BT-1399 High-Altitude Tethered Balloon Systems Study ... · ~ table of contents -'< l ~ sectlo 1 'i i summary 4 .,;, ii introduction ill tethfr cabi e types and properties iv tether

BT-1399

High-Altitude Tethered Balloon Systems Study

Goodyear Aerospace Corp

James A Menke

10 May 1967

r GER 13260

HIGH-ALTITUDE TETHERED BALLOON SYSTEMS STUDY

James A Menke

Goodyear Aerospace Corporation Akron, Oh10

Contract F 19628-67-C-0145

Task Report No 1 Schedule Sub- Line Item 1AA

10 May 1967

AFCRL ProJect Morutors Mr Lewis Grass Edward Young, Captam USAF

Sponsored by

ADVANCED RESEARCH PROJECTS AGENCY DEPARTMENT OF DEFENSE

Morutored by

AIR FORCE CAMBRIDGE RESEARCH LABORATORIES UNITED STATES AIR FORCE BEDFORD MASSACHUSETTS

FOREWORD

This research was supported by the Advanced Research ProJects Agency and was mom tared by the Air Force Cambndge Research Laboratones under Contract No F 19628 67 c 0145

The proJect IS bemg earned out under the directwn of Mr Lewis Grass and Captam Edward Young as Contract Momtors for the Air Force Cambndge Research Laboratones Mr James Menke IS the Goodyear Aerospace ProJect Engmeer Techmcal assistance was provided by Mr Loms Girard Mr Wilham Conley Mr Lewis Handler and Mr John Bezbatchenko The contractor s report number IS GER 13260

lli

~ ~

TABLE OF CONTENTS -'<

l

~

Sectlo 1 'i

I SUMMARY 4

.,;, II INTRODUCTION

ill TETHFR CABI E TYPES AND PROPERTIES

IV TETHER CABLE PROFILE PARAMETERS

'.} v BALLOON TYPES AND CHARACTERISTICS A Balloons '>elected fo1 Study

; B Ba..loon Descnpt10n ;I c Aerodynam1c Charactenst1cs

D Vv 1ght Analysis of Aerodynamically Shaped Balloons E Vve1ght Analys1s of Superpressure Natural Shape Balloons

) F Effects of Vanous Destcrn Parameters on Balloon Wetght G Net Lilt for Balloons Ope1atmg m Zero Wmd but D£>s1gned

for H1,h Wmd

VI BALLOON PERFORMANCE PARAMETERS

VII CABLE BALLOON SYSTEM OPTIMIZATION

VIII REVIEW AND COMPARISON OF CONCEPTS PROPOSED 1N

'i ARPA CO"l"THACT STUDIES A General B Concept P1 oposed unde1 ARPA Contl act SD 198 c C0ncept P1 oposed under ARPA Cont1 act SD 199 D Concept Proposed under ARPA Contract SD ?OO E Concept PI oposed under ARPA Contract SD ?01 F Compa11Son of Concepts G Cable Balloon System Solutwns H Commentc; and ConclusiOns

j IX CONCLUSIONS AND RECO\IIMENDATIONS F

' il AppendiX

I CABLE PROFILE ANALYSIS

II DETAILED ANALYSIS OF TETHERED AERODY.t>.AMICALLY SHAPFD BALI OONS

REFERENCES

OVERLAYS

v

Page

1

2

6

8

26 26 26 27 34 37 38

38

43

51

53 53 53 53 55 55 55 57 60

61

63

69

85

87

l I. I

I, r t I

I

r! ! j I

1\ lj I i

~ '

j

'j

~ I

~ ~~

I

l l J

I I

·I

Figure

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

LIST OF ILLUSTRATIONS

Vanahon of Wmd Velocity with Alhtude at Geographic Location I

Vanatwn of Dynamic Pressure With Altitude at Geographic Location I

Cable Weight versus Breakmg Strength for Vanous Tether Cable Matenals

Cable We1ght versus Cable Diameter for Vanous Tether Cable Matenals

Tether Cable Profile Parameters

Angle at Bottom End of Cable for Glastran at 50 000 Feet m Summe1 I Wmd

Blowdown Distance for Glastran at 50 000 Feet m Summer I Wmd

Cable We1ght for Glastran at 50 000 Feet m Summer I Wmd

Angle at Bottom End of Cable for MISSile Wire at 50 000 Feet 1ll Summer I Wmd

Blowdown Distance for Missile Wire at 50 000 Feet m Summer I W111d

Cable Wei0 ht for MISSile Wue at 50 000 Feet 111 Summer I Wmd

Angle at Bottom End of Cable for Glastran at 50 000 Feet m Wmter I Wmd

Blowdown Distance for Glast! an at 50 000 Feet In Wmtei I Wmd

Cable Weight fo1 Glastra 1 at 50 000 Feet m Wmter I Wmd

Angle at Bottom End of Cable for MISSile W1re at 50 000 Feet m Wmter I Wmd

Blowdown Distance for MISSile Wire at 50 000 Feet m Wmter I Wmd

Cable Weight for MISSile Wue at 50 000 Feet m Wmter I Wmd

Angle at Bottom End of Cable for Glastran at 100 000 Feet m Summer I Wmd

Angle at Bottom End of Cable for MISSile Wue at 100 000 Feet 111 Summer I Wmd

Class C and Ram Air C Balloon ConfiguratiOn

VI

Page

4

5

6

7

8

12

13

14

15

16

17

18

19

20

21

22

23

24

25

28

F1gure

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

Vee Balloon ConfiguratiOn

Modified Mark II Balloon ConfiguratiOn

Superpressu1 e Natural Shape Balloon Configuration

Potential Pressunzatwn Syc;tems f01 Superpressure Natural Shape Balloons

Aerodynamic Lift Coefficient versus Angle of Attac...k for Vanous Balloon Conf1guratwns

AerodynamiC Drag CoeffiCient versus Angle of Attack for Vanous Balloon Conftguratwns

Aerodynamic Lift to Drag Raho versus Angle of Attack for Vanous Balloon ConfiguratiOns

Aerodynamic Drag Coefficient versus Reynolds Number for a Sphere

Breahmg Strength versus Umt Wetght for Vanous Balloon Matenals

Balloon Weight versus Hull Volume for Vanous Balloon C onf1guratwns

Balloon Weight versus Altitude for Vanous Balloon Configurations

Balloon Wei ht \ersus Wmd Veloc1ty fo1 Vanous Balloon ConfiguratiOns

Balloon Wet ht versus An"'le of Attack for Vanous Balloon ConfiguratiOns

Net Ltft of Class C Balloon Conflguratwn Operatmg 111 a Zero Wmd Cund1tlon

Net L1ft of Vee Balloon Confiburatwn Operatmg In a Zero Wmd Co ld1t10n

Net Ltft of Modified Ma1 k II ConfiguratiOn Operatmg 111 a Zero Wmd Condttlon

Net Ltft of Ram A1r C Confi"uratwn Operatm"' 111 a Zero Wmd Condition

Net Lift and Drag Characteitstlcs of Class C Balloon fo1 Altitude of 50 000 Feet

Net Lift and Drab Charactenstlcs of Vee Balloon for Altitude of 50 000 Feet

Net Ltft and Drag Charactenstlcs of Mod1hed Mark II Balloo'l for Altitude of 50 000 Feet

Net Lift anrl Drag Charactenshcs of Ram Air C Balloon for Altitude of 50 000 Feet

Vll

Page

28

29

29

30

31

32

33

34

35

39

40

40

40

41

41

42

42

44

45

46

47

42

43

44

45

46

47

48

49

50

51

Net LJ.ft and Drag Charactenstlcs of Superpressure Natural Shape Balloon for Altltude of 50 000 Feet

Net Llit and Drag Charactenstlcs of Superpressure Natural Shape Balloon for Altitude of 100 000 Feet

Configurations Proposed by the ARPA Contractors

Altitude versus Wmd Velocity Assumed by the ARPA Contractors

Coordmate System

Internal Pressure Occurrmg m the Balloon at the Maximum Diameter

Buoyant Force on Balloon at the Maximum Diameter

Assumed AerodynamiC Loadmg on the Ma~nmum Diameter of the Balloon

Blower Weight versus Dlfferential Pressure for Volume Flow Rate of 4000 Ft3 IMw

Reqmred Blower Power versus Differentlal Pressure for Volume Flow Rate of 4000 Ft3 /Mm

Vlll

Page

48

49

54

56

65

72

72

73

77

79

Table

I

II

ITT

IV

v

VI

VII

VIII

IX

X

LIST OF TABLES

Seventy FIVe Percentile Wmds for Summer and Wmter at Three Geographic Locations

Summa- y of Tether Cable Profile Parameters Plotted

Physicd.l DimensiOns of Vanous Balloon ConfiguratiOns for a Hull Volume of 1 000 000 Ft3

Computer Prmtout Data for a Class C Balloon Coni1gU1 ahon

Superpressure Natural Shape Balloon Parameters (Summer I Wmd 100 000 Ft Altitude)

Summary of Balloon Performance Parameters Plotted

Superp1 es&ure Natural Shape Balloon Charactenshcs (Wmter I Wllld 50 000 Ft Altitude)

Summary of ARPA Contract Studies

ProportiOnality Constants for the Physical DimensiOns of Vanous Aerodynamically Shaped Balloons

Proportwn·1lltj Const'lnts for the Weights of Components of Va110us Aerodynamic'llly Shaped Balloons

lX

Page

3

9

26

36

37

43

50

58

70

74

SYMBOLS

b duference m we1ght dens1tles of a1r and 1nflabon gas (=0 862 Palt g) lb/ft3

aerodynamic drag coefhc1ent

aerodynamic lut coeff1c1ent

D aerodynamic drag lb

aerodynamiC. drag of balloon lb

net drag honzontal component of tenswn at the top end of the cable (for the lower segment m a tandem balloon system th1s mcludes the aerodynamic d1 ag of the m1ddle bal loon and the h011zontal component of tenswn at the lowe1 end of the top cable) lb

d blowdown distance or d1stance from top end of c'lble to bottom end mea sured parallel to earth plane ft

f

h

fineness ralw 01 rabos of len"'th to d1ameter

float all1tude above mean sea level ft

altitude above mean sea level at wh1ch cable 1s parallel to earth plane ft

L

q

aerodynamic h.ft lb

net lut of balloon or vertical com ponent of tenswn at the top end of the cable lb

dynam1c pressur€ (=1/2 PauV2) lb/ft2

t tlme at float alt1tude hr

V balloon hull volume ft3

v wmd velocity relative to balloon knots

W B total bal oon we1ght lb

W c total we1ght of cable segment lb

w umt we1ght of balloon fabnc lb/ft2

a.

Palt

Po

angle of attack deg

angle be>ween the cable and the vertical at the bottom end of the cable set,ment derr

de ns1ty of au at float alt1tude slurrs; ft '3

dens1ty of a1r at mean sea level slugs/ft 1

Note Pou 1ds 1n the above 1 st are pounds force

\\

I'

X

I

,( "' (

SECTION I

SUMMARY

An mvestlgatwn of the problems related to h1gh alt1tude tethered balloon systems 1s m progress Th1s report covers the work accomphshed dunng the flrst quarter of the program

Vanous te 11ered balloon systems were mvest1gated to determme what combmatwn of balloons and cables has the greatest potential for h1gh alt1tude tethenng Aerodynamic charac tenst1cs stress we1ght and other des1gn factors were evaluated for f1ve d1fferent balloon shapes Cable proflle parameters were evaluated constdenng we1ght cross sectwn area and breakmg strength of the three cable types Data 1s presented 1n graph1c form wh1ch relates balloon quantities to cable prof1le quantities for operatwn m v. mter and summer at two different geographiC locatwns and float altitudes of 50 000 and 100 000 feet

System concepts were evaluated under ARPA Contracts SD 198 through SD 201 (Referen ces 1 through 4) Smce different wmd profiles were assumed for each of these concepts mod1 ficatwns to balloon v. ewht and cable Size were made m an effort to compare each system on an eqmtable baSIS As a result It was found that the systems proposed by VItro CorporatiOn of Amenca and MmneapoliS Honeywell Regulator Company prov1ded solutwns However It should be emphas1zed that With other mod1hcatwns the systems proposed by Goodyear Aero space CorporatiOn (GAC) and General Mtlls Inc (GMI) may also provtde solutwns To summar tze the compansons are not too meanmgful because each contractor proposed a system for operation m different w md cond1t10ns

Results show that balloons can be tethered at altitudes above 50 000 feet but that no one system 1s best for all w1nd and altttude cond1t10ns Round or natural shape balloons prov1de better performance 111 light wmds at high altttudes whereas aerod} nam1cally shaped balloons pi ov1de better perfoi mance m h1ah wmds at mtermed1ate alt1tudes Cables made of glass fibers and epO'<) resm prov1de better overall perfo1 mance fo1 all w1nd and alt1tude cond1twns mvestibated than e1ther nylon 01 steel In a few cases where net lilt at the top of the cable 1s ( 7

\

very small steel WJI e appears to be better

1

SECTION II

-INTRODUCTION

Varwus tethered balloon concepts mcludmg systems descnbed In References 1 through 4 were mveshgated Dunng the course of the mveshgatwn It became apparent that aerodyna nuc effects on the balloon and cable are the most Important and that operatmg problems tele metry control requuements and ground eqUlpment needs are Similar for each system and of secondary Importance relahve to system feasibillty

Therefore the maJOr portion of the mvest1gat10n thus far was that of determmmg aero static and aerodynamic 11ft drag and weight for several balloon shapes d.S a funchon of Wind velocity alhtude and other factors A second maJOr effort was that of determmmg cable SIZe weight blowdown distance and angle at the ground for vanous loadmg conditions at the top end of the cable Vanables considered were float altitude wmd proille and cable matenals

Performance parameters for the balloons and cables are presented mdependent of each other For some wmd conditions a smgle balloon system cannot be tethered at altitudes above 50 000 feet but tandem balloon systems could proVIde a solution

The concepts p1 oposed m References 1 through 4 were mvestigated and compared It was difficult to make compansons because each system was designed for a different Wind profile A deciSIOn was made to assume a Summe1 I and Wwter I wmd profile for the design of each system and to calculate performance based on volume float altitude and balloon type proposed m References 1 through 4 Tins deCISIOn necessitated calculations of ne\\ balloon and cable weights to satisfy the wmd loads on the system

When It became apparent that the fl equency of occun ence of Winds and e:\.pected fh ht du1 atwns at the mtended opcratm locatwns were vital to the mvesti atwn AFCRL uutiated a study whereby design wmd p oflles wei e enerated based on JH obabil!ty calculatwns

The AFCRL study pro\ Ided \\ Ind desi,n cntena to be used In the sense of a fu st 1.pprox Imatwn evaluatiOn of se\ e1 al diffei ent tethered balloon systems The data represents best ht estimates of mte,rated Winds which take mto consideratwn the mte1 relatwns between wmds at one levelm the atmosphere and 1.11 levels above and below that level from the SUiface to 100 000 feet Development of the data was made by matclung cumulative frequency diStliiJu hons with mte"'rated wmd distnbuhons The 75 percentile frequency distnbutwns showed the best correlat ons th the 90 perce t le mte 1 ated wmd p1 oflles and the e are the d1.ta Iven These data should only be used 111 static evaluatwns I e the tethered S) stem IS fully deployed A much lar ,er statiStically representative sample of Wind profiles Will be needed to evaluate the operatwnal efhciencv of ascent of the systems to designed flcatm altitude

All balloon and cable parameters are based on wind profiles resultin, from the AFCRL study These wwd proflles a1 e ,Iven m Table I W111ds fo1 summer and wmter at locatiOn I were selected for desian calculatwns The Summer I profile rep1 esents a mode I ate \\ md and Wmte1 I the most severe wmd Velocity and dynamiC pressure p1oflles are presented m graphic form 111 Figures 1 and 2 The 1962 U S Standa1 d Atmosphere was used as the sou1 ce for all other atmosphenc data

All design facto1 s such as balloon and cable weight stres:;,e~ balloon superpressUI e and volume are based on a svstem where all balloons arc at their design float altitude I e loads on the system dUIInO" launch and reb Ieval have not been considered

Because of the lar"'e numbe1 of compulatwns required and m son e cases due to the type of solut10n available digital computer and plotter facilities we1 e used fo1 almost all of the calculations

2

He1ght (ft)

Surface

5 000

10 000

15 000

20 000

25 000

30 000

35 000

40 000

45 000

50 000

55 000

60 000

65 000

70 000

75 000

80 000

85 000

90 000

95 000

100 000

Table I Seventy Five Percentile Wmds for Summer and Wmter at Three Geographic Locations

Wmd Velocity (knots)

Wmter Locatwn Summer Locatwn

I II Ill I II

15 0 10 0 10 0 10 0 10 0

27 9 20 3 20 0 22 3 20 0

44 9 35 6 15 1 26 5 18 6

62 6 58 2 18 0 31 9 18 7

80 5 78 9 21 4 38 0 19 1

99 0 92 2 25 5 47 1 20 2

11.:> 9 105 4 29 7 56 3 21 3

125 1 111 6 35 9 64 7 25 8

125 4 115 8 43 2 72 8 32 2

113 9 110 7 38 2 62 8 36 2

- ---. r---! 02 5 105 5 \____ 31 4 50 4 39 8

91 4 97 3 25 0 37 9 43 1

79 6 75 5 23 0 25 0 42 9

b7 2 47 7 24 4 2::J 1 43 8

60 1 33 2 27 8 25 0 45 3

5J 7 29 9 33 2 27 3 48 2

d8 8 28 5 37 8 29 8 51 0

.>9 2 29 7 41 4 34 8 54 1

35 5 30 9 40 4 36 8 56 5

34 7 31 9 39 9 .>5 7 58 2

35 0 32 7 42 3 43 9 59 4

Note Data was provide by AFCRL t 3

III

7 0

12 0

16 5

19 0

20 7

19 2

17 6

18 3

20 2

20 8

21 3

22 9

30 0

34 7

40 0

46 1

51 5

55 3

61 3

68 1

72 6

100 000

90 000

80 000

70 000

60 000 ~

t-w w LL. ~

w 50 000 0 ::> t-

t--' <2:

40 000

30 000

20 000

10 000

0 0

". I I I

~' ,, I

""' I

/ I

I

\ I I I I

I

~ I I \ ',

..... ...... ~,,~SUMMER I ~ / Wll'-lTERI

', ~

-, ' ' ' ',

// /

/ /I

/ / / /

/ / /

/ v I I /__ / v~ I

/

/""/ 20 40 60 80 100

WIND VELOCITY (KNOTS)

F1gure 1 V1.natwn of Wmd Veloctty wtth Altttude at Geog1 aph1c Locatwn I

4

"' ) _/ v

120 140

100 000

90 000

80 000

70 000

'\.

60 000 f=' UJ UJ u.. -UJ 0 50 000 ::> f-

I--' <(

40 000

30 000

20 000

JO 000

0 0

I I

I I

I!\

\\ \ I~ \

' ~ ,, ' -....

~ ' ' r----- /WINTER I ', ' 1---......... r, r--

\ - r-----VSUMMERI

I) ,/ /

~ v

/ /

l:::::::: / I v--I ~ I ~ ,- ---I v ~

I

_/ 2 4 6 8 10 12

DYNAMIC PRESSURE q (LB/FT2)

Figui e 2 Variatwn of Dynamic Pre~sui e with Altitude at Geographic Locatwn I

5

14 16 18

!I I ! '

SECTION III

TETHER CABLE TYPES AND PROPERTIES

Brarded nylon rope mr& rle wrre and Glastran were selected as potentral matenals for tether cables Physrcal propertres data obtarned from three vendors are g1ven 1n F1gures 3 and 4 The data are representative of the three matenals used m cable construction Glas tran a stranded E glass fiber constructiOn manufactured by Packard Electnc DIVISIOn of General Motors has the hrghest strength per weight of any of the three types and 1t provrdes better overall desrgn features than the other two types for the wmd cond1t1ons assumed m this study MISSile wue a stranded steel cable manufactured by Amencan Cham and Cable Co lS used for a1rcrait tow targets For equivalent breakmg strengths m1sS1le wue has the smallest cross sectiOn and therefore aerodynamic forces would be expected to be less Brarded nylon rope made by Samson Cordage Works was selected as be1Pg representative of ropes made of nylon

1200

1000

r=-u.. 0 800 0 0

dl-_, .__. .......

600 I (.')

I.J.J

~ I.J.J _, co 400 <( u

200

0 0

0

ACCO / /

1 X 37 X 7 / 1-11 FLEX

~AMSON MISSILE WIRE_/_ BRAIDED -

/Yo ROPE (NYLON)

/ / /

1""/ v v //'

GLAST RAN

~ , ...... -< (NO JACKET) ,.. ...

~ v , ...

I , ...

/ ...... .................. ,..

~L _ ...

I ,.. ,.. L' ... './:)'" I p I-"" ,cr

... o-

~ 10 000 20 000 30 000 40 000 50 000 60 000 70 000

BREAKING STRENGTH (POUNDS)

Frgure 3 Cable We1ght versus Breakmg Strength for Vanous Tether Cable Matenals

6

80 000 90 000

1

'f ..._

t

J "

Although nvlon rope has a higher strength per weight than steel It IS he a VIer than Glas tran and also larger 111 cross sectiOn and therefore would not be expected to provide better de sign features Design data was therefore prepared for only miSSile Wire and Glastran smce It IS obvwus that results for Glastron would be better than for nylon m all wmd condibons It si-lould also be noted that strenrrth per weight IS constant for strength greater than about 9000 pounds and that strength per weight IS higher for strength values below 9000 pounds

It should also be emphasized t'J.at the performance results obtamed thus far m th1s study are based only on breakmg strength weight cross sectiOn area and speclfic Wind cond1bons Other factors such as cost handlmg problems fatigue abraswn resistance weatherab1hty sphcmg efficiency and ava1lab1hty of tapered construction need to be mvesbgated

Low drag cables havmg airfOll shaped sectwns were not considered because sufficient design data 1s not available at this bme

Smgle strand glas:, compOSite cables are expected to proVIde somewhat better perform ance than the stranded type however bend radn Will be larger for the larger cables

Another possible Improvement IS the use of S glass fibers mstead of E glass The hla ment strength of S glass IS about 665 000 lb/m 2 whereas E glass 1s 500 000 lb/m 2

I=' u.. 0 0 0

~ -' ~

I-I l? UJ

3 UJ

-' co <( u

1200

1000

800

600

400

200

0 0

~

ACCO I X 37 X 7

I ? HI FLEX j MISSILE

I WIRE

I I

II l GLAST RAN

i L I

J (NO JACKEl)

I ;

I V p I ,d !LoN

f f-'

d ~BRAIDED ROPE (NYLON)

J 6 / "

f' a" IS

~ ..,..,

cl 4 .cr~ ~

...... 0 og:. 0 2 0 4 0 6 0 8 I 0 I 2 I 4

CABLE DIAMETER (INCHES)

F gure 4 Cable Weight versus Cable Diameter for Vanous Tether Cable Matenals

7

-

I 6

SECTION IV

TETHER CABLE PROFILE PARAMETERS

The profile parameters chosen for representation are angle between the cable and the vertical at the bottom end of the cable (&B) top end excursion or blowdown d1stance relahve to the bottom end (d) and total weight of the cable segment 0N c) A supplemental factor IS

presented m conJunctwn With &B to defme the altitude at which eB occur:. (h 1) These para meters are shown m F1gure 5

Occaswns anse where the cable segment tends to become honzontal at pomts above mean sea level m which case the factor hl could be used to defme altitude at which a second balloon should be added

Parameters relatmg cable profile quantities to loadmg forces are p1 esented m Figures 6 through 19 Abscissas and ordmates for the curves are respectively net hft or vertical compo nent of tens10n at the top end of the cable (LN) and net hft to drag rat10 or tangent of the angle of appllcatlon of the tens10n force at the top end of the cable (LN/DN)

Selection of the parameters shown m the graphs was based on the followmg mformahon Float alhtudes were selected as the extremes of the regiOn of mte1 est namely 50 000 and

~---------------d------------~~

w I

h=FLOAT ALT

F1gure 5 Tether Cable Prohle Paramrte1 c;

8

100 000 feet Wmd profiles Winter I and Summer I were selected fro 11 Table I as represent mg a moderate and the most severe wmds existmg at the three locatwns Cable types chosen wei e based on the mformatwn presented m Fibures 3 and 4 winch relate cable properties

Flexibility of the cable design solubon 1s made possible by use of the equatwns blVen m Reference 1 GAC s IBM S/360 Model 40 dibltal computer was used for solutwns of these equatwns The computer pi ogram IS flexible m that specific values of cable weibht and dia meter can be assumed or cable wet llt diameter and breaJnng strength can be assumed to be a functwn of cable tenswn Any float altitude wmd prohle and cable strength weight dia meter relatwn may be specilied Dcs1"'n curves are then obtamed by specuymg particular values of LN and LN/DN Note that each pomt on the curves represents a umque cable design for the specified conditiOn That IS an Iteratwn for a new tapered cable solutwn based on a constant stl ess des1gn usmg a facto1 of safety as selected 1s obtamed for each LN/DN Th1s procedure results m a cable tapenn, from a maximum diameter at the top to some lesser value below It should be noted that a tapered cable may not be obtamable m all matenals due to lack of manufactunng methods and eqmpment Nevertheless results of these profile calcu latiOns show comparative performance and the data approximates a spllced configuratiOn con tammg vanous s1zes Denvatwn of the dliference equatwns and equatiOns dehmng cable properties IS grven 111 AppendiX I

Glastran cable was selected because Its strength to weight ratiO IS greater than nylon or miSSile Wire cables as shown 111 Figure 3 and thus Will result m lighter cables for a given stress As w111d forces mcrease however the diameter of the cable becomes Important for this reason miSSile wire was also chosen s1nce Its diameter to weight raho IS less than the other two

A summary of the guphs plotted IS I ven 111 Table II Fac.h of the graphs Is obtamed by faumg the desired parametr1c curve through the many LN versus L~/DN pomts plotted from md!Vldual computer runs The pi ocess mvolved here 1s mL.ch the same as uhhzed for draw111g contour maps For tins reason eyeball Judgment of the curvec::; was used m some areas where data powts were far apai t These fanuhes of curves how~>ver provide suffiCient ac cui acy for an m hal estimate of pi ohle paramete1 s as 1s the pm pose here

A method of us111g FI ures 6 through 19 and prelumnary conclnswns based on data g1ven m the fl u1 es are prec;ented It should be noted however that the p11mary purpose of the curves 1s to est1.bllsh a method of mahmg compar1sons and p1 ov1de '1 method for careful scrutmy

Tablf' II Summary of Tethe1 Cable P1 of1le Pa1 aneters Plotted

Float

I Wmd Cable Parameters Plotted

Alt1tude Profile Type e8 and 11 1 d we (ft)

50 000 Summer I Glastran F1rr 6 FJ 7 Ftg 8

50 000 Summer I M1ss11e wue Ft, 9 Ft 10 Fl 11

50 000 Wmter I Glast ran F16 12 F1g 13 F16 14

50 000 Wmte1 I M1ss11e wn e F1, 15 F1, 16 F1 17

100 000 Summer I Glast! an F1a 18 None None

100 000 Summer I Mtssle wtre F1, 19 !\one None

9

It ts not Intended that £mal conclusiOns be drawn from the curves but rather that selectwns of different values of the pa1 ameter::, be made for fUI ther study The different values are obtamed from analyses of other factors such as reahsttc safe cable loads resultm~ from fatigue tests analysis of gust loads on the balloon etc It would be presumptuous to assume that a problem With as many vanables as exist here could be solved With the limited number of curves pre sented Examples of the great number of Signlficant vanables to be con .... tdered are float alb tude wmd profile cable type number of balloons type of balloon volume of balloon and angle of attack

To use the curves proceed as follows

(1) Select tre proper group of graphs where float altituae wwd profile and cable type are common to ach

(2) Choose the value of eB and h1 d or We to be satic;fled by mterpolatmg between curves for the proper LN and LN/DN values By choosmg one of these para meters a hne 1'3 defmed on the respective curve that shows a contwuous range of LN and LN/D~ that Will satisfy the chosen paramete1 If one of tl}e othe1 parameters IS also chosen a second range of LN versus LN/DN values IS de fined If the chosen values are compatible the ImPs Will mter..,ect and the pomt of mtersect10n gives the only values of LN and LN/DN that Will satisfy both con ditwns

(3) Example

(a) GI \-en h 50 000 ft Wind - Wmte1 I cable type - miSSile wue

(b) Reqmrcd 8D

d

goo at 11 1 35 000 ft

15 000 ft

(c) Ft om Figure 15 tlw hne deflmng tan0 es of Ll\ and LN/DN for eB - goo at 1!1 = 15 000 feet IS found and from Ft,ure 16 the 1an e of LN and LN/DN f01 d = 35 000 feet IS found It can be seen thal these hnes mtei sect at Lr-.. - 54 000 pounds and LN/DN - 11 5 Cabl wcirrht (W c) IS now also de fmPd and 1 gtven tn FI!:,Ure 17 Cable weight for L~ 54 000 pounds and LN/DN = 11 5 IS about 40 000 pounds Tlus IS the total cable wei,ht ft om float altttudf' to 15 000 feet above mean sea level the pomt where It becomes hOIIZOntal

(d) The next step ts to detern 11e what balloon stze and tvpe net hit of 54 000 pounds and a net 11ft to d1 a"' ratw of 12 tins 1S I ven m a late I sect10n

If any Will have a An example of

Other vanahons for use of these cut ves can be made by speclfy n, other cable para meters 01 balloon paramete1 s as discussed 111 a late1 sectwn

Imtial concluswns Infe1 red fl om a study of the graphs are d.S folio rs

(1) Fot Summe1 I Winds and cables eJ\.tendmg downwa1d from 50 000 feet above mean sea le\-el

(a) Smrrle me rement cable solutiOns a1 e possible fo1 both ,lass cable and miSStle w1re provtded that adequate values of LN and LN/DN are apphed at the cable top end The defuut10n of smgle mcrement a used !'ere IS a length of cable havmg loads applied at each end and only aerodynamic forces and we10 ht ap phed over Its entu e lenrrth

10

f l

~ II tj r

t

! I

I I

I f F

! ~ .

f l i f

I l ! t

I

"""--"~

(b) Glass cable proVIdes soluhons w1th more favorable bottom end cable cond1 hans ( BB and h 1) than does miSSile wire for all cases except for very small LN values (less than 5000 pounds)

(2) For Wmter I wmds and cables extendmg downward from 50 000 feet above mean sea level

(a) No realistic smgle mcrement solutiOns are available for either glac:;s cable or miSSile Wire Reasonable solutiOns are available however 1f another balloon 1s utilized at an mtermed1ate alhtude (e g at altitudes from 10 000 to 30 000 feet) Smce a smgle mcrement solution IS not possible no com bmatwn of balloons where all balloons are at altitudes above 50 000 feet w1ll proVIde a solutwn

(b) Glass cable provides solutwns With more favorable bottom end cable cond1 hons than does m1ss11e Wire for all cases except for small LN values (less than 5000 pounds)

(3) For Summer I wmds and cables extendmg downward from 100 000 feet above mean sea level

(a) No reasonable smgle mcrement solutions are available for m1Ss1le w1re Reasonable solutions are available however lf another balloon IS utilized at an mtermed1ate altitude (e g at altitudes from 10 000 to 40 000 feet)

(b) Glass cable provides smgle mcrement solutions If adequate LN and LN/DN values are applied

(4) Glastran cable (Figure 18) exhibits an unusual senes of dips near a value of LN = 5000 pounds MISSile Wire (Figure 19) does not exhibit thiS d1p It IS be lie\ed that this dip can be explamed by the equation that was used to descnbe the strength v..eight relation of Glastran cable (See AppendiX I for equatwns used to defme cable properties ) A discontmuity ex1sts at a breakmg strength of 9000 pounds

11

16

14

12

z 0

......... z ....J

10 0 I-

~ <.!)

8 ~ 0

..... 0 !),:) I-

I- 6 u.. ....J ,_ w z

4

2

0

I I \

I \ I \ \

I ' \ I \ 1\ \

~

I \ \ "' "' & 1/.:::::-

I ' \ ~ !\ <too

\ "' ~,,' j§ \ \ \ f"'--.0 1\ f\. r-

J~ 'l\ \ ' "' ~ f\. lg 1\\ l' ' -- 50° 0 ~ -I

II

'~~~ -1--- I

/"' 1'- 60° 0 .....

70° 0 I f" I r---.,.· 9f.P Hl 000 90° 0 /1"--., ,... 90° 20 000 ~

0 10 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000

NET LIFT LN (POUNDS)

NOTES

EACH POINT ON THE CURVES REPRESENTS A UNIQUE CABLE FOR THE VALUES OF LN AND DN AT THE TOP END OF THE CABLE

2 EACH UNIQUE CABLE IS TAPERED SUCH THAT BREAKING STRENGTH IS EQUAL TO lWICE THE TENSION AT ANY POINT ON THE CABlE

3 SHADED AREA REPRESENTS LN AND DN VAlUES FOR CASES WHERE CABlE BECOMES HORIZONTAL TO GROUND PLANE AT ELEVATIONS ABOVE MSl

LN

t __ oNT SUMMER! --~

WIND __ ,;;

0'-v- h =50 000

~,~,,,l~',,,,,J,

F1gure 6 Angle at Bottom End of Cable f01<§;~ran at 50 O~eet 1~mmer I Wmd ') -............_._ .. -""'

.P ...fll I

16

14

12

z 0 '-... z

-' 10 0 i= <{ <:>::

0 8 <{ <:>:: 0

....... 0 c..:: I-

I- 6 u.. -' I-LU

z 4

2

0

J 1 'I' {

~

\ \

' ~ r\ I

i \ ' l 1 \ f\.

\ 1\ 1\ "' "' \ \ ~ \ ~--\ \ i\. ....._<o oa

1' '" '\.. ....... v I'..

.............. ~ ~

\ 1'\~ ~ "!'.... "' ~~0 'l\~~3 ~ooo r--

<~o- 0 Ooo ~ !'(o' so a ooo I"- r--.__ -Oa Vo r--.... r--~~~~--~~

-

0 lO 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000


J :; =~ 2$. :;:wauuwa:: w :Gdi20SU::d eels4ii &4 . !tUAtAE

NOTES


2 EACH UNIQUE CABLE IS TAPERED SUCH THAT BREAKING STRENGTH IS EQUAL TO TWICE THE TENSION AT ANY POINT ON THE CABLE

3 SHADED AREA REPRESENTS LN AND DN VALUES FOR CASES WHERE CABLE BECOMES HORIZONTAL TO GROUND PLANE AT ELEVATIONS ABOVE MSL

LN

t --oN

SUMMER I WIND - ~

--- ...._~"?" -~

~d

Figure 7 Blowdown Distance for Glastran at 50 000 Feet m Summer I Wmd

16

14

12

z a ~ z -' 10 0 i= «i. ~

(,:) 8 «i.

0::: a

..... 0 ~ I-

I- 6 u.. -' I-w z

4

2

0

l

! : I a3 \-

~~~ co co co -' -.I ...J

8 0 0 0 0 0 0 0 1.0 0

H~ - 1.0

\ I I I \ v I

~ I 1\ I I : : I ~ / I

...... /

J : 1 / I t--- . ...:::::::

I I I r

! I I F

J I I I I f

.. t• ( ' I f (

cQ co -./ -./ co 0 -./ 0 8 0 0

I~ 0 0

0

/:q I 1/g IJ

I J

I I / /" / -- ----- -,.. ,. '../

/ 1/

• cQ

~~--./

v.§ ;q ~8 ~f?-J s(J

I v -/

/' OB 90 h] = 0 -

NOTES




LN

t --oN

SUMMER I - < WIND -- ~

-t "'~ -- 0

- w

0 10 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000

NET LIFT LN (POUNDS}

Figure 8 Cable Weight for Glastran at 50 000 Feet In Summer I Wmd

16

14

12

z 0

.......... z

-.J 10

0 1-<( a<:

0 8 ~ 0

,..... 0 01 1-

1- 6 u.. .....J

1-Ul

z 4

2

0

H \ \ t:9 '\ ill \ (t

'll"oo r'-... !t( '\ ~ " ~ If I /

~: : \ \ - 0

\ il I \ " I I ...

I r\ \ "'-.. ~Soo I 1\.

t \ " ~ II 1 \ "- 1'--. II I \\ " "' ...... r-... !1 I ~ ~

~~ : \ ~ " ,.............

~ ~

~~ ! ...... ~ f'-....

7001 -t--~ r-... t-

i I I "r-::: 0

t' r-- 80° ~ r-\17 &a ;;; 9fi' h1 = 20 ooo -- 90o 0 ~!'o...

'· r---/ '

.....__ , ' ~ r-- r-- 90° IO 000 ~ r-- 1---r-r- 1--- 1-- 9QO 20,~ ~.-- I-- r-

"' ~ 1--r-" "" ""- 90° 30 000 1--1--t---1--1---- ~-1--I- 9QO 40 r

0 10 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000


NOTES


2 EACH UNIQUE CABLE IS TAPERED SUCH THAT BREAKING STRENGTH .1-S EQUAL TO TWICE THE TENSION AT ANY POINT ON THE CABLE

3 SHADED AREA REPRESENTS LN AND DN VALUES FOR CASES WHERE CABLE BECOMI:S HORIZONTAL TO GROUND PLANE AT ELEVATIONS ABOVE MSL

LN

t __ -oNT -- k.,

SUMMER I - ~'*' WIND -- ~

~ -- C)> h = 50 000 -- ~

~"''' ,!~,',"' "'' "),

Figure 9 Angle at Bottom End of Cable for Misslle Wire at 50 000 Feet m Summer I Wmd

,, ' ! ·~ ~

16

14

12 z

0 "-z -I

10 0 ;::: <( oe:

0 8 <(

oe: 0

..... 0 0') f-

I- 6 u... _J

I-w z

4

2

0

~

\ ~

\ ~

'\ ' I'..

', " "-\ ...... \ "'-.. ~ ...........

"""" ~ ~II:;

...-- -/'

L"' v-,. ..

1\ \ \

""' 1\ " !"'-.. ' ' f"<~<v [\ l"'o... Ooo-

'\ ~ """r--.......

I" ' "' "" "'-~ r--...

"' """" "r--... ~ ~ ~

~!'...... ..................... .... ~'--r-22 ooo I -

......... r-- 35 ooo {)8- ........... ........_ f',.~ -9()o ........_

...;;:r--..., h J:::: 0 r-.. 40 ooo ...... .. F::-r-. -- =-t-~ ·r--. --- ~000 ~-45 000 I-- - -- - 1-t-

~----1--1--~--- 40 000 --. 1--M 1--- r--~35 000 -,;;--1--. ~O_,Q£g

NOTES

EACH POl NT ON THE CURVES REPRESENTS A UNIQUE CABLE FOR THE VALUES OF LN AND DN AT THE TOP END OF THE CABLE



SUMMER I WIND ___ fv - ~~

X. - ~'V

~d 0 10 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000


Figure 10 Blowdown D1stance for M1ss1le W1re at 50 000 Feet m Summer I Wmd

'""- "" "''"' ·~- _...., 't $"' _.,. ( .,.-J J.. '*' ~ o><~~~-· ,...., z W:il. :1?'1.11 ],..>(. I k....,... 4,,..... ;r ....,07: ""'lil!l'.l[".(J.. .,;:;tiL L \...,- _,_ .., 1.1 .-..:k: T' .<. J ~'iii! I:CU .,. - _Q t2ib 2 !( ,$ ...,..-.z: _ _; l! .l!!idL! 5 .. I t£ - f' I Et I 1 ~

16

14

12

z 0 .....___

z -I

10 0 I-4: 0::

0 8 ~ 0

....... 0 -l I-

I- 6 u.. -I

I-w z

4

2

0

I I

~~~IIJ ~~=u==~=t-i~~-f-llt±==t==t=~=+--~§- ~ ~ ' i .- o I-'

tl • 0 - 0 <%)

. 1.() 0 -I

H-;_ o_ g- ~

.. :::? 0 0

1

1.()

8

- <Xl----t-~+--tjflll_/_ l ..... - _, I ?;l g m

. o- ~ -l

0 04--,-- ~~ rr M g- ~ I~ I 0 g ~~-1 [ " 0 - 'g II 1\ i.'! -/<>-1 u 0

t !I 'r L / 1-1 , I f 'l I f'"' I L, L

I' I' IT r ~ ~ ... .L , •• - 90°; h, o _ q l! l t 1 I 1 - I 1 . J. i .1 J ll I l 1 1 j 1 J -j I~ J J ~!j ~ l U -I' ~ l J. -,

1 i 1 l l--I I I

0 10 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000


NOTES



3 SHADED AREA REPRESENT~ LN AND DN VALUES FOR CASES WHERE CABLE BECOMES HORIZONTAL TO GROUND PLANE AT ELEVATIONS ABOVE MSL

LN

t SUMMER I ~

0N

WIND -- ~ -- <v -+- ~ L q

--~

- ~ w

Jil,

Figure 11 Cable Weight for Missile Wire at 50 000 Feet m Summer I Wmd

-------------

16

14

12

z 0

-....._,. z -' 10 0 1-<( 0::

0 8 <( 0:: 0

...... 0 co 1-

1- 6 LL.

-' 1-LLJ

z 4

2

0

~~ i \ \ \ '<:x>

_\~II

!! \ \ \ ib ·u I

\ \ :r-

' \~ B ' H I

\ 0

11 ' so 8 .u I

r, "0 \

11 rl ' 1\ . II ll 10 ' It 1\ ~ _\ g \. !! I~ \ I\~ \ 1', !~ I \ia ,~ .

t \

H11 ~~ \% \ \ -s- ~

' "t'--o~~ 0 ~tn ~, 1-00 l5- \ ' r..>,{ \g \ ..... ~ .. ~%~~ 1\ 1'. t'--,

' i'...., r---, ~\ ~ I'

fl\~\ " "· -.._

t--

H- ~~\~\. r--...

"""' t--t--

'• ~'

r- .... ,.__ I 'V ' . r-.... 1--+--~

/ %Y:· ......... 1--

r-- t-- r--t--1--)--...,_ t--t--r-- r---

t---1--~= ~== 1=-= ~=== t::= -l ~ r- ... t--t---1--.,..__ --!""- r--

~= ~= ~= I--r--~-t--r--r---I--

0 10 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000


NOTES




LN

i __ -DNT --< WINTER I -- Q'!

WIND -- t;-......_"«

0 h =50 000

~'~"' ,1 ~' ',"''"' J F 1gure 12 Angle at Bottom End of Cable for Glastran at 50 000 Feet m Wmter I Wmd

16

14

12

z a

' z ...J

10 0 f--<( ~

0 8 <( 0:: a

...... 0 <.0 f--

I- 6 u. ...J

f--w z

4

2

0

! : ! I

,. •

l I I I I ! ! I 1 •

: : i 1

ol s! §I 0 _o. 0

~f ;r ~: 0

fiS -u, I I -nl

I 1 I I

; I

I! I ' ! r: I ! 1 I i I ! J 7 I

\ •

: • ' .... \ / :......_ - """---· t---~- ~-

d=35 000 -,.. - -,-,-~- t--~--

' tl

~\ 0\ ~l

\ \

'· '\

\ \

~

........ r....._ r-- ~-- 1---~-~-1-- --"-

- ~-~- - -·

\ ', ' ' ',

1-- -· ~-1--M f-.- --1---1-- --

NOTES

l EACH POl NT ON THE CURVES REPRESENTS A UNIQUE CABLE FOR THE VALUES OF LN AND DN AT THE TOP END OF THE CABLE

2 EACH UNIQUE CABLE IS TAPERED SUCH THAT BREAKING SfRENGTH IS EQUAL TO TWICE THE TENSION AT ANY POINT ON THE CABLE


LN

i --oN

WINTER I WIND _

--~~~ --y

~d 0 10~ ~~ 30~ ~~ ~~ 60~ ~~ 00000


F1gure 13 Blowdown D1stance for Glastran at 50 000 Feet m Wmter I Wmd

I

16

14

12

z 0 '-.. z

.....1 10

0 f-<( 0:::

0 8 <( 0:: 0

N 0 0 f-

...... 6 u..

.....1

f-LU

z 4

2

0

.~ : ~ : \ I

• I \ I I

I I : t

~ I l

I I \ I I •

~ l I I : I ! I I

! I : I I Ia:;) I

!5 15 I~ , ......

I§ I§ ,o 0

J8 18 -t-_J~ 0 ,~ II , .... I~ I l I

rr : • l I

I

J I \ I I I I

! I I I I J

i I J J I I I

I f I / I I I ; j I // /I: I

J I /' / ~;"' ,

i\ \ I

' \ \ ~ T

t \5 \~

0 0 'g \8 lro IO ,n '¢

' \ I

~ I

~ I

1

I I I I I

: ,' :

I

1'/ -/ ;;... -

1 • \ -~ .. \

\ -.

cO _J

0 0 0

,o 11.1')

I

' l •

' ~ ' . I

I //

NOTES

1 EACH POl NT ON THE CURVES REPRESENTS A UNIQUE CABLE FOR THE VALUES OF LN AND DN AT THE TOP END OF THE CABLE



LN

t -- -DN

-- w

0 lO 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000


Figure 14 Cable Weight for Glastran at 50 000 Feet m Wmter I Wmd

see: a asa

16

14

12

z 0 '-... z

__J

10 0 ~ <{ <::<:

0 8 <{ <::<: 0

"" 0 ...... ~

~ 6 u... __J

~ UJ

z 4

2

0

I~ : ~ I~ . l I I ' ! ~ \ \ •

I I

' •

I I \ I I ' \ I I . l

I I ·~ ' \ 1 1 ' . . : : I'

\

1 ' \ \

l'\

t : 1\ ' ' I I \

! ~ 1', ......._ ?Eo 25 OOo

I ~ -- r--I ~

I ..... r..... ~ Jo ooo \c - ..._: " ~- 9QO 35 000 ._. --t--~ 9()o4Q 000- r- -1- - - 1----~9\f>r-To- --~-- 1-- ... 1--

~ \

\ \

\ ' \

ro-,~0

'i?~(b ...: ... -

~- - ,___

1----~ 1-- -f-- --1--

--1-- -.

~~ \. -£;,0

' .... ~; ..... ' Is

' Ooo ,........_

-~ ~-....; -. .__

.__ -1---~- --~--· >--- - 1-- ...

1-- - 1--1"-

.......

--;;

r----;;;;;

-t--

1---

NOTES

l EACH POl NT ON THE CURVES REPRESENTS A UNIQUE CABLE FOR THE VALUES OF LN AND DN AT THE TOP END OF THE CABLE



0 10 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000


Ftgure 15 Angle at Bottom End of Cable for Mtsstle Wtre at 50 000 Feet m Wmter I Wmd

. ·.=:--::------ --- ~~--~~··---,---·-~-------.. -- -·~- _______ ,_ ------~·-- ....

16

14

12

z 0 ""-z _,

10 0 I-<( ex:

0 8 ~ 0

N 0 N I-

1- 6 u.. _, 1-UJ z

4

2

0

i I ! 8l sf 81

r--~I Rj ~I r-- II f ""01 I : I f

If : 4

I I'

I ' I

f : I j I I I : _l • ! \ I I \ \

_j_ ' I \ ' \

I ' ' ....

~ ........

""""-t-- -· r-- -· 1-- -· ,__ -

~ I _._

§~ 8t ~I ~j

~ ' l

i J ' i _L

l _\

' \ 1 ' 1'_,

!"-'!'

' '· ...........

~ ..... ........ -. ~--t--- -t--- - 1--- - I"--

j §I

~r I

\ l

I'

\ \ ~

.........

-1'- t--

NOTES

1 EACH POINT ON THE CURVES REPRESENTS A UNIQUE CABLE FOR THE VALUES OF LN AND DN AT THE TOP END OF THE CABLE



WINTER I WIND - 47

_.£ <v

-- s'\.;

~d 0 10 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000

NET LIFT LN {POUNDS)

F1gure 16 Blowdown D1stance for Mtss1le W1re at 50 000 Feet m Wmter I Wmd

16

14

12

z 0 '-... z

-' 10 0 t-

~ (.') 8 <t: 0::: 0

t-v 0 c.v t-

t- 6 LL.

-' t-UJ

z 4

2

0

! ! ! ~ ~ ! l i i i I I • .

I I I I l I I I I : ! ' I I

~ : ! I I I

i I ; •

I I I I I I

f ! f : ; ! J I . I •

1<0 _! <D 1<0

d~ ~~-f5-<D a:l

-' -'

!§ :§ 1-'

~§_J§_ g 0

I§ 0 0 0

('it IIi) J2 V1 0 'g ~~ p~ - (\1 I n~

•

f ~ ! I ! I I I

i i i I

I ; I I ~ I I I I I . I

I : : ! : 1 } f ~ I • i ; i/

' I I I

! ! I I I / II

I ) ' # /

I , II I v / 1/ ~-""

0 1 0 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000


NOTES


2 EACH UNIQUE CABLE IS TAPERED SUCH THAT BREAKING STRENGTH IS EQUAL TO TW CE THE TENSION AT ANY POINT ON THE CABLE


LN

t -- -oN

WINTER I -- % WIND -- «.,

~ '=" I. q --~

-- -- ~ w

Figure 17 Cable Weight for MISSile Wire at 50 000 Feet m Wmter I Wmd

-~----=-- ---·- --- =- ·..:.:..~ --- -------

z 0 '-.. z

-'

0

0 I-

Iu.. -' 1-UJ

z

'

o~~--~--~__.~~--J---~~--~--~-J--~~~--L-~--~

0 5 000 1 0 000 15 000 20 000 25 000 30 000 35 000 40 000


NOTES

l EACH POINT ON THE CURVES REPRESENTS A UNIQUE CABLE FOR THE VALUES OF LN AND DN AT THE TOP END OF THE CABLE



LN

t __ -DNT --<

SUMMER I -- #" WIND --0''<' h=IOIOOO

~ *

F1gure 18 Angle at Bottom End of Cable for Glastran at 100 000 Feet m Summer I Wmd

32 I I I I

28 u I I

24 z

Cl

l: ij

"-.. z .....

20 0 f-

<t: 0::

0 16 <t:

0:: Cl

t-:)

0 c.n f-

I-12 u.

..... f-

11 ; ! 1 i ll jl

' LJ.J _L

z l 8 l

\ 4 .........

........... :...: -

0 -0

l ! I I l~ 1 : '

\ J • \ l . .. l .~ ~

. \

\

\ l

~ 1\ "

'..., .........

I' .... -· t-- -1-- 1---,....-:-: t== -· -· t--

5000

i \ 1 '

j\

1 ', r--

1 ' 1\

\ l'-

' ' ....... r-.... ~~ ~,

..... ·~

~"-- ~----r--

"'- -'--

..,__ ~-- -- ~---

~---f.-- f-- ~----r-- -!--- - ,....

r-- - r-- - ~-= -r--- ~---1.-- -· --· f== - f:== - : - ~----· ~~ -· r-- - r--r-

I'..., - -·

- --

- ..... -r--

---- -r-- --- r-- -

-I-- - ~· ~--- - -· f=- - -- -· 1--- - 1'"--

e8 ::::. 90° h 1::: 5 oo,g_ r-o -I"' _,.-. .. r-

90° 10 00£... '--·--9C:P 15 002.. _ ..

~'1-r 9CP 20 0~

~---r--,-,-90° 25 000

f---~-,-r-9()0 30 09fl_

1--- - r--,- r _19~0..£~ ~-

90° 50 OOQ_ r--1'"--·r-t---r- -· 1'"--- - r== r--+--~-r--r- 1'"--r--

NOTES




90 60 000 90° 70 000 90 80 000 90 90 000

10 000 15 000 20 000 25 000 30 000 35 000 40 000

NET LIFT LN (POUNDS}

Figure 19 Angle at Bottom End of Cable for M1sslle W1re at 100 000 Feet m Summer I Wmd

1

l- : I

"i

J

SECTION V

BALLOON TYPES AND CHARACTERISTICS

A BALLOONS SELECTE.D FOR STUDY

To evaluate the ments of vanous balloon shapes four aerodynamtcally shaped balloons and a superpressure natural shape balloon were mvestigated The aerodynamically shaped balloons mvestigated were Navy Class C Vee Balloon T modtfled Marh. II and ram air C These shapes were selected for mvestigatlon because a wtde range of physical and functional charactenstics such as aerodynam1c lilt drag hneness ratlo volume pE'r surface area fm stze etc ts encompa.,sed In add1t1on wmd tunnel test data 1s ava.tlable for all of the balloons except the natural shape and full scale vehtcles of each except the modified Mark II have been flown Realtstlc slZ~ and wetght scale factors can therefore be obtamed for analyzmg balloons designed for many wmd veloc1ttes and altitudes

B BALLOON DESCRIPTION

1 General

A ballonet systE>m for accommodatmg volume change and mamtammg pressure for all aerodynamically shaped balloons was assumed A blower and battery typt were assumed for all ballonet systems except am air C For this type It was assumed that dynamic pressure alone such as m the barrage balloons was suff1c1ent to retam pressun?atlon Add1honal wo1 k IS required to ascertam the performance capabthtles of dilatable t) pe balloons In th1s type elashc fabnc or cords are used to retam balloon pressure

In order to g1ve relative siZe of each balloon wtth respect 'o a different shape 01 com parable volume Table III hsts the bas1c d1mens10ns and areas for the vanous shapes each wtth a hull volume of 1 000 000 n3

Table III Phys1cal Dtmenswns ofVanous Balloon Conflguratwns for a Hull Volume of 1 000 000 Ft3

r~----.----.--~ d w

I J ( i ([ 2

E

( (

T I w

( l ( )

vyC J 5 0 /

I 30 000 7 250 3000 I 000 I 2 0 ( 76 600 I 0 2 000

t I ____J__

--!--± 0 I 900 00

oo I OB 000 I I I 00 3 I

20 7 00 0

---oa--1---------+---l-- \ _1 _ 52 2 1

M ( d 000 000 1 2 I G 00 ~ 7 -2 12 0 6 000 G BOO 2 T - I

I I 3 coo 000 7 2 0 6 600 0 2 000

0

! 0 0 0 00 000 000

k n

2 ;+ il2 i +rjj-· i-l-3ooo- -ooor-2sa·--; 000 00 6 o

1 o I o o o o o

_s _____;_ _ ___t_____j__j _ ___L_ l I 1 i

00 00

\1

1Trade mark Goodyear Aerospace Corporahon Akron Oh10

26

t ~

2 Navy Class C Configuration

The Navy Class C conflguratwn (Figure 20) was chosen because It represents the typical smgle hull streamhned shape tethered balloon The basic shape consists of a streamlined hull w1th a Y type ta1l The balloon exh1b1ts the lowest aerodynamic hit coeffiCient and drag coefficient of any of the aerodynamically shaped balloons selected for evaluatiOn

3 Vee Balloon ConflgUiatwn

The Vee Balloon (Figure 21) was chosen because 1t n.presents the h1gh aerodynamic hftmg type tethered balloon The configuratiOn cons1sts of two streamlme hulls JOmed at the nose to form a V A honzontal tall IS cOJmected between th hulls w1th the two vertical fms mounted on the ait end of each hull The balloon exh1b1ts one of the h1ghest aerodynamic hft coeffiCients and the highest drag coeff1c1ent of any of the ae1 odynam1cally shaped balloons selected for the evaluatiOn

4 Mod1fled Mark II Conf1gurahon

The modifled Mark II configuratiOn (F1gure 22) was selected because the aerodynamic charactenstlcs fall between that of the Navy Class C and the Vee Balloon The conf1gurat10n consists of a smgle hull balloon With large end plate type vertical fmc; mounted on the honzontal hns The balloon exh1b1ts one of the highest aerodynamic lilt coefficients of any of the aero dynamically shaped balloons selected for evaluatiOn and the drag coeffiCient IS between that of the Navy Class C and the Vee Balloon

5 Ram A1r C Confrrruratwn

The ram au C conh ur'lhon (FI0 UI e 20) IS Identical With the Navy Class C configurahon except fo1 the pres~unzatwn system It was assumed that a ballonet was kept full by the stag nation pressu1 e of the wmd smula1 to barraae type balloons

6 Supe1 p1 essure Natu1 al Shape Balloons

A natural shape balloon (F 1"ure 23) was selected for evaluat1on because rt offers possr brhtres for reefmcr These balloons are usually used 111 non tethered apphcatwns The bas1c shape 1s that of an 1m e1 ted teardrop and the balloons are usuall) desrgned to have ze1 o stress m the Circumferential duectwn The aerodynamic drag coefficient of the natural shape balloon was the hrghest of all the configuratwns evaluated

A specli1c p1 essunzatwn system was not selected howeve1 ~everal candrdate desrbns as shown m Fibure 24 could possrbly sahsfy the desian requirements

C AERODYNAMIC CHARACTERISTICS

Aerodynamic hft oeffrc1ents d1 ag coefficients and hft to drag ratio versu~ angle of attack for the aerodynaPucally shaped balloons are given m Figui es 5 26 and 27 The hull volume to the two th1rds power was used as a reference area

The angle of attach for zero lilt was modrfled slightly for the Vee Balloon In orde1 to be consistent With other wmd tunnel test data for thiS shape

Smce no w nd tunnel InformatiOn IS avarlable for the natural shape balloon the aerodyna nnc charactenshcs of a ~phere of equal volume were assunted The hft coefhcrent IS zero and the drag coefficient versus Reynolds Number rs given m Figure 28 The proJected area of the sphere was used a a reference area and data was taken from References 5 through 8 The drag coefflc1ent fo1 the ::,phere based on hull volume to the two thuds power for Reynolds Numbers of 300 000 and 500 000 IS plotted m F1gure 26 to "IVe a companson of relative ma6 mtudes

27

I;

I ~~

I I i

MAXIMUM DIAMETER

f------- 0 4 L ----·~

L--------------------~

Figure 20 Class C and Ram Air C Balloon Configura IOn

Figure 21 Vee Balloon Configur at1on

28

~ r

I

~---------l---------~

f---0 4L----1

DIAMETER

Figure 22 Mod1fled Mark II Balloon C..onflgurat on

F1gure 23 Superpressure Natural Shape Balloon Configuration

29

,, II i I I

, r I

j

I I

j

I

l !

l l

I

BALLONET TANGENT HARNESS TYPE

ADV NT GE D 5 D

L htw gh F h d p

2 l d 9 d r

N

r

B L ONET SUSPENSION H RNESS

B LLONET

T NGENT H RNESS

L E

GES

db b d d

TRACTION STORAGE DRUM TYPE

1

ADV NT GE

MOTOR STORAGE DRUM SSEMBL Y

TEl ER C BLE

D S D NT GES

p d dd p h h b b I

2 H

INVERTED TYPE

MOTOR GE R ASSEMBLY FOR CONTROLLING DISTR BUTION OF TETHER LOAD BETWEEN TOP AND BOTTOM END FIHING

I

ZERO PRESSURE LEVEL

CONFIGURATION ATL UNCH

ADV NT GES

2 l ghtw h b II PI d g

3 Refd dd

REEFED TYPE

0 NTAGES

I S p d 2 L 3 l

L htw h

b ld

po b

GUIDE ROLLS

G S RETENTION SLEEVE (ALSO CONFINES UNINFLATED PORTION OF BALLOON)

TOP END FITTING

CABLE

TETHER CABLE

DIS 0 ANT GE

H h d

lET ER C BLE

0 S 0 NT GES

R r 9 r d p bl

2 s b ty p {F b d

F1gure 24 Potential Pressunzahon Systems for Superpressure Natural Shape Balloons

30

-J u 1-z UJ

u u..

2 4

2 0

1 6

:t 1 2 0 u 1-u.. -'

u 08 ~ .:( z >-0 0 04 0::: w .:(

0

<A v 0 4

5

SOURCE OF DATA SYMBOL CONFIGURA Tl ON TYPE

GAC MEMO T 5618 0

SINGLE HULL f 4 7 MODIFIED TMI 4 SEPT l 1964 END PLATES ON HORIZ Fl NS MARK IT

GAC MEMO T 6372 6

2 HULLS f 4 (EACH) 35 DEG TMI 4 DEC 13 1965 HORIZ FIN BET'vVEEN HULLS VEE

GMI (UNIV OF 0

SINGLEHULL f=264 NAVY DETROIT PROJ 314) Y FINS RUN 86 CLASS C

_;~

/ /

/ /

/ v

" v

v ~

A ~

1

VEE BALLOON

MODIFIED A y v

MARK II ......

~ K'cLAss c ~ /

!f/ ~ ~

A

~ )_/ v / e 7

/

lP'

0 5 10 15 20 25 30 ANGLE OF ATTACK (DEGREES)

Figure 25 AerodynamiC Lift Coefficient versus Angle of Attack for Various Balloon Conflgurahons

31

35

I II

II 'I I i I !•

i! I ! i

1 4

1 2 b

0 u

1 0 1-

l z ~ u.J

1 u .l u..

~ u.. u.J

0 0 8

~ u l?

l' ~ 0

u :E 4:

0 6

z >-0 0 4 0 0::: u.J

4:

0 2 ,..._ >-.....

(~o..

0 5

SOURCE OF DATA SYMBOL CONFIGURATION TYPE

GAC MEMO T 5618 <>

SINGLE HULL f- 4 7 MODIFIED TMI 4 SEPT 1 1964 END PLATES ON HORIZ FINS MARK IT

GAC MEMO T 6372 6

2 HULLS f- 4 (EACH) 35 DEG TMI 4 DEC 13 1965 HORIZ Fl N BETWEEN HULLS VEE

GMI (UNIV OF 0

SINGLE HULL f 2 64 NAVY DETROIT PROJ 314) Y FINS RUN 86 CLASS C

0 SPHERE

I v I

I j

VEE BALLOON - v I

I (

v /

/ RN =300 000-

/ ('

/ ~ ~

VL MODIFIED ~~ MARK II

/ '/ / /

RN 500 000-,.... ~

I:' 1,--0 ~ )o-""-

"' - , CLASS C

1 l 0 5 10 15 20 25

ANGLE OF ATTACK (DEGREES)

Figure 26 Aerodynamic Drag Coefficient versus Angle of Attack for Varwus Balloon Conflguratwns

32

30 35

I -.l

l

5

4 Q

u ~ u

0 3 1-

~ <.:> ~ cr: 2 Q

0 1-

1-LL

..... u :E <( z >- 0 Q 0 cr: w <(

2

SOURCE OF DATA SYMBOL CONFIGURATION TYPE

GAC MEMO T 5618 0

SINGLE HULL f 4 7 MODIFIED TMI 4 SEPT 1 1964 END PLATES ON HORIZ FINS MARK II

GAC MEMO T 6372 6

2 HULLS f-4 (EACH) 35 DEG TMI 4 DEC 13 196 HORIZ Fl N BETWEEN HULLS VEE

GMI (UNIV OF 0

SINGLEHULL f=264 NAVY DETROIT PROJ 314) Y FINS RUN 86 CLASS C

v MJDIFI~D M1RK ri_ / "" .........._ /

) / \

CLASS C """' I ~ .,;. y

'I Y' Y"" ......... ~ L' r-....

~ .........

~ I J VEE-BALLOON

I I " ""' " I I ")

1

/ I II I I

t 'I v ~

·v <

5 0 5 10 15 20 25 30

ANGLE OF ATTACK (DEGREES)

Figure 27 Aerodynamic Lift to Drag Raho versus Angle of Attack for Varwus Balloon Conf1gurahons

33

35

:11 /I ! i

I I

j!

I

I L I;. jr I ' II

I '

'II til I I

'/::I i t' ' ' ' j' I

Ill, Ill , I

~~I ill

I! : J I I i

'1: I' , I 'I Ill II

I I j I

;, I rill .t I ,r

'I L I

I' ! I

1 I ~

f

L

0 u 0 6

>--z~

~~ U<>< u::<t u._. w<t o._ uz 00 <t"" ""u.

DRAG ........... ~ 1\ Co

qS

S =FRONTAL AREA OF SPHERE (rrR2)

c 0 (BASED ON y2/3) 1 21 Co (BASED ON FRONTAL AREA)

0 4

oz uO :EO <tw z~ >-<O 0~

"\. ~

0 2

0 "" w <t 0

30 000 100 000 000 000 10 000 000 100 000 000

REYNOLDS NUMBER

Figure 28 Aerodynamic Drag CoeffiCient versus Reynolds Number for a Sphere

D WEIGHT ANALYSIS OF AERODYNAMICALLY SHAPED BALLOONS

1 Stress Cons1derat10ns

Internal pressure m the balloon at float alhtude was based on the followmg requuements

(1) The nose of the balloon should not cup or d1mple m the wmd at that altitude wh1ch would create a large mcrease m drag causmc:r the balloon to loose 1ts aerodynamic charactenshcs

(2) The m1mmum operating pressure for a reliable pres.su1 e rehef valve should have a m1mmull' ope'1mg pressure of approx1mately 1/4 m H20

Therefore the I eqUired balloon mternal pressure was selC'cted to be 1 15 hmes the stagnation pressure at altitude or 1/4 m HzO whichever IS greate1 The cnhcal pressure required to prevent bucklmg of the hull was assumed to be less tf-Jan that requ1red to prevent d1mphng of the nose of the balloon Th1s was based on the assun ptwn that the suspensiOn or bndle system can be des1gned to reduce the bendmg moment to a neghgible level In most cases the cnhcal press re to prevent bucklmg w1ll be less than that requ1red to prevent d1mphng However 111 any further detailed design study or prototype development the vahd1ty of th1s assumpt1on must be venhed The actual stress used m the we1ght analys1s was the sum of the stresses caused by the mternal pressure buoyant lilt and aerodynamiC load

2 Balloon Matenal

At the present t1me matenal for fabncatwn of the balloon wa mvest1gated only on a strength to umt we1ght bas1s F1gure 29 1s a plot of breakmg strength versus umt we1ght for vanous ex1stmg matenals that are used for fabncabon of balloons The curve of F1gure 29 was used m tne weight analys1s to determme the hull matenal we1ght after the stress (allowmg a factor of safety of 3) had been deternuned

3 Balloon Weight

Once the stress lS determined for a particular balloon shape the we1ght can be estimated The product of wetted area and umt we1ght where wetted area depends on shape and umt we1ght depends on stress determmes the maJOr part of balloon we1ght An allowance of 10 percent

34

..,_

~

\

280

240

-z dt 200 -J --J -' u...

::r: 160 ..... (.')

z Ul <:<: ..... Vl

~ 120 <( Ul Cl::: co :::E :::> 80 :::E z :::E

40

MATERIAL VENDOR

SPEC

GX

STRATOF!LM

VISQUEEN

TEST

METHOD

ASTM D 1682 59T

ASTM D 882 61T AT 25°C

ASTM D 882 61T AT 25°C

GT 74

v GX301NOSII GX301NO!HO / I.

,/

o DACRON AIRSHIP COATED FABRIC FROM ON 59QS889

0 FILM CLOTH lAMINATE

• CLOTH WITH SPREAD COATS

t:. CLOTH WITH SPREAD COATS PLUS FILM LAMINATE

o FILM ONLY

0 NEW SPEC

I v

I v GX302.HNBI3!51• /

v GX201NI601t

1/ /

v /

GX302HN80941

I I

GX3021NIIOI i<JX311J0!541, X_ oGX GX311P0631 GX311N0631

GX301U0420 ~ I GX301U0451 GX302HNG0661

GT 76 G4ZI20~ / GX301U0!541 GX302HNB0861

I-GT7T~ ~ ! GT 3:~ GX311P04BI

GX211025 -' ~ X211P0311 GX2210210'"' / ..._Gx31tP0311

GT 12 I MYLA~ ~Til I Tl2

EEN X I~ ~(M L STI'!ATOFILM 7 Ml

2 4 6 8 10 12 14 16

WEIGHT {OZ/YD2)

Ftgure 29 Breakmg Strength versus Umt We1ght for Var1ous Balloon Matenals

was made for seam weight 1 e hull we1ght fln weight etc were mcreased by 10 percent Wetted areas were scaled up from ex1stmg s1zes or m the case of the mod1f1ed Mark II from model dimens10ns Where a blower lS proVlded for pressunzahon blower and batteryweight depend on design altttude balloon volume dliferentlal pressure and power dens1ty of the bat tery Other we1ght contnbuhons and the detailed method of calculatmg stress and wetght of aerodynamically shaped balloons are g1ven m AppendiX II Computer pnntout data for a 1 000 000 n3 configuratiOn 1s g1ven m Table IV

35

t I I

I I

r~ r: • I'

;I '

:I

' i j

l ' -1 I j I j I ., I

Table IV Computer Prmtout Data for a Class C Balloon Conf1gurahon

COMPUTER INPUT DATA Payload - 500 lb Alhtude == 50 000 ft Velocity - 85 ft/sec Angle of Attack = 50 Volume - 1 000 000 ft3 Operatmg T1me - 48 hr

Lift and Drag CoeffiCients - f (angle of attack)

Hull umtfabnc weight (lb/ft2) Stagnation pressure (lb/ft2) Design stress mcludes

safety factor of 3 (lh/ft) Hull length (ft) ProJection area of 1 honz

ta1l (ft2) Wetted area of 1 honz ta1l (ft2) Th1ckness of vert ta1l avg (ft) Total volume of balloon (ft3) 1 Wetted area of sphencal

ballonet (ft2)

0 022 1 3184

466 262

3000 7031 5 75

051 800

44 806 Volume lost by leakage

(ft3 /day) Volume flow thru blower (ft3) Aerodynamic stress by tether

489 1 973 800

tensiOn (lb/ft) Weil:,ht of hull fabnc (lb) Weight of Intersect attachments (lb) We1ght of mternal parhhons of

honz ta1l (lb) Weight of wternal partitiOns of

ve1 t ta1l (lb) Weight of ex1t valve (lb) Weight of ballonet seams aPd

attachments (lb) Weit,ht of suspenswn system (lb) Buoyant lilt (lb) Balloon weight (lb) Umt hft (lb/ft3) Internal design pressure

(lb/ft2) Max hull diameter (ft) ProJected vert ta1l (ft2) Wetted area of 1 vert ta1l (ft2) Volume of 1 honz tall (ft3) Ballonet volume (ft3) Intersect area (ft2) Volume req d for temp change

(ft3/day)

16 36 1199

0

129 6

129 6 72 3

31 1 574

10 610 3292

0 01009

1 516 99 2

3 000 7 031

17 253 890 730

0

105 180

36

Blower operatmg tlme at altitude (mw/ day)

Buoyant stress by tether tensiOn (lb/ft)

We1ght of hull seams (lb) We1ght of 1 honz ta1l (lb) Weight of 1 vert ta1l (lb) Weight of blower (lb) We1ght of check valve (lb) Weight of m1sc eqmp battery and

blower Gb) We1ght of handling llnes and

catenary (lb) Net lilt (lb) Drag (lb) Wetted hull(s) area (ft) Locahon of ma..x d1ameter (ft) Thickness of honz tall avg

(ft) Volume of 1 vert ta1l (ft3) Diameter of sphencal ballonet

(ft3) Volume flo\1. rate of blower

(ft3/mm) Volume to replace each day

(ft3 /day) Ma:x ..,tress due to uulatwn

(lb/ft) Intersect we1ght (lb) Weight of attachments of 1

honz ta1l (lb) Weight of attachments of 1

vert ta1l (lb) Weight of battenes (lb) We1ght of ballonet (lb) Aerodynam1c lilt (lb) L1ft coeff1c1ent Drag coef£1c1ent

13 4

39 120 152 152 127 63

22

134 9507

928 55 500

104 8

5 75 17 253

119

15 790

211 330

100 0

15 2

15 2 44 6

311 2689

0 204 0 0704

(

I ~ I:. I 1-

<l;

E WEIGHT ANALYSIS OF SUPERPRESSURE NATURAL SHAPE BALLOONS

1 Stress ConsideratiOns

Tn order to retam the shape of the balloon at float altitude the mmunum mternal pres sure was assumed to be equal to the stagnatiOn pressure at that altitude This mimmum value occurs at the bottom of the balloon

Stress levels were obtamed by computer solutiOns for equatiOns hsted m Reference 9 for a super pi essure natural shape balloon with 25 percent top loadmg A top loaded design was selected because stresses are lower than m a balloon With no top load

2 Balloon Matenal

Figure 29 .vas agam used to determme matenal strent;th versus umt weight for the basic balloon matenal

3 Balloon Weight

Once the stress levels are determmed for the superpressure natural shape balloon fly mg at a particular alt1tude and wmd condition the hull matenal can be selected The selection of th1s matenal IS based on a factor of safety of 3 or g1 eater throughout the maJOr portiOn of the balloon

The vanables that mfluence the we1ght of the hull of the balloon are altitude dynam1c pressure cable tensiOn at the bottom and top of the balloon volume and umt weight of matenal To obtam the total wewht of the balloon the followmg we1ghts were assumed

Item

Remforcement we1ght AdditiOnal nratenal for

end attachment InflatiOn ducts End f1ttm,s Reefm, system Seams

1; 61

35 10

Table V contams typ1cal total data obtawed for a superpressure natural shape balloon

fable V Superp1 essure Natural Shape Balloon Parameters (S ne I W1 1d 100 000 Ft Alt tude)

Balloon She 11 l\1ate 1 1al Total Balloon Load at Bottom J Draa Net Lift Volume We1ght Unit We1...,ht Wetght of Balloon I DA LN

(ft3) (lb) (lb rt2) (I b) (lb) I (lb) (lb)

961 000 352 0 0056 563 500 l 116 211 1 681 000 490 0 0056 784 1 000 177 206 3 038 000 693 0 0056 1 109 2 000 284 1 084 4 363 000 8b8 0 0056 1 389 3 000 378 1 979 5 659 000 1017 0 0056 1 627 4 000 454 2 890 6 942 000 1154 0 0056 1 846 5 000 529 3 808

13 220 000 1724 0 0056 2 758 10 000 820 8 466 25 730 000 2810 0 0060 4 496 20 000 1278 17 810 38 930 000 456 0 0075 7 226 30 000 1688 26 790 52 270 000 6335 0 0080 10 140 40 000 2050 35 700 65 770 000 8304 0 0101 13 280 50 000 2390 44 520

37

LN -DA

1 16 3 82 5 24 6 38 7 20

10 32 13 97 15 87 17 41 18 62

J I

I

J l i

l ~ >I I I

F EFFECTS OF VARIOUS DESIGN PARAMETERS ON BALLOON WEIGHT

1 General

To determme the effect of varymg the angle of attack alt1tude and wmd veloc1ty on the relative magmtude of the we1ght for the vanous balloon conf1gurat10ns one parameter was vaned wh1le the others were held constant Plots of the data ava1lable at th1s hme are shown m F1gures 30 through 33

2 Total Balloon Weight versus Hull Volume (See F1gure 30 )

As would be expected lf the hull volume IS mcreased the we1ght of the balloon mcreases Of the aerodynamically shaped balloons the modified Mark II 1s the heav1est the ram a1r C and Vee Balloon are llghtest at the smaller volume range plotted and the Vee Balloon IS the hghtest at the higher volume range plotted One reason the mod1f1ed Mark II 1s heavy IS be cause of the large fm area on the balloon The Vee Balloon IS hght because the stress (and therefore matenal weight) IS low due to the radms of the balloon bemg smaller than a smgle hull balloon of equal volume Stress IS not hnearly proporhonal to radius but depends on buoyant llft and hehum pressure head Equations 18 through 21 of AppendlX II show the method and assumptiOns used m denvmg design stress The superpressure natural shape balloon 1s hghter than any aerodynamically shaped balloon Note that th1s IS for a 50 000 foot altitude and Summer I wmds only

3 Total Balloon Weight versus Altitude (See F1gure 31 )

In a constant volume balloon the weight of each conf1guratwn decreases With mcreasmg altitude due to decreasmg aerodynamic and aerostatic forces

4 Total Balloon Weight versus Relative Wmd Veloc1ty (See Figure 32 )

As the wmd velocity mcreases the weight of each configuratwn mcreases due to the nse m stagnatiOn pressure However smce the mternal pressure for the aerodynamically shaped balloon has a nummum value equal to 1/4 m H20 the weight of the balloon remams practically constant for a stagnatwn pressure tunes 1 15 lower than 1/4 m H20

5 Total Balloon Weight versus Anble of Attack (See Figure 33 )

The weight of each aerodynanuc balloon configuratiOn mcreases as the angle of attack m creases due to the suspensiOn weight becommg heav1er with an mcrease m aerodynamic loads and higher stresses m the hull due to hirrher suspensiOn loads

G NET LIFT FOR BALLOONS OPERATING IN ZERO WIND BUT DESIGNED FOR HIGH WIND

Net hit for aerodynamically shaped balloons operatmg m a calm wind cond1t10n will be reduced from that occurring m the destgn wmd velocity The net hft remaining 1s that amount remammg after aerodynamiC llft IS deducted Furthermore net hft Will vary wtth the angle of attack for which the balloon IS designed For high des1gn angles of attack the aerodynamiC loads w1ll be htgh and hence a heav1er balloon w1ll be required Although It would be desirable to destgn the balloons for operatiOn at a small angle of attack gust loads and other transient cond1t10ns must be accounted for m the structural des1gn At th1s hme 1t 1s not possible to select an angle of attack for which the structure should be des1gned

Figures 34 through 37 show the vanatwn of net hft versus volume assuming that the balloon IS operatino- In a zero Wind but IS designed to operate m the Summer I or Winter I wmds at 50 000 feet A 500 pound payload at balloon IS also assumed These curves are also useful 111 checkmg that sufhctent net llft IS available to llft the cable that IS required for the hmes that the balloon IS to operate m the maximum design wmd From the curves 1t can be seen that only the ram atr C shape has a posthve net 11ft when the des1gn IS based on Wmter I wmds 50 000 foot altitude and 15 degree angle of attack

38

~ r ! l NOTES

'--

EACH POl NT ON THE CURVES REPRESI:NTS A UNIQUE BALLOON DESIGN FOR THAT CONDITION

2 ALTITUDE 50 000 FT

3 ANGLEOFATTACK=5°

4 SUMMER I WIND CONDITION (50 4 KNOTS)

f 36 000

I i i ' 32 000

vMARK 11 I I

'/ t I

,........-CLASS C I I

/1 I I

L ,.....,.-RAM AIR

I I

28 000

I Vjj_ I

~'vEE BALLOON I I

v;L v I_L I VII l

I! VI ~;, I

I -- I I /; v \

Vfj I I i i

!J v; I i I

,-... 24 000 <l'l

0 z ::> 0 a... ~

3c£l 20 000

,_ J: 0 w 6 000 3 z 0 0 ---' ---' 12 000 4: c£l

8 000 ljJ I

I

~ fj I ; SUPERPRESSURE I w NATURAL SHAPE ' v I

I I I

J ~ v I I

/ I

4 000

'L l..--~ j l I

0 2 000 000 6 000 000 10 000 000 0

4 000 000 8 000 000 12 000 000

HULL VOLUME ¥ (FT3)

Figure 30 Balloon Weight versus Hull Volume for Van ous Balloon Configur atJons

39

f ' I j

I v;-a

J z j :>

j 0 !::.

"' 3 ,_ :r: t:> w 3 z 0 0 -' ....J <{

"'

V1 a z :> 0 !::.

~ "' 3

~ ,_ :r: t:>

i w 3

~ z 0

i 0 __, __, <{

"' I i

NOTES I EACH POl NT ON THE CURVES REPRESENTS A UNIQUE

12 000

8 000

4 000

0

BALLOON DESIGN FOR THAT CONDITION 2 HULL VOLUME I 000 000 FT3 3 ANGLE OF ATTACK 5 4 SUMMER I WIND CONDITION (50 4 KNOTS)

1LLloN

rRAM AIR C

~ lr CLAS~ C ......_

~ bL MARK IT

~ ~ { SUPERPRESSURE

' ~ NATURAL SHAPE

!'---. I I I I 0 20 000 40 000 60 000 80 000 100 000 120 000

AL ITUDE h (FEED

F1gure 1 Balloon We1ght versus Altltude for Vanous Balloon Conflgur atwns

N01ES l EACH POINT ON THE CURVES REPRESENTS A UNIQUE

12 000

8 000

4 000

0 0

BALLOON DESIGN FOR THAT CONDITION 2 HULL VOLUME I 000 000 FT3 3 ANGLE OF ATTACK 5 4 AL TITUD!: 50 000 F

) MARK II J I

1 ; i CLASS C \

VEE BALIOO~ RAM AIRC l---::::~

---~~ ~~

I r I--I

1\ /v

cs:-:~~ ~7

SUPERPRESSURE -NATURAL SHAPE _., ~

F1gure 32 Balloon We1ght versus Wtnd Veloctt} for Vanous Balloon Conf1guratwns

201 40 60 80 100j 12 0

21 3 so 4 SUMMER ill SUMMER

102 5 WINTER 1

VELOCITY (KNOTS)

v;a z 10 000 :> 0 !::. 8 000

"' 3 6 000 I

w 3: z 0 0

4 000 l 1-l 1

__, __, <{

""

2 000

0 0

NOTES I EACH POINT ON THE CURVES RFPRESENTS ~UNIQUE BALLOON DESIGN FOR THAT CONDITION

2 HULL VOLUME I 000 000 FT3

3 ALTITUDE 50 000 FT 4 SUMMER l WIND CONDITION (50 4 KNOTS)

l -rT T lr V E BALLOON

(RAM AIR V E BALLOON\ If~ CLASS C i

~MARK IT ...1 i

' -L SUPERPRESSURE NATURAL SHAPE

I 1 I I I

2 4 6 B 10 12 14 16

ANGLE OF ATTACK a (DEGREES)

F1gure 33 Balloon 'We1ght versus Angle of Attack for Vanous Balloon Conf1gurahons

40

j

7 000 000 I I / ~ v; [7 I

I~ I / J v~ 177 I

I o. ·"' /o Vj V; I o II ,.0 d J L r4 ~a 15

' I

/ / / v [t._'a 1~ I .. '

6 000 000

5 000 000

r-[' I / a 5 ~ rz I

I I I~ ~ ~ 4 000 000 u..J

:::!: :;) ..... 0

I I

I 1-a 0

/ ~ ~ I

f / / ~v ~ 3 000 000

M

..... :;) I

,..._ ~ w :E ::J ..... 0 > ..... -' ::J J:

i I

! I I ~ v

i I I ~, A ~ ~ / SUMMER I WIND

~ ---- WINTER I WIND

I I 'I I

I// 1L

2 000 000

1 000 000

0 0 8 000 16 000 24 000 32 000 40 (,00 48 000 56 000

NET LIFT (POUNDS)

Ftgure 34 Net Ltft of Class C Balloon Conhgurahon Operating m a Zero Wtnd Condttlon

7 000 000 I / } ! VI A/ I I I

io ! l I / v // // f---1 -+-l - "' I v/ // I .~ 0 C) ,; I : .l I ; l i I 0 I L.fa 15 II ' I V I I ' r . / '

I I ,'I /; L ~-, I

l' 10 I ,· r 17/ I '

I - l I v /j lL '

I f-a 5 I //

I /i l/ I ~ '/ I I ! 0 l i

6 000 000

5 000 000

000 000

I Jt/ l'

~ v I I J

i I~ ~ I i I I i

3 000 000

! / / ~~ ~ i I I

i I I

! I /A ~ SUMMER 1 IND

2 000 000

I~ ---- \ INTER!\ IND

II i I ! ;

1 1 r r 1

I I

I I

lj i -l--J I

i ! • I I j I

I 000 000

0 0 8 000 16 000 24 000 32 000 40 000 48 000 56 000

NET LIFT (POUNDS)

F1gure 35 Net L1ft of Vee Balloon Configuration Operating m a Zero Wmd Cond1t10n

41

~

l 1

1 j I

-1 4 '

J I

"j

-'! i

"" ~

d

"' ~ . J

7 000 000 I v I / / / /

6 000 000 ~ /"">

I / v/ / / I I ;o I lo

I~ // // v/ I

5 000 000 / /¢ 1/ v/ // v

I

I / / l6 ~ I' I J -a 15

M" -.... I I v r-a 10 - 4 000 000 I / z ~ I /

i I I I <·~ ij ~a I ""' ::?:

::)

I

I 5 i I I

....<

0 >

I / .-a 0

....< 3 000 000 v l;L ~ l I , __ / I~ ~ I

....< ::) :c

~

::?: ::)

0

} II

2 000 000

l 000 000

0

; I I h (f J:._j_i '---

I I h ~ SUMMER I WIND I WINTER I WIND 1---,--

/ I~ w ----I

~ ~I i l

I

I i I 0 8 00 16 000 24 000 32 000 40 000 48 000 56 OuO

NET LIFT {POUNDS)

F1gure 35 Net L1ft of Mod1f1ed Mark IT Con.t1gurat10n Operatmg m a Zero Wmd Condition

7 000 000 R i J 1/ I / ll v /V/ l :':? l - 0 -y~/ v1~v ---r--

1 - '""' I L / + 6 ooo ooo H ~--c; e -+--v-i¢ / ~ ~~~-

15 .---i __

!1r:r- / / ¢ ;Wa 101 I r-5000000~~·~~1--+~+-~L-~~?7~~--~~~~ J-· ! / /I /~(Ita :5 I ~--

1 I i'_j / I 0:%t _.- ~ o J j 000 000 1--+--t---i!'-+--:- [/ L. ·~

; i 1 , 1 /v /.- 1 1 1 H-~--7r-' --l!' _ 1 / /v / -r--~ _ --1

> 3 000 000 ....< ....<

f /I ' 11 )/~v / ! ~ I l /~1 / $,~" I I T- I l :J

:I:

I f l~·~~ i : j

2 ooo ooo t-· .. 7ft W/ ! __l_ -(-

'I 1 / /AV 1 I SUMMER I WIND l_ I I 1 /Vff/ i ---- WINiER I\ IND ' ---+---i

I II' i I 1 oooooo ~~~---r_,--+-~--.--.--.--r--.-~--~~ /-'rl : 1

!JJ~~,. I I

8 000 16 000 24 000 32 000 40 000 48 000 56 000 NET LIFT {POUNDS)

F gure 37 Net Lift of Ram Air C Conftguratwn Operatmg m a Zero Wmd Condttlon

42

SECTION VI

BALLOON PERFORMANCE PARAMETERS

Curves relatmg balloon parameters to net hft and drag are presented m F1gures 38 through 43 The absc1ssas and ord1nates chosen for these curves are the same as those used m the cable proflle curves (F1gures 6 through 19) 1 e the abscissa IS net hft (LN) or re sultant of buoyancy aerodynamic lilt payload and balloon weight and the ordmate IS net lilt to drag ratw (LN /DA) or tangent of the angle of apphcatwn of the rPsultant forces acting on the balloon Balloon pa1 ameters represented are shape volume (¥) and angle of attack (a) Vanables mcludmg float altitude and wmd profiles are also mdicated m the flgures

Weight estimates as descnbed m Sectwn V were made and values of net hft and drag for each balloon were determmed Note that each balloon design IS made on the bas1s of car rymg a 500 pound payload Thus the net hft of every balloon has been reduced by th1s amount Each balloon dec;Ign IS umque m that a separate design IS made each time any parameter Is changed Obse1 ve for example m Figure 38 for a Class C balloon m a Summer I wmd several values of net lilt and drag are represented for a volume of 1 000 000 cubic feet That IS a separate des1gn 1s shown for each angle of attack as a result of d1ffenng stresses wh1ch cause a dilferent strength and we1ght fabnc Thus the hull wetght \\ 1ll vary wtth angle of at tack as well as w1th volume

A summary of the graphs plotted 1s g1ven m Table VI Note that no curves are presented for streamhned shaped balloons at an altitude of 100 000 feet All aerodynanncally shaped

Table VI Summary of Balloon Performance Parameters Plotted

Float Wmd Balloon Parameters Plotted

Altitude (ft)

Proflle Type m Fig

50 000 SJ.mmer I Class C 38

Vee Balloon 39

Modil1ed Mark II 40

Ram A1r Class C 41

Super pressure 42 Natural Shape

Wmter I Class C 38

Vee Balloon 39

Modifled Mark II 40

Ram A1r Class C 41

Superpressure 42 Natural Shape

100 000 Summer I Superpressure 43 Natural Shape

\hnter I Superpressure 43 Natural Shape

43

=I II ·

I I ll I '

I ,I l i

I II

I' i

<( 0

--...... z

--'

0 I-

~ 0 ~

B

0 .t>. .t>. 0

I-

I-u... --' I-u.J

z

10 000 20 000 30 000 40 000 50 000


SUMMER I WIND

60 000 70 000 80 000

NOTES

EACH POl NT ON THE CURVES REPRESENTS A UNIQUE BALLOON DESIGN FOR THAT CONDITION

2 PAYLOAD= 500 POUNDS

3 V = HULL VOLUME 10 6 FT3

F1gure 38 Net Lilt and Drag Charactenstlcs of Class C Balloon for Altitude of 50 000 Feet

~ CJ1

"'· ~" • I "'" ! .1" _.,, "I> I .,... _,-n. .....,. ...,_,....... ~~----

16

14

12 <(

0 .....__ z

--' 10 0 I-

~ 0 8 <( <:>:: 0

0 I-

l- 6 '---' I-UJ

z 4

2

0

Y.::::7o·

0 -~ --~- -a.-5 --F'" 0

~~K 1"-1,.. - 'P' Ct :=. 0 ' ·I- """ ~ -SUMMER I WIND ~ ~-=- -- 0 ~ .£ ..... J o::::\0

"?.~o-_f. 1--:. ~~ ~ -- 0::::15° r--j...- 1---r-- I /. ~r""- .. 1--1---- "' '

111 ~~ ~-~---/ v 0 0 a=1QO a :::15 7 s / / L --1,. __ ....

!----

I 0~ ~~

~-"' a 5° - '-

?. 0 --~t:--5;. 7 o-

Yk~ ~::: 1-"" ---L---~ ' WINTER I WIND I

~----/-V--~-~--a=O

I 0 10 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000


~IT" ,_.,., ........ .,....... ,.., '1!fl._......, <T"'7"'1

NOTES

EACH POl NT ON THE CURVES REPRESENTS A UNIQUE BALLOON DESIGN FOR THAT CONDITION


3 V = HULL VOLUME 10 6 FT3

Figure 39 Net Lilt and Drag Charactenshcs of Vee Balloon for Altitude of 50 000 Feet

------ ------=---=-....::.=:._-=-..:......::.:.=::.....::::___ .. _____ _ ______ ..__ ---· -- -- ~·-·-·- - -- ''"==-________ --- - ..:::::::--=- ==-----=---=- --- -.... .,..---- . -·

16

14

12

4: 0 ......... z

....... 10

0 1-4: <><::

(.) 8 4:

<><:: 0

.!'>-0 O'l 1-

1- 6 LL

....... 1-UJ

z 4

2

0

..,..--f....

/ "t\. -

()w---~ ----~-· ~-->-r------+-SUMMER I /':..~_.. ;:_-).~- ~ ~ o.

WIND [r:,~ ~ K 1 "\o-+------t----l--

,..-j,'/ ~"' ~0 "'-, If>' ,o I\ .~,o -~---'--· / ./,...... 1\ 1-).l--1-_.,.. ~

IM ~ ---- \,__ r-...... ~ r---+ll~__,.:..x/.1\ - '• 'i'-.

• \ \ '\. . cx-15° "l I \. - _,_ 'C ,_- ,_- --- - >. - - .._--' -- -- >--.

/a= so I? a= 10 -~~-t--1--+--1---L-.......-7 /

I / v I ;;_'- - r- ;-~~ (,)/~ <:) v I _.......~ .-J-- - ~ c o/ F-V" '1. ()~v-?> a..- :, () !..--"'"' ~ --r . ..... 0--y _ ~ v"'" V 7 O· a-\5

I(/ I ~V-..,.~--~-:::~-1/ WINTER I Lf,.-l....r- cx-0 WIND --t--+--

~

0 1 0 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000

NET LIFT LN (POUNDS

-------------~~=::oo....u............ ........ .. 'I' ..,. a;z=rr-,:!:'l

NOTES

EACH POINT ON Tt-'E CURVES REPRESENTS A UNIQUE BALLOON DESIGN FOR THAT CONDITION


3 V = HULL VOLUME x 10 6 FT3

i

F1gure 40 Net Lift and D1 ag Charactenstlcs of Mod1f1ed Mark IT Balloon for Altitude of 50 000 Feet

"' .t:! M.l ....t'..ll -..

16

14

12

<( Cl

......... z

-I 10

0 1-

~ (.')

8 ~ Cl

..!>--J 0

1-

1- 6 LL -I

1-UJ

z 4

2

0

I If . ,.v_: ~, ........ \ d- I; ...,. ~, .-::o \ / ~ ""-:;;.'S [\ ... <..;' 0-

~~ /" \ 1\ \

~ \ ~ ----~-,

0 4 ~-;::.\0

/JI ~ ..... ..,;--,- \ \~ ., 1\

If '/ ..1\" ,.

\~ \ t; \ ~, I~ ~,. ~ f :::150 i --f--- --~ i/' ·' ~ /v\ .... '_ ... _ .. ---~-;---

L o SUMMER I WIND

I 'o 1 ;" ... -l.1' ~

v ;·

a=10° /

Q so /_ ~ -"-... ...,...... .........-. -- ;;=150'"

-~'-4 ~6Y ......... y ]). ~ -3 <-'"\-~- _, WINTER I WIND

ILIL'd;oo-t'?J -j)l; ...

-~ - ~· -

0 10 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000

NET LIFT LN {POUNDS)

NOTES

EACH POINT ON THE CURVES REPRESENTS A UNIQUE BALLOON DESIGN FOR THAT CONDITION


3 ¥ = HULL VOLUME 10 6 FT3

F1gure 41 Net Lift and Drag Charactensbcs of Ram A1r C Balloon for Altitude of 50 000 Feet

... ..,.

. ~:.=- --~~~- =-~~.--_ _:_-:..~"'·~~~--~ ~ -~-=~ :,~-- ~~:::-~:::-~~;~~c· ·~c;~_:-:_::- ::;~:;:-_:-..=:,;.-:;:::;~ -=------· - £~"'1-"MM --~ •.. -=--=-::.c·-~· --~ .. _=::-___ ~~-,_:~,_.----":.""::.~ ::....=-.. =---------- -=----·- ···-··- - =d'.J

16

NOTES I

Y =VOLUME x 10 6 FT3 14

2 25/ TOP LOAD

12 <{

Cl '-... z -l

10 0 I-

Y=5 ~/ v

/ SUMMER I v WIND

40/

3 PAYLOAD -500 POUNDS

<{ 0:: v l? 8 ~ Cl

"""

/ 3) v

co 0 1- / 1- 6 u.. -l

1-w z

4

/ 2 ov/"

17 1 o/

0~ v

Y=6 0 WINTER I

~1 0 2 0 3 0 4 0 5 0 to· ") WIND

'

~*

2

0 0 10 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000


F1gure 42 Net Lift and Drag Charactenshcs of Superpressure Natural Shape Balloon for Altitude of 50 000 Feet

"""' co

28

24

-<{ 0 20

......... z -'

0 1- 16 -<{ 0:::

0 ~ 0

0 12 1-

1-u.. -' 1-UJ 8 z

4

0

._._.._ 43':!?"' Nfll ....,.,. ~Wo:f'-' "l r- 1..,.tr,r ?Jl1'1r-r"'\ 11 ,..,.,.._. .,...,... ..... i ~

I I ~

WINTER I ~/~-t----j-+---lr-[_-t--t-+-t---t--J-j wc;c / ¥ = 30 --1--+-t--t---"1-

L v ~~~--~~,--/~~~20 SUMMER!

~ WIND _

~ --~ 1--t-----uL.c,_ 10 v ..-~1---+-4--+---t-1---.,

I ~ V /v 20

~~- 40

/5 ~ 1~ ~~+4~rr~~~

I JL5 W--t-+--H--H----t-tii--r-t- f.( 3

</-

0 5 000 10 000 15 000 20 000 25 000 30 000 35 000 40 000


NOTES

¥=VOLUME x 10 6 FT3

2 25 I TOP LOAD


F1gure 43 Net Ltft and Drag Charactenshcs of Superpressure Natural Shape Balloon for Altitude of 100 000 Feet

-=--.:...~ =-=-:~~-==~-=-~-===~~~==----..:....:.:.-===-~:~ -· --. ----·· ··--=---- __ :::· ___ -··-· ------·-·-·------·---·-----·-·------ -- -=:-.:... . ..;;._.,:-:-:-:-.....t ..:::;::-• ...... ~- ·-- .... ~

I ~

Balloon Volume

(ft 3)

148 000

284 000

414 000

545 000

680 000

1 340 000

2 644 000

3 950 000

5 270 000

6 561 000

Table VII Superoressure Natural Shape Balloon Charactenshcs (Wmter I Wmd 50 000 Ft Alt1tude)

Shell Matenal Total Load at

Drag Net Umt Balloon Bottom of Lilt

We1ght We1ght We1ght Balloon DA LN (lb) (lb/ft2) (lb) (lb) (lb) (lb)

43Cj 0 0240 701 1 000 2 874 237

757 0 0290 1 211 2 000 4 072 1 046

1 026 0 0322 1 642 3 000 5 213 1 884

1 300 0 0350 2 080 4 000 6 147 2 720

1 615 0 0378 2 584 5 000 7 002 3 531

3 024 0 0481 4 838 10 000 10 690 7 686

5 702 0 0594 9 123 20 000 16 250 16 080

8 406 0 0684 13 450 30 000 20 000 24 500

11 230 0 0760 17 970 40 000 3 960 32 800

13 790 0 0821 22 070 50 000 27 100 41 200

LN/DA

0 0825

0 257

0 361

0 442

0 504

0 719

0 990

1 220

1 367

1 521

balloons mvestlgated are too heavy for operahon above approximately 80 000 feet m the wmd cond1t10ns assumed

Lilt to drag ratiOS for the natural shape balloons are small for \hnter I when compared to Summer I wmd at a 50 000 foot altitude due to mcreased hehum pressure head (which re suits m a heavier balloon) required to retam shape and the mcrea e 111 aerodynamic drag Typ Ical values are g1ven m Table VII

Maximum LN/DA ratw for aerodynanncally shaped balloons occurc; at angles of attack less than the angles for max1mum aerodynamic 11ft to drag ratw That 1~ ma.ximum LN/DA occurs between 0 and 5 degrees for Summer I wmd condition and near 10 degrees for W1nter I wwds for all aerodynamically shaped balloons

In all cases except for the natural shape balloons at 100 000 feet the LN/DA ratio IS greater m Summer I v.md than 111 Wmter I wwd Wmd velocrty 1s h1ghe1 m sumner at 100 000 feet 111 area I

For the aerodynamically shaped balloons LN vanes nearly d1rectly With volume for all cases of wmd loadmg and angle of attack The LN/DA ratw however exhibits considerable vaneties For large volumes the LN/DA ratw tends to be constant For small volumes and low wmds the LN/D<\ ratw mcreases greatly with small changes m volume

For the Wind cond1tlons assumed only natural shape balloons provide a poss1ble solutwn for tethenna at a 100 000 foot altitude

From Figure 42 It appears that aerodynamic drag for the Wmter I wmd 1s very h1gh thereby reducmg LN/DA Wmter I wmd IS charactenzed by a veloc1ty of 102 5 knots at an altitude of 50 000 feet

50

SECTION VII

CABLE BALLOON SYSTEM OPTIMIZATION

Curves of cable tens10n components (F1gures 6 through 19) and net h.ft and drag charac tenshcs of balloon shapes (F1gures 38 through 43) have been presented Each group of curves relates cable or balloon pa1 ameters and presents them as funct10ns of LN and LN/DN That IS after float altitude and wmd prohle are chosen given values of LN and LN/DN completely defme a particular Glastran or nusslle wire tether lme Additionally these values of LN and LN/DN completely defme a Class C Vee Balloon modified Mark II ram a1r class C or natural shape balloon provided that the angle of attack IS specified

The total balloon cable system requirements may be defmed by notmg values of LN and LN/DN that are common to both balloon and cable After a particular balloon cable system IS defmed by this method It must be checked to determme If the system Will be adequate If the wmd velocity reduces to zero To make this check compare the cable weight as determmed m Figures 8 11 14 and 17 to the net lilt for the balloon under a zero wmd condition as shown m Figures 34 through 37 If the cable weight IS less than this new net hft the system will be capable of performance m a zero wmd condition as well as m Its design wmd conditlOn An allowance should be made for the reduct10n 111 cable length to be hited 111 a zero wmd but proVIslOns for makmg this check are not presented m this report

The curves showmo; net lilt m zero wmd are obtamed from computer runs of a balloon type m which the balloon weight IS that weight required for design at a particular wmd velocity The net lilt In ze1 o wmi IS the remauuna lilt available after aerodynamiC 11ft has been deducted

The optunum system would be determwed by compann solut10ns for other balloon cable system combmatwns Puformance factors mcludm base cable an"'le and blowdown distance must be consideied 111 add1t10n to cost and rellabihty

The design a~ desuibed above IS adequate fo1 systen operatiOn at a prescnbed altitude for the prescnbed '' md conditlOns and the system can operate at any altitude between float altitude and the ground p1 ovided that the design dynamic p1 eSSUI e at mtermed1ate altitude IS not greater than at the design float altitude

The proccdUI e fo1 combmed use of the curves IS given below

1 De ternnn the folio VI 1, basic sy ste 1 eqmrements and design cond1tlons a Float altitude of payload b Wmd pi oflle

2 Select requu ed balloon pa1 ameters such as the followm"' a Balloon type b Desian Lntelia fo1 balloon solutwn I e angle o attack to be used m design

3 Select 1 equ~red cable parameters such as the followmg a Cable tvpe b De~Ign c1Ite1Ia fo1 cable solutiOn I e nummum anale pernutted at base of

each segment blowdown distance or total cable weight

4 Usmg 0 1 aphs rep1 esentmg the above requu ements 1 e one graph givmg cable pa1 ameters and another givmg balloon pa1 ameters check vanous balloon cable systems that satiSf) the conditwns Solutwns are possible at powts on the hvo g1 aphs where LN and LN/DN are equal For a tandem balloon system ralcula twns are required to hnd LN and DN at the top end of Intermediate cable lenaths

51

I ,, '

I

~ J

, "" i\1

' ~ ~ ~ , ~ " -1 ~ ~ Ill'

s l';i

~ ~ , ~:i i'!

~

5

6

1 e cable tens10n components 1mmed1ately below the lower balloons Methods of compann(T performance of tandem ba..loon systems W1ll be presented m Task Report No 2

Check des1gn for fhght capab1hty m a zero wmd cond1t10n

Compare workable systems and choose the most des1rable

52

r

A GENERAL

SECTION VIII

REVIEW AND COMPARlSON OF CONCEPTS PROPOSED IN ARPA CONTRACT STUDIES

Vanous concepts to place a 500 pound payload at a 100 000 foot altitude usmg a tethered balloon system were ongmated from stud1es conducted under ARPA Contracts SD 198 SD 199 SD 200 and SD 201 These stud1es are reported m References 1 through 4 Each system proposed vaned m the number of balloons used volume of each balloon the shape of the bal loons tether cable strength altitude at which each balloon was to be flown (except the topmost balloon which was at 100 000 feet) and m one case the tether line matenal Figure 44 de p1cts the balloon and tether systems proposed

An extensn e descnpt10n of handling equipment and fac1hhes 1s giVen m two of the re ports A d1scuss10n of these reqUirements IS not mcluded 111 this report smce It 1s of second ary Importance to system feasibility Later w the program when performance capabilities of the vanous systems are more completely defined equipment and fauhhes reqUirements w1ll be cons1dered as well as costs Bnef descnphons of the vanous concepts are given m th1s section

B CONCEPT PROPOSED UNDER ARPA CONTRACT SD 198

General Mills Inc proposed U1e use of a smgle balloon ::.ystem The balloon portion of the system conslbts of a 215 000 cub1c foot natural shape launch balloon to be Jettisoned dunng ascent and a 12 360 000 cubic foot natural shape mam balloon The tether lme proposed was a spliced cable made from miSSile \\11 e of 11 different d1ameters varymg from 0 106 to 0 230 mch m d1ameter

In moderate wmds the balloon and anborne wmch are released from an explodmg shelter and allowed to nse At an altitude of 5000 feet the Winch unreels cable at a rate equal to that of the ascent rate of the balloon When the balloon reaches 80 000 feet the wmch which IS still at 5000 feet 1s retneved by a helicopter and the entire system IS towed to the tethenng s1te where the remamder of the cable 1s Winched out In Winds below 15 knots the airborne wmch IS attached to the around and the balloon ascends m the conventiOnal manner Durmg retneval the payload IS released and steered to the launchmg area by a parasall The balloon IS wmched down to 50 000 feet where It IS ruptured A parasall op ns and the cable 1s wmched 1n faster than the parasall descends If the balloon IS ruptu ed above 50 000 feet the parasall opens and depos1ts the cable m a predeternuned locat10n A hellum detectiOn device such as a thermal conductiVlty cell was proposed for mountmg man open duct so that when the pressure mcreases the sensor In the duct Will cause a switch to close thereby opemng a pressure relief valve

C CONCEPT PROPOSCD UNDER ARPA CONTRACT SD 199

Goodyear Ae1 ospace Corporatwn proposed the use of a mulhballoon system The balloon portiOn of the system consists of five balloons stationed at vanouc; altitudes the top two bal loons are of the smgle hull design and the other three are Vee Balloons Spliced m1Ss1le w1re was propoc;ed for the tether cable

To protect the topmost balloon from the h1gh dynam1c pressures at the lowe1 altitudes 1t 1s Imbedded 111 the top of the No 2 balloon wh1ch IS substantially more rugged

53

j

il

H '' ' '

i I

U1 >~'>-

--------- -- .-.. ~~...14.1 lA" r.JJ: ~ue ...._~""':'l.-..£...:....£...'Ll!!.L.......Biil.l!t'~ !ntt£"'1'\. rr; __ _p-....

100 000 ..----------1.. }---------"'"" }---------------"'"" }------------''-... NO 2 NO 1 NO 1 12 360 000 FT3 5 370 000 FT3 8 000 000 FT3

90 000~------+--------------+---------------+----------------~~----~

NOTE 80 000 I I NO 1 JETTISONED-+---------------{

DURING ASCENT

70 000~----~~------------~------------r-------------------~------~

GAC GMI HONEYWELL VITRO ~ 60000L_ ____ _J~~-----------!~~~~~---r~---------------~,-------~ uu uu u_

----Q 50 0001 ' ~

~ 40 QOQ. / j~,~ ~00 '~----1----------~~i-------l 30000~--t-------------f------------,~----------------~~~~~~

w~ .. NO 3

1 0 000 200 000 FT3 -------"'" NO 5 500 000 FrJ SLlL ___ _j_ ____ _j_ _____ ....L_ ___ ~

F1gure 44 Conftgurahons Proposed by the ARPA Contractors

The hrst balloon launched IS the No 2 balloon Each success1ve balloon 1s then attached at the appropnate locatwn to the tether lme untll the No 2 balloon reaches an altitude of ap proximately 40 000 feet At th1s time the top balloon With the payload attached IS released and ascends to the reqmred 100 000 foot altitude

The payload IS recovered by lettmg 1t free fall m a proJectile shaped body until It reaches an alb ude of 15 000 fept where a parachute IS deployed

While the payload 1s bemg retneved the balloons are reeled m and removed from the system as they reach the ground The top balloon IS possibly destroyed as It descends mto regions of high dynamic pressure

All the balloon except the top balloon are equipped w1th ballonets pressunzed by ram a1r mflat10n The top balloon IS fabncated m such a way that the outer skm lS m rad1al folds that peel away as the balloon ascends to altitude thus keepmg the balloon pressunzed

D CONCEPT PROPOSED UNDER ARPA CONTRACT SD 200

Mmneapohs Honeywell proposed a two balloon system A 5 370 000 cub1c foot natural shape balloon was proposed for the top balloon and a 715 000 cub1c foot smgle hull aerody nam1cally shaped balloon for tethenng at an altitude of 50 000 feet A tapered nylon rope was proposed for the tether cable between the balloons and a tapered m1ssile Wire between the lower balloon and the ground The balloons were to be constructed of a plastic hlm/f1ber com pos1te scnm matenal

The payload IS retneved by lettmg It shde down the cable and then retneVIng It with the lower balloon The upper balloon IS cut free m high winds

Launch and ascent techmques were not descnbed

A roll diaphragm pump was suagested as a possible means of pressunzmg the aerodyna mically shaped balloon and the natural shaped balloon was to be reefed

E CONCEPT PPOPOSED UNDER ARPA CONTRACT SD 201

VItro C01 poratwn also p1 oposed the use of a multiballoon system The balloon portion of the system consi!:>ts of three balloons stationed at vanous altitudes the top two balloons are of the natural sha.pe design and the bottom balloon IS a smgle hull design Fourteen segments of miSSile Wire spliced together were suggested for the tether cable Wne diameter vaned from 0 121 to 0 251 mch m diameter

The top balloon IS launched first with the payload attached and each successiVe balloon IS then attached at the appropnate locatiOn to the tether lme until the payload reaches an altl tude of 100 000 feet

Fo1 retneval the balloons are reeled m and removed from the system as they reach the ground In an emergency the payload would be eJected and recovered by parachute while the cable above the bottom balloon would be severed The lower balloon would then be reeled m and recovered

Pressunza.t10n for the natural shape balloons IS achieved by reefing bands that are cut as the balloon ascends to altitude No pressunzahon system was proposed for use dunng descent

F COMPARISON OF CONCEPTS

In order to make an eqmtable companson of system proposals modlf1catwns were made to the systems proposed by the vanous contractors Each contractor had assumed a different des1gn wmd profile therefore compansons cannot be made w1thout changmg the balloon and

55

l i

~ I

l :

-1

t

I

90 OOOr--+--+-~+/;,\~~+-~~~~r--+--+-~---r--+-~--~--r--+--~~ v ~ ~ //

I / I

80000r--r--+-~·~'--HH~~r;'~---r--r--+--~--r--+--~~---r--+-~--~ /; If I

~OOOr--+--~r'+-~~'~~'~r--+--+--+--,_~r--r--+--+--+-~--,_~ ( \~

60 80 100 120 140 160 180 WIND VELOCITY {KNOTS)

Figure 45 Altitude ve1 sus Wmd Velocity Assumed by the ARPA Contractors

56

1

i

'-1

cable proposed des1gns m some way For tins reason all systems are compared on the basiS of the same wmd profile rather than the varwus prohles proposed F1gure 45 shows the wmd profiles assumed by the contractors Other changes m proposed quanhhes concern the weight of balloon and cable components Balloon we1ght of streamlined balloons 1s obtamed as descnbed earher m tins report We1ght of natural shape bd.lloons IS obtamed by assummg that the balloons have zero circumferential stress zero superpressure a flat top and are designed m accordanre w1th the design sigma tables given m Reference 9 Balloon surface area was as sumed to be the theoretical value from the sigma tables and end remforcements were assumed where load m the matenal exceeded the design strength

Cable weight IS also computed as proposed prevwusly a tapered constant stress cable IS

generated as part of the computer solutwns for cable profile With these changes care should be exercised 111 the concluswns drawn smce the balloon systems p1 oposed by the contractors may be subJected to a loadmg condition entuely dilferent from that assumed by the contractor

Table VIII IS a summary of the ARPA contractor proposed concepts It 1s seen from Table VIII that a Class C balloon was assumed where a smgle hull streaml111ed balloon was spec1hed The Vee Balloon was used for specific cases of the GAC concept Design angles of attack of 6 degrees fo1 the Class C and 4 degrees for the Vee Balloon were selected so that LN/DN 1s maximum for each type

For the sake of companng the effects of certam changes 111 cable type and number of balloons m the systems proposed mod1hcat10ns are mcluded 111 Table V1Il

G CABLE BALLOON SYSTEM SOLUTIONS

F1 om the data m Table VIII cable balloon system solutwns \\ere performed for each system Observ1.t10ns and compansons of the system solutions are descnbed m the followmg pa1agraphs

1 Balloon W e1ght

We10 hts of natu1 al shape balloons we1 e calculated to be reater than those proposed by GMI and Honeywell by approxunately 58 percent and 17 percent respectively The two natural shape balloons oftheVItrostudy we1e however too hcaV) by 15 and 36 percent For the study p1 esented here the we1ght of natu1 al shape balloons IS the same fo1 Wmter I or Summe1 I wmds In reality the we1ght should be slightly dilferent due to the d1fferent wmds and there fore the superpresslil e requu ement

In all cases the WPlghts proposed for the st1eamhned balloons v.ere heaVIer than those proposed by the conh actor Here allowance for heaVler balloons was made as the wmd cond1 t10ns became mur e seve I e Note that at 100 000 feet a more severe des1rrn cond1bon occurs for Summer I wmd than for Wmte1 I wmd

2 Net Lilt

Values of net lilt a1 ven m Table V1II are the summatwn of lift at the top end of each cable segment Tlus ltft not only mcludes forces actmg on the balloon but also the cable load from segments cJ.bove the cable sectiOn of mterest Note that 111 the case of GAC balloon No 1 the we1ght proposed re~ulted m a negat1 ve net lilt Uswg the contractor s proposed we1ght however a pos1bve net lilt was obta111ed To obtam a solutiOn th1s contractors proposed net lift was utrllzed It 1s reasoned th1.t by choosmg a slightly larger natural shape balloon th1s net lift could be real1zed A natural shape balloon would have resulted m a larger drag Th1s fact was not accounted for here As w1ll be shown later tre result of th1s solutwn w1ll be use ful for the sake 1f companson however the reservatiOn of tlus assumptiOn must be kept m nund

57

' I' \

. I:: ' :I I' . I

rl\; i: I i ,, , I, : 111· I : 'j:

f

Table VIII Summary of ARPA Contract Stud1es (Sheet 1 of 2)

I w 0 ) ( ) ta

l.la AI n E Pop d E d I 0 I l.la I l (I )

pc (l) (l 3) (d ) op d w S mm w s w I l.la II s w I I I I I

(l 3) I

5 GMI

2 00 000 3GO 000 30 4 747 7870 6 23 6 2 2 0 3 000 3 000

I 100 oco 5 3 0 000 14 0 2 018 2 018 2 4 2 2 2

8 200 4 353 627 )'V. 2 l c 50 000 7 0 0 G 2000 2 335 6 9 8 552 09

0 8 00 0 0 2 980 3 880 3 8

2 0 0 000 0 I 29 0 2 5 3 2 5 3 5 6 0 398 000 2 8 28 503

I J c 0 ol

I G 0 259 3 208 9 35

!-0 2 000 0 2 0 87 56 440 53 28

( odl 0

8 2 Cl c 000 3 000 000 6 8620 22 9 7 8 05 45 506

< (, 3 I 2 00 500 000 22 0 3 5 8 544 8 70 50 000 33 55 0 304 "'

;

9 000 500 000 2 0 3 053 7 52 66 080

00 5 0 0 0 2 0 3 6 983 7 172

r 0 1 co so s ( c c I O.ly)

I. 0 0 2 00 220 G

I\ 6 I

I 3 0 22 9 5 06 i I i

I 00 0 0 000 0 0 2 9 0 J 80

I 0 2 ? r I

3 Cable Data

A d1scusswn of the cable prohle solutwns 1s presented so that those systems that pro v1de solutwns may be determmed before exanumng total we1ght of all balloons In Table VIII note that certaw we1ght values represent the balloon we1ghts chosen for use w the prohle study In all cases the we1ghts as proposed w tlus report were used except for the case as noted above and for the GMI s ngle balloon Th1s GMI exceptwn 1s made to c;how that no proflle solu tlon ex1sts even though a balloon of underestimated we1ght was ut1hzed

4 Summer I Wmd Solunon

Elements of the cable proflle solutwn are self explanatory It can be observed that the only systems that prov1de solutwns 111 a Summe1 I wwd are the \ 1tro and the mod1fled GAC systems The system proposed by Honeywell would requ1re only a slight mod1hcatwn to pro VIde a solutwn Presently the lowe1 end of the bottom segment becomes honzontal approx1 mately 4000 feet above the g1 ound For purposes of makwg compansons 1t was assumed that the cable reached MSL The GMI system would result w the cable becomma honzontal approx 1mately 18 000 feet above MSI

58

i l

Table VIII Summary of ARPA Contract Stud1es (Sheet 2 of 2)

I I w h T I IJ.l h D I c I 1 z

c I H ib ( b be s g (f l s s Wnd I m

S<! fib Ty \ ) (I ) (!b) (I l Ch k

l>e (! I " s w ~ IW ~ JW s w s w S mm s w c 1 I 1 I (I b)

I 1 00 0 0 33 33 3 55 287 39 5 8 2 8 6 59 5o 28 39 5 8 6 23 7 2 8 6 59 5 300

50 00 3 80 2 0 29 4 9 5 2 2 412

3 58 9 9 023 12 098 6 685 50 0 0 0 5 32 3 2 65 292 45 0 38 1 79

- 20 000 8 3 803 2 335 226 1 202 3 880

"' 60 00 5 32 08 23 703 4 683 0 786 39 55 576 3 95 0 586

20 000 4 0 949 0 6 52 f-

M 59 000 5 H 48 7 6 3 706 41 354 9 3 7 207

"' Cl I 7 000 2 20 6 540 24 8 6

000 9 2 6 9 3 369 3 87 2 8 5 0

-M 8 000 20 5 2 605 3 369 39 6

...J 1 000 2 9 3 32 2 9 6 36

v I D RP s TE 0 ruso s (D c p Leb )

9 000 57 3 706 9

5 94 32 0 00 9 2 239 32 269

0 000 3

(, 0 9 3 8 2

E

d

5 Wmte r I Wu d SolutiOn

None of the proposed S) stems was capable of proVldmg a solutwn m a Wmter I wmd con ditlOn although only mmor modlf1catwns to the Honeywell and GAC systems would be reqmred to proVlde a workable system

6 Total System Blowdown

Total blowdown of all cable segments w the &lmmer I wmd md1cates that the three balloon V1tro sy tern results m the least amount of blowdown w1th 39 400 feet the GAC system 1s second w1th 43 900 feet and Honeywell 1s th1rd w1th approxtmately 73 600 feet

7 Total Wetght of All Cable Segments

For the Summer I wmd solutwn the two cable system of Honeywell 1s llghtest at approx tmately 9000 pounds VItro second at approximately 14 000 pounds and GAC th1rd w1th approx1 mately 54 800 pounds The nylon rope proposed b) Honeywellts not the best cho1ce As shown m Table VIII Glastran cable prOVldes a lesser blowdown dtstance and a hghter cable m add1t10n

59

'

!f

il ' '

li i ,,

1 j

1 j

~ l

l I 1 .~

] j

l 1 1

~~ J

I

' '

~ 1 i 1 J 1

8 Total Weight of All Balloons

For the Summer I wmd conditwn the Honeywell system IS ltghtest at approx1mately 4 400 pounds V1ti o IS second at approxrmately 24 BOO pounds and GAC thrra at approxrmately 33 600 pounds

H COMMENTS AND COJ\CLUSIONS

Choice of balloon volume altitude and numb~r of balloonf:> m the c;ystem IS very cntr cal A smtable method of malmg these selections has not as yet been determmed

A modified solution of the GAC proposal IS proVIded m Table VIII The lower three bal loons were removed w1thout changmg the volume of the upper two balloons or the cable type The new solutwn mdicates that total balloon and cable we1ghts reduce srgmhcantly whrle blowdown mcreases as would be eApected This modrfled GAC concept IS still many times heavrer than the Honeywell system The s1gmflcant dlfferences m the systems are the bal loon volumes That IS the top balloon of the GAC system IS 2 000 000 cubic feet whereas the Honeywell balloOI IS 5 370 000 cubic feet The mtermedrate balloons are 3 000 000 and 715 000 cubrc feet respectively

The comments presented herem do not compare any desrgn conditlOn except those at float altitude Launch and retneval problems must be considered before a fmal companson can be made

Although the balloon volume p1 oposed for a smgle balloon system d1d not provrde a solu tron selectiOn of a larger balloon 25 000 000 to 30 000 000 cubic feet w11l provrde a solutwn as can be seen from Firrures 18 and 43 This system appea1 s to be lea t complex Of the sys tems that p1 ovtded solutwns the two balloon system proposed by Hone)'\vell appears better than any other system proposed hom the standpomt of system complex1ty balloon we1ght cable WCt 0 ht and system loads Thts Judgment Is made even though net lilt avarlable IS msuf flctent to lilt the cable v.hen aPl odynanuc lilt 1s reduced to zero

Performance cha! acter sties arc better for the VItro and GAC systems when total blow down lS considered

Best performance as measured by small blowdown drstances 1s obtamed from a system of many b1.lloons and favo1 able base cable anrrles for each segment Compare the blowdown of the lower fou1 seaments of the GAC system (d -12 200 feet h 41 000 feet) wtth that for the lowe1 sc ment oi the Hone)".vell system (d 53 500 feet h 50 000 feet)

To obtam a munmum wer ht solutwn proportwmng of balloon volumes appears to be such that the lower end of eac'1 cable se 0 1 ent becon es nearl) horrzontal

Tapered nnssile wue appears to be a good chmce of cable whe eas nylon prov1des no apparent advantage for the condrtwns assumed 111 thrs study Tapered Glastran cable provides a shohtly better solutwn for the smrrle companson made that of the V1t o concept

60

t l

I

-1 1

l I

~J t~ ic

~-- I 1 i 1

~ i

SECTION IX

CONCLUSIONS AND RECOMMENDATIO:t-.8

InvestigatiOn of methods for determmmg optimum smgle and multiple balloon systems Will be contmued A method for determmmg a workable balloon system has been established with a multiple balloon system the only solutiOn m many of the wmd and altitude conditions considered However a method for optimizmg the number of balloons float altitude and balloon SIZe ha5 not yet been developed at this hme

Equatwns of motion of the balloon and cable system durmg ascent and descent should be denved and computer solutiOns obtamed

Mettods of penetratmg the regwn of hrgh dynamic pressure Without structurally over desrgnmg the balloon for operatiOn at float altitude should be mvestigated Launch as a free balloon and means of contamment m a second balloon are methods that ment further study

A revrew of all potential balloon pressunzatwn systems 1s needed particularly methods of reefmg a natural shape balloon

61

I I'

r I I f

r

APPENDIX I

2 CABLE PROF1LE ANALYSIS

A MATHEMATICAL ANALYSIS

The mathematical analysis of a cable balloon system subJected to a wmd vector profile mvolves techmques Similar to those used m the soluhon of related cable stud1es ansmg m a vanety of engmeenng diSCiplmes These studies mclude problems on towmg cables moonng lmes supportmg cables m bndges cable car lmes electnc power hnes submanne cables etc Problems of thiS type m their greatest generality mvolve determmatwn of cable tenswn as well as three dimenswnal cable shape for a transient conditiOn I e time dependent cable configuration while reduced problems mvolve determmatwn of above parameters m two dimen swns for transient as well as steady state condition and also three d1mens10nal steady state conflgurahon

Many problems have been worhed out m two d1mens1ons for a flexible cable for a steady as well as transient motwn of a cable The shape and tenswn of a cable subJected to a fluid flow have been studted by H Glauert (Reference 10) for a steady condition on the assumptwn that the cable IS umform and the speed of the flu1d IS the same at every powt of the cable In this study only the normal component of cable drag was considered neglecting tangential or a fnctwnal component v. h1le a study which Incorporates both the normal and the tanbent1al components was performed by L Landwebe1 and M H Protter (Reference 11) A transient cable motwn has been studied by F 0 Rwgleb (Reference 12) and by T S Walton with H Polacheck (Reference 13) In the former work the change 111 cable tenswn was Investigated due to a sudden Impulse while In the latter an extensive analysis has been performed on cable tenswn due to a pe110diC mot10n of one end of the cable with the other end fixed

The techmques developed f01 the above two dimenswnal problems are useful for the three dimenswnal problem at hand The plime ObJective of these studies IS to select appropnate balloon cable deswns such that thev wlll be operable at a desired altitude under a vanety of wmd vector profiles as well as to determwe the operative envelope 1 e to 111d1cate the optlmum configuratiOn of different paramete1 s for vanous operative conditions

B STEADY CONDITION

The problem for a steady state cond1t10n IS to determmc the tension 1n a cable as well as the shape w t1 one end of the cable attached to a h ee balloon at a given altitude and the other end fixed at ti-Je ground From tlus then It IS possible to deternune the elevatwn re quired at tether i:>Ite In the solutwn of the problem the vanatron of the followwg parameters IS considered

(1) Wmd vector profile 111 the operatwg range (2) Wmd vector at flo1.t 1.ltitude (3) Float altitL.de (4) Terram he1ght at tether side (determmed parameter) (5) Cable geometry diameter as function of cable length (6) Cable weight/length as functwn of cable length (7) Cable wei6ht (8) Balloon buoyancy and drag at float altitude

To evaluate the effect of these par1.meters on cable form and tens10n a mathematical model IS developed mcorl)orahng these quantities

2 Subsections A through D of this appendiX are excerpts from Reference 1

63

I I

I

ir

d ·II \ • I

I I I

II I I

I ! I I

I I I , , I ;I I

' . ' , I

" ' II'

C MATHEMATICAL MODEL

In developmg a mathematical model for the steady state cond1t10n a set of assumptwns are 1mposed so as to make the problem tractable It IS assumed that the only forces actmg on a cable element are the gravity force pressure drag force and tenswn The graVIty 1s as sumed to be um.:form m the operatmg range m the light of the fact that the change 1s approxi mately 1 0 percent The skm fraction drag 1s neglected due to the fact that the skm frachon drag coeffiCient 1s smaller by two orders of magm.tude as compared to bas1c drag coefhCIPnt (see Reference 14) and the fact that the cable 1s nearly vertical The buoyancy on the cable 1s neghg1ble compared to other forces and also IS not taken mto account It 1s assumed that the moments a1 e not transm1tted m the cable thus 1mplymg that the cable 1s perfectly flex1ble A physical assumption made 1s that the drag force on the cable element normal to the element can be deternnned usmg the wmd vector component normal to the element This 1s so called cosme or sme pnnc1ple dependmg on the deflruhon of angle of attack

Selectmg the ongm of the coordmate system at the balloon (see F1gure 46) and equating the sum of the force on an mhmtesimal cable element to zero three equatwns are obtamed

where

(ds) F unx (T stn o cos e)s + (T sm cp cos e)s +ds = 0

(ds) F uny (T sm 9 Sin e )s + (T sm cp Sin e )8 + ds = 0

(ds)Funz (Tcos¢)s+(Tcoso) 5 +ds w(ds) 0

T 1s cable tenswn

s ts length of cable fi om the 011 m to the element

ds ts tnfmitPc;tmal cable length

9 and e are phe11cal coordmates that determme the dtrectwn of tangent vecto1 to thE cable at pos1t10n s

w 1s wetght of cable/len0 th as functiOn of s

u 1S magmt1..de of wmd vector as functiOn of z

(1)

a ts dtrectwn of wu d vector honzontally as functiOn of z (the vert1cal IS neglected)

F unx IS dra force on cable element /length m x dtrechon

F uny 1s d1 a., force m y d11 ectwn

F unz 1s drag force z dllect1o1

To evaluate the d1 aa f01 ces a no1mal component of the wwd vector has to be computed (as mentiOned above) from wh1ch the d1 aa force normal to the element can be evaluated lead mg thus to the destrEd results whtch become

Wlth

where

Funx

F uny

Funz

D

D [cos a sm2 o cos e cos ( 8

D [sm a sm2 o su1 e cos (e D [s1n 6 co::. o cos (e a)]

u IS w1nd speed

p 1s an dens1ty as functiOn of z

64

a)]

a)] (2)

{

r l

' f

F1gure 46 Coordmate System

Cn 1s cable drag coefhc1ent

d 1s d1ameter of cable as funchon of s

z

t

BALLOON AT FLOAT ALTITUDE

T + dT

DlVldmg each of the equations 1n set 1 by (ds) and m the lumt as ds-o the followmg dlfferentlal equations are obtamed

d (T sm o cos 8) + F unx 0 = ds

d (T sm 9 Slll 8) + F uny 0 = ds

d (T cos 9) + Funz w = 0 ds

(3)

w1th the boundary cond1tlons T - T 0 8 = 80 and 9 - 60 at s s 0 It 1s of wterest to note at th1s pmnt that for u - o everywhere (except at float altltude) and w mdependent of s the above three dlfferentlal equations s1mpllfy to a Simple equatwn wh1ch 1s the equation of a catenary

d2> A-dx2

where A 1s arb1trary

To fmd an analytical solutwn to the three dlfferenhal equatwns 1s an extremely dtfflcult lf not 1mposs1ble task smce the d1ameter of a cable and the hnear density are arbitrary func tlons of s as well as wmd vector proflle and a1r dens1ty are both functwns of z In the llght of these facts an approximate techruque has to be developed Th1s 1s accomplished by represent mg the dlfferent1al equatwns by a set of dlfference equations wh1ch can eas1ly be evaluated by means of a digital computer Denotmg the pos1tlon s on a cable by 1 and the pos1hon s + ds by 1 + 1 the followmg set of equatwns result from set 3

8 - 8 + arc tan urun unyl I

[

(ds) F sm 81 (ds) F cos 8 ]

1+1 1 Tl sm 91 (ds) F UilXl cos el (ds)Funyl sm el

65

I

.I ;

;I

I .I

" ., i

.I

I I ,I

II

£

II t

I

1

w I (ds) + TI cos ct>I (ds) F unzi Tl+1 == cos cpl+ 1

l

Zl+1 == (ds) L cos cjlk

k-0

I

Xl+1 == (ds) L sin ¢k cos ek

k 0

I

Yl+1 == (ds) L: Sin Qk Sin 1\ k 0

ThiS set of SIX equations together With boundary conditions are used to compute cable form as well as the tenswn for a given Wind vector profile and a giVen cable hence known d - d(s) and w - w(s) It IS of Importance to get an approximate error resulting from the difference equatwns An estimate of this IS presented below

D ERROR ANALYST~

The errors m the cable form and tenswn resulting from approximate computing tech mque depends of course on the magmtude of cable Increment chosen for the computation the smaller the mcrement the greater the accuracy In the two quantities However With decreas mg mcrement the computatwn time mcreases thus leadmg to a trade off between accuracy and cost Prellnuna1 y analysts mdtcates that the ratiO (ds)/(cable length) m the range 1/200 to 1/240 IS qmte sat! '>factory to satisfy the two requirements

The companson of the approximate solutwns IS possible w1th an exact one 111 special cases 1 e when the dtfferer tlal equatwns can be solved analytically Such a companson has been made w1th thP result that the errors 111 cable posihon and tenswn mcrease with cable length as would be expected w1th maximum errors of 0 75 and 0 45 percent respectively at approxtmately half of the reqmred length The maximum error for the entire cable would be nearly double these numbers

E SOLUTIONS OF DIFFERENCE EQUATIONS

The duferentlal equatwns m subsectwn C lead to duference equatwns 111 unknowns e 9 and T The duference equatwns were denved as follows

T1 sm 91 cos 81 + F unx ~S == 0

T1 sm ¢1 sm 81 + F uny ~S 0

w ~s 0

66

(

I

f

r I I

Solutwns for unknowns e <f> and T are found sequent1ally

T 1 sm <f>1 sm 81 F uny ilS tan el+ 1 = --=~-~---=-----=:=..~_:____

T 1 sm <f>1 cos e 1 F unx ilS

For small vames of el+1 where sm el+c-o an alternate equatwn rs used

F unx t.S tan ¢1+1 =

(T1 cos ¢1 F unz t.S + w AS) cos el+1

Then to a\ ord angle adJustment due to quadrant vanatwns the solutrons for e and cp are changed to dJ..fference equatwns by the rdenhty

tan (a tan a tan b b)-------

1 + tan a tan b

Tan (81+1 81) and tan (61+1 61) are therefore computed bPfore solvmg for el+1 and ¢1+1 Then

TI+1 -T 1 cos o1 F unz AS + w t.S

unless ¢1+1-- go degrees where cos ¢1+1-o But lf ¢1 1 --go degrees the computatwn rs ternunated smce at 91+ 1 - 90 degrees the cable rs parallel to the ground plane

F DESIGN OF CONSTA.l'\fT STRESS CABLE

1 General

An optm1Um cable design would of course be one where stre5s was constant over 1ts entire length tor mstance sectwns at the higher end must have adequate strength to lut the lower end and therefore must be of larger size proVIded that the cable has homogeneous proper ties In a hke 'nanner cable size should be tarlored w accordance With distnbutwn of aero dynamic load Therefore m solvmg the drfference equatiOns the cable properties as shown m FI!,Ures 3 and 4 were assumed to be representative of the types of cables available In order to calculate parameters c:;uch as blowdown distance cable angle and total cable weight for a tapered constant stress cable The equatwns defirung physiCal properties were denved by frttmg the curves of Frgures 3 and 4 to the data proVIded bv manufacturers of the three cable types These equatwns are given m the following paragraphs

2 Glastran

a Cable We1ght/Foot (lb/ft)

w = (0 001) (5 6 + 0 662 s2) for 0 < s < 9

where S B S 1000 = F S x tenswn

1000

s w = 153 for S > 9

67

b D1ameter (feet)

= 1 ( w ) 1/2 d 12 0 596 for 0 < w < 0 150

1 (w 0 009) l/2 d - 12 0 573 for 0 15 < w ? 0 582

3 M1SS1le W1re (Acco 1 x 37 X 7)

a Cable We1ght/Foot (lb/ft)

s w -112 5

for 0 < S < 9

w - o oo1(8o s 9 ) + 0 0772 for S ;:: 9

b D1ameter (feet)

1 ( w )1/2 d l2 1 888 for all values of w

4 Sampson Bra1ded Rope (Nylon)

a Cable We1ght1 Foot (lb 1ft)

w 0 001 ( 0 1 ~05 ) for all values

b D1ameter (felt)

1 ( (J., ) 1/2 d l2 0 256 for all values

68

f

l

I r r I

1

APPENDIX II

DETAILED ANALYSIS OF TETHERED AERODYNAMICALLY SHAPED BALLOONS

A GENERAL

Th1s appendlX contams add1bonal Information on the physical dimenswns stress analy SIS and weight analysis of the aerodynamically shaped balloons

B PHYSICAL SHAPE

For geometncally Similar balloons the llnear dimenswns are proportwnal to the one thud power of balloon volume and the surface area 1s proportwnal to the two thirds power of balloon volume Therefore the vanous lengths and surface areas for vanous balloon shapes can be obtamed by determmmg the appropnate proporhonahty constants These scalmg fac tors (proportwnahty constants) for the Class C ram au C a.nd mod1fled Mark II balloons were based on wmd tunnel models and the scahng factors for the Vee Balloon were based on actual balloon des1gns

Table IX wh1ch contams scalmg factors and the relatwnsh1ps hsted below were used m the computer program to determme the physical siZe for each balloon shape

Hull Length (ft)

L Kl vl/3

Ma.:omum Hull D1ameter (ft)

D __!__L f

Wetted HuE(s) Area (ft2)

Ah = KJV 213

ProJected Area of One Honzontal Ta1l (ft2)

Apht K4 V 2/3

ProJected A1ea of One Vert1cal Ta1l (ft2)

2/3 Apvt - 1\:s v

Locat1on of Max1mum D1ameter (ft)

Lmax d KL L

Wetted Area o One Honzontal Ta1l (ft2)

Awht - Kh Apht

Wetted Area of One VertJcal Ta1l (ft2)

69

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

I

I' ,I

I

i t'

{

I [

J

Table IX Proportwnahty Constants for the Phys1cal D1menswns of Vanous Aerodynamically Shaped Balloons

Balloon Type

Used Vee Mod Navy

Proporhonallty Symbol ln Balloon Mark Class Constant Eq II c

Hull Length K1 4 2 56 3 53 2 62

Fmeness Raho f 5 4 00 4 70 2 64

Wetted Hull(s) Area K3 6 6 97 6 70 5 55

ProJected Area of One Hon K4 7 0 707 0 725 0 30 zontal Ta1l

ProJected Area of One Verb K5 8 0 0785 0 515 0 30 cal Ta1l

Locatwn of Ma..'nmum D1ameter KL 9 0 45 0 400 0 40

Wetted Area of One Honzontal Kh 10 2 21 2 21 I 2 3439 Ta1l

Wetted Area of One Vertical Kv 11 2 32 2 41 2 3439 Ta1l

Tall Th1ckness Kt 12 0 105 /o 105 0 105

Number of Honzontal Ta1ls nht 16 1 12 2

12 Number of Vertical Talls nyt 16 2 1

Hull Intersect Area Kmt 20 0 336 /o 0 i

Gas Leakage Rate Constant Kle 21 0 00639 ft3;ft2 /day

Rat1o of Temp Difference Ktemp 22 0 1 0 1 0 1 over Avg Temp at Altitude

Average Th1ch.ne & of Honzontal Tall (ft)

Average Thickness of Ve1 tical Tad (ft)

hvta Kt ~vt Volume of One Honzontal Tall (ft3)

Vht - hhtaApht

Volume of One Vertical Ta1l (ft3)

V vt - hvtaApvt

Volume of Total Balloon (ft3)

Vtot = V + r ht Vht nvt Vvt

70

Ram A1r c

2 62

2 64

5 55

0 30

0 30

0 40

2 3439

2 3439

0 105

2

1

0

0 1

(12)

(13)

(14)

(15)

(16)

I~ I •

I

~

1

Ballonet Volume (ft3)

( Palt)

vbnt = 1 -p0 Vtot

Diameter of Sphencal Ballonet (ft)

Dtrt == 1 2 4 (vbnt?13

Wetted Area of Sphencal Ballonet (tt2)

Abnt == 4 84 (vbnt)2/3

Hull Intersect Area (ft2)

A t - K t y2/3 in - m

Volume of Gas Lost by Leakage (ft3 /day)

Vleak - K1e (Ah + nhtAwht + nvtAwvtl

Volume due to Temperature Change at Float Altitude per Day (ft3 /day)

'~~temp = Ktemp Vtot

C STRESS ANAL 't SIS

1 General

(17)

(18)

(19)

(20)

(21)

(22)

As noted m the text of the report the design stress used m the balloon analysis was the sum of the stresses caused by the mternal pressure buoyant hft and aerodynamic load With the appropnate factor of safety Bendmg moment was neglected Therefore

where

Ndes F S ( N1 + Nb + Na) (23)

Ndes IS design stress for selectwn of balloon matenal (lb/ft)

F S iS factor of safety

N1 iS stress due to mternal pressure {lb/ft)

Nb 1s stress due to buoyant lift (lb/ft)

Na iS stress due to aerodynamic loads (lb/ft)

Maximum stresses on the balloon due to mternal pressure and buoyant 11ft occur at the maJomum diameter of the balloon Maximum stresses due to aerod} namic loads occur some what forwat d of the maximum diameter but for this analysic; were conservatively assumed to act at the maximum diameter Therefore the location of maximum stress occurs at the maximum d1ameter Just above the attachment points of the balloon suc;pens10n (bndle) system which were assumed to be attached near the equator of the b.liloon The calculatwns gtven m the followmg paragraph& determme the stresses m the balloon skm at the equator

2 Stress due to Internal Pressure

The required balloon mternal pressure at altitude as explamed m Section V was selected to be 15 percent g1 eater than the dynamic pressure at altitude or 1/4 m H20 - 1 3 lb/ft2

whichever IS greater Therefore PI - 1 15q or 1 30 lb/ft2 whichever IS greater This pressure was as::,umed to be at the bottom of the balloon

71

il I

1

II

:I I

,i t

j.

f

0 862 p lt9 D/2

Figure 47 Internal Pressure Occurnng m the Balloon at the Maximum Diameter

Refernng to Figure 47 the pressure at the balloon equator IS

D Peq =PI+ 0 862Paltg 2

The second term repre&ents the bellum pressure head at altitude between the bottom of the balloon and the equator

The ma.-....Imum mternal pressure stress IS

D Peq 2

- (PI + 0 862 Palt g ~ ) ~ lb/ft

3 Stress due to Buoyant Lilt

From Figure 48 the maximum stress due to buoyant load at altitude acting on a one foot section of the ht..ll IS

Nb - ~ [ Lb(one foot sectwn)J

where

Lb - buoyant lilt of hehum at alhtude

= b x volume of the sectwn

Therefoi e

Nb ~ [(o 862 Palt g) (rr ~2 ~lb/ft

4 Stress due to Ae1 adynamic Loads

(24)

BALLOON SUSPENSION SYSTEM

Figure 48 Buoyant Force on Balloon at the Maximum Diameter

(25)

From wmd tunnel tests on the General Mills Aerocap Model Balloor (Reference 15) the maximum local pressure was determmed to be approximately

x 0 lqa

72

where

x ts maxtmum local pressure (lb/ft2)

q IS dynamic pressure (lb/ft2)

a IS angle of attack (degrees)

ThiS occurs at approximately 30 percent aft of the balloon nose However for this analysis It was assumed to act at the maxi mum dtameter (see F1gure 49)

Therefore the total aerodynamic force acting on the one foot sectwn (assummg a lmear load dtstnbutwn) Is

F = (x) ( ~) - 0 lq a ~ lb

This load ts I eacted by the suspension lines of the balloon Therefore the stress m the fabnc dtrectly above the suspensiOn lines 1s

Ftgure 49 Ass.1med Aerodynamic Loadmg on the Maxi'11um Dtameter of the Balloon

Na + F - 0 05q a(~) lb/ft (26)

D BALLOON \~EIGHT

1 Balloon Matenal

Once the dPs1gn btl ess has been determmed the umt fabnc wetght can be determmed to be

w - 0 451} 10 4Ndes lb/ft2 (27)

or

0 01041

whichever 1s t,reater

Tins 1S the equatwn of the hne 111 Figure 29 for values of matenal weight up to approx1 mately 8 oz lyct2 Due to ground handlmg problems a mmmmm we1ght matenal of 1 5 oz/yd2 (0 01041 lb/ft2) was assumed to be the lightest matenal from wh1ch an aerodynamically shaped balloon would be fabncated

2 Hull Tatl dnd Ballo net Weights

Based on the deternnned umt matenal weight and the \anous phystcal dtmenswns that were determmed 1n the previOus sectwns ofth1s appendiX the hull and ta1l wetghts can be de termmed However smce lJ..ttle dlfferenhal pressure acts across the ballonet a one oz/yd2 (0 00695 lb/ft2) ballonet matenal was assumed for all SIZes of all balloon types

Proportwnahty constants for the weights of components of vanous aerodynamically shaped balloons are gtven 111 Table X The equatwns used m the computer solution are as follows

Weight of Hull Fabitc (lb)

Whf - wAh

73

(28)

0 'nj •,

I

Table X ProportwPality Constants for the We1ghts of the Components of Varwus Aerodynamically Shaped Balloons

Proportwnahty Constant

Factor of Safety on Fabnc Stress

Seam We1ght

Umt W e1ght of Ta1l Fabnc

Umt We1ght of Parhhon Matenal

Umt We1ght of Ballonet Matenal

Power Dens1ty of Battery

M1scellaneous Equ1pment We1ght

Total Balloon W e1ght

Symbol

Ktat

Used lll

Eq

21

27

30

32

36

45 47

Balloon Type

I Mod Vee

Balloon j Mark II

I

3 h 0 10 Ia 10

Navy Class

c

3

0 10

w jw w

2wt 12wt 2wt

o 00695 lo 00695 o 00695 lb/ft2 llb/ft2 lb/ft2

3600 watt mmutes /lb---

1 I

~ ~91 I~ 5

791

0 5

1 791

3

Ram A1r

c

0 10

w

2wt

0 00695 lb/ft2

Not ap ph cable

0

1 791

SuspensiOn Lwe We1ght

Kme

Ktb

Ksus

Khl

48

54

55

56

o ooos91 lo 0 234 ! 0

000591 0 000591 0 000591

Handlmg Lme and Catenarv 234 0 234 0 234

We1ght of Hull Seams (lb)

(29)

Intersect We1ght (lb)

w ~nt (30)

We1"'ht of Intersect Attachments (lb)

(31)

We1ght of One Honzontal Ta1l (lb)

(32)

We1ght of Attachments of One Honzontal Ta1l (lb)

(33)

We1ght of Intenor Part! 1ons of One Honzontal Ta1l (lb)

W1ha - wp Apht (34)

We1ght of One Vertical 1 a1l (lb)

wvt - Wt Avvt (35)

We1ght of Attachments of One Vertical Ta1l (lb)

Wvta KsWvt (36)

74

'l: I

l

I I

Weight of Inten01 Partitions of One Vertical Tall (lb)

Wlva = Wp Apvt (37)

V. eight of Ballonet (lb)

Wbnt = Wb Abnt (38)

Weight of Ba.llonet Seams and Attachment (lb)

(39)

3 Blower Battery and Exit Valve Analysis

a Volume and Volume Flow Rate of Au through an Exit Valve or Blower The volume of air to be expelled through an ex1t valve of a balloon dunng ascent or to be filled by a blower durmg descent may be determmed by the expressiOns given below It IS assumed that the total volume of the balloon remams constant and that the weight of a glVen mass of air IS constant throughout the elevatwns considered

The weight of a certam volume (V) of air at an altitude (h) IS given by

wh = Yh vh lb

where yh IS the weight density (lb/ft3) of air at float altitude h Also at alt1tude h dh

w h dh - ( y h + d 1 ) v h dh

but

Therefore

or

Vh dh -(rh :h d,;) vh Let Qt be the volume filled dunng the change 1n altitude from h to h dh Therefore

d(Qt)

dy Yh + dy

Neglectmg second ordei effects

d(Qt) V dy

hYh

However Vh - constant = v-tot

75

' ~ i tl I

d ! I k )·i

If!

l!

1 I I I

I r

I I

I I' I I I

I' It

I I

I

I

Therefore

where

0 Qt = ¥tot J

h

Qt 1s volume fllled by blower (ft3)

Vtot 1s total volume of balloon (ft3)

Yo 1s we1ght density of a1r at sea level launch altitude (lb/ ft3)

yh IS weiaht density of air at float alhtude (lb/ft3)

(40)

To determme the volume flow rate (Q) through the exit valve or blower an ascent and descent rate of 400 ft/mm was assumed

Q Qt ( 4~0 ) n3 /mw

or 2000 ft3 /mm WhiChever IS greater (h IS agam the float altitude Of the balloon

b Blower and Check Valve We1 ht An emp1ncal relatwn based on wformatwn hsted m a blower catalog Reference 16 1s given m F1gure 50 The plot contatl'S blower we1ght versus dlfterential pressure for blowers rated at 4000 n3 /mm Blowers used ln thlS plot mclude rated flow rates from 500 to 4000 ft3 /nun which wei e modlfied to an eqUivalent rate of 4000 ft3 /nun by use of the followmg relatwn

( 4000 )

Wactual Qrated

whe1e

Wblo lS blower WClbht eqUivalent (lb)

Wac tual 1s blower \\ e Ibht lls ted m catalog (lb)

Qrated ts flow rate of blowe1 as llsted 1n catalog (ft3 /mm)

Ratmgs for these blowers are for standard atmosphenc conditwns presswn based on F1gure 50 1 s

where

Q 4000

(7 5 plO + 17 8) lb

P1o 1s the differential pressure at sea level 111 m H20

The resultm ex

Use of this blower at h1gher altitudes w1ll result m dlfferenhal pressures that vary w1th the dens1ty of the au hemg blown That 1s

Part 1 2 P 1 - ~ P10 0 1922 lb/ft (42)

76

I I I f

where

Thus

~

<1"1 Q z :::::> 0 a.. ._.

0 ..0

3: 1-:r: ~ w

3: 0::: w

~ -J co

140

120

lOO

80

60

40

20

0 0

0

/ v

/ 0 v 0 ~ v

v '\1 co

c 0( ~ ~ (:)

0 ~0 1

v 0 /

~ /

/ ~ v

A '/

NOTE CURVE REPRESENTS OPTIMUM WEIGHT VERSUS DIFFERENTIAL PRESSURE BASED ON EXISTING DESIGNS

2 4 6 8 10 12

DIFFERENTIAL PRESSURE AT SEA LEVEL P 0 (IN H20)

Ftgure 50 Blower Wetght versus Differential Pressure for Volume Flow Rate of 4000 Ft3 /Mm

P1 lS dtfferential pressure at altitude

Palt -P- 1s ratw of a1r dens1ty at alt1tude to sea level

0

Po ) P pl + 17 8 lb alt

where Q 1s the des1red flow rate of the blower (ft3 /nun)

/ v

14

(43)

The check valve 1s mounted on the blower and therefore 1ts weight was assumed to be proportional to the blower we1ght Prevwus expenence has shown that th1s constant of pro portwnahty 1s approximately 1/2 Therefore the wetght of the check valve 1s

1 Wchk - z Wblo lb (44)

77

'I

ij

I ,, II

" I' ;j I

il I

I

I I, I! I

,I

lj

d II I

I' ,I I! I! il I i :l

:I I! j: ! I I i I II L I I· , I

'I

I II I ! ; I ! i II ~~

I I

II

II il I! , I

I II 'i

I' ,I ; I II

c Battery Werght Battery power rs requrred to operate the blower at altrtude to account for daily temperature changes and leakage losses and to operate the blower dunng descent to marntarn a full ballonet The typical equation for battery wetght rs

where

Ptoper

Kbat

Wbat 1s thE; battery wetght (lb)

P rs the power requn ed (watts)

toper rs the operatmg t1me of the blower (mmutes)

Kbat 1s the power density of the battery (watt mm/lb)

By plottrng batter; pov..er versus sea level differential pressure for equrvalent 4000 ft3 /rum blower capanty an empincal relation for power reqUired to operate the blowers can be determrned to be

P - 1000 P 10 watts

where P 10 as preVIously defmed IS the duferenttal pressure at sea level m m H20 (see Frgure 51)

Battery werght requrred at altrtude rs that required to cper ate the blower at an equivalent sea level pressure of

Palt p plO

0

1 0 1922

as defined rn Equatwn 42 Thus the power required IS

p

However tins pO\\Cl would operate the blower at sea level at altitude varies directly with the density of the arr bemg blown qUlred for the batter) rs

Palt p p Po

Palt P p - (1000) (0 1922) __::_Q_ pl

Po Palt

192 2 PI watts

whereas the power required Thu~ the actual power re

The battery weight was analyzed as that requrred while at float altttude and that reqmred dunng descent The1 efore

where

Wbat - Wbat a + Wbat d (lb)

Wbat a IS amount of battenes requrred at alhtude (lb)

Wbat d 1s amount of battenes reqmred dunng descent (lb)

78

--V> 1-1-<(

3: .._.. c....

cc: w

6 0...

0 w 0:::

:::> 0 w 0::

14 000

12 000

10 000

8 000

6 000

4 000

2 000

0 0

l I

FI,ure 51

v v

/ l6~

/._~~

0 / v Vc

IV

0

v v ~ v

/ u

2 4 6 8 10 12

DIFFERENTIAL PRESSURE AT SEA LEVEL PO (IN H20)

Requued Blower Power versus Differential Pressure for Volume Flow Rate of 4000 Ft3 /Mm

~

14

The equivalent tlmc of operation of the blower at altitude IS equal to the volume of atr to be replaced each day (V repl) dn'1ded by the 4000 tt3/mm blower rate and multiplied by the number of days at float altitude (t;24) Thus the battery weight reqUired at altitude 1s

192 2PI (Vrepl) (t/24) Wbat a = Kbat (4000) pounds (45)

Note that V repl 1c; mod1fled 111 the computor program to p1 ov1de a factor of safety of 2

The work done on the gas dunng descent lS eqUivalent to the wo1 k done on the gas 1f en tlrely fllled at sPa level It Will be assumed that the differential prec:;sure to be mamtamed m the balloon at all hmes lS P 1 the pressure that was required at alht tde Th1s assumptwn neglects the fact that dynannc pressure at lower alt1tudes w11l probably be greater than that des1gned at altitude

However the fabnc 111 the balloon 1s also des1gned for cond1t10ns at alt1tude whtle neg lechng conditions below so that the assumptiOns are consistent ThL.s

which IS Identical with Equatwn 40 when

79

The operatmg hme of the blower dunng descent IS that hme reqmrPd for a 4000 n3 /mm blower to flll the ballonet or (Vbnt/4000)

where

Therefore With a safety factor of 2

192 2PI Vbnt

Wbat d = (2) 4000

192 2P1 vbnt = (2) Khat (4000)

The total battery weight IS

lb

192 2PI [ ( t ) J What - Kbat (4000) Vrepl 24 + 2 Vbnt lb

PI IS duferenhal pressure at altitude (lb/ft2)

Vrepl IS volume of air that blower has to replace at altitude (ft3 /day)

t IS float hme at altitude (hr)

Vbnt IS balloon ballonet volume (ft3)

The weicrht of tre miSCPllaneous equipment for the blower and batte1 y IS

(46)

(47)

(48)

which was mcluded to cover the weight of the battery heater Winng etc See Table X for the values of Kbat and K, 1e

d Weight of E;.,.It Valve The volume rate of flow through an onflce IS given w any flmd mechamcs book (e g Reference 17) as

where

Q CA )2gZ

Q IS volume 1 ate of flow through orifice (ft3 /mm)

C IS discharge coeffiCient

A IS exit area of onflce (ft2)

Z 1s pressure head on the flmd at the orifice (ft)

The p1 essure head (Z) may be wntten as

z = p y

80

r

I f

where

p 1s pressure head (lb/ft2)

y 1s we1ght dens1ty of the flUld (lb/ft3)

Therefore

Q = CAV2g ~ Q = CA J2 %

(49)

For purposes of scalmg the weight of the valve assume that the we1ght lS proportional to 1ts exit area That 1s

= (50)

SolVIng Equahon 49 for A1 and addmg the subscnpts 1 we have

1 Ql Al -C ~

yzP! (51)

However the value of the discharge coeff1c1ent may be obtamed usmg data from an ex1st mg valve smce C IS a constant for a particular orrl1ce type Thus

Q2 (52) c- R P2

A'J fi2

Subshtuhn Equations 51 and 52 mto EquatiOn 50

or

Values for a typ1cal ex1t valve are as follows

S1ze 28 mch m d1ameter

A2 4 24 n2

Q2 8500 I 3 /mw

Pz 3 w HzO = 15 62 Ib/ft2

81

l I

,:

: 1:

' I ~

;p., I I

1 l

~I

~j

w2 - 31 0 lb (alummum)

P2 - Po at sea level

= (31 0) ~ ~ Ql y Po y p 1 ssoo

= 0 01445~

To compute the we1ght of a value requ1red at float alt1tude note the followmg changes m notation

pl Palt

Pl = pl

Therefore

wl o 01445~r Po Qr (53) ~

e Suspens10n (b11dle) System We1ght The we1ght of the suspens10n system 1s proportwnal to the length of the balloon and the tether tens10n m the bndle

Wsus or:: LT

or from Equat10n 4

W or:: -v:l/3 T sus

However to obtam the tether tens10n the we1ght of the balloon (wh1ch we are trymg to estimate) has to be known Therefore an m1t1al estimate of the total we1ght 1s made by summmg the already eshmat d parts of the balloon wh1ch mclude everythmg except the sus pens10n system handlu g hne and catenary we1ghts and mult1plymg by an appropnate factor

where

The 1mhal estimate of the tether tens10n 1s

T1b - HLa + Lb P (Ktb) Wl(tot)J2

+ Db2 (

La aerodynam1c hft

Lb buoyant 11ft = 0 862gVtot Palt (lb)

P 1s payload package we1ght (lb)

Ktb 1s the factor to obtam total balloon we1ght

W 1(tot) 1s the 1mhal est1mate of we1ght wh1ch mcludes all we1ght except the sus pens10n handhng hne and catenary we1rrht (lb)

Dt aerodynamic drag on balloon - c0 q.v2/3 (lb)

82

(54)

Therefore the weight of the suspenswn system IS

W sus = Ksus Tlb (Vtot) l/3 lb

The we1ght of the handlmg lme and catenary 1s

See Table X for the values of Ktb K us and Khl

(55)

(56)

f Total Balloon Weight The total balloon weight can be obtamed for a particular balloon type (Vee Balloon Class C etc) from the prevwus equations by Imputmg the followmg mforma bon

Payload weight P (lb)

Float altitude h (ft)

Wmd veloc1ty v (knots)

Angle of attack a (degrees)

Hull volume V (ft3)

Operatmg Time at alhtude t (hr)

The total balloon v. eight IS equal to the followmg

+ Wval + Wchk + Wbnt + Wbnt s

+ w 111€ + w SUS T whl (pounds)

83

(57)

REFERENCES

1 Feasibihty Study for a High Alhtude Tethered Balloon System (Haltoon) (U) Techrucal Report 2452 ARPA Contract SD 198 Electnc DIVISlOn of General Mills Inc St Paul Mmnesota 21 October 1963 (Downgraded to Confidential)

2 Feasibility Study High Altitude Tethered Balloon System for Advanced Research Pro 1ects Agency Techmcal Report GER 11287 ARPA Contract SD 199 Goodyear Aero space Corporation Akron Ohw 23 October 1963

3 Fmal Report Feasibility Study (U) Techmcal Report 1724 TR1 ARPA Contract SD 200 Mmneapolls Honeywell Regulator Company Aeronautical DIVlSlOn Mmneapohs Mm nesota 8 October 1963 (Conf1dent1al)

4 One Hundred Thousand Foot Tethered Balloon Feas1b1hty Study (U) Techmcal Report TR 01820 01 1 Prepared for Office of Secretary of Defense Advanced Research Pro 1ects Agency ARPA Contract SD 201 V1tro Laboratones DIVISion of V1tro Corpora bon of Amenca 9 October 1963 (Conf1dentlal)

5 Fage A Expenments on a Sphere at Cntlcal Reynolds Number R & M 1766 Septem ber 1936

6 Sauerwem R T Sphere Drag Determmed by Coastmg through Still Air Journal of the Aeronautical SClences, Vol I July

7 Horner S Tests of Spheres With Reference to Reynolds Number, Turbulence and Sur face Roughness NACA TM No 777 October 1935

8 Zahn A F Flow and Drag Formulas for S1mple Quadr1cs NACA Report No 253 1927

9 Smalley J H Deternunatwn of the Shape of a Free Balloon Summary Fmal Report AFCRL 65 92 Litton Systems Inc Applied Sc1ence D1v1S10n 5 February 1965

10 Glauert H The Form of a Heavy Flex1ble Cable Used for Towmg a Heavy Body below an Aeroplane Reports and Memoranda 1952 Bnbsh AdVlsory Comm1ttee for Aero naubcs February 1934

11 Landweber L and Protter M The Shape and Tenswn of a L1ght Flextble Cable m a Umform Current Journal of Applied Mechamcs June 1947 pp A 121 to A 126

12 Rmgleb F 0 Motion and Stress of an Elastic Cable due to Impact Journal of Applied Mechamcs March 1957 pp 417 425

13 Walton T S and Polacheck H CalculatiOn of Nonlmear Trans1ent Mohon of Cables David Taylor Model Basm Report 1279 1959 A condensed paper 1s g1ven m Mathematics of Computation (The S1am ReVIew) No 69-72 1960 pp 27 46

14 Hoerner Sigh1.rd F AerodynamiC Drag Published by the author 1951 page 138

85

15 Wmd Tunnel Tests of the General M1lls Aerocap Model, Part 1 Umvers1ty of Detr01t ProJect 314 March 1960

16 A1rcraft and Electromc Fan Catalog (ReVIsed) Joy Manufactunng Company

17 Mark s Mechamcal Engmeers Handbook 6th Ed1hon 1958 p 3 62

86

r

r I I r

r

Documents

BT-1399 High-Altitude Tethered Balloon Systems Study ... · ~ table of contents -'< l ~ sectlo 1 'i i summary 4 .,;, ii introduction ill tethfr cabi e types and properties iv tether