gunnery problemexactly the same as does the M38 computing sightand is constructed, mounted, and operated the same,with the following exceptions:

a. The main support bar is extended to hold anadditional reflex sight M24C on the right end.

b. The computing box, computing box positioninghandwheel, and vertical pivot box are mounted tothe rear of the main support bar, with a longer paral-lel link and an added vertical deflection linkage.

c. As with the M38 computing sight, a steel bandis used as the means of transmitting lateral motion tothe reflex sights. This band runs through the entiresight supporting mechanism, beginning and endingat the vertical pivot box. A pulley wheel is attachedto each rflex sight at each end of the main supportbar. The steel band runs around, and is pinned to.these two pulley wheels, then continues around athird pulley wheel in the vertical pivot box. Thisthird pulley wheel is rotated by the swivel shaft, andlateral movement of the stem ball, when the leadrack is moved laterally. The tension of the steelband is regulated like the band in the M38 computingsight.

d. A series of linkages, between the vertical pivotbox and the main support bar, provide the means ofpositioning the reflex sights vertically. An arm isattached rigidly to the vertical pivot box; fastened

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1403

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to this arm is the vertical deflection linkage. Anotherarm is attached to the other end of this linkage, whichin turn is attached rigidly to the main support bar.As the vertical pivot box rotates vertically, the mo-tion is sent through the vertical deflection linkage tothe main support bar, which rotates on its longitu-dinal axis and elevates or depresses the two reflexsights simultaneously. The angle turned by thereflex sights must be the same angle rotated by thevertical pivot box, since the motion of the verticalpivot box is obtained from the vertical movement ofthe lead rack, through the connecting stem ball andswivel shaft. A check and adjustment should there-fore be made when the sight is installed and at reg-ular intervals thereafter. To make this check andadjustment, the procedure is:

(1) Set the computing box an at azimuth of± 1,600 mils.

(2) Set the target course arrow at the maximumangle of dive.

(3) Set the speed at zero(4) Place a gunner's quadrant on the vertical

pivot box quadrant seat. Adjust the quad-rant arm to center the level bubble andrecord the reading.

(5) Place the quadrant on the reflex sight in astationary position. Adjust the quadrantarm to center the level bubble and recordthe reading.

(6) Change speed from 0 to 700 miles per hour.(7) With the quadrant still on the reflex sight,

adjust the quadrant arm again to center thelevel bubble, and record the reading.

(8) Again place the quadrant on the vertical

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pivot box quadrant seat, adjust the quad-rant arm to center the level bubble, andrecord the reading.

(9) The difference between the two readingstaken on the vertical pivot box and thosetaken on the reflex sight will give two angleswhich should be within 1 mil of each other.

(10) If the two angles turned are not the samewithin 1 mil, loosen the two lock nuts onthe vertical deflection linkage and adjustthe sights by rotating the turnbuckle. Thisnecessitates a trial and error method of.adjustment. Adjust the turnbuckle, andcheck the angles turned by the verticalpivot box and the reflex sights until thoseangles are within tolerance.

e. Computing Box Leveling. The M19A1 com-puting box must be level throughout the entire ele-vation limits of the gun tube and within a toleranceof - 2 mils. The leveling procedure is:

(1) Fine level the gun mount.(2) Place a gunner's quadrant on the sight

bracket quadrant seat.(3) Elevate the gun bore to 0° , 150, 30° , 45°,

600, and 75° , in turn, and record thegunner's quadrant reading at each test posi-tion. Approach each test position from thesame direction to eliminate backlash errors.

(4) If the readings obtained in step (3) aboveexceed ± 2 mils, the computing box mustbe leveled within tolerance, and the follow-ing steps (5) to (12) must be performed:

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(5) Bring the gun bore up to zero degrees ele-vation.

(6) With the gunner's quadrant set to read zeromils on the sight bracket quadrant seat,center the level bubble by adjusting theparallel link.

(7) Elevate the gun bore to 90° and with thequadrant, check the number of mils thecomputing box is off level. If the error inlevel is in the positive direction, place shimsunder the front of the parallel link bracketon the gun trunnion. If the error is nega-tive, place shims under the rear of the samebracket. For each mil of error, place ap-proximately 0.003 thickness of shim underthe proper side of the bracket.

(8) Return the gun bore to zero elevation, andagain with the quadrant set to read zeromils on the sight bracket quadrant seat,center the quadrant level bubble by theparallel link adjustment.

(9) Again elevate the gun bore to 900 and checkthe level of the computing box. If notlevel, repeat step (7) above, adding or sub-tracting shims.

(10) Then repeat steps (8) and (9) above.(11) Continue this procedure until the comput-

ing box is level at both 0° and 900.(12) Elevate the gun bore to 15° , 300, 450, 600,

and 750, in turn, and record the reading ofthe gunner's quadrant on the sight bracketquadrant seat at each test position. Any

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deviations from level should now be withinthe ±2 mils tolerance. If not, repeat theentire procedure until the computing boxis level within tolerance.

93. Adjustments to Obtain HitIn computing sight fire control, if the lead setter

is able to make definite tracer sensings, adjustmentscan be made.

a. Line.(1) Crossing courses. If the tracers are high,

the lead setter turns the head of the targetcourse arrow away from himself; if thetracers are low, he turns the head of thearrow toward himself.

(2) Alternate method. Line adjustments mayalso be made on crossing courses by adjust-ing the angle of climb or dive with the ar-row adjusting knobs or with the bail. Ifthe tracers are high, the head of the arrowis moved down; if the tracers are low, thehead of the arrow is moved up.

(3) Low angular height. Line may be adjustedon crossing courses by either of the aboveprocedures. At low angular heights of thegun bore, a more effective adjustment willbe obtained by using the change in climbor dive. However, the judgment and ex-perience of the lead setter will determinewhich adjustment should be used.

(4) Incoming or outgoing courses. If the tracersare right, the lead setter turns the head of

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the arrow left; if the tracers are left, heturns the head of the arrow to the right.

b. Lead. If the tracers are ahead, the lead setterdecreases speed; if the tracers are astern, he increasesspeed. To adjust on a target flying directly at thegun, speed is zeroed, the position of the targetcourse arrow ignored, and firing continued. Neces-sary corrections are then obtained by tracking off.

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CHAPTER 13

ANTIAIRCRAFT ARTILLERY AUTOMATICWEAPONS SURFACE FIRING

Section I. GENERAL94. General

Antiaircraft artillery automatic weapons may beassigned a surface mission against ground or navaltargets which may be engaged by either direct orindirect fire. Direct fire is used for rapid engage-ment of surface targets which are visible to thetrackers of the weapon. Indirect fire from defiladedpositions is used whenever possible to engage targetswhich cannot be seen or laid upon effectively throughthe direct fire sights of the weapon. This method ispreferred primarily because it affords protection ofpersonnel and equipment. The AAA (AW) bestsuited for surface fire is the twin 40-mm gun M42.The multiple caliber .50 M16A1 is less accurate andmore difficult to lay in azimuth and elevation, but isequipped with azimuth and elevation scales suitablefor either direct or indirect fire.

95. Aimed FireThere is one important difference between the

determination and analysis of firing data for surfacefire and that established for AAA fire. In surfacefire, a hit is expected with each round, including theinitial round fired; opposed to the premise in AA

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fire that round for round hits are not expected be-cause of the gunnery problem involved.

96. Basic Elements of DataRegardless of the method or devise used in surface

fire, there are certain basic elements of firing datawhich are present in the gunnery problem.

a. Direction, Oun to Target. Alining the axis ofthe gun bore in the same vertical plane containingthe target and gun is performed either visually orwith instruments.

b. Angle of Site. This is the vertical angle betweenthe horizontal plane and the gun-target line, corre-sponding to Ep, the future angular height in theantiaircraft artillery automatic weapons problem.It can be measured by inspection or estimation, froma map, by surveying instruments, or boresightingon the target and measuring the gun bore elevationwith a gunner's quadrant.

c. Range, Cun to Target. This is the distance, inyards, from gun to target. In AAA (AW), thisrange is horizontal. Range determination is neces-sary in order to apply superelevation which corre-sponds to the sum of the field artillery terms "firingtable elevation" and "complementary angle ofsite." Range is normally estimated or taken froma map to the nearest 100 yards.

d. Description. The automatic weapon gun crewshould know the type of target to be fired upon inorder to select the proper type of ammunition formaximum lethality, and to determine whether tofire area or precision fire. The dimensions of thetarget also aid in range determination with binocularswith mil scale reticles (see FM 6-40).

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Section II. DIRECT FIRE

97. General ProcedureSince direct fire is engagement of targets within

view of the enemy and with limited defilade, thisprecludes deliberate, time consuming methods ofgun laying. The weapon must be fired as rapidlyas possible and displaced to avoid counterfire.

a. Azimuth. The vertical sight reference line(vertical cross-hair or imaginary vertical line throughthe center of the sight) must be laid on center of massof a stationary target, or somewhere ahead of amoving target.

b. Elevation. The horizontal sight reference line(horizontal cross-hair or imaginary horizontal linethrough the center of the sight) must be laid oncenter of mass, above, or below the target. In orderto determine how much above or below the targetthe horizontal sight reference line is laid, the angleof site and superelevation must be estimated (fig. 45).

(1) Angle of site. During the majority of AAA(AW) direct fire missions, the angle of sitewill not be measured, due to the limitedtime available. If the target is within 20 °

of the same level with the firing weapon,the angle of site at a given range will notcause a significant change in 0,. Normally,the angle of site plus generated 48 is auto-matically determined when the sights arelaid on the target. If, however, sufficienttime is available to deliberately lay thegun, the direct command procedure (par.107) or quick quadrant measurement ofthe angle of site can be used. Utilizing the

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149

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sighting device oriented for AA fire, trackthe horizontal sight reference line onto thetarget and measure the quadrant elevation.This quadrant elevation will not be theangle of site, however, since the gun borewill be at an elevation (9 or 10 mils) abovethe tracker's line of sight. To determinethe true angle of site, subtract the 9 or 10mils (the amount of superelevation orientedinto the sight) from the measured quadrantelevation.

(2) Superelevation. Normally in direct fire, the9 or 10 mils superelevation generated bythe sight is used as a means of estimatingthe application of correct superelevation.With the knowledge that the superelevationgenerated by the M38 computing sight, forexample, is 9 mils for a fixed range of 1,160yards, the horizontal sight reference linewould be properly laid above center of massof the target if estimated range to the targetwere greater than 1,160 yards; or belowcenter of mass with ranges less than 1,160yards. The generated superelevation of10 mils with the M18 speed ring sight iscorrect for 1,080 yards range. Time per-mitting, the required superelevation to hitthe target may be determined by enteringthe tabular firing tables or GFT withangular height and particular range to thetarget as arguments. Algebraically addthe required superelevation to the angle ofsite and set the amount on the gunner'squadrant. Place the quadrant on the

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breech casing of the gun and elevate ordepress the gun tube until the quadrantlevel bubble is centered. Direct fire canbe used on targets up to 1,500-2,000 yardsrange.

98. Specific Methodsa. Stationary Targets.

(1) Computing sight MS8. Manual control isused for stationary surface targets. Afterspeed is zeroed the azimuth tracker usesthe M38 metal speed ring sight, and manu-ally alines the vertical sight reference lineon center of mass of the target. Adjust-ments for deviations in azimuth are madeby using the splash or burst as a referencefor moving the gun according to deviationsobserved by the azimuth tracker. Forexample, the azimuth tracker tracks off,moving the point of burst located in thesight (with reference to the vertical lightreference line) onto the target (fig. 46).Adjustments are continued until fire foreffect is ordered. In elevation, the eleva-tion tracker should use the reflex sightM24C, if mounted, instead of the metalspeed ring sight. The angle of site andsuperelevation are applied by trackingcenter of mass of the target with the hor-izontal sight reference line; then modifyingthis setting according to target range, bytracking higher or lower. Range deviationsare corrected by the splash-on-targetmethod of adjustment, i. e., the elevation

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tracker tracks off, moving the point ofburst located in the sight (with reference tothe horizontal sight reference line) onto thetarget (fig. 46). Adjustments are con-

fx

x

b.

a. SIGHT PICTURE WHEN FIRST SPLASH IS OBSERVEDb. SIGHT PICTURE AFTER PROPER ADJUSTMENT

Figure 46. Splash-on-target adjustment.

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tinued until correct, then fire for effect isordered.

(2) Speed ring sights. For all speed ring sights,the tracker(s) alines the vertical sight refer-ence line on center of mass of the target.The horizontal sight reference line is laidon center of mass, high, or low on the target,depending on range. Corrections for rightand left deviations and for range are madeby the splash-on-target method.

b. Moving Targets.(1) Computing sight M38. The speed knob is

set at zero and the course arrow disregarded.The azimuth tracker tracks the vertical sightreference line in the metal speed ring sighta specified amount ahead of the target,depending on estimated speed. The aver-age initial lead is one apparent target lengthahead of the leading portion of the target.The elevation tracker, using the reflex sightM24C, considers the present superelevationof the sighting device and tracks with thehorizontal sight reference line high, low,or center of mass on the target, dependingon range. Both trackers adjust by tracerobservation or splash-on-target.

(2) Speed ring sights. In utilizing speed ringsights on moving surface targets, manual oraided tracking may be used. The tracker(s)tracks off in both azimuth and elevation,depending on range and speed of the target.Adjustments are made by tracer observationor splash-on-target.

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Section III. INDIRECT FIRE

99. EmploymentThe following paragraphs refer only to the self-

propelled twin 40-mm gun M42. However, the samegeneral procedures and techniques apply to otherlight AAA (AW). When using indirect fire tech-niques in a surface mission, 40-mm guns are normallyemployed by platoon (4 weapons-8 barrels). Aplatoon fire direction center is located at or near theposition area. 40-mm guns are also employed usingthe direct command or tank azimuth procedures withno FDC (Fire Direction Center) which is discussedin paragraphs 105 through 107.

1i 00. Emplacementa. Due to the flat trajectory of the 40-mm pro-

jectile, gun positions must be carefully selected tosecure the maximum defilade and still provide thedesired target area coverage. To obtain the correctdensity of fire on all targets, it is desirable thatguns be emplaced about 20 yards apart so they canapply a parallel sheaf 60 yards in width. However,the tactical situation may often require that weaponsbe dispersed at a greater interval. If this results ina platoon front greatly in excess of 60 yards, cor-rections are applied at the time the platoon isoriented to reduce the width of the sheaf (par. 104).

b. No matter how the weapons are numberedwithin the platoon, guns in a surface-firing positionare normally numbered from right to left, facingthe direction of fire.

c. Gun carriages should be cross-leveled, whentime permits, to eliminate errors produced by cant.

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The level may be checked by using the gunner'squadrant on the two sets of quadrant seats (set atright angles to one another) located on the leftpedestal of the M42.

101. Calibrationa. Within the battalion, gun barrels should be

calibrated and barrels having similar shooting char-acteristics should be grouped together within eachplatoon and on each mount (FM 6-40). Thiscalibration should be conducted with instrumentsinitially by ordnance personnel. To supplementthis, or if no ordnance calibration is possible, thebattery should make a comparative calibration byfiring. However, as no firing table data are availablefrom which a VE (velocity error) may be computed,the relative shooting qualities of various barrels aredetermined by a comparison of corrections (K's) inyards per thousand yards of range. Using theaverage range of all centers of impact as standard,barrels are grouped according to their variationfrom that standard as expressed by a plus or minus K.

b. Within the platoon, the longest-shooting barrelsshould be used on the base piece because additionalfiring of that weapon will tend to reduce their muzzlevelocities faster than other weapons of the platoon.Calibration should be repeated as a check on sub-sequent barrel wear and barrels should be regroupedif necessary.

102. Orientation in ElevationSince each round is aimed in elevation with a

gunner's quadrant, no orientation in elevation isrequired. Quadrant seats are provided on the breechcasing of the left gun.

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103. Orientation in AzimuthSelf-propelled twin 40-mm guns are laid for direc-

tion by means of azimuth indicators. The M42 hasa clock-type azimuth indicator graduated in milsfrom zero to 6,400. For a more complete descriptionof the azimuth indicator, see TM 9-761A and FM44-61. There are two methods of orienting the gunsusing the azimuth indicator.

a. Known Datum Point Method. Bore sight theleft barrel of the gun by traversing to the knowndatum point. Without moving the gun, set theazimuth to that of the known datum point on theazimuth indicator, using the resetter knob.

b. Backsighting Method. In order to employ thismethod, an aiming circle must be available. Set upthe aiming circle at least 60 yards from the guns;orient it with reference to grid north, using the com-pass needle of the aiming circle or surveyed orientingline (FM 6-140). Bore sight the left barrel of thegun on the aiming circle by traversing it until theaxis of the bore coincides with the optical center ofthe aiming circle. With the azimuth knob (uppermotion), turn the line of sight of the aiming circleonto the axis of the bore of the gun barrel. Whenthe axis of the bore of the barrel and the line of sightof the aiming circle coincide, the back azimuth of theangle on the aiming circle is set on the azimuthindicator as described in a above. When each gunin the platoon has been oriented in a similar mannerand the same azimuth has been set off on the azimuthindicator, the gun barrels will be parallel.

104. Adjusting the Sheal of a PlatoonIf the width of the sheaf of a platoon is too great

for proper target area coverage (par. 100a), it may be156

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adjusted to an effective width by announcing specialcorrections in azimuth to each of the guns afterorientation. The platoon commander determines bythe mil relation the number of mils in azimuth eachgun must shift to close or open the sheaf to form a60-yard sheaf at a range of 3,000 yards. A range of3,000 yards is chosen arbitrarily as one which willcause a sheaf of optimum effectiveness to be formedat ranges customarily used. This shift is computedby determining the difference between the existingweapon interval and the desired interval (20 yards)for a 60-yard sheaf. This difference in yards isconverted to mils at 3,000 yards range, using the milrelation. Each weapon, except the base piece, istraversed toward (or away from) the base piece therequired number of mils. Without changing thepositions of the barrels, the azimuth indicators ofthese pieces are then reset to their previous reading.

Example:

a. Computation of Shift.

Platoon front ------------------------ 105 yardsBase piece -.............-- ----- Gun No. 2Interval between guns 1 and 2 ------------ 35 yardsDesired interval (60- 3)-..-- 20 yards

Difference --.................... 15 yards15.-3.0=5 mils

Interval between guns 2 and 3 --------- 30 yardsDesired interval -......---------- 20 yards

Difference ------------------------- 10 yards10- 3.0=3.3 or 3 mils

Interval between guns 2 and 4 - 70 yardsDesired interval - ..................---. 40 yards

Difference -----------.- ---- 30 yards30- 3.0= 10 mils

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b. Application of Shift. Guns have been orientedand laid parallel at azimuth 1,800 mils.

(1) No. 1 gun traverses to the left 5 mils (A,1,795) and resets azimuth indicator at1,800.

(2) No. 2 gun, the base piece, does not change.(3) No. 3 gun traverses to the right 3 mils (A,

1,803) and resets azimuth indicator at1,800.

(4) No. 4 gun traverses to the right 10 mils (A,1,810) and resets azimuth indicator at1,800.

105. Observer Procedure-GeneralTwo methods of bringing fire on targets by the

commands of an observer may be employed.a. Target Grid Procedure.b. Direct Command Procedure.

106. Target Grid ProcedureThis is the observer procedure described in FM

6-40. It is the normal procedure employed with allAAA weapons ii indirect surface firing.

107. Direct Command Procedurea. General. This method is intended primarily

for use with self-propelled light AAA (AW) firingfrom the protection of defiladed positions. It pro-vides a rapid, accurate means of placing fire ontargets at ranges beyond the effective vision (ap-proximately 1,500 yards) of on-carriage sights orwhen visibility from the guns is reduced by dust,smoke, defilade, or other causes. It is suitable foruse primarily with single weapons where a fire direc-

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tion center is not available. However, with propercoordination, it may be used to fire a platoon orbattery.

b. Limitation. Direct command procedure canbest be used when the displacement of the observerfrom the gun position in any direction is less thanone-tenth of the gun-target range (fig. 47). Theobserver may transmit his commands direct to thegun without resorting to the use of a fire directioncenter, as in target-grid procedure. However, if theobserver is located at a greater distance than thisfrom the guns, target-grid procedure is preferable.If it is apparent that more than one target is to be

DIRECTIONOF

1/10 TH OF GUN FIRE OBSERVER MAY BETARGET RANGE ANYWHERE WITHIN

SHADED AREA

Figure 47. Displacement of observer from gun position.

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engaged from any one position, the observer shouldselect an observation point so that his lateral locationfrom the gun is less than one-tenth of the gun-targetrange to the most critical target.

c. Initial Data. The squad leader of the self-propelled AAA (AW) weapons is normally theobserver. Upon entering a surface (indirect) firingposition, he determines certain initial data which arenecessary to orient the weapon and to place initialrounds on or near the target.

(1) Orientation. The squad leader selects a ter-rain feature which is visible from the gunas a reference point. He determines theapproximate azimuth from the gun to thereference point by means of a map or com-pass, or he may assume an arbitrary azi-muth for this direction line (par. 108).The weapon is oriented in azimuth by thetrackers alining the barrels on the referencepoint and setting the azimuth to that pointon the azimuth indicator.

(2) Initial firing data. From his observationpost near the gun, the observer determinesinitial data in azimuth and range which willplace initial rounds on or near the target.

(a) Azimuth. The observer determines theazimuth to the target by use of a com-pass, or by measuring the angle betweenthe reference point ((1) above) and thetarget with binoculars or any suitableangle-measuring device. The initial azi-muth is announced to the gun as AZI-MUTH (so much) in mils.

(b) Site. The difference in altitude between

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the gun and target is normally estimatedor scaled from a map. This differencein altitude, in yards, is converted to avertical angle in mils by use of the milrule. If an angle-measuring instrumentis available, the angle of site may bemeasured directly. This is announcedto the gun as SITE PLUS (MINUS) (somany) MILS.

d. Sequence of Fire Commands. Initial fire com-mands are transmitted in the following sequence:

Note. Fire commands used in the direct command proce-dure using only one piece are indicated with an asterisk (*).

Sequence Example(1) Pieces to follow comrn- NO. 1, ADJUST.

mands.(2) Projectile --------- SHELL HE.(3) Pieces to fire ------ (Omitted where the pieces to

fire are the same as the piecesto follow commands).

(4) Method of fire*_____ ONE ROUND (on twin-gunmounts, this command maybe preceded by the designa-tion of a single barrel tofire, e. g., RIGHT (LEFT)BARREL, ONE ROUND.If no mention is made ofbarrels, each barrel will firethe designated number ofrounds).

(5) Direction* -------- AZIMUTH 1,800.(6) Site* ------------- SITE PLUS 8.(7) Range* ----------- RANGE 4,000.

e. Application of Initial Fire Commands at the Gun.The initial fire commands of the observer are appliedto the weapon in the following manner:

(1) The first four commands serve to alert the

388163 0-56----11 161

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crew and designate the ammunition to beused.

(2) The command for azimuth is transmitted tothe azimuth tracker, who traverses theweapon to the announced azimuth.

(3) The commands for site and range are trans-mitted to the quadrant setter. From aGFT (graphical firing table), the quadrantsetter determines the elevation correspond-ing to the announced range. He adds theangle of site algebraically to this elevationand sets the resulting sum on the gunner'squadrant. When the quadrant bubble hasbeen leveled, he gives the command FIRE.

f. Subsequent Corrections. The observer adjuststhe fire of the gun on the target by sending correc-tions for subsequent rounds directly to the guns.Shots which are off the observer-target line arebrought to that line by commanding a shift in theappropriate direction in mils, e. g., RIGHT (LEFT)5. The target is bracketed for range, using normalobserver procedure, by commanding changes in rangein yards, e. g., ADD (DROP) 400. The initial rangechange should be large enough to insure bracketingthe target. This bracket is successively split untilthe target is within a bracket of suitable size, de-pending on the nature of the target. Fire for effectis begun at the center of that bracket. It shouldbe noted that at ranges up to 4,000 yards the frag-mentation effect of the 40-mm projectile is mainlyforward of the point of impact with some side sprayand a negligible amount of base spray. Therefore,when firing at less than 4,000 yards, fire for effect

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is normally placed short of the center of the target.Corrections are announced in the following sequence:

Sequence Ezample

(1) Change in ammunition ----- SHELL AP.(2) Change in method offire: for 10 ROUNDS, (or

example, to change the BOTH BARRELS).number of rounds uponentering fire for effect orto change from singlebarrel to twin barrels tofacilitate sensing.

(3) Deviation correction -------- RIGHT 10.(4) Range correction ----------- DROP 50.

Note. Subsequent corrections are always terminated witha correction for range. Any element which is not beingchanged may be omitted, except range; if no change isdesired in range, the observer sends REPEAT RANGE.

g. Application of Subsequent Corrections at Gun.(1) When a change in azimuth is announced

by the observer, the azimuth tracker tra-verses the gun until the new azimuth isset on the azimuth indicator. The azimuthtracker must bear in mind that azimuthsdecrease when moving to the left andincrease when moving to the right. Forexample, a shift of RIGHT 60 from anazimuth setting of 1,367 would result in anew setting of 1,367+60=1,427. A sub-sequent command of LEFT 35 wouldchange the setting to 1,427-35=1,392.

Note. The gunner's aid dial (outer dial) of the azimuthindicator is used as an aid in the computation of new azimuths(fig. 48). For complete instructions on the use of the azimuthindicator and the gunner's aid dial, see FM 44-61.

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I-MIL POINTERGUNNER'S AID RESETTER

DIAL _KNOB

100-MIL I-MILPOINTER SCALE

TANK 100-MILAZIMUTH SCALEPOINTER

Figure 48. Gunner's aid dial.

(2) In handling subsequent corrections in range,the quadrant setter uses the c (number ofmils elevation equivalent to a 100-yardchange in range) corresponding to theinitial range command. The value of c inmils is taken from a graphical firing table.The quadrant setter multiples c by therange correction expressed in hundreds ofyards. He adds the resulting value in milsalgebraically to the last quadrant fired.

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For example, assume a round was fired ata quadrant of 70 and that c=3 mils. If arange change of ADD 400 were ordered,the quadrant setter would set his quadrantat 70+3X4=82. A subsequent correctionof DROP 200 would result in a quadrantsetting of 82-3X2=76.

108. Direct Command Procedure Using Tank AzimuthsThe use of assumed tank azimuths provides a

rapid and effective means of preparing initial dataand orienting self-propelled weapons for firing, usingdirect command procedure. This method is espe-cially applicable to situations where neither the timenor the means are available to determine gridazimuths. To employ tank azimuths, the azimuthindicator of the weapon is set at zero with the gunslocked in the forward traveling position. Tankazimuths are clockwise angles measured from thecenter line of the vehicle with the front of the vehicleassumed to be zero azimuth (fig. 49). The observeruses the direction in which the vehicle is pointingas a basis for computing tank azimuths to targets.If time is available before the weapon occupiesposition, the observer selects a reference point towardwhich the driver will point his vehicle upon movinginto position. This reference point is assumed tohave an azimuth of zero mils and an approximateorientation on this assumed azimuth is accomplishedwhen the vehicle is lined up on this 'point. Theobserver determines the tank azimuth to the targetby measuring directly from the reference point.Before the weapon has occupied position, the driverhas the reference point identified to him and the

165

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/

I: V~

~~~jJ~ ~ ~

166~ ~~~~~~~~~~~~·

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crew is given sufficient data to enable the initialround to be fired immediately upon occupying posi-tion. These data should include:

a. Shell.b. Method of fire.c. Tank azimuth to target.d. Angle of site.e. Initial range.

109. Illustrative Example, Direct Command ProcedureArea fire mission; target, machine gun position;

mission, neutralization; materiel, one 40-mm weapon(M42). The weapon has been oriented on a referencepoint with an approximate azimuth. The observeris 120 yards to right of the gun position. He esti-mates azimuth to target as 1,800 mils. Range totarget is estimated at 4,000 yards and difference inaltitude is + 30 yards. Angle of site is therefore30--4=+8. The tabulated illustrative example isas follows:

167

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c ~~~~~~~I'

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173

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APPENDIX IREFERENCES

DA Pam. 108-1 Index of Army Motion Pic-tures, Television Record-ings, and Filmstrips.

DA Pam. 310-5 Index of Graphic TrainingAids and Devices.

DA Pam 310-series List of Training Publications.SR 320-5-1 Dictionary of United States

Army Terms.SR 320-50-1 Authorized Abbreviations.AR 385-63 Regulations for Firing Am-

munition for Training, Tar-get Practice, and Combat.

FM 3-5 Tactics and Technique ofChemical, Biological, andRadiological Warfare.

FM 5-15 Field Fortifications.FM 5-35 Engineers' Reference and Lo-

gistical Data.FM 6-40 Field Artillery Gunnery.FM 7-15 Heavy Weapons Company,

Infantry Regiment.FM 7-20 Infantry Battalion.FM 7-40 Infantry Regiment.FM 8-5 Medical Department Units of

a Theater of Operations.FM 8-10 Medical Service, Theater of

Operations.

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FM 20-32 Employment of Land Mines.FM 21-5 Military Training.FM 21-30 Military Symbols.FM 21-40 Defense Against CBR Attack.FM 21-41 Soldiers Handbook for De-

fense Against CBR Attack.FM 21-48 CBR Training Exercises.FM 25-10 Motor Transportation, Oper-

ations.FM 30-30 Aircraft Recognition Manual.FM 31-15 Operations Against Airborne

Attack, Guerilla Action,and Infiltration.

FM 31-50 Combat in Fortified Areasand Towns.

FM 44-1 Antiaircraft Artillery Employ-ment.

FM 44-8 Antiaircraft Operations Cen-ter and Antiaircraft Artil-lery Information Service.

FM 44-57 Service of the Piece, MultipleCaliber .50 Machine-GunMotor Carriage M16 andMultiple Caliber .50 Ma-chine-Gun Motor CarriageM55.

FM 44-61 Self-Propelled Twin 40-mmGun T141.

FM 100-5 Field Service Regulations,Operations.

FM 100-10 Field Service Regulations,Administration.

FM 100-11 Signal Communications Doc-trine.

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FM 101-10 Staff Officers' Field Manual,Organization, Technical,and Logistical Data.

TM 9-761A Self-propelled Twin 40-mmGun M42 T141.

TM 44-234 Antiaircraft Artillery ServicePractice.

ATT 44-3 Antiaircraft Artillery Auto-matic Weapons Battalion(Self-Propelled).

ACP 125 Joint Communications In-structions, RadiotelephoneProcedure.

JANAP 164 Joint Radiotelephone Proce-dure for the Conduct ofArtillery and Naval Gun-fire.

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APPENDIX II

ANTIAIRCRAFT ARTILLERY (AUTOMATICWEAPONS) TRAINING AIDS

388163 0-56 12 177

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5 .

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-7

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179

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V VY

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teo

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Figure 60. Computing sight aid. Made of /%" rods paintedred and white. Model aircraft slides on target course rod.Do and D, rods pivot at base. Target course arrow moves inall directions.

182

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Figure 61. Azimuth indicator aid. Mounted on heavy card-board, the indicator arm and center pivot are wood and arepainted black. Dial is drawn on face of cardboard.

183183

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APPENDIX 111

MATHEMATICAL ANALYSIS OF LEAD

1. Analysis of Required Lead Equation

Sin LR = V t Sin aD.

This equation means that the sine of the requiredlead angle (sin LR) is the product of: target speed (V)in yards per second; the quotient of a value for slantrange divided into its corresponding value of time of

flight (, the range factor); and the sine of the

angle of approach (sin a). These factors will beanalyzed individually to determine their effect onthe magnitude of the required lead.

a. V (Speed). In order to visualize the effect ofvarying speed on the value of the required lead,

assume that the remaining factors (DP and sin a

are constant. Assign them values, the origin ofwhich will be seen below, then insert varying speedsinto the equation. Assuming a value of 0.00116 for

DP Xsin a and V=]00, 200, and 400 yd/sec, respec-

tively:

sin Lg==100X0.00116=0.11600 then; LR=118 milssin LR=200 X 0.00116=0.23200 then; LR= 238 milssin LR=400X 0.00116=0.46400 then; LR=491 mils

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Thus it is clearly shown that by doubling speed, thevalue of sin LR is doubled, and for all practical pur-poses, the magnitude of LR itself is doubled. There-fore, for all practical purposes, the magnitude ofthe required lead angle varies directly with the targetspeed.

b. t or Range Factor. Because of the high muzzle

velocity developed by AA (AW), the range factor isalmost constant within the effective ranges of anti-aircraft artillery automatic weapons sighting devices.Time of flight increases or decreases almost propor-tionally to range. In order to observe the smallvariations of the numerical value of this factor, selectthree future ranges, extract corresponding times offlight from 40-mm firing tables, divide them by theranges, and compare the resultant range factors:

D, (yards) t, (seconds) Range factor

500 0. 58 0. 00116\,0 00007

1, 000 1. 23 0. 00123 00009>0. 00016

1, 500 1. 98 0. 00132/

Between 500 and 1,000 yards the difference is only0.00007; between 1,000 and 1,500 yards the differenceis only 0.00009. Between 500 (a short range) and1,500 yards (close to maximum effective range ofAAA automatic weapons), the variation is only0.00016. How will this variation affect the magni-tude of the required lead? By selecting a speed of400 mph (200 yds/second) and comparing futureranges of 500 and 1,500 yards, the lead required tohit the target with TO at midpoint can be computed.

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(When To is at midpoint, the angle a is 900 and sin ais 1.0).

For D, of 500 yards: For Dp of 1,500 yards:

sin LR=200X0.00116X1 sin LR=200XO.00132X1sin LR=0. 232 00 sin LR=0.2640 0

LR= 2 3 8 Xi LR=272ir

The required lead has changed only 34 X for 1,000yards change in range; an average of only 3.4 fi per100 yards of range change at midpoint. Since theeffect of varying range as expressed by the rangefactor is so slight, the two types of sighting devicesused with AAA (AW) were designed about a fixedvalue for this factor. This assumption permittedthese sights to be simple, light, and rugged, with arelatively small sacrifice in accuracy.

c. Sin a. The angle of approach is always meas-ured from To to C and T,. It is an acute angle onthe approaching leg, a right angle at midpoint, andan obtuse angle on the receding leg; varying, intheory, from 0° to 1800. In the required lead equa-tion, use the sine of the angle of approach whichvaries from 0 to 1 for corresponding values of theangle a. Thus, the effect of sin a as a factor in therequired lead equation will be the reduction of therequired lead far out on the approaching and recedinglegs and an increase to maximum at midpoint.Hence, the value of the sine of the required leadangle varies directly with the sine of the angle ofapproach. Now that the factors of the requiredlead equation have been analyzed, the required leadand the equation should be used to compare LGwith LR. This permits an evaluation of differentsights and the methods by which they may be putto use.

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2. Required Lead Curvea. The first step in such an evaluation is the prep-

aration of a graphical representation of the requiredlead throughout a given target course. *By assuminga target speed (V) and midpoint range (Di), a targetcourse and its location in relation to the gun aredetermined. These are all the facts needed forcomputing a lead curve, since a slant plane has beenestablished. By selecting sucessive values of Dp andby the trigonometric solution of a series of triangles,a series of values for LR in mils are computed. Thesevalues are plotted against time (in seconds) requiredfor the target to fly from To to midpoint. This plotwill yield the lead required to make the projectileintersect the center of mass of the target at differentlocations along the course line. The following are thecomputations involved in determining points withwhich to plot a required lead curve, assuming V as200 yards/second and Dm as 600 yards.

b. Midpoint range and target speed must beassigned for each curve to be computed (fig. 62).

V------

Dm

GFigure 62. Midpoint range and target speed.

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c. A DP is selected within the maximum effectivehitting range of the weapon (fig. 63).

d. Knowing Dp, a corresponding value for tp maybe extracted from firing tables.

e. To obtain distance ToT,, multiply V by t,.This further locates To, a, and L (fig. 64).

T. Tm

aD Dm

GFigure 63. Selected D,.

T Vt Tp

P Dm

G

Figure 64. Location of To, a, and L.

f. The angle GTpTm equals (a+L), since it is sup-plementary to angle GTpTo. Therefore, in the right

triangle GTpTm; sin (a+L) . Thus the valueDp

(a+L), may be found in mils.

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g. To determine distance TT, (necessary for thesolution of triangle GToTm):

Tan (a+L= m or TpTm=TpT. oT mtan (a+L)

h. To determine distance TOTm:ToTm=ToTp,+T,Tm. When To is less than t,

seconds from Tm (on the approaching leg only):ToTm= TpTm- TT,. When TO is on the reced-

ing leg:To=T- TmT,- TTP,.

i. To determine a:

Tan a= -DoTm

j. Once a has been determined, subtract it from(a+L) to obtain LR.

k. To determine the time required for the targetto fly from To to Tm (the second argument for theplot of the curve); divide distance ToTm by V to ob-tain time in seconds from midpoint. Figure 650 isa typical required lead graph to hit center of mass.

1. Figure 65( is the required lead graph for hittingthe tail and nose of the same target in figure 650.To plot these curves, subtract one-half the length (1)of the target (for LT) and add %2 the length of thetarget (for LEN).

The formulae for plotting the curves are then:

1Sin l'N=(D to nose) Sina

Sin LT to ta Sin

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240

220

LEAD 200

MILS160

80

1460

12 10 8 6 4 2 0 2 4 6 8

T. - TIME IN SECONDS FROM MIDPOINT

Figure 66. Required lead graphs.

240 _ _ _ -

220

200 N:LEAD 180

IN L RN

MILS 160 :- -

120

_-_ - -'i . .--.- t-- t :I00

6012 10 8 6 4 2 0 2 4 6 8

T.-TIME IN SECONDS FROM MIDPOINT

Figure 65.-Continued.790

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3. Generated Lead Curvea. General. Each type of sighting device solves

the lead problem in a different manner. The leadgenerated by these devices, however, is based onsome variation of the required lead equation. Tounderstand each sighting device more fully and to beable to intelligently analyze the lead performance ofa gun crew, the supervising officer should know howthe solution of lead of a sight compares with therequired lead.

b. Speed Ring Sights. The speed ring sightgenerates a lead based on an estimated speed, afixed (F), range factor, and fixed angle of approach.The generated lead equation for speed ring sights is:

sin L = V (sin a)F

Dp for all speed ring sights is 1,000 yards. (sin a)F isa constant 1.00, because a is 900. Assuming a speedof 400 miles per hour, utilizing a 40-mm gun, theequation becomes:

1.23sin LG=200X 1-3 X1.00=.2460

LG=253r1 (approx)

If a target traveling 400 mph, and flying a coursewith a midpoint range of 600 yards, were trackedon the 400 mph speed ring, the lead generated wouldbe too great for the entire course. The rule, however,is to track on the speed ring representing %4 estimatedtarget speed. The generated lead equation thenbecomes:

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1.23sin L=150OX Xoo1.00=.1845

L o=189ni (approx)

To graphically compare this generated lead with therequired lead, draw a line on the line representing189 ri on figure 650. It can be seen that thegenerated lead comes within the required lead curveat only two places. This, however, is better thanhaving the lead too great throughout the entirecourse, thus the reason for applying the %8 speed rule.

c. Computing Sights. The computing sight gen-erates a lead based on estimated speed, fixed, (F),range factor, and a variable angle of approach.. Thegenerated lead equation for computing sights is:

sin La=V(t ) sina

D, for computing sights is 900 yards.t, is a constant 1.09 seconds.Assuming a speed of 400 miles per hour, at midpoint,utilizing a 40-mm gun, the equation becomes:

1.09sin LG=200X X1.00=.218900

La=224i (approx)

If a target traveling 400 mph, and flying a coursewith a midpoint range of 600 yards, were trackedwith a computing sight speed set at 400 mph and thetarget course arrow was set parallel to the targetcourse line, the lead generated would be-withintolerance (fig. 66). With the generated a changing

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all along the course, however, the lead would change.Utilizing a target course of 600 yards midpoint rangeand a speed of 400 mph, it is then possible to solveand plot the generated lead curve for computingsights. By superimposing the LG curve over the LRcurve for the same course, it is possible to analyzethe lead performance of the computing sight (fig. 66).

260

IN 240T C

160 i I I

D, t . ii mRT N

180 ... , = .

60

1 60 ; 6 4 2 ' 2 4- :. :

Figure .. Re: uired and generated lead: I .

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APPENDIX IV

GLOSSARY OF ANTIAIRCRAFT ARTILLERYAUTOMATIC WEAPONS SYMBOLS AND

TERMS

Section I. SYMBOLSSymbol Name Dcfinition

a________ Alpha ------- Angle of approach.L-- . .... L -------- Lead angle.LG ------ L sub G --. Generated lead angle.

LR------ L sub R- ... Required lead angle.D/-- .... D -------- Slant range.D, ------ D sub m ... Slant range to midpoint.

DO . . .... D sub o ---- Slant range to present (observed)position.

Dp ...... D sub p- ... Slant range to future (predicted)position.

E-- . .... E ------- Angular height.E,..- . .E sub m ---- Midpoint angular height.E..- .... E sub o ---- Present (observed) angular height.E._.-.. E sub p ---- Future (predicted) angular height.E. . ...... E sub s ----- Slant plane angular height.a------- G -------- Pintle center of the gun...------ phi -------- Quadrant elevation.

-, ------ phi sub s ... Superelevation.tp t sub p --- Time of flight.IV V ------ --- Speed of target.T- . ..... T -------. Target position.Tm ..... T sub m --- Midpoint.To . - --- T sub o ---- Present (observed) position.T-_-.... T sub p ---- Future (predicted) position.

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Section II. TERMS

Ahead-In tracer observation, a sensing on a tracer,which passes in front of the target.

Angle of approach-The angle formed by T,, Tp, andG with the apex at To.

Angle of site-In surface gunnery, the vertical anglebetween the gun-target line and the horizontal.

Approaching leg-That portion of the target courseline where the target is flying toward midpoint.

Astern-In tracer observation, a sensing of a tracerwhich passes to the rear to the target.

Center of mass-That point representing the meanportion of matter in a given target.

Climbing course-A target course with increasingaltitude.

Cone of sight-In tracer observation, a general conewith the apex at the observer's eye, having a crosssection shaped as the contour of the target andextending to infinity.

Crossing course-Any target course which does notpass directly over the gun.

Directly-at-the-gun course-A target course line whichpasses through the pintle center of the gun.

Diving course--A target course with decreasing alti-tude.

Downcourse observer-In tracer observation duringfiring practice, a person stationed a specified dis-tance from a gun or guns opposite the receding legof a previously determined course for the purposeof obtaining lead sensings.

Eclipse-In tracer observation, a tracer beingmomentarily blotted out by the target as it passesbetween the tracer and the observer.

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Fly-through-A condition in firing where the leadangle generated by the sighting device is equal tothe mathematically correct lead angle required tohit any portion of the target.

Fly-through time interval-The length of time duringwhich a fly-through occurs.

Gunnery chain-A set of four conditions, or steps,which help to meet the two requirements for a hit.

High-In tracer observation, a sensing of a tracerobserved to pass above the target.

Horizontal plane-A geometric plane surface estab-lished by the point at the pintle center of the gunand all other points at that same elevation dis-regarding curvature of the earth.

Image spin-The apparent climbing, level flight, anddiving of a target while flying a crossing course.

Incoming course-A target flying toward a line erectedperpendicular through the pintle center of the gun.

Lead tolerance-Half the angle subtended at the gunby the length of the target.

Level course-A target flying at, a constant altitude.Line-In tracer observation, a tracer which pierces

the cone of sight.Line tolerance-One-half the angle subtended at the

gun by the diameter of the target fuselage.Low--In tracer observation, a sensing on a tracer

passing below the target.On-In tracer observation, a sensing on a tracer cor-

rect for line and/or lead.Outgoing course-A target flying away from a line

erected perpendicular through the pintle centerof the gun.

Receding leg--The portion of the target course linewith the target flying away from midpoint.

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Silhouette-In tracer observation, the tracer is super-imposed over the target in the background.

Sight reference axis-A line through the optical orgeometric center of a sight, perpendicular to thegeometric plane formed by the reticles or concen..tric rings of the sight.

Target course line-A straight line of infinite lengthformed by the longitudinal axis of a target fuselage.

Target path-The course a target actually takes inflight; not necessarily a straight line.

Tracer control-The art of adjusting fire based oninformation from tracer observation.

Tracer hump-An optical illusion of curvature of atracer stream exhibited when firing at movingtargets; the point of maximum apparent tracercurvature.

Tracer observation-The technique of visually determ-ining the location of projectile tracers in relationto a target.

Tracer sensing-A decision as to the relative positionof a tracer to a target made by observation.

Tracker's line of sight-A line from a tracker's eyethrough or along a sighting device.

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INDEX

A AA (AW) employment of: Paragraph PageAA mission ----------------------- 4 4General mission ------------------- 3 4Surface mission ------------------- 5 5

AAA (AW) problem ------------------- 61 63AAA (AW) weapons, characteristics and

capabilities ------------------------- 28-32 18AAAIS ------------------------------- 48 48AAOC ------------------------------- 48 48AAOO - - -- - -- -- -- --- 7 5Action status ------------------------- 47 47Air defense warning, conditions of ------- 47 47Alternate positions --------------------- 38, 51 32, 50Ammunition, types and uses ----------- 27 17Basic assumptions ------------------ 61 63Battalion:

Commander ---------------------- 7 5Organization --------------- 6 5Reconnaissance -- --- ----- 33 25Staff ----------------------------- 8-18 6

Battery:Commander -- ___- 20, 22 14, 15Organization --------------------- 19, 21 14Reconnaissance --------------- 33 25

Calibration -------- 101 155Characteristics of AAA (AW) weapons --- 28-31 18Clearance, mine emplacement ----------- 52 51Communication:

General -------------------------- 40, 43 35, 37Nets ----------------------------- 44 38Radio ---------------------------- 41, 45 36, 40Wire ------------------------------ 42, 46 37, 45

Condition of readiness ------------ 47 47

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Defense: Paragraph PageAA ------------------------------ 33-35 25Perimeter ------------------------- 52 51Surface ------------- ------------ 36-39 30

Definitions:Angular height_ ----------------- 67 70Lines ---------------------------- 66 66Planes_ -......................... 64 65Points --------------------------- 65 65Slant range -- 66 66Symbols -------- ------- ------ App. IV 194

Direct command procedure ----------- 107-109 158DIRECT fire:

Adjustment ----------- -------- 98 151Angle of site --------. --------. 97 148Azimuth ------------ ---- --- 97 148Elevation --- - _ .................. . 97 148Range --------------------------- 96 147Superelevation .------------- 97 148

Dummy positions----------------- 38, 51 32, 50Duties of-

Battalion commander -------------- 7 5Battalion staff--------------------- 8-18 6Battery officers --------------- 19-22 14Fire unit leader -- ----- 25 15

Elements of data:AA fire, definitions -------------- 63-67 64Surface fire, definitions ------------- 96 147

Emplacement, considerations in --------- 35, 39 29, 33Engagement, rules for .--------- 25, 86, 88 15, 111,

119Fire:

Adjustment, surface fire -- 98, 104, 107, 109 151, 156,158, 167

Direction center (FDC) ----------- 99, 107 154, 158For effect ------------------ 98, 107, 108 151, 158,

165Indirect ------------------------- 99-108 154Sector of ------------------------- 34, 35 25, 29

Fortifications .-.. ............... 51 50Future position -.---------------------- 65 65

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Paragraph PageGlossary --------------------------- App. IV 194Ground defense ---------------------- 50-52 50Gunnery, definition -------------------- 61 63Gunnery chain, links of________ 69, 72, 73, 86, 90 73, 78, 81,

111, 125Headquarters battery ------------------ 19 14Hopeless case ------------------------- 87 118Indirect fire ------------------------- 99-108 154Laying:

Direct command ---------------- 107-109 158Direct fire ------------------------ 94-98 146

Lead:Generated --------------------- 67,86,90 70, 111,

125Initial ---------------------------- 98 151Required ------------ ____ 67, 70,73,86,90 70, 74, 81,

111, 125Sensings -------------------------- 76-79, 81 90, 96Tolerance- . ................ 70, 72, 73 74, 78, 81Leveling:

Computing box --------------------- 91, 92 129, 139Weapon mounts --------------------- 35 29

Line:Establishment --- ____--- 68, 70, 71, 72, 87, 93 73, 74,

77, 78,118, 144

Shot ------------------------------- 76 90Tolerance -------------------------- 70,72 74,78

Loading plan --------------------------- 57 60Local security:

Materiel ---------------------------- 52 51Plan ------------------------------- 52 51Responsibility ------------- 52 51SOP ------------------------------. 52 51

Limitations:Radio communications --------------- 41 36Wire communications ----------------- 42 37

Machine guns -.- - - --- 28-31 18Medical service -..-.- 56 60Messing .----------- -- ------------... 59-60 61Mines, booby traps --------------------- 52 51

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Mission: Paragraph PageAir defense ------------------------- 4 4General ------------------- - -------- 3 4Surface ---------------------------- 5 5

Mobility -------------------- - ----------- 58 61Occupation of position -----------..------ 35, 39 29, 33Off-mount observer ------------- _------ 107, 108 158, 165Organization, battalion --------------...- - 6 5Orientation:

Computing sight ------------- - ------ 91 129S/R Sight -------------------------- 85, 86 109, 111Surface mission -------------- __--- 102, 103 155, 156

Passive defense ---------------- - -------- 51 50Perimeter defense:

Daytime ----------------- - --------- 52 51General ------------------ - --------- 52 51Night time ---------------- - -------- 52 51

Position:Alternate ---------- , . ..___, 38, 51 32, 50Dummy ---------------------------- 51 50Future ----------------------------- 65 65Occupation ------------------------- 35, 39 29, 33Present ---------------------------- 65 65Selection --------------------------- 35, 39 29, 33

Present position ------------ -.--------- 65 65Problem, the LAA (AW):

Analysis and application ------------ 71-73 77General -------------------------- 61 63Solution ------------------------- 68-70 73

Radio:Nets ----------------------------- 44, 45 38, 40Transmission security --------------- 43 37

Range:Slant ---------------------------- 66 66Horizontal ------------------------ 96 147

Reconnaissance:Aerial ---------------------------- 34 25Battalion ------------- 34 25Battery ------------------- 34 25Ground -------------------------- 34 25Map ----------------------------- 34 25

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Reconnaissance-Continued Paragraph PagePlatoon -------------------------- 34 25Surface -------------------------- 36-38 30Types --------------------------- 34 25

Reconnaissance, selection, and occupationof position (RSOP) - 33-39 25

Recognition, aircraft .--------------- 49 49References --------------------------- App. I 174Rules of engagement - 25 15Security, local ------------------------ 50, 52 50, 51Sights:

Computing .--------------------- 89 120M/18 ---------------------------- 83-88 104Speed ring ---------------- 85 109M 24C-.-------- -------- ------- 91 129

Slant Plane Concept ------------- __---- 62, 63 64Standing operating procedures (SOP) - 52 51Superelevation:

Definition ------------------------ 67 60Establishing ---------- - 69, 72, 73, 86, 90 73, 78, 81,

111, 125Initial insertion ------------------- 91 129

Supply:Agencies ------------------------- 54, 55 59Classes -------------------------- 53 58Evacuation ------------------------ 56 60

Symbols:AA (AW) gunnery -_- . ........__. . 65, 67 65, 70Glossary ----------------------- App. IV 194

Target, AA (AW) assumed -------------- 61 63Tracer observation:

Basic principles --------- -.------ 75 85Crossing courses ---- ----------__--- 76, 79 90, 94Directly-at-the-gun ---------------- 80 95Downcourse ---------------------- 81 96Incoming courses ------------------ 77 93Outgoing courses ------------------ 78 94

Trajectory, curvature of --------------- 80 95Transportation:

Mobility and Security ------------- 58 61Organic -------------------------- 57 60

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Warning: Paragraph PageAir Defense ---------------------- 47 47Signals .--.......................... 51 50

Warning system, necessity for ..- . ...... 47 47Wire:

Nets ----- ------------ ------------ 46 45Use of-....- - 42 37

[AG 472.93 (1 May 56)]

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By Order of Wilber M. Brucker, Secretary ofthe Army:

MAXWELL D. TAYLOR,General, United States Army,

Official: Chief of Staff.JOHN A. KLEIN,

Major General, United States Army,The Adjutant General.

Distribution:Active Army:

Tec Svc, DA (1) AAA Gp (10)Tec Svc Bd (2) Abn Gp (2)Hq CONARC (13) FA Bn (2)Army AA Comd (5) Armd Bn (2)OS Maj Comd (5) AAA Bn (5)OS Base Comd (5) AAA Btry (5)MDW (1) USMA (10)Armies (10) Gen & Br Svc Sch (5)Corps (3) except CGSC (10)Div (5) PMST FA ROTC UnitsTng Cen (2) (2)AAA Brig (10) PMST AAA ROTCFA Gp (2) Units (2)Inf Regt (2) Mil Dist (3)Armd Gp (2)

NG: State AG (6); units--same as Active Army exceptallowance is one copy to each unit.

USAR: Same as Active Army except allowance is onecopy to each unit.

For explanation of abbreviations used, see SR 320-50-1

U. S. GOVERNMENT PRINTING OFFICE: 1956 0 -388163 205