oo"c3

C ^ )

ru u i

NATIONAL CENTER FOR A T M O S P H E R I C R ES EARCH

B O U L D E R , C O L O R A D O

No. 18, March 1965

Issued each March, May, July, September and

N'ovember.

Second-class postage paid at Boulder, Colorado.

IQSY-EQEX

Balloon Expedition to IndiaThis is a slightly abbreviated version of a paper delivered

at the 1964 AFCRL Scientific Balloon Symposium, held in the middle of October.

Early in 1963, the United States Committee for the IQSY of the National Academy of Sciences began study­ing the feasibility of sending a balloon expedition to the vicinity of the equator (hence, E Q E X ) during the IQSY to conduct research on cosmic radiation. The committee held several meetings with interested ex­perimenters and found that there was strong interest in such an expedition.

Informal discussions were then held with Professor M. G. K. Menon, Director of the Cosmic-Ray Labora­tory, Tata Institute of Fundamental Research, Bombay, about the possibility of organizing a joint expedition. Menon’s group also expressed strong interest in such a venture and official sanction for the expedition was obtained from the Indian IQSY Committee.

The program thus became a joint Indo-American IQSY activity. A proposal for funding the expedition by the National Science Foundation was submitted and approved. The present authors, Robert Kubara of the National Center for Atmospheric Research and Bertram Stiller of the U. S. Naval Research Laboratory, are serv­ing respectively as Project Manager and Scientific Co­ordinator.

Approximately 16 flights will be flown, all of them planned to reach at least 120,000 feet and to stay at floating altitude for at least 8 hours. The table on page 3 summarizes both the experiments and the conditions necessary for successfully carrying them out. Two im­portant scientific reasons for making these flights in India are:

To obtain cosmic-ray data near the earth’s geo­magnetic equator at altitudes much higher than previously attained.

To obtain these data during the IQSY so as to permit comparison with data obtained at other latitudes during the same part of the solar cycle.

(Continued on page 2)

SCIENTIFIC BALLOONING

In addition, due to the development of new measuring techniques and equipment, such as spark chambers and solid-state de­tectors, it will be possible for the first time for cosmic-ray physicists to intercompare data obtained by a large variety of detecting systems. This possibility is of special inter­est when analyzing data obtained near the geomagnetic equator because the earth’s magnetic field permits mainly galactic cos­mic radiation to reach the detectors. Such data can be used to study astrophysical problems connected with the origin of cos­mic rays and with stellar evolution.

Two major problems faced the expedition in addition to the usual ones connected with diplomatic clearances, logistics, and funding.

First, the location of the launch site in India and the time of year had to meet the general requirements of long floating times and need for recovery. Although wind con­ditions are fairly well known up to about100,000 feet for Central India where long- duration flights are possible, essentially nothing is known about wind conditions above 120,000 feet. On the basis of a thor­ough operational anaylsis by Mr. Samuel Solot of NCAR, using available data, it was decided to launch the flights in March and April 1965. During a recent survey trip to India for site location, discussions held with Indian meteorologists led to the same con­clusions. Additional discussions with mem­bers of the balloon group at Tata Institute of Fundamental Research, who have suc­cessfully flown and recovered 60 cosmic-ray experiments in Central India during the last several years, further strengthened our de­cision. The primary launch site will be Hyderabad, but two secondary sites, one on the east coast and the other on the west, were also selected to allow for strong east­erly or westerly winds at floating altitudes. In order to make trajectory forecasts, sound­ing balloons carrying hypsometer-equipped radiosondes will be launched daily and tracked by our AN/GMD-1 unit. This pro­gram will commence about two weeks be­fore the cosmic-ray flights, in order to pro­vide current information about the wind conditions above 120,000 feet.

(The second major problem had to do with the low tropopause temperatures en­countered over the equator. A series of test flights, known as Operation Coldtrop, were conducted by NCAR personnel to de­termine which one of two balloon materials would most successfully survive these tem­peratures. This flight series is reported in the September 1964 issue of Scientific Ballooning. Editor.)

The flight operations will be conducted by Raven Industries and the anchor-line launch technique will be used for all flights, with the exception of the 2000-pound pay­load for the Tata Institute. This will be launched dynamically, using a launch arm mounted on a truck. All flights will be tracked by an aircraft which will also direct surface vehicles to the area of impact for recovery of payloads. If weather and other conditions permit, one flight will be launch­ed every other day so that approximately five weeks will be needed for all of them. The authors will be in the field for the duration of the expedition and will serve in their respective capacities in order to insure that optimum conditions exist, from the point of view of each scientific group, be­fore a balloon flight is attempted.

Large Captive Balloon A va ila b le

have a large captive balloon and the neces­sary crew and equipment support for it available for lease on a monthly basis. The balloon is 112 feet long, 40 feet in diameter, and stands about 70 feet high, including rigging. This 84,000 cubic-footer is capable of holding approximately 2/2 tons aloft at1,000 feet altitude. For more details, please ( write directly to Raven Industries, Inc., Sioux Falls, South Dakota 57101, Attention E. M. Frisby, Director, Meteorological Re­search.

M ARCH 1965 3

Cosmic-Ray Flights From India — 1965

Experimenter Type of Apparatus* Number of FlightsWeight

(pounds)Altitude

(feet)Duration(hours)

K. A. Anderson, U. of Calif. Gamma- & X-ray counters 3 40 130,000 8+

J. G. Dutbie, U. of Rochester Gamma-ray spark 2 (day-night) 250 + 120,000 15

J. T. A. Ely, AFCRL Charged particle counter telescope

2 90 140,000 10+

M. F. Kaplon, U. of Rochester

Solid-state detector telescope

2 (day-night) 220 140,000 12

S. A. Korff, New York U. Neutron counters 2 100 140,000 2+

K. G. McCracken, Grad. Res. Ctr. of S.W.

Counter telescope 2 100 120,000 8+

M. M. Shapiro, NRL Nuclear emulsions 2 100 140,000 12+

C. J. Waddington, U. of Minn.

Nuclear emulsions 1 120 140,000 12+

J. R. Winkler, U. of Minn. Ionization chamber Several hitchhikes 10 Any Any

M. G. K. Menon, Tata Inst. Nuclear emulsions 1 2000 100,000 30

M. G. K. Menon, Tata Inst. Emulsion chamber Several hitchhikes 5 Any Any

‘ Recovery of all scientific packages is required.

M a te ria ls R e p o rts A v a ila b leThree NCAR Facilities Division reports

on balloon material testing methods and re­sults are now available. Tests of Balloon Materials (FRB-1-64) shows and discusses the results of approximately 2000 tests of present and potential balloon films and film- filament composites.

Standard Test Methods for Balloon Ma­terials (FBR-2-64) is a review of federal, military, ASTM, and commercial methods of testing for mechanical and physical prop­erties of films, elastomers, and fabrics with an evaluation of these methods for use as balloon material tests. Variations of stand­ard tests and some new special tests are proposed in Non-Standard Tests for Balloon Materials (FRB-3-64). Included in this re­port are static, dynamic, and physical- properties tests, along with discussions of

design criteria and statistical implications.These three reports have been distributed

initially to manufacturers and users of bal­loon materials. Others can receive any of these reports by requesting them from the Manager, NCAR Scientific Balloon Fa­cility. Please state your area of interest.

As additional materials having possible application in ballooning become available, supplementary materials studies will beN performed and reports issued. No general distribution of these reports is planned; announcement of their publication will be made in Scientific Ballooning and copies sent to those requesting them. The first of these supplementary reports, Strength Char­acteristics of DuPont Surlyn A Film ( FRB- 4-65) is being printed and will be available soon.

4 SCIENTIFIC BALLOONING

THE FLIGHT RECORD

Date(1964-1965) Location Sponsor Investigator

Flightoperationconducted

by

Balloon specifications (polyethylene unless specified; volume in

cubic feet)

July 21 Holloman AFB, N. Mex. NASA G. Steffan (Hughes Aircraft)

AFCRL 2 mil, 125,000

Aug. 11 Holloman AFB, N. Mex. AFCRL, OAR W. Wagner (AFCRL) AFCRL 1.5 mil Mylar, 20,600

Aug. 14 & 18

Holloman AFB, N. Mex. AFCRL, OAR W. Wagner (AFCRL) AFCRL 1.5 mil Mylar, 20,600

Aug. 20 Holloman AFB, N. Mex. AFCRL, OAR B. Gildenberg (AFCRL) AFCRL 2x1.5 mil, 250,000

Aug. 26 Holloman AFB, N. Mex. AFCRL, OAR Northwestern U., Georgia Tech., AFCRL, Hi-Altitude Instrument Co.

AFCRL 0.75 mil

Aug. 28 Artesia, N. Mex. AFSC, SSD AFCRL 2x1.5 mil, 122,700 ^

Sept. 3 White Sands Missile Range, N. Mex.

AFCRL, OAR Lt. Lindenfelser (AFCRL) AFCRL 2x1.5 mil, 250,000

Sept. 10 Chico, Calif. USAF AFCRL AFCRL 1.5 mil, 2.94 million

Sept. 18 Hobbs, N. Mex. AFSC, SSD -------------- AFCRL GT-12 Dacron-Mylar scrim, 460,000

Sept. 23 Chico, Calif. AFCRL J. Dwyer (AFCRL) AFCRL 2 mil, 806,000

Sept. 25 Chico, Calif. AFCRL Capt. Crummie (AFCRL) AFCRL 1.5 mil, 2.94 million

Sept. 30 Holloman AFB, N. Mex. RTD, AFSC Honeywell, Inc. AFCRL GT-11 Dacron-Mylarscrim

Oct. 22 Phoenix, Ariz. SSD, AFSC AFCRL GT-1£ Dacron-Mylar scrim

Oct.22 Holloman AFB, N. Mex. NASA G. Steffan (Hughes Aircraft)

AFCRL 2 mil, 125,776

Oct. 28 Holloman AFB, N. Mex. AFCRL, OAR J. Strong (Johns Hopkins) AFCRL GT-12 Dacron-Mylar scrim, 3.2 million

Oct. 29 Truth or Consequences, N. Mex.

RTD, AFSC Honeywell, Inc. AFCRL GT-12 Dacron-Mylar scrim, 1.6 million

Oct. 30 Holloman AFB, N. Mex. AFCRL, OAR J. Payne (AFCRL) AFCRL 1.5 mil, 641,566

Nov. 7 Holloman AFB, N. Mex. SSD, AFSC AFCRL GT-12 Dacron-Mylar scrim, 1.6 million

Nov. 8 Palestine, Tex. NASA A. Barrett (MIT) NCAR 0.75 mil, 1 million

Nov. 9 Palestine, Tex. NASA C. Hemenway (Dudley Obs.)

NCAR 1 mil, 1.25 million

Nov. 10 Palestine, Tex. NASA T. Parnell (U. ofN.C.) NCAR 0.6 mil, 2.94 million |

Nov. 12 Holloman AFB, N. Mex. AFCRL, OAR Honeywell, Inc. AFCRL 1.5 mil, 641,566

Nov. 13 Palestine, Tex. NCAR NCAR Balloon Facility NCAR Top balloon: 1.2 mil, 58,000. Bottom balloor 1.5 mil, 2.94 million

M ARCH 1965

Floataltitude

(feet)

Flightduration(hours)

Payloadweight

(pounds) Experiment Balloon performance notes

1,200 1 594 Surveyor mock-up; tethered flight Successful flight

67,900 3 50 Balloon boundary-layer temperature study

Successful flight

66,00067,800

2830

5052

Obtain sunrise and sunset thermal pack data

Successful flight

77,450 3 350 Obtain digital radar & ROTI data on tropopause penetration and optical & digital radar data on open parachute deployment

Successful flight

122,700 4 665 UV spectra studies using on-board sun-seeker and WSMR telemetry

Successful flight

56,000 8 672 Atmospheric measurements Successful flight

76,700 2 350 Cross-check of on-board accelero­meter, WSMR optics, digital radar

Successful flight

104,000 10 1153 Balloon evaluation Successful flight

57,600 34 2546 Atmospheric measurements Successful flight

81,000 100 1200 Evaluate air-baffle duct concept Successful flight

104,000 10 790 Feasibility study of present VOR system for locating balloons

Successful flight

78,300 7 3142 Photo-reconnaissance techniques Successful flight

60,800 1% 2540 Atmospheric measurements Successful flight

1,200 1 565 Surveyor mock-up; tethered flight Successful flight; maintained within 80 feet of ground zero

87,500 7 3385 Spectral study of Venusian clouds Successful flight

78,900 36 3036 Photo-reconnaissance techniques Successful flight

88,000 5 557 Balloon evaluation Successful flight

77,150 38 3040 Atmospheric measurements

99,000 4 625% Oxygen spectrum studies Successful flight

110,000 9K 192 Meteoric dust collector Flight terminated early, balloon leaked

124,000 10 271 Cosmic-ray studies Successful flight

87,000 5 689 Contamination study, frost- point hygrometer

Successful flight

890 Two-balloon system to photo­graph ascent failures

Bottom balloon burst at 46,800 ft.; photographs of burst successfully obtain

6 SCIENTIFIC BALLOONING

THE FLIGHT RECORD (Continued)

Date(1964-1965) Location Sponsor Investigator

Flightoperationconducted

by

Balloon specifications (polyethylene unless specified; volume in

cubic feet)

Nov. 18 Holloman AFB, N. Mex. DASA Capt. Reddy (AFCRL) AFCRL GT-12 Dacron-Mylar scrim

Nov. 22 Palestine, Tex. NASA L. Peterson (U. of Calif.) NCAR 0.5 mil, 3 million

Nov. 23 Palestine, Tex. NSF, ONR, NASA

M. Schwarzschild (Princeton U.)

Vitro Dacron & Mylar scrim: Launch balloon; 0.5 mil, 300,000. Main balloon; 0.35 mil, 5.25 million

Nov. 23 Chico, Calif. USAF AFCRL AFCRL 1.5 mil, 2.94 million

Dec. 1 Palestine, Tex. NASA J. Arnold (U. of Calif.) NCAR 1.5 mil, 96,000

Dec. 5 Palestine, Tex. NSF, ONR, NASA

M. Schwarzschild (Princeton U.)

Vitro Dacron & Mylar scrim: Launch balloon: 0.5 mil, 300,000. Main balloon: 0.35 mil. 5.25 million

Dec. 5 Chico, Calif. AFCRL J. Payne (AFCRL) AFCRL Merfab, 298,000 /Dec. 9 Holloman AFB, N. Mex. AFCRL D. Murcray (U. of Denver) AFCRL 1.5 mil, 2 million '

Dec. 14 Palestine, Tex. NASA C. Hemenway (Dudley Obs.)

NCAR 1 mil, 1.25 million

Dec. 15 Truth or Consequences, N. Mex.

BSD, AFSC Giannini Controls Corp. AFCRL 1.5 mil, 2.94 million

Dec. 22 Sioux Falls, S. Dak. Raven Raven Industries Raven 0.75 mil, 800,000

Jan. 6 Holloman AFB, N. Mex. AFCRL, OAR Capt. Jessen (AFCRL) AFCRL 2 mil, 27,000

Jan. 8 &10

Chico, Calif. AFCRL N. Sissenwine (AFCRL) AFCRL 1.5 mil, 511,000

Jan. 8 Palestine, Tex. U. of Wis. A. Hasler (U. of Wis.) NCAR 0.75 mil, two balloons, 2,400 ea.

Ja n .14 Holloman AFB, N. Mex. AFCRL Honeywell, Inc. AFCRL 1.5 mil, 641,566

Jan. 14 Page, Ariz. NASA NCAR Balloon Facility NCAR Dacron & Mylar scrim, 2x2.5 mil Mylar,1.5 million

Jan. 16 Sioux Falls, S. Dak. Raven Raven Industries Raven 9 million

Jan .23 & 27, Feb. 1

Page, Ariz. AEC G. Frye (Case Inst.) NCAR 0.55 mil, 3 million 0.55 mil, 3 million 0.55 mil, 6 million

Jan. 24 & 26

Page, Ariz. NASA T. Parnell (U. of N.C.) NCAR 0.5 mil, 2.94 million 0.7 mil, 2.94 million

Jan .28 Page, Ariz. NASA C. Hemenway (Dudley Obs.)

NCAR 1 mil, 1.25 million

Jan. 30 & Feb. 1

Page, Ariz. AEC G. Frye (Case Inst.) NCAR 0.75 mil, 3 million

Feb. 15 Palestine, Tex. NASA G. Clark (MIT) NCAR 0.55 mil, 6 million ,

Feb. 17 Chico, Calif. AFCRL A. Kom (AFCRL) AFCRL 0.75 mil, 13.5 million

Feb. 22 Palestine, Tex. Princeton U. R. Danielson (Princeton U.)

NCAR 1 mil, 254,000

Feb. 24 Chico, Calif. AFCRL N. Sissenwine(AFCRL) AFCRL 1.5 mil, 511,000

M ARCH 1965 ^

Float Flight Payloadaltitude duration weight

(feet) (hours) (pounds)

64,600 5 4500

130,700 4S 238

— 11,000

96,000 53 1250

10,000 139/2

— 11,000

91,000 14 271

102,500 4 932

110,000 6‘A 204

107,400 3 737

1,200 2 395

88,283 7 50788,450 9 508

46,600 % 39%

82,500 5 915

94,000 5% 1500

334130,000 ~6X 342136,200 7% 347

127,000 283

109,700 16 244K

335123,800 8*2 336

_ 273%

42,000 26 450

91,200 1/2 192

87,300 7 300

Experiment

“C” launch technique

Gamma-ray telescope

Visible light, high-resolution photography

Balloon evaluation

Payload let-down reel test

Visible light, high-resolution photography

Thin-film balloon evaluation

IR background measurements

Meteoric dust collector

X-ray densitometer

Proprietary balloon design test

Tethered balloon & winch system

Stratospheric humidity measurements

Test of special radiosonde

Contamination study, frost - point hygrometer

Test of new Dacron and Mylar scrim material

Proprietary balloon design test

Gamma-ray astronomy

Cosmic-ray studies

Meteoric dust collector

Gamma-ray astronomy

Cosmic-ray studies

Balloon evaluation

Test of cosmic-ray effect on phototube for Straoscope II

Statospheric humidity measurements

Balloon performance notes

Successful flight

Successful flight

Launch balloon ripped prior to launch

Successful flight

Successful flight, flight terminated

Before launch, reefing sleeve opened allowing main balloon to sail. Inertia ring and mercury bearing damaged

Successful flight

Successful flight

Successful flight

Successful flight

Successful evaluation flight

Successful flights. Main senor let out at 2000 ft. first flight; 600 ft. on second flight.

Successful flight

Successful flight

Successful flight

Balloon burst at 36,300 ft.Successful flight Successful flight

Balloon split upon bubble release Successful flight

Collector not recovered

Balloon burst at 86,000 ft.Successful flight

Helium loss during inflation, cancelled due to tears in balloon

Successful flight

Successful flight

Successful flight. Main sensor let out at 2000 ft.

8 SCIENTIFIC BALLOONING

UPCOMING FLIGHTS

Date

(1965) Location Sponsor Investigator

Balloon specifications (polyethylene unless specified;

volume in cubic feet)

March Page, Ariz. NASA T. Gehrels (U. of Ariz.) 1 mil, 4 million

March Sioux Falls, S. Dak. U. of Mich. F. Bartman (U. of Mich.) Mylar, 3.2 million

March Palestine, Tex. NSF A. Bainbridge (NCAR) 1.5 mil, 360,000

March Palestine, Tex. NSF NCAR Balloon Facility Launch balloon: 1.5 mil, 90,000. Main balloon: 0.75 mil, 6 million

March Palestine, Tex. NASA G. Clark (MIT) 0.55 mil, 6 million

March Palestine, Tex. NASA K. Frost (GSFC) 0.75 mil, 10 million

March Palestine, Tex. NSF NCAR Balloon Facility Launch balloon: 2 mil, 96,223 Main balloon: 0.75 mil,8.04 million

March Palestine, Tex. NASA K. Frost (GSFC) 0.75 mil, 10 million

March Page, Ariz. NSF Z. Sekra (UCLA) 1.5 mil, 250,000

March Palestine, Tex. NASA J. Overbeck (MIT) SVT, 0.5 mil, 6 million

April Palestine, Tex. NASA J. Overbeck (MIT) 0.5 mil, 2.94 million

April Palestine, Tex. NASA T. Parnell (U. ofN.C.) 0.7 mil, 2.94 million

April Palestine, Tex. NSF NCAR Balloon Facility Scrim, 2.3 million

April Palestine, Tex. NSF, ONR NCAR Balloon Facility Scrim, 4.5 million

May Palestine, Tex. NSF G. Newkirk (NCAR) GT-11 Dacron-Mylar scrim, 3.2 million

May Palestine, Tex. NSF NCAR Balloon Facility 9 million

May Palestine, Tex. NASA P. Meyer (U. of Chicago) 0.75 mil, 3 million

May Palestine, Tex. NASA J. Fazio (Smithsonian Inst.) 0.75 mil, 4 million

May Palestine, Tex. NASA M. Kaplon (U. of Rochester) SVT, 0.55 mil, 6 million

May Palestine, Tex. NASA L. Peterson (U. of Calif.) 0.55 mil, 3 million

May Palestine, Tex. NSF NCAR Balloon Facility 1.5 mil, 2.94 million

June Palestine, Tex. NSF G. Newkirk (NCAR) GT-11 Dacron-Mylar scrim, 3.2 million

June Palestine, Tex. NSF, ONR NCAR Balloon Facility 0.75 mil, 9 million

M ARCH 1965

Floataltitude

(feet)

Flightduration(hours)

Payloadweight

(pounds)

116,000 10 600

105,000 8 550

80,000 5 500

135,000 5 300

140,000 14 275

130,000 8 350

135,000 7 300

130,000 8 350

80,000 6 450

140,000 10 230

130,000 12 230

127,000 10 285

130,000 6 300

100,000 8 1200

140,000 6 400

125,000 12 285

125,000 12 530

135,000 12 350

130,000 12 240

800

100,000 8 1200

140,000 2 250

Experiment

Test of Mariner photo-polarimeter

Air sampling

Polyethylene tandem balloon system test flight

Cosmic-ray studies

Gamma-ray studies

Polyethylene tandem balloon system test flight

Gamma-ray studies

Skylight polarimeter flight

Cosmic-ray studies

Cosmic-ray studies

Cosmic-ray studies

Balloon evaluation

Balloon evaluation

Solar corona studies

Balloon evaluation

Cosmic-ray studies

Vidicon spark chamber flight

Gamma-ray studies

Solar gamma-ray measurements

Balloon deployment study

Solar corona studies

Balloon deployment study

Remarks

2 flights

Reinforced top, 3 flights

Down-camera technique

Down-camera technique

10 SCIENTIFIC BALLOONING

Comments on

Clues To Balloon Failure(The following paper was received in response to the November 1964 issue of Scientific Bal­looning on balloon failures. Because of its gen­eral interest to our readers, we are reproducing it here. Editor)

The factual and derived data in Ref. 1 are most interesting, and invite somewhat more penetrating analysis. This discussion will be concerned mainly with the valuable con­cept of the asymmetrical bubble. An ex­treme form of this condition will be found in the cylindiical type of balloon which is merely gathered in at the top, rather than tailored or shaped. The problem of the shaped balloon, however, is different, at least in degree. Here the size and asym­metry of the bubble are much less pro­nounced, but may be even more dangerous, as in a balloon designed to minimize cir­cumferential stress. This result is due to a peculiarity of stress distribution that makes the upper area very sensitive to even small

changes in shape, however caused.A largely qualitative approach to this

condition is made in Ref. 2, followed by more detailed mathematics in Ref. 3. A good visualization of the basic problem can be had by inspection of the general equa­tion for circumferential stress in a surface of revolution:Tc = tcr(. = (x/sin 9) ( AP Tm/Rm) (1) where, in the symbols of Ref. 1, x/sin 6 = Rt and T,„ = ter,,,; x being the radi­us of the given point from the axis of revolu­tion, and 8 the angle of the meridian- tangent to the horizontal. This equation omits the term due to surface weight, and assumes no weight carried above the given point.

The “natural shape,” generated by as­suming Tc = 0 throughout, is defined by the equation:

R„,xy = constant; or xy oc Rm—1 (2)

Proposed Skyhook

Month Location Sponsor InvestigatorVolume

(cubic feet)Altitude

(feet)

Northfield, Minn. ONR A. Kroenig, U. of Minn. 10 million Max. obtain.

April Minneapolis, Minn. GSFC D. Guss, GSFC 10 million 140,000

April Calif. ONR D. Struble, Sea Space 500,000 100,000

June Fort Churchill* GSFC D. Guss, GSFC 10 million 140,000

June Fort Churchill* GSFC C. Fichtel, GSFC 1.3 million 150,000

June Fort Churchill* ONR J. Earl, U. of Minn. 800.000 113,000

June Fort Churchill* NASA R. Vogt, Cal. Tech. 3 million 130,000

June Fort Churchill* NASA W. Weber, U. of Minn. 1.6 million 3 million

130.000130.000

June Palestine, Tex. GSFC C. Fichtel, GSFC 10 million 130,000

July Fort Churchill* NSF M. Kaplon, U. of Rochester 10 million 136,000

July Fort Churchill* NASA P. Meyer, U. of Chicago 1.6 million 10 million

125.000135.000

July Fort Churchill* ONR C. Waddington, U. of Minn. 10 million 150,000

July Fort Churchill* NASA K. McCracken, Grad. Res. Ctr. of S.W.

1.6 million 3 million 80,000

125.000135.000110.000

August Fort Churchill* ONR K. Anderson, U. of Calif. 100,000

August Flin Flon* NSF K. Anderson, U. of Calif. 3 million 140,000

*Fort Churchill and Flin Flon are located in Manitoba, Canada.

M ARCH 1965

where cc means “varies directly as” and where y is measured up from the level at which AP = 0, for the usual linear relation­ship. For points near the axis on the upper portion of the curve, Ref. 2 and 3 show that the curve is approximated by the cubic parabola (ymax — y ) cc x3, making 6 oc sin 6 cc x2 and Rm oc x—*. Thus, as the axis is approached, the factor x/sin 6 approaches °o, AP is constant but finite, from which Tm/Rm must differ only by a second-order infinitesimal if T,. is to be really zero. The critical nature of this requirement is still more apparent from the fact that Tm/Rm itself here approaches the indeterminate value oo / oo.

The top of the balloon is thus shown to be extremely sensitive to small distortions of shape whether viewed as changes from the basic profile or as a shift of the polar axis or “stress center.” Ref. 3 shows quanti­tative results in stress from slight changes in the exponent of x near the top of the bal­loon, even with no departure from polar symmetry “a condition that should be

guarded against either by providing a definite surplus of material there or by strong reinforcements circumferentially.” Further consideration showed reinforce­ment to probably be necessary in any case, since added local fullness would have the effect of shifting the critical level down­ward and would also increase any tendency to unsymmetrical bulging.

As incidental observations on the text of Ref. 1, it is important to note that the structurally effective radius in the circum­ferential or transverse direction is not the horizontal coordinate x, but x/sin 6; also in considering dynamic effects, to include the large effect of movement in the surrounding air, equivalent to approximately half the total mass of air displaced, with inertial re­sultant through the center of volume. It is here recommended that reinforcement be especially strong near the edge of what is referred to in Ref. 2 as the “taut cap” at the most critical altitude in the planned ascent.

A liberal and correct use of water models is the cheapest way to determine the re­

Flights — 1 965Flight duration Payload weight

lunds) (pounds) Experiment Remarks

1 25 Airglow, ozone measurements Surplus GT-66 balloons10 130 Counters Test flight6 400 Balloon development Composite material

12 130 Emulsions, counters 3 flights10 12 Emulsions

10 120 Counters 4 flights15 70 Counters 4 flights8 40 Counters 2 flights8 100 2 flights

270 Spark chamber15 400 Spark chamber 4 flights15 227 Counters 4 flights15 600 Spark chamber 4 flight?24 150 Emulsions 2 flights24 150 Counters 4 flights12 100 Emulsions 2 flights

18 Counters 10 flight?

8 flights24 40 Counters 25 flights no recovery

SCIENTIFIC BALLOONING

quired strength of material and its pre­ferred distribution. It would be instructive to try a graduated circumferential fullness over the entire upper portion, enough to eliminate the taut cap but not enough sur­plus to permit more than a small movement of the stress center. The reinforcing might then be confined to a relatively small area near the top. Variations of material and workmanship alone leave no chance of safe­ly eliminating top reinforcement.

That the requirement of top reinforce­ment cannot properly be met by any overall safety factor is obvious for the idealized condition of Tc = 0. The actual mechanism by which this condition is approached, is usually the bulging or scalloping of the surface skin between finitely spaced meri­dian tapes or seams. This distortion from the assumed surface of revolution, together with asymmetrical bulging, must of course be included in a complete analysis. In a tentative approach, however, it seems con­servative to assume that a near-failing stress in the transverse direction will smooth out the scallops locally, restoring the transverse radius almost to its full value Rt = x/sin 6

for a surface of revolution. If this condition is due to shift of the stress center, the orig­inal transverse direction then carries ex­tremely high meridian stress. But as already shown, the transverse stress can also be high with a distortion that retains polar symmetry.

To sum up: strong top reinforcement is a price that apparently must be paid for re­lieving the rest of the balloon of above transverse stress, a condition that auto­matically prevails in almost any balloon in­flated to a fraction of its full volume.

References

1. Lead articles in Scientific Ballooning, No. 17, November 1964.

2. Upson, Ralph H.: “Stresses in a Partially In­flated Free Balloon;” Journal of the Aero­nautical Sciences, February 1939.

3. Upson and Holdhusen: “Balloon Shape—or Stress Analysis and Design of Thin, Axially Symmetric Fluid Containers;” Report No. 1143 to Mechanical Div., General Mills, Inc., Sep­tember 1952.

Ralph H . UpsonSeattle, Washington

Published by theNational Center for Atmospheric ResearchOperated by theUniversity Corporation for Atmospheric Researchand sponsored by the National Science FoundationAddress requests for copies to NCAR, Boulder, Colorado 80301

Balloon Tracker H A Test — An improved, 4-channel model,

shown at the left, of the successful tracking package flown

from Japan (Scientific Ballooning, July 1964) was given a

short test flight in mid-March. In addition to making it

possible to locate, during daylight hours, the approximate

position of a balloon system with only a single non-directive

receiving system, this unit will permit monitoring up to four

balloon or atmospheric parameters. The tracker, being held

by the man on the right, was carried aloft by a super­

pressure balloon. This combination of balloon type and

tracking package will be used in the GHOST-concept evalu­

ation tests scheduled for the Southern Hemisphere later this

year.