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Copyright © 1999 by Willy Radinger & Wolfgang Otto.Library of Congress Catalog Number: 99-066588

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Contents

6 Dedication

7 Foreword

8 Introduction

14 Bf 109 F-1 and F-2

16 High speed trials

19 Bf 109 F-4

20 Testing of underwing armament

23 The Bf 109 Gustav series

33 The Bf 109 H high-altitude fighter

35 Bf 109 K

39 Bf 109 L

40 Me 109 Z/Me 609

42 Preliminary experiments for the Me 209

43 The Messerschmitt Regensburg factory, aircraft production Bf 109 G

50 Color section

65 Photo section

151 Trials with 660 x 150 wheels

Dedication

I was associated with the Bf 109 fromthe first stroke of the pen until (he testflights to determine its terminal divingspeed. And this is how it happened: aftermy final examination as a machine con-struction engineer in 1931 and my subse-quent employment in a textile machine fac-tory, in 1934 I moved to the BayerischeFlugzeugwerke at Augsburg-Haunstetten.There I was initially employed in the de-sign bureau, "wing department." under thedirection of Dipl.-Ing. Robert Prause. Itwas there that I first came into contact withthe Bf 109. which was then being workedon under Project Number P 1034. Amongother things I designed the wing cutouts forthe retractable main undercarriage. Thenfrom 1937 I was active as group leader inthe preparation bureau, where I was in-volved exclusively with the developmentof the Messerschmitt variable-pitch propel-ler (Me P 6, Me P 7, Me P 2). From October1937 up to and including June 1938 Iearned my military pilot's license at the"Flight Practice Station Munich-Oberwie-senfeld."

Back to Messerschmitt — the BFWGmbH became the Messerschmitt AG in

1938. At first I continued working on thevariable-pitch propellers, but I also con-ducted individual and endurance trials withthese. Because of this the managementmoved me to the flight test department asan engineer-pilot. Since I had amassed alarge number of hours testing propellers,virtually all of the flight tests associatedwith the development of this type were giv-en to me. Through these many and variedmissions I came into intimate contact withthe Bf 109 and its variants. Approximately80% of all my flights were in the Bf 109. Aswell. I made similar test flights with the Bf108 (propeller), Bf 110, Me 210, Me 309,Me 410, and toward the end of the war alsoin the twin-engined Me 262 jet.

I remember one test flight, which willbe the subject of its own chapter, especiallywell: determining the terminal dive veloci-ty of the Bf 109 (G-series). Carrying outthis task was the high point of my flyingactivities in general, and with the Bf 109 inparticular.

I wish this Bf 109 book many readers,especially younger ones who have grownup in the "jet age," so that they might gainsome idea of what "propeller flying" waslike back then.

Augsburg, 12 June 1996Lukas Schmid

6

Foreword

The first volume on the early versionsof the legendary Bf 109 has proved verypopular with readers. Now the second vol-ume on the Bf 109 F to K plus several spe-cial developments up to the preliminary ex-periments for the Me 209 record-breakingmachine and the Me 309. Messersehmitt'slast propeller-driven fighter, is ready. Thisvolume, too. concentrates on the technicalaspects and testing of this remarkable air-craft.

First several comments on type desig-nation: since this aircraft was created bythe Bayerischen Flugzeugwerke, it wasdesignated the Bf 109. In 1938 the Bay-erischen Flugzeugwerke became the Mess-erschmitt AG, however, the earlier designa-tion continued to be widely used. However,the designation Me 109 also came into use.including in official documents, and itbecame very popular, especially outsideGermany. For reasons of simplicity, in thisbook all series are identified as Bf 109.while the subsequent new developmentsare designated Me 209 and Me 309.

The Bf 109 F to K were the most po-tent versions of this successful standardLuftwaffe fighter. Few other fighters re-mained in production for more than ten

years and were built in such a plethora ofvariants, and the development potential ofthe basic Bf 109 concept of 1935 is aston-ishing. But, as the Allies introduced newer,more potent fighters during the course ofthe Second World War the limits of the Bf109 became increasingly apparent. Never-theless, it must be acknowledged that WillyMesserschmitt had created a ground-breaking design in the Bf 109. The Bf 109is one of the most interesting and importantaircraft in aviation history. This is under-lined by the fact that several air forces, in-cluding those of Czechoslovakia. Spain.and Israel, used the Bf 109 with great suc-cess in the postwar period.

Co-author of this volume is Herr Wolf-gang Otto, who carefully evaluated the ex-tensive original sources and documents.My thanks also go to Herr Dieter Herwig.who made available many photographs andtechnical material. This book is enriched —as was the first volume — by the outstand-ing drawings of Günter Sengfelder. In se-lecting the photos and proof-reading thebook I was again able to rely on the supportof Hanfried Schliephake, whom I wouldlike to thank most sincerely at this point.

I hope that this volume, too, will findmuch interest among readers.

Willy RadingerAuagburg, October 1998

7

Introduction

Bf 109 Bf 109 F to KThe Messerschmitt Bf 109 in its many ver-sions and prototypes from "Friedrich" to"Konrad."

The Messerschmitt Bf 109 is one ofthe most significant designs produced bythe German aviation industry.

Designed by Willy Messerschmitt, itsbasic design was adapted to accept engineswith outputs of 600 to 2,000 H.P. during itsproduction life and achieved speeds from450 kph to 720kph.

List of VariantsOrganized according to TypeCompared to the Bf 109 E, the Bf 109 Fwas much improved in terms of aerody-namics. To achieve this the entire aircraft,including the wing, was redesigned.

Bf 109 F-01 V21 D-IFKQ; CE + BNWerk-Nr. 5602Bf 109 F-02 V22 D-IRRQ; CE + BOWerk-Nr. 1800Bf 109 F-03 V23 CE + BPWerk-Nr. 5603Bf 109 F-04 V24 VK+ABWerk-Nr. 5604

Bf 109 F-0 10 pre-production machines

Bf 109 F-1

Motor:Armament:Radio equipment:

DB 601 N2 MG 17,1 MG FF/M (motor cannon)FuG VIIa R/TSupercharger air intake of "Emil" variant.Werknummer blocks from 5605 to 5620, all builtat Regensburg.

Surviving specification from 16 June 1941Motor: DB 601 NArmament: 2 MG 17,1 MG FF/M (motor cannon)Radio equipment: FuG VIIa

First version with larger supercharger air intake(more aerodynamic)

Bf 109 F-2 Surviving specification from 16 June 1941Motor:Armament:Radio equipment:

DB 601 N2 MG 17,1 MG 151/15 (motor cannon)FuG VIIaWerknummer blocks from 5758 beginning inMarch 1942

8

Bf 109 F-2/B Fighter-bomber version of the F-2Motor: DB 601 NArmament: 2 MG 17,1 MG 151/15 (motor cannon)Radio equipment: FuG VIIa

ETC 250 bomb rack

Bf 109 F-2/Z Surviving specification from 18 September 1941Motor: DB 601 NArmament: 2 MG 17,1 MG 151/15 {motor cannon)Radio equipment: FuG VIIa

GM 1 system installed

Bf 109 F-2/trop Surviving specificationMotor: DB 601 N 1,175 H.P. for takeoff at 2,600 rpmArmament: 2 MG 17, 1 MG 15 1/15 (motor cannon)Radio equipment: FuG VIIaSand filter in front of supercharger air intake. Tropical equipmentsuch as rifle, rations, water, flare pistol

Bf 109 F-3

Bf 109 F-4

Project onlyMotor:Armament:Radio equipment:

FighterMotor:Armament:Radio equipment:

DB 601 E, 1,350 H.P. for takeoff2 MG 17,1 MG 151/15 (motor cannon)FuG VIIa

DB 601 E, 1,350 H.P. for takeoff2 MG 17,1 MG 151/20 (motor cannon)FuG VIIa

Bf 109 F-4/B Fighter-bomber equipmentMotor: DB 601 E, 1,350 H.P. for takeoffArmament: 2 MG 17,1 MG 151/20 (motor cannon)Radio equipment: FuG VIIa

Bf 109 F-4/trop FighterMotor:Armament:Radio equipment:

Bf 109 F-4/Z

DB 601 E, 1,350 H.P. for takeoff2 MG 17,1 MG 151/20 (motor cannon)FuG VIIaSand filter in front of supercharger air intake.Tropical equipment such as rifle, rations, water,flare pistol

F-4 with GM 1 systemMotor: DB 601 E, 1,350 H.P. for takeoffArmament: 2 MG 17,1 MG 151/20 (motor cannon)Radio equipment: FuG VIIa

9

Bf 109 F-4/R1 Bomber destroyer with underwing armament(1 MG 151/20 beneath each wing)Motor: DB 601 E 1,350 H.P. for takeoffArmament: 2 MG 17,1 MG 151/20 (motor cannon)Radio equipment: FuG VIIa

Bf 109 F-4/R6 ETC rack for 295-l drop tank or 1 SC 250 bomb or withER 4 adapter 4 SC 50 bombsMotor: DB 601 E 1,350 H.P. for takeoffArmament: 2 MG 17, 1 MG 151/20 (motor cannon)Radio equipment: FuG VIIa

Bf 109 F-4/B Reconnaissance version, existed only as prototypeMotor: DB 601 E 1,350 for takeoffArmament: 2 MG 17Radio equipment: FuG VIIaRb 20/30 mounted in fuselage

Bf 109 F-6 Reconnaissance version of the F-4, existed only as prototypeMotor:Armament:Radio equipment:

DB 601 E 1,350 H.P. for takeoffnoneFuG VIIaRb 20/30, Rb 50/30, Rb 75/30 mounted in fuse-lage behind the cockpit. The only existing "F-6"was Galland's personal machine with additionalarmament of 2 x MG/FF

Bf 109 G-0 VJ + WA 12 prototypes

Bf 109 G-1 Light fighter with pressurized cockpit, data sheet from 8 March 1943Motor: DB 605 AArmament: 2 MG 17 and 1 MG 151/20Radio equipment: FuG VIIa + XXV

Bf 109 G-1/R2 Light fighter with pressurized cockpit, data sheet from 8 March 1943Motor:Armament:Radio equipment:

DB 605 A2 MG 17 and 1 MG 151/20FuG VIIaNo underwing armament, no head or back armor,no light metal armor, no protected tanks, nobombs or drop tank

Bf 109 G-1/U2 Light fighter with pressurized cockpit and GM 1Data sheet from 8 March 1943Motor: DB 605 AArmament: 2 MG 17 and 1 MG 151/20Radio equipment: FuG 16ZEquipped weight: 2600 kg

10

Bf 109 G-2 Light fighter without pressurized cockpit,data sheet from 8 March 1943Motor: DB 605 AArmament: 2 MG 17 and 1 MG 151 /20Radio equipment: FuG VIIaEquipped weight: 2520 kg

Bf 109 G-2/R2 Reconnaissance aircraft with Rb 50/30, data sheet from 8 March 1943Motor:Armament:Radio equipment:Equipped weight:

DB 605 A2 MG 17 and I MG 151/20FuG 16Z2619 kg

Bf 109 G-3 Light fighter with pressurized cockpit, data sheet from 8 March 1943Motor: DB 605 AArmament: 2 MG 17 and 1 MG 151 /20Radio equipment: FuG 16ZEquipped weight: 2545 kgBuilt in small numbers (50 examples)

Light fighter without pressurized cockpit, data sheet from 8 March 1943Motor: DB 605 AArmament: 2 MG 17 and 1 MG 151/20Radio equipment: FuG 16ZEquipped weight: 2585 kg

Bf 109 G-4/R2 Reconnaissance aircraft with RB 50/30 no pressurized cockpitdata sheet from 8 March 1943

Bf 109 G-4

Motor:Armament:Radio equipment:Equipped weight:1 x 300-l drop tank

DB 605 A2 MG 17 and 1 MG 151/20FuG 16Z2695 kg

Bf 109 G-4/R3 Armed reconnaissance aircraft with Rb 50/30, no pressurized cockpit,data sheet from 8/3/43Motor:Armament:Radio equipment:Equipped weight:

DB 605 A1 MG 151/20FuG 16Z2 595 kg2 x 300-l drop tanks and additional 15-l oil tank inplace of MG 17 ammunition boxes

11

Bf 109 G-4/U1 Light fighter with braking propeller,data sheet from 8 March 1943Motor: DB 605 AArmament: 2 MG 17 and 1 MG 151/20Radio equipment: FuG 16ZEquipped weight: 2585 kg

P6 braking propeller and steerable tailwheel forbraked landings

Bf 109 G-4/U3 Tactical reconnaissance aircraft without pressurized cockpit,data sheet from 8 March 1943Motor: DB 605 AArmament: noneRadio equipment: FuG 17Equipped weight: 2695 kg

With 2 x Rb 12.5/7x9 cameras

Bf 109 G-5 Light tighter with pressurized cockpit; converted from G-6,data sheet from 8 March 1943Motor: DB 605 AArmament: 2 MG 131 and 1 MG 151/20Radio equipment: FuG 16ZEquipped weight: 2600 kg

Bf 109 G-5/U2 Light fighter with pressurized cockpit.data sheet from 8 March 1943Motor: DB 605 A + GM 1 systemArmament: 2 MG 131 and 1 MG 151/20Radio equipment: FuG 16ZEquipped weight: 2600 kg

as per G-5

Bf 109 G-6 Light fighter without pressurized cockpit,data sheet from 8 March 1943Motor: DB 605 AArmament: 2 MG 17 and 1 MG 151/20Radio equipment: FuG 16ZEquipped weight: 2600 kg

Bf 109 G-6/R2 Reconnaissance aircraft with Rb 50/30, data sheet from 8 March 1943Motor: DB 605 AArmament: noneRadio equipment: FuG 16ZEquipped weight: 2710 kg

Bf 109 G-6/R3 Armed reconnaissance aircraft with Rb 50/30,data sheet from 8 March 1943Motor: DB 605 AArmament: 2 MG 17 and 1 MG 151/20Radio equipment: FuG 16ZEquipped weight: 2610 kg

12

Bf 109 G-6/R6 Heavy fighter with underwing MG 151/20 armamentMotor:Armament:Radio equipment:Equipped weight:

DB 605 A2 MG 131 and 1 MG 151/20FuG 16Z2610kg2 x MG 151/20 in underwing gondolas

Bf 109 G-6/U1 Light fighter with braking propeller.data sheet from 8 March 1943Motor:Armament:Radio equipment:Equipped weight:

DB 605 A2 MG 17 and 1 MG 151/20FuG 16Z2600 kg with P6 braking propeller and steerabletailwheel for braked landings

Bf 109 G-6/U3 Tactical reconnaissance aircraft without pressurized cockpit,data sheet from 8 March 1943Motor: DB 605 AArmament: 2 MG 17 and 1 MG 151/20Radio equipment: FuG 16ZEquipped weight: 2695 with 2 x Rb 12.5/7 x 9 cameras

Bf 109 G-8 Light fighter without pressurized cockpit,data sheet from 8 March 1943Motor:Armament:Radio equipment:Equipped weight:

DB 605 AnoneFuG 16Z2600 kg(as G-6/U3 but new-build aircraft)

Bf 109 G-10 Light fighter without pressurized cockpitMotor:Armament:Radio equipment:Equipped weight:

DB 605 AS/D/D-2/DC/DB2MG 131 and 1 MG 151/20, in some cases MK 108FuG 252600 kg or greater, depending on equipment

Bf 109 G-12 Two-seat training aircraft, conversions of single-seat machinesMotor:Armament:Radio equipment:Equipped weight:

DB 605 A/AS and othersusually removedFuG 16Z and RB10-A intercomfrom 2550 kg

Bf 109 G-14 Light fighter without pressurized cockpitMotor: DB 605 AM/ASArmament: 2 MG 131 and 1 MG 151/20, in some cases MK 108Radio equipment: FuG 25, in some cases 16ZYEquipped weight: from 2600 kg depending on equipment

13

Bf 109 F-1 and F-2

Compared to the earlier Bf 109 E, theBf 109 F was much improved aerodynami-cally. The entire engine section was rede-signed. The propeller spinner was enlargedand now blended smoothly into the entirelynew engine cowling. Including spinner,hub. blades, and blade mounts, the three-blade VDM 9-11207 propeller used for theBf 109 F-1 and F-2 weighed 138 kg. Thispropeller underwent further development,resulting in broader blades and a reduceddiameter of 3 meters from the F-4 version.Furthermore, the entire wing was rede-signed, the most obvious change being thenew elliptical wingtips. The wing radiatorswere shallower and set farther back on thewing.

The split flaps located behind the radi-ators were thermostatically controlled. Asbefore, dihedral was 6° 32'. The secondmean chord was 1 732 mm. The entireaerodynamic win area was 16 m2 with thelanding flaps accounting for 2 x 0.522 m2,the radiator flaps 2 x 0.4 m2 and the leadingedge slats 2 x 0.311 m2. The surface area ofthe ailerons was 2 x 0.387 m2.

The undercarriage used VDM 8-2787-05 oil-damped oleos, each filled with 1.1liters of "shock-absorber fluid green." At650 x 150, wheel size was the same as onthe "Emil." The tailwheel, on an EC orKronprinz hub, was fitted with a 290 x 110lire. Another obvious change was the dele-tion of the bracing struts for the horizontalstabilizer. While this was an obvious aero-dynamic improvement, there were staticproblems.

As a result of the aircraft's increasedperformance and following several crash-es, external stiffeners, so-called reinforcingstrips, were fitted externally over the em-

pennage attachment points. These werenecessary because of tail nutter at highspeeds, which usually resulted in structuralfailure. Power plant was the DB 601 N.which, with a displacement of 33.91 and acompression ratio of 1 : 8.2/8.5 (left/right),developed a maximum output of 1,175 H.P.Maximum revolutions for takeoff/emer-gency power were 2600 for a maximum ofthree minutes at a boost pressure of 1.35ata. Resulting fuel consumption was 215 to225 g/PSh. Reduction gearing was 1:1.55.

The Bf 109 F-1 weighed 2015 kgempty, all-up weight in the fighter role was2762 kg. in the fighter-bomber role with 1x 250 kg bomb 3 041 kg. and in the fighterrole with a 295-1 drop tank 3 026 kg. Theempty weight of the Bf 109 F-2 was exactlythe same as that of the Bf 109 F-1. All-upweight in the fighter role was 2,795 kg, andin the fighter-bomber role with 1 x 250 kgbomb 3073 kg.

These weights were applicable forLoad Class H4. For the fighter role only,2820 kg was the maximum allowable grossweight for Load Class 5. For all other oper-ational roles the maximum allowable grossweight was 3100 kg for Load Class H4.Wing loading was 176.2 kg/m2 at 2820 kgand 193.75 kg/m2 at 3100 kg. Power-to-weight ratio was 2.76 kg/H.P. at 2820 kgand 3.03kg/H.P. at 3100 kg.

The power-to-weight ratio improvedat an altitude of 4800 meters at an output of1050 H.P. to 2.68 kg/H.P. (at 2820 kg) and2.95 kg/H.P. If the transmitter or receiverwas removed, trim weights of 10 or 8 kgrespectively had to be fitted in its place.Maximum speed in level flight at groundlevel was 530 kph. Pilots were warned notto exceed the maximum allowable airspeed

14

of 750 kph, as this would overstress the air-frame. This was not always possible in aircombat, since no altitude-compensatingairspeed indicator was installed, and there-fore the true airspeed based on height couldnot be determined exactly. As a result, therewere repeated crashes not due to enemy ac-tion. As a result of demands from the front-line units, trials were resumed to determinethe aircraft's maximum diving speed. Ar-mament was limited to two MG 17 ma-chine-guns synchronized to fire through

the propeller disc and one unsynchronizedMG 151/20 firing through the propellerhub. This "light" total armament came un-der much criticism, especially from AdolfGalland.

The result was a so-called special con-version with an additional MG/FF cannonin each wing, similar to the installationused in the Bf 109 E-3. This machine wassupposedly designated the F-6/U. In termsof handling characteristics the Bf 109 Fwas probably the most capable version ofthe Bf 109.

15

High-Speed Trials

Initial high-speed trials were carriedout by the E-Stelle Rechlin, by HeinrichBeauvais, among others. Later, after pro-tests by Ernst Udet in June 1941 (two let-ters to Messerschmitt personally), these tri-als were handed back to the Messerschmittcompany's test pilots.

This was probably due to the prevail-ing opinion in the RLM that the manufac-turer should determine an aircraft's maxi-mum speed. An accident on 17 July 1938involving Dr. Jodlbauer (vertical crash) andthe near crash of Heinrich Baeuvais inearly 1941 undoubtedly played a part inthis decision.

At first Messerschmitl shelved thistheme and nothing happened. The existingdo-not-exceed speed of Bf 109 variants todate was in the area of 750 kph at allheights. But after the front-line units expe-rienced an increase in accidents, for exam-ple, 20 within a two-month period, the in-vestigation into maximum speed had to beresumed.

From Willy Messerschmitt came thepersonal message: "The terminal divingspeed of the Bf 109 is to be determined."Therefore, from January to March 1943 so-called "high-speed stress analysis experi-ments" were carried out. These experi-ments were conducted by test pilot LukasSchmid using Bf 109 F-2 Werknummer9228, code TH + TF. The aircraft under-went minor modifications in preparationsfor the experiments.

An ejection seat was installed, and lat-er aileron deflection was reduced to 50 per-cent of normal. The machine was subse-quently brought to the flight test depart-ment for installation of the necessary in-strumentation. This included an automaticcamera for photographing the instrumentpanel and two ASKANIA recorders for air-speed and altitude. The first factory testflights now took place.

The following is Lukas Schmid's de-scription of his experiences:

"On 29 January all was ready, it wastime to carry out the first diving flight. KarlBauer thought that, having already carriedout the factory test flights, that I shouldalso begin the next phase. During the firstflights I climbed to an altitude of 7 000 to 8000 meters. At the very outset it proved im-possible to trim the horizontal stabilizer forpull-out. It turned out that the grease usedto lubricate the horizontal stabilizer adjust-ing jack could not withstand the cold andfroze in temperatures of -30 to -40 de-grees. This was surely the cause of many ofthe reported accidents. Cold-proof greasewas immediately specified for the front-line units.

With the stabilizer trim now in order. 1conducted a test flight to find a stabilizerposition in which the elevator control forcewas manageable; this position was limitedby a stop.

As speed was increased — I was in thearea between 850 and 890 kph — an aileron

16

also received no bonus for these riskyflights. Such bonuses were standard. Forexample, I received 3,000 Reichsmarks fora diving flight in a Bf 109 with wooden tailassembly to 850 kph and a 6 g pull-out.Hermann Wurster received 10.000 Reichs-marks for the first flight in the Bf 110. At a

18

time when a bread roll cost 3 Pfennigs, thatwas a lot of money."

As a result of the lessons learned inthese trials the entire vertical tail, includingthe rudder, was heightened by 135 mm.Both metal and wooden versions of thelarger vertical fin and rudder were intro-duced.

Bf 109 F-4

The next variant, the Bf 109 F-4, en-tered service in June 1941. It used the re-vised VDM 9-12010 three-blade propeller,whose diameter had been reduced to 3meters. Total weight, including blades,blade mounts, and spinner was 132.6 kg.Externally the F-4 was similar to the F-2,however, a new Daimler-Benz engine us-ing Pz.Art.Rgt. BR fuel was installed.

This was the DB 601 E which pro-duced 1,350 H.P. for takeoff or emergencypower at 2,700 rpm at 1.42 ata. Output wasinitially restricted to 1,200 H.P. at 2,500rpm. During production changes weremade to the supercharger air intake. Thiswas made larger in diameter and more tear-drop shaped. The fighter's empty weightrose to 2086 kg. Gross weight was 2860

kg. The highest permissible gross weight inLoad Class H5 was 2870 kg. For the ex-tended-range version only Load Class H4at 3123 kg was allowable. The GM-1 sys-tem was installed in the Bf 109 F-4/Z. Thissystem increased engine output above theengine's rated altitude.

This increase in performance wasachieved by injecting so-called laughinggas (oxygen carrier) prior to the super-charger. As a result, a short-term perfor-mance increase could be achieved for amaximum of ten minutes. The system wasinstalled in the wing between nose ribs 6and 8, The fluid was contained either ineight so-called LUTZ bottles or in two cir-cular tanks. Weight of the fluid was either34 or 42 kg. Total weight of the system was46 and 75 kg.

19

Testing of Underwing Armament

The weak basic armament of the Bf109 made it necessary to increase firepow-er for the anti-bomber role. One Bf 109 F-4was therefore equipped with Rüstsätze(equipment sets). Bad weather preventedthe machine from being ferried to Tarne-witz for firing trials, however. Consequent-ly, the equipment sets had to be sent thereby rail. They were then installed onWerknummer 7449. The first static firingtrials also produced the first problems,such as belts breaking. After modifications

to the drum and ammunition feed, as wellas the installation of a guide tray on thefeed side of the weapon, it performed satis-factorily on the test stand. When installedin the aircraft, however, new problemsarose. With the left weapon the belt kinkedbefore reaching the weapon, while with theright the empty belt failed to disintegrate.These problems were eliminated aftermodifications to the feed chute. The firstair firing trials were carried out on 24March 1942. During the course of these

Testing of Underwing ArmamentAir firing with 2 x MG 151/20 W.Nr. 13149

Dale:

28/5/42

29/5/42

30/5/42

30/5/42

30/5/42

31/5/42

31/5/42

31/5/42

01/6/42

01/6/42

02/6/42

02/6/42

02/6/42

02/6/42

02/6/42

Flight No

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Ammo load

135/135

135/135

135/135

135/135

135/135

135/135

135/135

135/135

135/135

135/135

135/135

135/135

135/135

135/135

135/135

Left weaponL Rbelt jamafter 60 shots

empty belt jamafter 80 shots

belt kinked

normal

normal

normal

normal

normal

normal

weapon failure(extractor)

normal

double loadafter 116 shots

normal

normal

normal

Right weapon

normal

normal

normal

normal

normal

normal

normal

double loadafter 95 shots

normal

normal

normal

normal

normal

normal

normal

Remarks

left spent belt chutemodified

left belt feed reset

20

trails new problems arose which at firstcould not be identified. Sixty flights wererequired to identify the cause of the irregu-lar stoppages, namely failure of the emptybelts to disintegrate.

The end of the belt hanging from theejection chute was seized by the slipstreamand pulled so forcefully from the weaponthat it was no longer able to function prop-erly. A horizontal extension was thereforeapplied to the spent belt ejector chute. As aresult of this arrangement the empty beltcould no longer be immediately seized bythe slipstream and was better able to disin-tegrate. During the course of subsequenttesting at Rechlin four aircraft were fittedwith these modifications. Of a total of 27air firing tests, 16 were completed with nostoppages of the left weapon and 17 withnone of the right weapon. On the basis ofthese results the aircraft were ferried toWiener-Neustadt for conversion to produc-

tion standard and introduction of thechanges into production. The four aircraftwere converted during the period from 11to 16 May 1942. Since the unit was about tobe transferred to the front, air firing trialscould only be carried out with one serviceaircraft.

The modifications were subsequentlyapplied to Werknummer 13149 (E-StelleTarnewitz), and leather flaps were installedon the spent belt and shell chutes to keepout sand and dust. The flaps were closed onthe ground during takeoff and landing andwere only opened during firing by the spentshell casings or belt links. After being fer-ried to Tarnewitz. Werknummer 13149 wasused for firing trials with the MG 151/20 invarious flight altitudes. A minor modifica-tion to the spent belt chute near the weaponalmost completely eliminated the jammingof spent belts, which was still a problem,and the system was deemed reliableenough for installation.

Air firing with 2 x MG 151/15Date:

05/6/42

05/6/42

05/6/42

05/6/42

05/6/42

12/6/42

12/6/42

12/6/42

12/6/42

12/6/42

Flight no.

1

2

3

4

5

6

7

8

9

10

Ammo load

135/135

100/100

100/100

100/100

100/100

100/100

100/100

100/100

100/100

100/100

Left weapon

belt jammed

spent beltblockage

normal

gun stoppageafter 60 shots

normal

belt jammedafter 65 shots

normal

normal

normal

normalejector brokeafter 90 shots

Right weapon

normal

normal

normal

normal

normal

normal

normal

normal

normal

normal

Remarks

flight abortedafter 12 shots

The ammunition supply for one MG 151/20 is 135 rounds.It takes two men ten minutes to load the weapon.The weight of the armament equipment set is: without ammunition 158 kg, with ammunition 208 kg.Trajectory chart Bf 109 F-4/R1 and Bf 109 G.

21

The installation of a continuous beltrack in the drum in place of the previouscartridge holder spring made loading mucheasier and ensured a problem-free ammu-nition feed. Further problems arose duringtrials with 15-mm ammunition, for exam-ple, jamming of the ammunition in thedrum on account of its smaller diameter,caused by the limited radius of the ammu-nition belt. The problem was eliminated byloading just 100 rounds per drum and tak-ing particular care in installation. (Thedrum had to be shaken to prevent the am-munition from piling up.)

At a range of 100 m with 21 roundsfired, the shot pattern of the MG 151/20was 60 x 39 cm for the left weapon and 48 x49 cm for me right weapon. The final phaseof testing was cold trials at minus 60 de-grees. Problems were again encountered,for example, belts breaking, which were at-tributable to roughness of the drum.

Following modifications (drum open-ing enlarged, inner drum wall thinned, etc.)and checking with a tolerance belt theweapon functioned satisfactorily. As a re-sult, it was determined that: "The MG 151/20 wing gondola armament performs satis-factorily."

22

The Bf 109 Gustav Series

The G-series, or Gustav, was a furtherdevelopment of the F-series. It seemed thatall development possibilities had alreadybeen exhausted with the Bf 109 F. Then, atthe end of December 1941, the new DB605 A became available. This power plantwas first installed in the G-1, while the Bf109 G-0 pre-production series was pow-ered by the DB 601 E.

Designed in 1940, the DB 605 was alogical development of the DB 605 A 601E. The most significant difference was anincrease in displacement from 33.9 liters to35.7 liters through boring out the cylinders.plus an increase in compression from 7.2 to7.5. The resulting performance of the DB605 A was 1475 H P. for takeoff at 1.42 at-mospheres of boost.

The initial installation of this engineproduced some cooling problems, whichresulted in the first of the so-called "bulg-es" which were to become synonymouswith the Gustav. These were intake scoopsto provide cooling air for the ejector ex-hausts and spark plugs.

The scoops were installed on bothsides of the engine cowling and were rivet-ed to the metal skinning over the oil tank.

Much larger bulges appeared later, theresult of larger wheels and. from the G-5.the replacement of the MG 17 by the MG131 machine-gun.

Bf 109 G-1The Bf 109 G-1 was designed as a lightfighter with a pressurized cockpit. Prob-

lems with the pressurized cockpit made se-ries production impossible at that time,however, and this version was built in sev-eral small batches. Production began at Re-gensburg in November 1941. Twenty ma-chines were also built by Erla (Leipzig).The standard power plant was the DB 605A using B4 (87 octane) fuel. The engine'scompression ratio was 1 : 7.3/7.5.

Takeoff and emergency power of1,475 H.P. was achieved with 1.42 ata ofboost at 2,800 rpm. This output was initial-ly banned by VT-Anw.Nr.2206 and was notreinstated until 8 June 1943 when Daimler-Benz issued a technical directive. Gearingratio was 1 : 1.685. Engine weight was700kg plus 3 percent.

The main undercarriage used enginecowling wheels with channel rims for the650 x 150 tires. Until December 1942(when the G-4 was introduced) the tail-wheel was fitted with an EC flat rim with a290 x 110 tire.

The propeller was a three-blade VDM9-12087 A variable-pitch type with a diam-eter of 3 meters. Pitch control was either"electro-mechanical"" (automatic) or "man-ual-electric" using a thumb-switch on thethrottle lever.

The basic 12 o'clock position on thepilch indicator equated to a blade angle of25 degrees. This pilch indicator in thecockpit was fitted with an analogue clock.Takeoff position was 11:45.

23

Original Extract: Flight Performance

Altitude

km

0123456789101112

Max.Truekph

525544563583602622642649648643630609555

speedIndicatedkph

525517510502492482470452424398367332280

Climb speed

kph

280280280280280280280280275270265260255

Time lo climb

min./sec.

-0/471/352/243/164/115/146/237/469/3611/5415/4124/02

Climb rate

m/sec

21212119.818.617.415.813.310.98.36.03.51.0

The performance figures shown are based on battle and climb power, or 2.600 rpm, 1.3 ata of boost. Atpresent the DB 605 A is not cleared for takeoff and emergency power.

For effect of bombs, tanks and underwing weapons on speed see range table.

Maximum boost altitude at full throttle, horizontal flight 6.4 kmMaximum boost altitude in climb 5.7 kmTakeoff run to height of 20 m, normal 585 mTakeoff run to height of 20 m, with bomb 740 mLanding run from height of 20 m, normal braking 770 m

Bf 109 G-3Only fifty examples of the G-3 were built atRegensburg during the period from Janu-ary to February 1943. It was similar in de-sign to the G-1 and was fitted with a pres-surized cockpit. Like the G-1. it could beidentified by the air scoop on the left sideof the engine cowling above the super-charger air intake. Radio equipment con-sisted of a FuG 16Z in place of the earlierFuG VIIa.

Equipped weight for the fighter role,which did not include the pilot, fuel, andammunition, was 2545 kg. On the whole,performance was similar to that of the G-1.

More Directionally-Stable300-1 Drop TankFor drag-reduction experiments with the300-1 drop tank the FAV performance

branch installed a metal fairing betweenthe fuselage and the drop tank. Flight testsconducted by Fritz Wendel with Bf 109Werknummer 15939 revealed serious staticinstability about the vertical axis, both inhigh and low speed flight.

A modified version of the fairing wassupposed to be tested in an attempt to over-come this instability. Finally, after variousexperiments, a metal streamer was weldedonto the fairing, which was attached to theunderside of the fuselage by a bolt at itsrear upper end and to the rear end of thelank by means of a clamping ring. The ma-chine test flown with this modified fairingdisplayed full stability about the verticalaxis.

Testing took place between 16 Augustand 16 September 1943, however, the mod-ified tank was never introduced into ser-vice.

24

Trials with Fixed Rudder Trim TabsRudder ineffectiveness at small deflectionshad an unfavorable effect on firing passesand aiming corrections. This led in earlyJune 1944 to the testing of so-called "bentrudder tabs." Werknummer 110039 servedas a test-bed, and in several practice gun-nery flights it proved the effectiveness ofthe rudder labs. These tabs consisted of two1-mm-thick Dural sheets of varying widthand depth.

The upper tab was bent to the right, thelower to the left. After several flights withlabs of various depths it was discoveredthat effectiveness was fully sufficient at adepth of 30 mm.

The distance between the tab and thetrailing edge of the rudder was 10 mm. ABSK 16 gun camera was used to photo-graph the experiments.

Elevator Vibration on the Wooden Tailof the Bf 109On 10 July 1944 Regensburg Messer-schmitt director Lindner reported to thehandling characteristics project bureau thatvibration was being encountered in aircraftwith the wooden tail. Regensburg reportedthat since the prolonged rainy period at thebeginning of July and the use of elevatorswith doubled fixed trim strip length (wood-en elevators), a greater number of ma-chines had been experiencing vibration inelevator control at speeds above 600 to 700kph. The vibration appeared after severaltrouble-free flights. An immediate investi-gation was ordered. On 10 July 1944 HerrNürnberg and Herr Baumann of the stressbureau and Herr Blümm of the project bu-reau of the Obernminergau research insti-tute were sent to Regensburg to investigatethese incidents. Herr Bosch (design bu-reau—tail section) and Herr Blümm(project bureau) followed on 17 July. Atthat lime the following types of elevatorwere held in the Messerschmitt AG Re-gensburg's stocks:

First, the standard metal elevator withshort fixed trim strip; second, the woodenelevator built by the Wolf Hirth Firm of

Nabern (WHN) with 1.5-mrn skinning be-tween Ribs 2 and 6; and third, the woodenelevator built by the DEAG Firm of But-schowitz with 1-mm skinning betweenRibs 4 and 6. plus wooden elevators byWHN of the same type as those made byDEAG. The control surfaces made by theWHN Firm were preserved according toLackkette 33. while those by the DEAGFirm were preserved using the method ofthe Warnecke and Böhm Firm. All of thecontrol surfaces which had produced vibra-tion and were removed in Regensburg weresubsequently examined. There were 29 intotal, all built by DEAG. All exhibited seri-ous damage as a result of weather. In mostcases glued joints had failed, especially onRib 1 and along the rim strip. One of the el-evators was sent to Oberammergau for aninvestigation of the preservation process.

It was determined that painting hadbeen carried out without the prescribedfabric covering, which was contrary to pro-cedure. This system (Warbecke and Böhm)was always rejected by materials testing onaccount of the fact that it allowed throughtoo much water. This was not the main rea-son for the vibration, however, rather it wasthe inadequate conservation protection ofthe glue. Reference was made to earlier in-vestigations in March 1943.

At that time the wooden tails built byFokker in Amsterdam also used a skinningof 1-mm between Ribs 4 to 6. The thenconfirmed speed of 750 kph produced noneof the current complaints. Further investi-gations saw several Bf 109 G-14s exposedto simulated rain overnight in order to eval-uate the effects of dampness. Then on 18and 19 July 1944 test flights were conduct-ed at various times of day by HauptmannObermaier of BAL2 Regensburg. These re-sulted in vibration at speeds of 680 to 750kph with elevators with 1-mm skinning andthe DEAG type, as well as several built byWHN.

By far the majority of complaints in-volved the elevators produced by DEAG.

2 BAL = Bauaufsicht Luftwaffe (Luftwaffequality control)

25

However, Regensburg's original assump-tion that the cause of the vibration was thelong fixed trim strip applied to these con-trol surfaces was proved to be wrong by anexperiment at Regensburg. Reducing thesize of the trim strip and finally cutting itoff completely failed to eliminate the vi-bration. As a result, it was determined thatthe cause of the vibration clearly lay in theelevator itself. The vibration only appearedin elevators with 1-mm plywood skinningbetween Ribs 4 to 6, but not in all such ele-vators. Ultimately, rudders were only per-mitted to be installed with 1.5-mm skin-ning between Ribs 2 to 6.

The elevators by the DEAG Firm with1-mm skinning and the unreliable War-necke and Böhm preservation without fab-ric covering could no longer be used at all,on account of their permeability to waterand the resulting effect on glued joints. Allproduction was immediately switched to1.5-mm skinning. In spite of all these mea-sures there continued to be accidents in-volving wooden tail units, such as the oneinvolving Bf 109 G-14 W.Nr. 460 628 atStargard on 19 October 1944. The machinecrashed from a height of 2 000 meters after

several parts of the aircraft broke away.The subsequent investigation revealed thatthe likely cause was the separation of thehorizontal stabilizer from the tail sectionbearer.

Other complaints were registered withthe following: Bf 109 G-14 W.Nr. 464 396(ERLA). Bf 109 G-14 W.Nr. 464 365(ERLA), and Bf 109 G-6 W.Nr. 412 373.This was only the tip of the iceberg, how-ever. A report to the E-Stelle Rechlin re-vealed that a total of 154 aircraft were ex-amined by JG 27 and one Gruppe of JG 26during the period from 8 to 13 December1944.

A significant number of problems withthe wooden tails were found, and 36 ma-chines could not be found airworthy. Theprobable cause was the inability of thewood to withstand the prevailing badweather (dampness), and in particular bador inadequate preservation. Among themost pressing demands to come from thiswas that ground crews be better trained inregard to the wooden components, and thata more expeditious way be found to trans-mit technical directives and announce-ments (in spite of the overall war situa-tion!).

26

Report No. 109 11 E 44 Date 29/7/44 Page II

Weather

MachinePilotDateTime of day

Horiz. Stab.ManufacturerComplaint

ElevatorManufacturerSkinningMethod ofPreservationGluing

Dihedral

LoftUpper side leftLower side leftUpper side rightLower side right

Bulges

Trim strip

Result

Clear, hot

109 G-14 W.Nr. 165 706

18/7/44morning

WHNformation of stepon leading edge

WHN1.5 mm betw. Ribs 2-6

Lackkette 33satisfactory

0 mm

(2) 0, ( 4 ) - 2 , (6 ) -1 .5-0.5 0 0-1 -2 +0.5-0.5 0 0

right bottom 5 mmotherwise good

short

satisfactory

109 G-14 W.Nr. 166 277

18/7/44morning

WHNformation of stepon leading edge

WHN1.5 mm betw. Ribs 2-6

Lackkette 33satisfactory

4 mm

(2)-1 (4 ) -3 .5 ( 6 ) - 2-0.5 +2 0-0.5 -0.5 0

+0.5 0 0

right bottom 4 mmotherwise good

short

satisfactory

109 G-14 W.Nr. 165 721

18/7/44afternoon

WHNformation of stepon leading edge

WHN1.5 mm betw. Ribs 2-6

Lackkette 33satisfactory

4 mm

(2}+ 1.5 (4) 0 (6) 0-1.5 0 -1.5

0 -0.5 00 +0.5 0

deep impressions bottom

short

satisfactory

109 G-14 W.Nr. 165 699

18/7/44afternoon

WHNformation of stepon leading edge

WHN1.5 mm betw. Ribs 4-6Warnecke & Böhmwithout fabric coveringRib 1 beginning toSeparate0 mm

(2) 0 (4) -6 (6) -20 +1 -0.50 -1,5 -0.50 +0.5 0

long

109 G-6 W.Nr. 166 249

18/7/44afternoon

WHNformation of stepon leading edge

DEAG1.0 mm betw. Ribs 4-6Warnecke & Böhmwithout fabric coveringRib 1 separated

—

long

DEAGAs well, on 18/7/44ten machines werecounted with WHNelevators and 1.5-mmskinning betweenRibs 2-6 whichwere satisfactory.

27

Test Reports

Messerschmitt AGAugsburgTest ReportNo. 109 18 E 43Canopy Jettisoning 109 GFlight Test Dept.Date 2/11/43

Cause:In spite of repeated improvements to thecanopy jettisoning system of the 109 G,complaints were still being received thatthe canopy refused to jettison at all or didnot do so without problems. Further jetti-son trials were subsequently carried out.the results of which appear below.

Test Procedure:A normal G canopy with the markings No.109.135-135-002 and 109.117-003 was in-stalled on the test-bed. In addition, the can-opies were fitted with a relief spring withthe marking No. A 17729 Z. Jettison trialswere conducted with the above-namedcanopy.

Result:The experiments were carried out as fol-lows based on various theoretical consider-ations. First, the normal canopy lock wasopened and then the jettison lever pulled.This sequence was chosen in spile of thefact that there is a placard in the cockpitwhich specifies that the lever be operatedin exactly the opposite sequence. Theoreti-cally, it is impossible to first pull the jetti-son lever and then unlock the canopy, sincewhen operating the jettison lever the pilotmust place his head in the forward part ofthe cockpit for safety. It is then no longerpossible to operate the canopy lock, sincethe canopy center section may fly off to the

side at any lime after the jettison lever ispulled.

In the first experiment the canopy lockwas activated at a speed of 350 kph and ayaw angle of 10 degrees. The canopy cen-ter section jammed. When the center sec-tion was knocked over the limiting wiresnapped and the canopy struck the side ofthe fuselage and then remained hanging.As a result of the impact the two pins on theright side of the canopy were so stressedand bent that releasing the jettison lock wasno longer possible.

Subsequently, a forced landing wasmade at Lechfeld with the canopy sectionhanging to the side. The jettison proceduremay be seen on Page 4.

After the normal jettison procedurefailed to function smoothly, additional jet-tisoning assistance was installed based on aproposal from flight testing. As depicted inIllustrations 1 and 2, the upper end of thelever on the rear part of canopy 109.117-003. which activates the locking bolts, waslengthened.

A cable was attached to the lengthenedlever and the rear wall of the canopy (Illus-tration 3). At a specified opening angle (af-ter the limiting wire is broken) this pulls thelocking pin. This ensures that the centersection cannot swing out and bend thelocking pins. At the same time, the cockpitcenter section is placed in the wing's down-draft and is thus guaranteed to fly away be-neath the wing. The following page con-tains a description of the jettison procedurewith the additional release mechanism. In-stallation of the additional pull cable isseen only as an interim solution to be retro-fitted in the 109 G cockpit. It can easily beinstalled by the units themselves. For aneventual series introduction Herr Caroli's

28

was uneventful. On the ground great forcewas required to pull the emergency jettisonlever.

2nd Test(5/10/43)

State of aircraft:Additional cable on the canopy, whichopens the lock after the limiting wire is bro-ken. Otherwise as in 1.

Result:The canopy lock was released in straightand level flight at a speed of 350 kph. Af-terwards, the folding canopy immediatelyopened to the right and the restraining wireimmediately broke. As the canopy openedfurther, the additional cable released thelocking bolts and the canopy with rear sec-tion was jettisoned smoothly. A detailed re-port on the experiment with photos of thejettisoning is being issued by FAVA1.

Augsburg, 7/10/43FAFb/Wi/He.

MesserschmittFlight DepartmentTesting of Tail wheel Lockingon tall tailwheel Me 109 - tailwheelQualities GroupTest ReportNo. 109 20 E 44Date 8/11/44Copy 12

Cause:Frequent occurrence of swinging, especial-ly on landing, during factory test flightswith aircraft with the tall tailwheel, deviceNo. 8-2926 G-5. There the cause was seenas imprecise installation of the tailwheel,while the FAM placed most of the blame onthe uncommanded unlocking of the tail-wheel, which could occur with minimallateral forces on account of the rake of thelocking bolt and its limited locking path.

Procedure:First tailwheel track deviations were mea-sured using several Me 109s, and a testflight was conducted with the aircraftwhich produced the highest value. As thetailwheel delivered with W.Nr. 330 105 un-locked after a short time, leading to astrong swing, during the course of repeatedmodifications a version of the lock was de-veloped, which so far has not led to furthercomplaints. At the same time a tailwheeldelivered by the Waiblingen Firm is undertest on W.Nr. 167 227.

1 FAVA = Flight operations department/experi-mental section

30

Results to Date:The greatest measured deviation of theneutral tailwheel position to the side was1.2° to the left, furthermore, the tailwheelhad sideways play of up to ±1.8°. Takeoffsand landings were possible without diffi-culty with a toe-in of 1.2°. Flight tests witheccentric locking bolts with up to 5° toe-inare now in process in order to more closelyexamine the effect of tailwheel track devia-tion on takeoff and landing behavior.

The lock now installed in W.Nr. 330105, with 5° angle of pressure on the lock-ing bolts, external unlocking spring.lengthened tension spring in the pull cableplus lengthened cable length has so far notyielded any complaints in 20 flights.

The new Elma tailwheel installed inMe 109 W.Nr. 163 227 with supplementaryretraction spring on the connecting leverhas not produced a complaint in 27 flightsto date. The details of the modificationsand dimensions of the new parts are con-tained in the following section.

Conveyor Line Production of theBf 109 G WingIn the beginning the airframe sector of theGerman aviation industry was forced tobuild using the production line method be-cause the numbers were initially lackingfor conveyor line production. Wartimeconditions resulted in a change in the fight-er program which required considerationof mass production techniques.

Although other aircraft were built inlarge numbers, it was generally acknowl-edged that conveyor lines could only beused for pure assembly work. The decisionwas made to also produce the 109 G wingon the conveyor line. The greatest difficul-ties arose from the fact that the Bf 109 wasa type which had not been designed forconveyor line production. This means thatthe wing lacks the design breakdown,which is standard today.

An attempt now had to be made tobuild the wing on the assembly line withoutdesign changes. In addition, use of the as-sembly line was of vital importance to in-creased production and had to begin by acertain deadline. Thus, no experimentswere possible. Furthermore, because of thestage the program was at, it was necessarythat numbers produced should increasecontinuously from the very first day.

The conveyor line had to work fromthe very outset, and in particular produceinterchangeable wings. Further difficultieswere encountered in the spaces available,which were in no way suitable for convey-or line production. Available hall space wassimilar in Regensburg and Leipzig at 40 x100 m (4000 m2), while at Wiener-Neus-tadt Hangar 58 with 8100 m2 was avail-able. There the conveyor line fixtures hadto be arranged to permit a reasonable linedivision. Furthermore, it was necessary tobuild the structural frames stiff enough sothat the continuous forward movement hadno effect whatever on assembly precisionof the wings.

31

As a further condition a significantlymore precise component part productionhad to be achieved so that no fitting or ad-justment work was necessary during as-sembly. More precise presswork tools wererequired, plus inspection gauges withwhich to check the ribs after manufacture.

Since interchangeability was of partic-ular importance, it was necessary to installthe mounting points for fuselage, ailerons,landing flaps, slats, and wingtips in thestructural framing. Furthermore, new useshad to be found for construction jigs ren-dered superfluous by the raw materialsshortage. A work platform was attached tothe construction framing so that the work-ers could move with it. Moving the con-struction frame back posed a particularproblem, as there was very little roomavailable and idling the production line hadto be avoided if at all possible.

The construction frame ran on a trackand was moved forward by means of a roll-er chain. Propulsion was by gear drive,whose revolutions could be adjusted bychanging a set of gears. The resulting linespeed was 4.1 to 24.5 cm per minute, whichequaled to the output of 90 to 525 sets ofwings for a monthly operating time of 220hours (status at the end of 1942).

Altogether, three months after start-upof the line total time saved was 300 hours,which after the line got broken in was re-duced a further 300 hours to 940 hours.

Reconnaissance Aircraft withJumo 213 EIn September 1944 a G-series Bf 109 wasconverted into a high-altitude reconnais-sance aircraft. It was powered by a Jumo213 E engine using E-4 fuel plus MW 50.The four-blade propeller, which had a di-ameter of 3.1 meters, was housed in a VS19 hub. The greater engine output meantthat the radiator had to be enlarged. A radi-ator with an area of 60 dm2 was selected.which only increased the CWK value to 1.6compared to the 1.45 of the smaller radia-tor (42 dm2). Theoretically, this shouldhave resulted in a maximum airspeed lossof 10 kph. Expected maximum speed withclimb/combat power and MW 50 was 780kph at an altitude of 9 800 meters. Withoutpower boosting maximum speed was 780kph at 10 800 meters. These figures do nottake into account the Mach effect! Thiswould produce an approximate loss ofspeed of 25 kph at an altitude of 10800meters and 40 kph at 9800 meters. The air-frame was equipped with larger horizontaland vertical tail surfaces. The main under-carriage had no mainwheel fairings, how-ever, the tailwheel was re tractable. No ar-mament was planned, instead the aircraftwas to carry a Type Rb 50/30 or Rb 75/30camera. Takeoff weight was 3 700 kg. Thismachine. Werknummer 410 528, was testedat Berlin Staaken on 12 October 1944. Un-fortunately, no further information is avail-able.

32

The Bf 109 H High-Altitude Fighter

The RLM's demands for improvedhigh-altitude performance were becomingever more urgent, since the operating alti-tudes of enemy bomber and fighter forma-tions and combat altitudes continued to in-crease. In the spring of 1942 Messer-schmitt AG received a contract from theRLM to develop simultaneously with the"Special Carrier Single-Seater" a "SpecialHigh-Altitude Fighter." Since lack of pro-duction capacity made the prospects of ini-tiating two special aircraft programs al-most nil, especially if a rapid start-up ofcarrier aircraft production was to beachieved, a version of the Bf 109 G with alengthened wing and sturdier undercar-riage was chosen. At the same time it wasplanned to bolster the aircraft's armamentby installing two MG 151s in the wingroots.

By exchanging the DB 605 for a DB628 and adding extended wingtips, it wasbelieved that a high-aititude fighter couldbe produced which met all of the currentrequirements (ceiling 14 km). Develop-ment of this type, which was designated theMe 155, proceeded very slowly in Paris.

This was due in part to the recentlyformed design bureau of the SNCAN firm,and also to the inadequate support providedby the local representative from the Augs-burg project bureau, which at that time wascompletely overtaxed with developmentwork on the Me 309. When, in January1943, the carrier program and with it theMe 155 carrier aircraft was halted, thehigh-altitude version based on the Me 155became the basis of the Me 209, which hadby then taken the place of the Me 309. (On

instructions of the RLM the Me 155 projectwas transferred to Blohm & Voss inFinkenwerder where it continued as the Bv155.) On 23 April 1943 the proposal "Me209 high-altitude fighter with DB 628" wassubmitted to the RLM.

The performance figures for theproject were almost the same as those ofthe Me 155 high-altitude version. TheRLM suggested to Messerschmitt verballythat it investigate ways to achieve evengreater high-altitude performance, even ifit increased costs. The result was the Mess-erschmitt Projekt 1091 (extreme high-alti-tude fighter). Anticipated power plantswere the DB 628 and the DB 603 with TKL15 (exhaust-driven turbosupercharger 9-2279 by Hirth).

In a report by Messerschmitt AG dated26 July 1943 it was also proposed that a de-velopment series of high-altitude aircraftbe produced in three stages. The first stageconsisted merely of modifying a few com-ponents, especially the installation of a wincenter-section. Also given considerationwas installing the DB 603 supercharger onthe DB 605.

In the second phase the wingspan wasto be increased by lengthening the wingcenter-section, and the fuselage length-ened, as well. The third stage was to see theinstallation of the DB 603 power plant withturbo-supercharger. This would involvewidening the fuselage in the area of the ex-haust and supercharger air lines. Since theassociated planning indicated that seriesproduction of this type could not begin be-fore the end of 1944. in summer 1943 theMesserschmitt AG received a development

33

and construction contract from the RLMfor a "high-altitude fighter quick solution"based on the Bf 109 G.

The intention was to increase the ser-vice ceiling of the Bf 109 with as little costas possible. The main operational role ofthis type was to be the interception of ene-my high-altitude bombers and reconnais-sance aircraft. A reduction in structuralstrength and a possible degradation of han-dling qualities in order to achieve im-proved high-altitude performance was ac-cepted for both of these operational tasks.

In order to save weight, the pilot'sback armor was deleted and armament waslimited to three weapons. Bf 109 G-3 W.Nr.16281, which had been built at Regensburgin February 1943, was fitted with the DB628 V8 and became prototype V 49.

In trials the aircraft failed to achievethe predicted performance. On 22 Decem-ber 1943 Heinrich Beauvais took the DB628-powered V 54 (code DV + JB.Werknummer 15708) up on a flight whichlasted from 14:42 to 15:00 hours. He as-sessed the flight, which took place at Augs-burg, as follows:

"The Messerschmitt AG companywanted an evaluation of yaw axis charac-teristics. The test was hampered by the loosmall horizontal tail in conjunction withthe lateral moment, which was known to beloo great. The vertical tail was insufficientfor a production version! The lateral oscil-lations were uncomfortably high. Ruddereffectiveness was poor, and, as mentioned,an enlargement of the entire vertical tail isnecessary. In no case should the standardproduction ailerons be used."

The production state of the aircraftwas as follows: G-5 fuselage; wingspan13.26 m; wing area 21.9 m2 aspect ratio1:8.5; ailerons 2.12 m, normal ailerons ex-tended outboard by 1.46 m; standard G hor-izontal tail; vertical tail raised by 125 mm,no horn, with Flettner, gross weight ap-proximately 3.4 tons.

In the attempt to achieve an optimumhigh-altitude fighter the idea of installing aJumo 213 A in the 109 was also discussed.As at the department heads conferencewith Gen.Feldm. Milch on 29 October1943, there was a lively debate concerningthe expected performance and the consid-erable cost involved. But in the end no sig-nificant advantage could be seen for in-stalling the Jumo 213 in the Me 109. At thebeginning of 1944 several officials of theMesserschmitt AG proposed adopting the109 H as a universal fighter.

In a letter dated 2 February 1944Project Director Hügelschäffer detailed thereasons against this idea. The performanceof the Bf 109 H was compared to that of theBf 109 K. The Bf 109 K was approximately20 kph faster at ground level, furthermore,the K's speed advantage continued to riseto about 25 kph at maximum boost altitude.The Bf 109 H had in its favor a greater ser-vice ceiling and a somewhat better rate ofclimb.

The H's roll rate was significantlylower than that of the Bf 109 K. Accordingto flight tests the Bf 109 H required 6 sec-onds to complete a roll, while the figure forthe K was 4.5 seconds. Furthermore, theoverall armament of the H was rated belowthat of the Bf 109 K.

Finally, there was the reduced structur-al strength of n=4.5, which made it impos-sible for the Bf 109 H to exploit its lowerwing loading. Further testing was over-shadowed by a crash involving test pilotFritz Wendel on 14 April 1944; Wendel es-caped by parachute. Ludwig Bölkow hap-pened to witness the accident. The end ofthe Bf 109 H came in April 1944 when theRLM ordered the DB 628 dropped. Thereason was the RLM's contention that theDB 628 was not production ready. Thus, inthe end only a few examples of the Bf 109H powered by the DB 605 were built anddelivered to the units.

34

These were used sporadically over En-gland. An important point in the cancella-tion of Messerschmitt's high-altitude fight-er was the advanced state of developmentof the Jumo 213-powered Fw 190 D-9 andthe Ta 152. Furthermore, the situation inthe air war suggested that operational alti-tudes were not about to increase as drasti-cally as once expected.

Bf 109 K

The Bf 109 G series was produced by sev-eral factories in a total of 16 variants with82 different models. This led to increaseddifficulties in repairs and in the exchangingof parts (fit, accuracy of size). Far morethan 1,000 changes had been introduced,and these were noted in modification direc-tives. And so it was that Messerschmitt, atthe urging of the RLM (fighter staff), initi-ated a special action.

Ludwig Bölkow was asked by thehead of the supervisory board, Fritz Seiler,if he would assume direction of this majorrationalization effort. The resulting versionwas to receive the designation Bf 109 K.The objective of the Bf 109 K project wasto equal or surpass the performances of Al-lied aircraft, such as the Spitfire XIV and

P-51D Mustang. But this meant achievingan increase in speed over existing variantsof 50 to 70 kph. This was the challenge fac-ing project director Ludwig Bölkow. Hewas assigned the former design chief of theBf 109. Richard Bauer, one of the "mostgifted designers," as Bölkow said.

As well, there came the series bureauof Messerschmitt Regensburg, plus ten ex-perienced Bf 109 designers. His workingstaff consisted of a total of 140 men. AsBölkow himself said, for him this was thebest apprenticeship with a big total respon-sibility. The tasks of the "Bf 109 develop-ment bureau" still had to be laid down. Thefirst planned point was the reworking of allseries drawings for the Bf 109 G, incorpo-rating the many modification directives.

Also on the priority list was the elimi-nation of the type's weak points, for exam-ple, the frequent undercarriage failures andits tendency to swing on takeoff and land-ing. Further changes were the installationof the DB 605 D or L engine, which offeredbetter high-altitude performance, the previ-ously mentioned speed increase, and theinstallation of an engine-mounted MK 108cannon. All of these changes and improve-ments would not be allowed to delay or in-terrupt production.

The first step was to relocate to WienerNeustadt, which was still considered safefrom Allied air attacks. The design bureaubegan its work in Wiener Neustadt at thebeginning of 1943. For flight testing thevarious modifications, however, the teamhad to use what was available there. Lack-ing were a wind tunnel and various measur-ing devices. The aerodynamic reworkingbrought various improvements with it.Most of the bulges that characterized the Bf109 G were eliminated. For example, theengine cowling was broadened by about 70mm in the area of the belt feeds for the MG131s and was faired into the fuselage. Aswell, the new DB 605 D production engine,which used the larger supercharger of theDB 603, was installed.

35

The greater engine output meant that alarger oil cooler was also needed. Further-more, as had been the case with the DB 605AS engine, a larger supercharger air intakewas necessary. Several improvements werealso made in the area of the undercarriage,for example, the long tailwheel. As Dr.Ludwig Bölkow reported, all of this wentback to a comparative measurement of theFw 190. The latter had a taxiing anglewhich was 2° less than that of the Bf 109,1° was subtracted, and the Bf 109 K waslaid out based on the new angle, which ledto a longer tailwheel. This was fully retract-able and equipped with automatically-re-tracting wheel well doors. The bellcrankfor the rudder had to be modified to allowthe longer tailwheel to retract.

This bellcrank, which was mountedhorizontally in the tail section bearer, wasreplaced by two individual levers mountedvertically in the end of the fuselage. As aresult the two small bulges on either side ofthe tail section bearer, features of the G-version, disappeared. Recently it has beenstated in various literature that the tail-wheel doors could also be closed on theground: the doors were controlled by thetailwheel, therefore they were open on theground.

Since the tailwheel retracted when themain undercarriage was raised and had nolock, leakage in the hydraulic systemsometimes allowed the tailwheel to drop tosome degree during flight. This led to con-siderable turbulence through the openwheel well and increased drag. Conse-quently, the doors were often forced closedby the units, as a result of which the tail-wheel could not be retracted. Because ofthe aircraft's increased weight the main un-dercarriage truss was strengthened andlarger 660 x 190 wheels were mounted on13" rims. The larger wheels made it neces-sary to replace the bulges on the wing up-per surface with more aerodynamic fair-ings and add small bulges to the wheel welldoors. Another change was the deletion ofthe antenna mast on the fuselage spine. TheFuG 16ZY's loop antenna on the fuselagespine was moved back to Fuselage Section

3. Furthermore, the access hatch on the leftside of Fuselage Section 5 was relocated toFuselage Section 4 because of the revisedinternal arrangement. The shape of thehatch followed that of the fuselage frame.As a result of relocating the compass sys-tem to a position further aft in the fuselage,the round access hatch on the left side ofthe fuselage beneath the recessed foot stepwas deleted. Further design changes werecarried out in the area of the cockpit, forexample, the cockpit floorboards and mostpilot seats were made of wood. The switchbox with the automatic circuit breakers onthe right cockpit wall was made larger andeasier to scan. The operating controls forthe radio and oxygen systems to the right ofthe pilot's seat were mounted in a sort ofconsole. The standardized blind flying pan-el, which was also used in the Me 262, wasformed as part of the instrument panel. As aresult, a vertical speed indicator was nowavailable. The four-lamp system for the un-dercarriage was replaced by three lamps orindicators. A mechanical indicator for theextended undercarriage, similar to that ofthe Bf 109 F, was fitted.

This indicator, which was visible fromthe cockpit, consisted of two metal rods;painted red, these projected from the uppersurface of the wing when the undercarriagewas extended. The door to the baggagecompartment behind the pilot was enlargedand made more square. Two other impor-tant changes were a switch to thin steelsheet from aluminum for the leading edgeslats and the use of wood in construction ofthe tail section. The wooden tail gave im-proved aerodynamics, however, it weighed2 to 10 kilograms more for the same struc-tural strength.

The installation of the MK 108 re-quired further important changes. Theshape of the control stick had to be changedso that this weapon could be removed to therear. As a result it was bowed to the rightside. The entire rudder mechanism was re-designed on account of the ammunitionbox, now consisting largely of sheet steel.

Dr. Bölkow reported, "that at the timea draftsman reworked the rough drawing

36

from the Augsburg design bureau: but noexaminations for stiffness were carried out.Fortunately the test pilot aborted his flightand noted 'everything is too soft.' The de-sign was changed within one night. Twodays later the pilot flew again and then ev-erything was in order."

The changes compared to the Bf 109 Gproved successful, and the specified speedand performance was achieved. Thus, theBf 109 K was undoubtedly the most capa-ble version of the Bf 109 and the most de-manding to fly. At the same time it showedthe limits of what could be achieved withpiston-engined fighters.

Bf 109 K-4The Bf 109 K was the only version of theK-series to be built in large numbers. Bythe end of 1944 a total of 856 K-4s left theRegensburg factory alone. Further con-firmed numbers are not available. The air-craft never reached the units in these num-bers, however, which was in part due tosabotage and the resulting accidents. Forexample, on 18 March 1945 the technicalofficer of JG 6 reported:

Extract from the Chronicle ofPeter Schmoll, the Messerschmitt Fac-

tories in the Second World War

Newly-delivered aircraft are veryprone to problems in the first 5 to 10 flyinghours. It is almost always the same com-plaints, which are a burden to the unit tech-nically and reduce its operational readi-ness. Complaints of the following natureappear almost regularly: elevator play inthe mounting lever; loose spacers on the el-evator control rods; too-long mountingbolts on the undercarriage suspension fit-tings; absence of slip markings on themainwheels; leaky or plugged lines in theMW 50 system; shorts in the electricalsystem... loose and improperly fittedsparkplugs; loose mounting clamps on thehoses, etc.

The following Rüstsätze (equipmentsets) were planned for the K-4: Rüstsatz 1consisted of gravity weapons (bombs), 1 x500 kg, or 1 x 250 kg. These were mountedeither on an ETC 500/IX B or a Type 503integral rack beneath the fuselage. TheRüstsatz also included a ZBK 241/1 fusingbattery box in Fuselage Section 5 and aZSK fusing switchbox. The gravity weap-ons were controlled by the bomb-releasebutton (B2 button) on the KG 13 A controlcolumn grip and by the ZSK 244A on theback-up panel. Rüstsatz 3 consisted of a300-liter drop tank, which was mounted onthe Type 503A-1 rack. The fuel was trans-ferred from the drop tank into the main tankby means of supercharger air. The droptank could be jettisoned at any time inflight. Rüstsatz 4 consisted of two MG 151/

37

20 cannon, one beneath each wing in gon-dola-shaped fairings. The weapons werefired using the B-1 button on the KG 13 A.The weapons were cocked automaticallyby switching on the safety switch on theSZKK (switch selector control box). Rüst-satz 6 was to be the installation of a BSK 16ballistic gun camera in the left wing be-tween nose ribs 3 and 4. Operation was au-tomatic when the guns were fired. The fol-lowing data are from a report by the GL/C-E 2 (RLM) on 13 August 1944. Perfor-mance figures for the Bf 109 K-4/R2 re-connaissance aircraft were as follows:takeoff run was 380 m. Rate of climb at

ground level was 13.5 m/sec. Economicalcruising speed was 645 kph at an altitude of8.4 km. Range at that speed was 585 kilo-meters. Time to climb to 6 000 meters was8 minutes. Maximum speed at emergencypower was 580 kph at ground level and 710kph at maximum boost altitude of 7 500meters. Landing speed with a landingspeed of 3 tons was 150 kph. The MW 50system was also the subject of frequent dis-cussion, for example, the question of dis-pensing with the overflow limiter in theMW 50 tank. On 26 June 1944 it was de-cided by C-E 2 III Bormann to proceedwith the overflow limiter in the MW 50tank in order to avoid further delays.

38

Me 109 L

The Me 109 L project was directly as-sociated with the end of the Me 209 pro-gram. Following a conference of depart-ment heads at the office of the TechnischeAmt GL/C-E on 16 December 1943 theOberammergau project office proposed theMe 109 L project. Wingspan was to be 13.3m, which gave an aerodynamic area of 21.0m2 with an aspect ratio of 1 : 8. The outerwings were to be taken from the Bf 109 H-1 with reinforcements. The wing had to bemodified forward of the spar in the under-carriage area in order to accept a longer,wide-track undercarriage. This wide-trackundercarriage was designed without cam-ber and toe-in, and to accept either 700 x175 or 740 x 210 wheels. The inner wingwas to be built as a rectangular center sec-tion, with a continuous spar running atright angles to the fuselage axis, plus a tankarea of 170 liters between the main sparand the rear auxiliary spar. The fuselagewas to be the same as that of the Bf 109 H-1or Bf 109 K. Two modifications wouldhave to be made, however. For one, the riv-eted wing bearer would have to be re-moved. In its place fittings were installedfor the one-piece spar, which compared tothe spar position of the Bf 109 G if it hadbeen moved forward in the fuselage 260mm. Another planned change was the cre-ation of a separation point for the standardpower plant with the corresponding enginemounts.

Me 109 L Weights

AirframeEngineFixed equipmentOther equipmentArmament:

Armor

Equipped weight

PilotFuelOilAmmunition:

GM 1 + equipment

2 x MG 1511 x MK 108

570 l x 0.79

MK 108MG 151

kg13391879

10493

1058714

3 621

106455

5038

100160

4 530

The horizontal tail, which had a sur-face area of 2.8 m2, was to be taken fromthe Bf 109 H-1. The new vertical tailshould have matched the current state offlight testing. The anticipated engine wasthe Jumo 213 E standard power plant withannular radiator. This engine was to driveeither a Junkers VS 9 four-blade woodenpropeller with a diameter of 3.2 m or athree-blade Me P8 wooden propeller with adiameter of 3.4 m. Planned armament con-sisted of one engine-mounted MK 108 can-non with 70 rounds, plus two unsynchro-nized MG 151/20 cannon in the wings with200 rounds each. No prototype of the Me109 L is known to have been built.

39

Me 109 Z / Me 609

The idea of creating a single-seat de-stroyer or high-speed bomber from twosingle-seat fighters first appeared in a sub-mission made on 9 December 1942. It wasin keeping with a proposal to standardizeaircraft to a few types. The first proposalsfor a fast aircraft from two single-seatfighters were based on the Bf 109 and Me309.

Such a combination had the advantageof taking less time to develop and put intoproduction than a completely new aircraftfor the same role. The cost for redesign andthe designing of jigs and tools was only30% of that of a new design.

Another advantage of using an exist-ing type was of course the accelerated test-ing, since prototypes could be producedquickly and, if necessary, in large numbers.Time wise, the so-called "double Bf 109."based on the Bf 109 G and its DB 605 en-gine, was the most effective solution.

Another development possibility, al-beit a more expensive one. was the use ofthe Jumo 213 power plant. The followingchanges were seen as necessary for thedouble aircraft: the creation of a new wingsection between the two fuselages. Thiswould be easy to manufacture, since rect-angular wing attachment points were avail-

able. Modification of the main undercar-riage made necessary the relocation of theundercarriage attachment points pluschanges to the wheel wells in the wing.

The higher all-up weight meant thatlarger wheels were required. Lengtheningof the ailerons and slats was also necessary.It was anticipated that extra fuel tankswould be installed in the second fuselage inplace of the pilot seat. A new. rectangularhorizontal tail likewise had to be produced.The rest would be taken from existing pro-duction. Armament for the destroyer rolewas to be five MK 108 canon or four MK108s and one MK 103. The bomber versionwould carry a reduced armament of twoMK 108s but would have increased fueltankage of 1140 liters.

The planned bomb load was 2 x 1000kg. Preliminary designs for a combinationof two Me 309s powered by DB 603 G en-gines displayed similar possibilities tothose of the Bf 109. Because of its morepowerful engines, this version was expect-ed to have a better performance.

Structural layout was similar to that ofthe Me 109 Z. The destroyer version was tobe armed with two MK 108 and two MK103 cannon, plus two further MK 108s inthe outer wings. Neither the Me 109 Z northe Me 609 was built and tested.

40

Double Bf 109 = Me 109 Z

Provisional performance figures

PurposePower plantEngine data:

at 0 m

at opt. alt.

FuelTakeoff powerClimb and combat powerMax. continuous powerClimb and combat power

Equipped weight

Gross weight

Max. Speedsat 0 m

CrewFuelOilAmmunitionBombs

Takeoff power

Climb and combat power

At opt. alt.

Rate of climbat 0 m,

Takeoff powerClimb and combat power

climb and combat power

DB 605B 41,475 H.P.1,310 H.P.1,075 H.P.1,230 H.P/7.1

4 9 0 0 kg10082590340(500)6 2 0 0 kg

580 kph

560

710 kph690

-17m/sec

DestroyerJumo 213B41,7501,6001,3501,410/7.5

530010082590340(500)6 6 0 0 kg

630

610

740720

-22

C32,0001,7001,4301,430/8.5

8300 kg

660

633

>760750

-26

BomberDB 605

4 7 0 010011401251702 0 0 08300 kg

Jumo 213

5 1 7 010011401251702 0 0 0

Loss of speed by 1 x1000 kg bomb ca. 50kph at 0 m,75 kph atopt. alt.

These performance figures were calculated in haste and must therefore be treated as approximate values.

Mach numbers were not taken into consideration.

Double Me 309 = Me 609

Provisional performance figures

PurposePower plantEngine data:

At 0 m

FuelTakeoff powerClimb and combat powerMax. continuous power

At opt. alt Climb and combat power

Max. speedsAt 0 m

Equipped weightCrewFuelOilAmmunitionBombsTakeoff weight

takeoff power

climb and combat powerat opt. alt. takeoff power

Climb and combat power

DestroyerDB 603 GB 41,750 H.P.1,575 H.P.1,375 H.P.1,480/7.16 380 kg1001 35085410(500)8325 kg

595 kph

580760735

C 31,7401,5501,3501,450/8.5

595

580>770>760

BomberDB 603 G

6 1001001500851452 0 0 010100 kg

loss of speed through 1 x 1000bomb approximately 50 kphat 0 m 75 kph at opt. alt..

Rate of climbat 0 m with climb and combat power -17m/sec

These performance figures were calculated in haste and must therefore be treated as approximate values.Mach numbers were not taken into consideration.

41

Preliminary Experiments for the Me 209

Bf 109 F-1 Werknummer 5642, whichhad been built in November 1940, was con-verted to a wide-track undercarriage forpreliminary experiments for the Me 209.The modified machine was coded SG +EK. The aircraft was powered by a DB 605D engine cleared for 1450 H.P. for takeoffand emergency power, furthermore, a re-tractable belly radiator was used. Totalweight was 3100 kg.

Testing began in February 1943 andencompassed takeoff characteristics, three-point landings, night landings, dynamiclongitudinal stability, and stalls. These re-vealed identical landing characteristics tothose of the Bf 109 F or G.

Furthermore, a stall in a turn with flapsretracted and engine at emergency powerproduced the same flow pattern as the Bf109. Coming from outboard and inboard.the flow entered the area of the slats at anangle, leaving a relatively small triangulararea behind the slats undisturbed.

In this condition the aircraft wobbledstrongly about the longitudinal axis, andthese movements increased in intensity aswing loading rose. A full stall occurredonly at large angles of attack.

With the Me 209's high wing loadingthe effectiveness of the leading edge slatshad to be improved. But since tests showedthat extending the slats farther brought noimprovement and the undercarriage onlypermitted a minor lengthening of the slats

(100 to 150 mm), poor stall behavior wasaccepted for the Me 209. Director of flightoperations Baur carried out further trialswith W.Nr. 5642; for example, night land-ing trials at Lechfeld at the end of March1943 produced the following results:1. The exhaust flames are a significant hin-

drance at night.2. The bulb in the reflector sight (Revi)

must be separately blacked out. since it istoo bright even at the lowest setting.

3. UV instrument lighting is recommended,there is no illumination of the horizontalstabilizer pilch indicator.

During the second night landing thetorque link on the left undercarriage legbroke, whereupon the mainwheel turnedsideways. Further trials were flown byFritz Wendel in Werknummer 14003, VJ +WC. The machine had a takeoff weight of3780 kg (!) and a landing weight of 3650 kg,According to a report dated 29 April 1943,stalling behavior deteriorated worse thanexpected. At the stall there was such a vio-lent aileron movement that the pilot wasunable to compensate even with both handson the stick. At small angles of attack theaircraft rolled very quickly to more than 90degrees.

As well, no improvement could be ex-pected by enlarging the slat openings.Takeoff and landing characteristics werebetter than those of the Me 309 at the sameweight.

42

Messerschmitt Regensburg Factory Aircraft Production Bf 109 G

Assembly of Bf 109 G Acceptance Flight Activity Dec. 1941 - Dec. 1942

Month

NovemberDecemberJanuary

February

MarchApril

MayJune

JulyAugust

SeptemberOctoberNovemberDecember

Year

19411941194219421942194219421942194219421942194219421942194219421942194219421942194219421942

Total production from Nov. 1941

Model

G-1G-1G-1/R2G-1G-1G-2G-1G-2G-1G-1G-1G-1/R1G-1/R1G-1/R1G-2G-2G-2G-2G-4G-4/tropG-4G-4G-4/trop

Werk-Nr.

1400114003140101401514022140281402914036140371403914064140751409214133141511418414231142461600116039160931614116183

- D e c . 1942:

tototototo

to

tototototototototototototototo

Werk.Nr.

1400214009140141402114027

14035

140381406314074140911413214150141831423014245142681603816092161401618216220

Quantity

2

75761712

2511174!1833471523 converted to trop3854484238

488

Bf 109

2

0

101

2768

525050

46544880

488

G-1

2

9

23

281

3

1

67

G-1/R2

1

12

4033

2

1

80

G-2

2

18

4827

3

98

G-2/trop G-4

20

3 38

4842

23 128

54

38

92

G-4/trop

43

Messerschmitt Werke Regensburg Aircraft Production Bf 109 G

Assembly Bf 109 G

Month

Januar

Februar

März

April

Mai

Juni

Juli

August

September

Oktober

November

Dezember

Total produced

Year

1943

1943

1943

!943

1943

1943

1943

1943

1943

1943

1943

1943

1943

1943

1943

1943

1943

1943

Jan. 1943

Model

G-4 / t rop

G - 3

G - 3

G - 4 / t r o p

G - 6

G - 6

G - 6

G - 6

G - 6

G - 6

G - 6

G - 6

G - 6

G - 6

G - 6

G - 6

G - 6

G - 6

-Dez . 1943:

Werk -

16221

16251

16270

16301

16313

16354

16524

18001

18046

18071

18276

18513

18781

160001

160121

160196

160364

160566

Nr.

bis

bis

bis.

bis

bis

bis

bis

bis

bis

bis

bis

bis

bis

bis

bis

bis

bis

bis

Werk - Nr.

16250

16269

16300

16312

16354

16523

16650

18045

18070

18275

18512

18780

18900

160120

160197

160363

160565

160835

2168

Stück

30

19

31

12

42

170

127

45

25

205

237

268

120

120

77

168

202

270

Total

Flight Activity

Test Flight Activity Jan. 1943 - Dez.1943

Bf 109

49

85

170

196

205

237

268

241

77

166

202

270

2166

44

Messerschmitt Werke Regensburg Aircraft Production Bf 109 G

Assembly Bf 109 G Test Flight Activity Jan. 1944 - Dez.1944

Month Year Model Werk - Nr .Werk - Nr. Quantity B f 1 0 9 G - 6 G - 6 / A S G - 1 4 G - 1 4 / A S G - 1 0 K - 4

Januar

Februar

März

April

Mai

Juni

Juli

August

September

Oktober

November

Dezember

1944

1944

1944

1944

1944

1944

1944

1944

1944

1944

1944

1944

Total produced Jan.1944 - Dez. 1944: 6316

434

305

135

343

550

659

650

704

701

755

543

537

Total

Flight Activity 6316 3165 325 479 1373 118 856

45

Messerschmitt AGLicense Production

Nb 7b

To be delivered

G-1Er la G-2

G-2 tpG-4 tp

G-5

K-1

G-6 tp

G-6

G-6/U2

K-2

Studie G -1

v. 10.9.43 G-2G-2 tpG-4 tp

G-5

K-1

G-6/U2G-6

K-2

Ausgestellt am:

Aussteller:

Delivery plan

Total

20

160

384266

930

298

1524

500

4810

9281

20

160384

266

391930

5002X50

6530

12031

21.9.43

delivered bybis 31.7.4320

160384

26669

298

324

1521

20

160384266

69

622

-

1521

TypeBf 109

1943

8

35

165

200

1721

31

169

200

1721

9

40

170

210

1931

46

194

240

1961

10

45

195

240

2171

45

235

280

2241

geändert am:

11

50

60

140

250

2421

50

280

330

2571

12

50

50

160

260

2681

50

300

30

3802951

Programm 223

vom 15.8.19431944

1

50

60

160

270

295!

50

200

170

420

3371

2

50

190

40

280

3231

50

410

4603831

Geheim!

, Anderungsstand B

3

50

250

300

3531

50

450

500

4331

4

50

60

210

320

3851

50

290

210

550

4881

5

50

290

340

4191

50

500

550

5431

6

50

310

360

4551

50

500

550

5981

7

50

330

380

4931

50

500

550

6531

1. Dies ist ein Staatsgeheimnis im Sinne des §88 RSTGB2. Weitergabe nur verschlossen

8

50

350

400

5331

50

500

550

7081

9

50

370

420

5751

50

500

550

7631

10

50

390

440

6191

50

500

550

8181

11

50

400

450

6641

50

500

550

8731

+

12

50

400

450709!

50

500

5509281

1945

1

50

380

4307521

50

500

550

9831

2

50

350

4007921

50

450

500

10331

3

50

300

350

8271

50

450

500

10831

Umschaltung auf Höhenjägervorgesehen z.Zt. in Bearbeitung

4

50

250

3008571

50

350

400

11231

5

50

200

250882!

50

250

300

11531

6

50

150

200

9021

50

150

2(X)

11731

7

50

100

1509171

50

100

150

11881

8

50

30

80

9251

50

50

UK)

11981

9

30

30

9281

30

20

5012031

46

Messerschmitt AGLicense production

To be delivered

C-2WNF G-2/R1

G-4

G-4/R3G-6

G-6/U4

K-2

G-6/R3

G-6/R2

G-8

Studie G-2/G-2/RI

v. 10.9.43 G-4G-4/R3

G-6G-6/U4

K-2

G-6/R3G-6/R2

G-8

Ausgestellt am:

Aussteller:

Total

91410

636

HO1420

1445

10340

4(1

250

2100

17235

924

636

8016383199

1399540

240

2040

22792

21.9.43

Delivery planNB 7b

Delivered by

bis 31.7.4391410

63580

64846

-

22

-

-

2355

924

63580

64846

22

-

-

2355

19438

1

182

64

18

15

2802635

1

150

13

13

5

182

2537

Type

Bf 109

9

170

100

10

20

3002935

220

65

5

20

310

2847

9

10

130

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47

neath the wings and thetwo large circular bulgesover the MG 131s. Notethe lovely spiral on thelarge propeller spinner.

Beginning with the G-5series, the Bf 109's fire-power was increasedthrough the replacementof the two 7.9-mm MG 17machine-guns with two13-mm MG 131s. This re-sulted in the characteri-stic bulges on both sidesof the engine cowling.The aircraft's basic ar-mament consisted of twoMG 131s and an engine-mounted MG 151/20.

Front view of the Bf 109G-5. In spite of the twobulges, early examples ofthis variant were charac-terized by a good aerody-namic shape.

Bt 109 G-6/R6 parked atthe edge of a forest for con-cealment. This photo pro-vides an excellent view ofthe MG 151/20 cannon be-

94

Beginning in May 1943some Bf 109 G-6s had theMorane antenna mastfor the FuG 16ZY radiosystem fitted beneath theleft wing. This radio wasused in conjunction withthe Y-method of fightercontrol.

Arming the MG 151/20wing cannon of a Bf 109G-6 of JG 27 in North Af-rica.

95

The instrument panel ofa Bf 109 G. SZKK 3switch-counting and con-trol box, Revi C 12/g gun-sight, cluck, magneto sel-ector switch, repeatercompass, turn-and-bankindicator, propeller pitchindicator, undercarriageposition indicator, fine-coarse altimeter, air-speed indicator, boostpressure gauge. RPM in-dicator, coolant and oiltemperature gauge, fueland oil pressure gauge,altimeter, and fuel gauge.

106

Bf 109 G-6. On the far leftnext to the gunsight is therepeater compass, besideit the turn-and-bank indi-cator, beneath it the air-speed indicator and besi-de it the fine-coarse alti-meter. Clearly visible be-neath the instrument pa-nel is the mount for theengine-mounted cannon,which has been removed.

Some late variants of theBf 109 G had their arma-ment bolstered throughthe installation of Rüstsatz5, which consisted of twoMK 108 cannon in the un-derwing gondolas.

Three-view drawing ofthe Bf 109 K-4 takenfrom an aircraft typesheet.

This American proudlyposes for a souvenir pho-to in front of a Bf 109 G-10 on a south-Germanair base after the end ofthe war.

117

General ArrangementDrawing Bf 109 K-4(Günter Sengfelder)

122

123

Bf 109 K-6:General arrangementand control surface de-flections.

124

125

Trials with 660 x 150 Wheels

For the purpose of undercarriage legtrials Bf 109 G W.Nr. 14003 was brought toa takeoff weight of 3.8 tons. This resultedin increased numbers of tire failures andled to extended trials with the 660 x 150wheel with tire and inner tube. As well,there were growing complaints from thefront-line units. During the period fromJuly to August 1943 far in excess of 100takeoffs and landings were made by thetest-beds W.Nr. 14003 and W.Nr. 160031 inan effort to determine the cause of the fail-ures. At the same time, comparative trialswere conducted with 650 x 150 and 660 x160 wheels with free-lying steel brakedrums. In some cases the normal tires had avery short life, some only 2 to 4 circuits,and such was the problem that an immedi-ate solution had to be found in conjunctionwith the Continental Company. Trials werecarried out at Lechfeld airfield near Augs-burg. The poorest areas of this landing fieldwere comparable to conditions at forwardairfields. Two new wheels with new tiresand inner tubes were installed on the Bf109 G-1 test-bed. Werknunmer 14003. Thewheel loading at rest was divided as fol-lows: 1.6 tons per mainwheel and 0.6 tonson the tailwheel. The brakes were usedharshly on all landings, and once on theground the tightest, alternating turns weremade. The trials revealed that the tirescould just stand up to 3 or 4 circuits on dry.uneven, and stony ground. Comparativelandings and taxiing on concrete showed athree- to four-fold increase in tire life. Butthere, too, when thermal load increased

(braking) the tire failures reappeared. Thesubsequent use of reinforcing bands in-creased the life of the same tire to an aver-age of 15 to 20 circuits. This was such animprovement that a message was immedi-ately sent to the units. This was no ideal so-lution, however, and therefore the trialswent on. Redesigned Elektron die castwheels with free-lying steel brake drumsby EC4 (drawing no. 8-2089 B-2) were nowput into use. A total of 120 circuits wereflown with these wheels under identicaltest conditions. Heavy braking was used tosimulate the thermal loads and high exter-nal temperatures to be expected in front-line use. The average daytime temperatureduring these experiments was 32° C. Thestress through brake heat was increasedfurther by Hying circuits in quick succes-sion, in some cases 25 circuits in the spaceof one hour. In spite of these stresses thetires withstood 120 circuits and even afterexamination by the EC Company were insuch condition that they were approved forfurther use. The tires were changed onlyonce per wheel. The reason for this canonly be suspected to be pushing the test-bed too hard. These new engine cowlingwheels with free-lying brake drums repre-sented such an improvement that it seemedadvisable to replace all 660 x 160 tires withinternal brake drums with them. While thesimultaneous trials with the 650 x 150wheel produced less thermal load on thetires and greater life, the results could notstand up to these. It was also subjected toless load.

4 Elektron-Co m.b.H. Bad Cannstadl

151

The Bf 109 undercarria-ge. Here details of the un-dercarriage leg withmain wheel, fairing, bra-ke line, stub axle, andshock strut head.

152

Front and rear views ofthe Bf 109 K mainwheel(660 x 190).

153

Bf 109 K SeriesDeliveries of the K-Series, which was to be the finalmajor production variant of the Bf 109, began in mid-October 1944. The previously-mentioned RLM tran-script from August 9,1943 reveals that the manufac-ture of 10 pre-production aircraft by WNF was plannedfor September 1943. Series production of the Bf 109K-2 was subsequently to begin at Erla, WNF andMesserschmitt Regensburg in February 1944. Fur-ther, the Bf 109 K-1 was supposed to replace the G-5 in production at Erla from July 1944 and it wasspecified that, like the G-5, the K-1 was to be

equipped with a pressurized cockpit. Quantity pro-duction was also planned of a K-3 series which wasto be built as a fighter and, in its K-3/R2 form, as areconnaissance aircraft with a pressurized cockpit.In March 1944, however, it was decided that in theinterests of a standardization of Bf 109 production allother K-Series would be cancelled pending the intro-duction to production of the K-4 series. Therefore theonly variant of the K-Series to reach quantity produc-tion was the Bf 109 K-4.

This Bf 109 K-4 with the Werknummer 330 130 was flown by the Messerschmitt factories in various trials in theautumn of 1944. The identifying features of the K-Series are clearly evident: the revised, forward location of the fueltank filler point and the octane triangle beneath it, the DF loop which was displaced further back along the fuselagespine, the revised equipment hatch door, the tall tailwheel and the tall fin and rudder with two fixed trim tabs.(Radinger)

Bf 109 K-4 167

Bf 109 K-4While the K-1 to K-3 Series, which got no further thanthe project level, were to retain the DB 605 A powerplant, the K-4 was conceived around the DB 605 Dand accordingly differed little from the G-10. Incontrast to the G-10, K-Series aircraft were notconversions of older machines, and unlike the G-10the vast majority of the aircraft delivered wereequipped with the DB 605 D engine, although a fewexceptions are known among early series aircraftwhich retained the DB 605 AS engine.

According to the existing production programs,which were also continually revised regarding K-4production, at one time the construction of over12,700 K-4s was planned, with production stretchingfrom July 1944 until March 1946. In fact only afraction of these projected numbers were built anddelivered. The actual number of K-4s built is un-known; a total of 534 had been delivered by Novem-ber 30, 1944, and it may be assumed that at leastanother 1,200 machines had been built by the timethe war ended. The known K-4 Werknummerblocksare:

330000-331000331300-331500332000-333000333800 - 334000334000 - 334300335000 - 335300570000-571000

Mtt Reg.Mtt Reg.Mtt Reg.Mtt Reg.Mtt Reg.Mtt Reg.Erla

The vast majority of K-4s were built by Messerschmitt,and the company's planned production figure, ac-cording to the production program as it stood onNovember 30,1944, was 3,598 aircraft, all of whichwere to be delivered by July 1945. In addition, Erlawas to build 2,895 of the K-4/R6 version in the periodJanuary-April 1945. Production did in fact beginthere, probably in early 1945, but it is not known howmany aircraft were built and delivered before Leipzigwas occupied by American forces on April 19, 1945.The only known example of an Erla-built K-4/R6 isWerknummer 570362, which was accepted by BALon February 16,1945. Furthermore, WNF was sup-posed to construct another 2,820 K-4/R6s from May1945 to March 1946, while KÖB was to construct1,000 K-4s in the period March-June 1945 and afurther 2,700 of the K-4/R6 version by March 1946.It is not known if production of these planned seriesbegan and if so what Werknummerblocks they wereassigned.

The K-4 began reaching active units assigned tothe Reich Defense in mid-October 1944 and those inthe East somewhat later. Thus deliveries of the K-4obviously began some time before those of the G-10, The first known loss of a K-4 occurred on October19, 1944, when Werknummer 330305 crashed whilebeing flown by Uffz. Pospiech of 3./FIÜG 1 (S). Thesame day the Sonderkommando OKL lost a K-4 withthe Werknummer 330319. The aircraft's pilot, Ofw.Galli, was apparently injured in the incident.

By the end of the war the K-4 had been deliveredto the following units:

Messerschmitt Bf 109 K-4

Messerschmitt Bf 109 F, G, & K Series • An Illustrated Study

The following photographs were taken in November at Neuruppin, where III./JG 77 was resting and refitting andreequipping with the K-4. Here Hptm. Menzel is seen preparing for a practice sortie in "White 1," a K-4 of 9. Staffelwith the Werknummer 330 204. This aircraft was lost on January 1, 1945, while taking part in Operation "Bodenplatte,"when Lt. Abendroth was shot down by flak in the Rosendaal area and subsequently taken prisoner. (Buck)

"White 2," another K-4 of 9./JG 77 at Neuruppin inNovember 1944. (Buck)

A ground collision involving two K-4s of 9./JG 77. Sittingin "White 8," which is just visible beneath "White 3," wasUffz. Schulz. Luckily Schulz escaped serious injury andwas able to climb out of his wrecked machine. (Buck)

168

Bf 109 K-4 169

III./JG 1, II./JG 2, III./JG 3, I., III./JG 4, II./JG 11,III./JG 26, II., III., IV./JG 27, III./JG 51, II., III./JG 52,II., III./JG 53, I., II., III./JG 77, I./NJG 11, II./KG(J) 6and I. and II./KG(J) 27. Most of these Gruppen wereonly partially equipped with the K-4 and continued tofly numerous G-14s and G-10s as well. Only III./JG3, III./JG 26, III./JG 53 and III./JG 77 were equipped,at least for a time, solely with the K-4.

Externally, the K-4 differed little from some G-10s.The engine installation of both versions was identi-cal. The K-4 also had the new, wide-bladed VDM 9-12159 propeller and the deeper F0 987 oil cooler, aswell the two side fairings to accommodate the largercrankcase of the DB 605 D. Like the G-10, MW-50

power boost was standard equipment on the K-4,and as a result the complete engine designation wasDB 605 DM. In addition the K-4 was built with radiatorcutoff valves like those which had been retrofitted tolimited numbers of F-Series aircraft in 1941.

The cockpit area, too, was virtually unchangedfrom that of the G-10. The K-4 exhibited the variousknown styles of the so-called "agglomerations", theriveted-on fairings behind the bulged engine cowl-ing. The K-4 received the Erla-Haube as standardequipment and the antenna mast was often dis-pensed with; in this case the aerial was attached tothe fuselage spine in the usual manner. Because ofthe high attrition in antenna masts and safety springsresulting from the Erla-Haube being opened too far,

Four K-4s of 3./JG 77 at Neuruppin airfield on a dreary, foggy November day. All wear the Geschwader emblem of JG77 on the engine cowling. (Buck)

Two shots of "White 17," a K-4 of 9./JG 77 with the Werknummer 330 230. On January 1,1945, Uffz. Munninger of 10./JG 77 was shot down and killed by anti-aircraft fire near Tilburg while flying this aircraft. Behind the fuselage one cansee Lt. Renzow, the Staffelführer of 10./JG 77. (Buck)

170 Messerschmitt Bf 109 F, G, & K Series • An Illustrated Study

Aircraft of 11./JG 77. In the center is "Yellow 8," a K-4 with the Werknummer 330 176. This aircraft was lost as theresult of a mid-air collision near Neuruppin on November 27,1944, its pilot, Lt. Zieher, losing his life. (Böttner)

a technical directive was issued in November 1944(TAGL II Bf 109 A2 Nr. 3, 427/44) which containeddetailed instructions to the front-line maintenanceshops for the replacement of the antenna mast and,if required, conversion of the antenna installation tothe current production standard. In the modificationprocess the aerial was simply hooked into a hole inthe fuselage spine, led through the DF loop andattached to the fin with a metal lashing. The fixedantenna, with an overall length of 3.5 meters, con-sisted of impregnated hemp rope (85 cm), an eye,flexible wire (40 cm), the actual antenna between theinsulators (167 cm), flexible wire (41 cm) and thesafety spring, which was hooked onto the fin. Thefuselage antenna lead-in, which was attached 51 cm

in front of the rear insulator, sloped forward 74 cm tothe fuselage spine.

The filler point for the main fuel tank was movedforward to a location between Frames 2 and 3-asalways on the left side of the fuselage. Converselythe DF loop was moved aft and installed betweenFrames 3 and 4. The round sheet-metal plate overthe footrest behind the wing root was deleted on theK-4. The radio equipment access hatch was alsomoved forward and was located between Frames 4and 5 in a somewhat higher position than before.The hatch is often depicted with a sloped upperedge, but this was in fact horizontal, while the bottomedge sloped slightly to the front.

The enlarged tail unit was a standard fit on the K-

Uffz. Fröhlich of 11./JG 77 in front of a K-4 of 10./JG 77with the code "Red 2," photographed at the end ofDecember 1944 at Düsseldorf-Ratingen. It is obvious thatthis aircraft does not yet carry the white/green fuselageband which was first used by JG 77 in the operations onNew Year's Day 1945. (Fröhlich)

K-4s of 11./JG 3 parked and meagerly brish-camouflagedat Pasewalk airfield in February 1945. (Kallerhoff)

Bf 109 K-4 171

Hptm. Strasen, who took over III./JG 4 just before the endof the war, by the tail of his K-4, which wears the black/white/black fuselage band of JG 4. Visible on the fuse-lage band is the vertical Gruppe bar, which on aircraft ofthe Gruppenstab of Ill./JG 4 was red. (Strasen)

4, and in most cases the aircraft's rudder featuredthe Flettner tab as well as the two fixed tabs; how-ever, there were rare examples which did not receivethe fixed tabs. In general all K-4s were supposed toreceive the long tailwheel, which was intended to beretractable. The tailwheel size was 350 x 135. A fewK-4s were nevertheless fitted with the short tailwheelof the G-6. Those aircraft with the long, retractabletailwheel were fitted with two clamshell doors tocover the tailwheel recess.

The wing of the K-4 had the large, rectangularfairings for the 660 x 190 mainwheels, and externallywas almost indistinguishable from that of the G-10series. There were several differences, however.The ailerons of the K-4 were fitted with small insetadjustable trim tabs. It was also planned to introduce

Above: Lt. Landt, Staffelführer of 11./JG 53, in the cockpitof his aircraft "Yellow 1" at Kirrlach, February 22,1945.This K-4 may be the same machine - W.Nr. 332 660 - inwhich Lt. Landt collided with a Mustang during a dog-fight near Bretten a day later. Landt was injured in theincident and was forced to bail out of his damagedaircraft. (Landt) Right: "Yellow 1" again. The blackfuselage band worn by aircraft of JG 53 is clearly visiblebehind the Balkenkreuz. (Landt)

172 Messerschmitt Bf 109 F, G, & K Series • An Illustrated Study

Lt. Potreck, a pilot in the Stab of III./JG 53, seated in hisbrush-camouflaged K-4 during preparations for a sortiein March 1945. (Landt)

"Yellow 15," a K-4 with the Werknummer 332 956,belonged to 11./JG 53 at Kirrlach in March 1945. On theleft is Ofw. Polak and on the right Ofw. Scheer. Note thelast four digits of the Werknummer on the aft fuselage.(Scheer)

Two pilots of 11./JG 3 - Gefr. Zitzmann and Uffz. Lehnen- in front of "Yellow 2," a K-4 with the Werknummer 332506. This aircraft was lost in combat with Yak-9s nearStettin, when Uffz. Günter was shot down and killed.(Suhr)

Uffz. Suhr by the tail of his K-4, on whose rudder theWerknummer 334 210 may be seen. This aircraft has theshort tailwheel, but it appears that the tailwheel recessdoors for the long tailwheel are nevertheless present.(Suhr)

Bf 109 K-4 173

Three shots of "Yellow 8," a K-4 of 11./JG 3 at Pasewalk in March 1945. The pilots of 11./JG 3 in front of "Yellow 8."Standing, from the left, Uffz. Zimmermann, Uffz. Massing, Gefr. Zitzmann, Lt. Walter, Uffz. Deskau and Uffz. Suhr;sitting, FhjFw. Gogler, a Luftwaffe Female Auxiliary and Uffz. Lehnen. Note the antenna wire which runs through theDF loop and is attached to the fuselage spine. (Suhr)

Above: The open, uncamouflaged placement of the K-4sof 11./JG 3 is noteworthy, because by this time theRussian Air Force was in almost complete command ofthe skies over eastern Germany. In the foreground thepersonnel of 11./JG 3 once again; from left Uffz. Massing,Lt. Walter, FhjFw. Gogler, Gefr. Zimmermann and anunidentified pilot. (Suhr)

Left: This aircraft was flown by Lt. Walter, later trans-ferred to IV./JG 3 and here seen in front of his aircraft.Note the octane triangle specifying 87 octane fuel andthe name "Mary" beneath the cockpit. (Suhr)

174 Messerschmitt Bf 109 F, G, & K Series • An Illustrated Study

Fw. Strebel of 11./JG 3 in front of his aircraft "Yellow 4,"presumably again the K-4 with the Werknummer 334 210.Note the end of the antenna wire behind the fuel tankfiller inlet, the octane triangle with the c3 marking and thename "Ingeborg" beneath the cockpit. (Suhr)

the small mainwheel well doors similar to thosewhich had been planned for the earlier Bf 109 G.These well doors were often removed by the front-line units. Installation of the antenna mast for theFuG 16zy below the left wing was standard. Onechange not externally visible was the relocation ofthe oxygen bottles from the rear fuselage to the rightwing.

Armament of the K-4 consisted of an engine-mounted MK 108 cannon, which by now was in-stalled on the production line, as well as two MG 131machine-guns above the engine. There were air-craft, however, which were delivered with an MG151/20 engine-mounted cannon. Radio equipmentwas similar to that of the G-10, with the FuG 16ZYand 25a as well as the Peilrufanlagfedirection finding(DF) equipment.

A series of Rüstsätze was planned for the K-4, ofwhich only R3, the standard range-increasing modi-fication with 300-liter auxiliary fuel tank, saw large-scale use. R1 was the planned installation of an ETC500 IXb rack for one 250 kg or 500 kg bomb, R4 twounderwing, gondola-mounted 20-mm cannon andR6 the installation of a BSK 16 gun camera in the leftwing. Like the G14 and G-10 before it, a bad-weatherversion of the K-4 was to be built, designated K-4/R6. It has not been confirmed that this version wasin fact built in large numbers. And finally there was areconnaissance version, the K-4/R2, which could beequipped with an Rb 50/30 or Rb 75/30 camera aswell as an FuG 16 ZS in place of the FuG 16 ZY.There is likewise no proof that the K-4/R2 wasactually built.

A K-4 of Ill./JG 51 takes off from Junkertroylhof in April 1945. Visible behind the Balkenkreuz are the last three digitsof the Werknummer, 334 175. (Aders)

Bf 109 K-4 175

Different styles of attaching the antenna wire to the vertical stabilizer. The tailwheel doors are illustrated in the openand closed positions.

Lt. Landt of 11./JG 53 taxis out for takeoff in "Yellow 14," a K-4, in early 1945. Note the small wheel well doors beneaththe wings, while the undercarriage leg fairings are absent (Landt)

A K-4 of 11./JG 53 taxis out onto the landing field from the cover of the surrounding woods before taking off on asortie from the forward airfield at Kreuzstrasse in April 1945. (Landt)

176 Messerschmitt Bf 109 F, G, & K Series • An Illustrated Study

Wrecked German aircraft at Kaufbeuren airfield in the summer of 1945. On the right is "Chevron 1," a K-4 of theGruppenstab of Ill./JG 53 which Lt. Bernhard had been forced to belly-land at the airfield on April 19, 1945. Note thebroad, black fuselage band with the Gruppe bar behind it, as was usual on aircraft of Ill./JG 53 in February 1945.(Chapman)

The adjutant's aircraft of Ill./JG 27, a K-4 with the Werknummer 330 255, as found at Wunstorf air base by advancingAllied troops in April 1945. All the characteristic features of the K-4 are clearly visible - the equipment bay door whichhas been moved forward, the revised locations of the DF loop and fuel tank filler inlet, the large wheel bulges on thewing upper surface and the long tailwheel. Also evident are the large mainwheels and broad propeller blades.(Petrick)

Bf 109 K-4 177

The remains of "White 16," a K-4 of 9./JG 53, as it looked on a forward airfield in southern Germany after the end ofthe war. Note the broad fuselage band with the Gruppe bar behind it. Clearly visible are the large mainwheels andbroad propeller blades. (Petrick)

Bf 109 K-6

The K-6 series was to enter production alongside theK-4 in January 1945. The production of 3,570 ma-chines was planned, 2,070 by Erla and 1,500 byWNF. According to a report by the main departmentof the OKL (Hauptausschusses) on October 31,1944, it was planned produce the K-4 and K-6 in aratio of 2:1. In any case it is not known if the K-6actually entered production and there is still noknown Werknummer block for the K-6 series. It isknown, however, that at least one K-6 was beingtested at Rechlin as early as autumn 1944.

The K-6 was to be largely similar to the K-4; theonly difference was to be the installation of two MK108 in the wings, which is why the K-6 was desig-nated a "heavy fighter."

On the other hand the projected Bf 109 K-10 andK-12 variants progressed no further than the projectstage.

"Black 2," another K-4, originally belonged to 14./JG 53.In June 1947 it still lay in a forest at the former forwardairfield at Reichenbach. Note the wavy line, used as aGruppe symbol by IV./JG 53, on the black fuselage band.(Willbold)