i thermal radiation properties of some polymer …i thermal radiation properties of some polymer...

i THERMAL RADIATION PROPERTIES OF

SOME POLYMER BALLOON rABRICS

I1 q Technical Report VII

report to

I: OFFICE OF NAVAL RESEARCH

I!

I DDC

i " JUL 14 1967!!UUn , u LFL,[

B

__ ~ 4Ivbn -hRittit, Inc.

[ RECEIVEDUL 1IKeproduction in whole or in part is permitted by the

X L 2 1 1 7 U. S. Government. Distribution of this document isCFSTi unlimited.

T

THERMAL RADIATION PROPERTIES OFSOME POLYMER BALLOON FABRICS

Technical Report VI

Report to

OFFICE OF NAVAL RESEARCH'[ PHYSICS BRANCH

CONTRACT NO. Nonr-3164(O0)

By

1. W. Dingweil

June 1967

"rJ 'Ii C-62944

" N

Reproduction in wholeor in part is permitted

by the U.S. Government.

Distribution of this

document is unlimited.

p.,-

TABLE OF CONTENTS

Page

jti T List of Figures ii

List of Tabl:s iv

I. SUMM0ARY

II. INTRODUCTION 2

III. MEASUREMENT OF PROPERTIES 3

A. TECHNIQUES 3

B. EXPERIMENTAL EQUIPMENT 3

C. CHECKING TECHNIQUES AND EQUIPMENT 4

IV. CALCULATION OF PROPERTIES 5

A. REFLECTIVITY 5

B. ABSORPTIVITY - SINGLE PASS 5

C. ABSORPTIVITY - MULTIPLE PASS 6

D. CALCULATION PROCEDURE 6

V. THERMAL RADIATION PROPERTIES OF SOME POLYMER FILMS 7

y A. POLYETHYLENE FILMS 7

B. MYLAR COMPOSITES 8

C. OTHER MATERIALS 8

VI. NOTES TO THE BALLOON DESIGNER 9

A. THERMAL RADIATION 9

S - B. RADIATION ABSORPTION 9

C. RADIATION EMISSION 93

REFERENCES 34

APPENDIX. FORTRAN LISTING OF COMPUTER PROGRAM USED TO 35CALCULATE INTEGRATED ABSORPTIVITY

* DISTRIBUTION 39

2 li

LIST OF FIGURES

Figure

No fae1 Integrated Transmissivity of Polyethylene 10

Films of Varying Thickness

2 1 Polyethylene .75 Mil 11

3 5 Raven/Visqueen 1.5 Mil Roll 2580 11

4 6 Raven/Visqueen 1.5 Mil Roll 9988 11 !5 8 Raven/Visqueen 1.5 Mil Roll 9996 11


7 23 Schjeldahl/GT 66 .25 Mil Scrim, Min i

8 23 Schjeldahl/GT 66 .25 Mil Scrim, Max 129 24 Schjeldah!/S-1l .35 Mil Scrim, Min 120 24 SchjeldahliS-ll .35 Mil Scrim, Min 12

11 24 Schjeldahl/S-ll .35 Mil Scrim, Max 12

12 24 Schjeldahi/S-11 .33 Mil Scrim, Max 12

13 26 Sea Space,'erfilm .17 Mil 12

14 27 Sea Space/Merfilm .28 Mil 13

15 35 Polypropylene .5 Mil 13

16 33 Winzen/Polyuretbane .3 Mil 0% Elong 13

17 33 Winzen/Polyurethane .3 Mil 50% Elong 13

18 34 Sea Space/Polyurethane 0% Elong 13

19 34 Sea Space/Polyurethane 1. Mil 100% Elong 13

20 1 Polyethylene .75 Mil 14

21 2 Viron/Polyethylene 1 Mil 14

22 4 Winzen/Polyethylene 1.5 Mil 14

23 5 Raven/Visqueen 1.5 Mil Roll 2580 1424 6 Raven/Visqueen 1.5 Mil Roll 9938 14



27 23 Schjeldahl/GT 66 .25 Mil Scrim, Max 15

28 23 Schjeldahl/GT 66 .25 Mil Scrim, Min 15

29 24 Schjeldahl/S-ll .35 Mil Scrim, Min 15

i

thttr .it "

- - - . -. wr-...r..-. - ,---a---.~~ -.- 9

LIST OF FIGURES (Cont)

FigureNo. Page

30 26 Sea Space/Merfilm .17 Mil 15

31 27 Sea Space/Merfilm .28Mil 15

32 28 Sea Space/Merfab Single Scrim, Min 16

33 28 Sea Space/Merfab Single Scrim, Max 1634 29 Sea Space/Merfab Scrim, Min 16

35 29 Sea Space/Merfab Scrim, Max 16

36 30 Sea Space/Merfab Load Web Scrim, Min 16

37 30 Sea Space/Merfab Load Web Scrim, Max 16

38 31 Sea Space/S-Fab 17

39 32 Sea Space/S-Fab Seamed With Scrim, Min 17

40 32 Sea Space/S-Fab Seamed With Scrim, Max 17





p 45 35 Polypropylene .5 Mil 18

Ii

I

[: iii

LIST OF TABLES ae

TABLE Page

NO,

II Thermal Radiation Properties - Solar Spectrum 19

II Thermal Radiation Properties - Infrared 24

I

T

I

iv

I avthur 2.3Uttjv.3jn

A-

IiI. SU~ARY

This report is sixth in a series on the motion of high altitudeballoons which have been prepared for the Office of Naval Research undercontract Nonr-3164(00).

As the absorption of solar and earth atmosphere thermal radiation

is an important factor in the vertical motion of high altitude balloons,the thermal radiation properties of the thin films that compose balloonfabrics must be determined. This report presents the results of propertymeasurements made with spectrophotometer, emissometer, and thermal radi-ation measuring equipment. The films which were considered fall intothree categories:

1a. Polyethylenes

]b. Mylar Composites

c. Other Fabrics

Polyethylenes are very transparent to thermal radiation. They havesharp, narrow bands at 3.5- ? and 14 microns. Mylar composites tend toabsorb more radiation as they have a broad band of absorption from 6 to10 microns. The mylar composites tend to be affected by the reinforcingmesh (usually dacron) which raises the absorptivity.

V

'l

71

II

II. INTRODUCTION

The performance of high altitude balloons is related, to a great7 extent, to the thermal radiation environment in which they operate.

Thermal radiation to and from the balloon system is an importantmode of heat transfer. Balloons absorb radiation- from two primarysources; the sun (direct radiation and earth albedo) and, the earthand its atmosphere. Balloons also emit radiation as grey bodies inthe range of temperatures of -60*C to +30'C. As the helium gas isvirtually transparent to all thermal radiation, the absorbing andemitting surface is the thin polymer film which encloses the helium.In the case of a balloon floating at altitude, the rapid decrease inaltitude following sunset is a dramatic example of the effect of ther-mal radiation on the balloon system.

Arthur D. Little has developed an analytical model which representsthe vertical height time history of a high altitude balloon system

1 '2.

In order to properly analyze this dynamic system, the thermal radiationproperties of these thin pilymer films must be known. Inspection ofthese properties, particularly the absorptivity, is of great use inpredicting balloon performance. Thus, this data should be of importanceto the balloon system designer.

-I'

2

2Tthur ZPL3LUtcjfi.3jr

TT III. MEASUREMENT OF PROPERTIES

A. TECHNIQUES

Since-these thin (.001 inch) films are highly transparent, the

absorptivity is difficult to measure. Several techniques may be used.

The spectral transmissivity and reflectivity may be measured and the

absorptivity deduced from these measurements. Or the back of the film

can be coated with a film of highly reflective material (vapor deposited

aluminum) and the absorptivity measured by comparing the reflected

radiation to the incident radiation. Or the emissivity of the coated

film may be measured directly with a emissometer. The last two techniques

require highly sensitive instrumentation to detect small differences in

radiation and that each sample be coated with vapor deposited aluminum.

Considering the available instrumentation and the number of samples

H to be processed, the measurement of film transmissivity was chosen as

the most practical experimental technique.

PThe spectral absorptivity and emissivity of a film that both re-flects and absorbs radiation are given by the following expressions:

Fa = 1. - R(X) - T())

and 0) = (1-R(A)) (l-r(A))11-R(A) T(A)

in which

A = wavelength, microns

a(A) = spectral absorptivity

R(X) = spectral reflectivity

* T() = spectral transmissivity

- ) spectral emissivity

B. EXPERIMENTAL EQUIPMENTIiiThe spectral transmissivity T(X) and reflectivity R(X) can be

measured by spectrophotometer equipment in the solar (.2 - 3. micron)

and infrared (1. - 100. micron) spectral regions. In the solar spectrum,a Beckman DK Spectrophotometer was used.

The reflectance attachment to this spectrophotometer (an MgO coatedintegrating sphere) was used to make measurements of diffuse reflectivityof the front and back of the film. Because of the low reflectivity,

accurate measurements of reflectivity were not possible and these measure-ments were not considered to be valid.

3

~, I Zr~hur l3ittlek1tw

Initial spectral measurements indicated low values of transmissivity-,especially at the short wavelength (.2 - .4 micron portion) of the spec-trum. When the reflectance attachment wts-mounted behind the sample,the transmissivity measurement ir:reased. We believe that without theuse of the reflectance attachment as a collector, the back surfacescattering from the original transmissivity measurements was not beingdetected. To a great extent, the integrating sphere collected this

-_. diffuse scattering and provided more realistic measurement of trans-missivity. A Vitrolite - MgO standard was used to provide absolutereference values of reflectivity.

In the infrared region, a Perkin-Elmer Infrared Spectrophotometer(Model 421) was used. This is a double-beam, optical-null instrumentwhich requires no reference standard. The resultant measurements oftransmissivity appeared to be satisfactory We believe that backscattering is reduced at the longer, infrared wavelengths and can beconsidered to be unimportant.

C. CHECKING TECHNIQUES AND EQUIPMENT

The spectrophotometers were used to determine the spectral trans-missivity of the films. This data must be numerically integrated overthe solar spectrum to obtain the total transmissivity. Selective checksof the total transmissivity were made by measuring directly the amountof energy transmitted through the film. To do this, a bismuth-silvercircular thermopile made by the Eppley Laboratory was exposed to sunlighton a clear day with and without film samples covering the 3/8 inch diametersensor. The quartz window covering the sensor is transparent to solarradiation in the bandwidth from .3 to 3. microns.

As another check, the room temperature emissivity of three balloonfilm samples were measured after a coating of aluminum was vacuumode-posited on the back side of the film. An emissometer was used which wasdeveloped by Arthur D. Little, Inc., for the measurement of the emissivityof high reflective insulating films.

4

2,rthur ~iB3Utt~,3%nr.

IV. CALCULATION OF PROPERTIES

A. REFLECTIVITY

SAs mentioned, the small amount of energy which is reflected fromthe surfaces of the film is difficult to measure directly with sufficient

- accuracy. Early attempts to do this indicated that the reflectivitywas less than .10. However, interference fringes were noted which re-sulted from internal reflections in the film. The reflectivity can becalculated from the refractive index determined by means of the inter-ference $ringes. Let a fringe maximum at wavelength A, be numbered n.The refractive index, I , may be computed from two values n n2,observed at the corresponding wavelengths A1 X2 noted on tel spectrom-

Heter record:

H Td2- (nl - n2)( IX 2 (2)r ( A1- 2 )(2

where d is the thickness of the film. From this, the reflectivity RBmay be computed according to the Fresnel formula (for normal incidence):(I - 1 .)2

R r +1.) (3)

We have found that the reflectivity calculated in this manner was in the'1 " range of .04 to .06 for most balloon films. We have selected the valueof .05 as a standard value for all balloon films.

B. ABSORPTIVITY - SINGLE PASS

At wavelength, A, the radiation incident on the film is !(A). Ifthe spectral transmissivity, T(X) and spectral reflectivity, R(X) areknown, then the energy absorbed by the film is

I l(A) a(A) = I(A) (I - R(A) - T(X)) (4)

Integrating this expression over the solar energy spectrum and

the infrared spectrum gives the integrated absorptivity of the balloonfabric.

(A2

L JA1 ia(X) I(X) dA

21(A) dA

A1

5

II ~l

C. ABSORPTIVITY - MULTIPLE PASS

-b Thin films of high transmissivity in a spherical shape absorb more

energy due to multiple passes and internal reflections. Reference 2shows that the effective absorption of energy of spherical shapes is:

eff (6)-R

If the integrated transmissivity, T, is high (.80) and the reflec--- tance, R, low (.05), then the effective absorptance of incident radiation

is nearly twice that of a single pass.

D. CALCULATION PROCEDURE

The integration of Equation 5 was carried out by digital computer.The solar energy spectrum was used without atmospheric absorption ofenergy. The water vapor and carbon dioxide absorbing bands may be in-cluded in the calculations, but as balloons normally operate above theselayers, this attenuation of solar energy was omitted. For infraredspectrum, the radiation energy spectrum was calculated from Planck'slaw. A FORTRAN listing of the computer program is included in the

Appendix.

le6

A

I thnr .3Uttk.,3Jnr.

V. THERMAL RADIATION PROPERTIES OF SOME POLYMER FILMS

A. POLYETHYLENE FILMS

Twenty-three samples which were identified as polyethylene wereanalyzed. This material is one of the most transparent to solar andinfrared radiation. Sharp absorption bands occur at 3.5, 7 and 14microns in the infrared. There are no noticeable absorption bands inthe solar spectrum. The integrated transmissivity, % integratedabsorptivity, a, and the effective absorptivity, a , for these

ffsamples are listed on Tables I and II. The transmissivity of the filmswas measured from .22 to 20 microns. For room temperature and 225*Kr eeradiant sources, the proportion of total emitted energy is 72% and 58%,

.respectively, in this bandwidth. Therefore, an estimate of the trans-missivity has been made from 20 to 100 microns using the measured valueof T at 20 microns. The estimated effective absorption, test, for the

spectrum of 3 to 100 microns, has also been computed and is listed ing Table 1.

The integrated transmissivity of these films has been plotted onFigure 1 for the range of thicknesses which were tested. As films tendto have exponential transmission characteristics, the following rdla-

; i,- tionship is also plotted.

T = (1i- R)e _ (7)

T = integrated transmissivity

R = integrated reflectivity 'Equation 3)

Y - absorptivity coefficient

t = film thickness (mils)

A value of y of .045 is used on the curve as reasonable correlation.

The spectral transmissivity of these films has been plotted onFigures 2 to 6 for the bandwidzh .22 to 3 microns and on Figures 20 to26 for the bandwidth 3 to 20 microns.

The checks of the solar transmissivity and infrared emissivitywhich were made tend to validate the computed absorptivity. In most

cases, the variation was less than 5%.

The emissivity of the 1 mil polyethylene film was found to be.215. This included radiation emitted from the vapor deposited aluminumcoating on the backside of the film. If the emissivity of the aluminum

is taken to be .05, then the emissivity of the polyethylene film is .165.

From this, the absorptivity can be computed to be .835 which is slightlylower than most values obtained from spectrophotometer measurements.

7

2thur BJ3Litt~c,3ihtc.

§

B. MYLAR COMPOSITES

Mylar films exhibit strong absorption bands from 6 to 10 microns.-For a room temperature souyce of radiation, the peak intensity is at

10 microns and 23% of the radiant energy is centered in the 6-10 micronbandwidth. Mylar, therefore, tende to have much lower values of trans-missivity than polyethylene for comparative thicknesses. The additionof a reinforcing mesh (usually dacron filaments) can only decrease thetransmissivity.

In making measurements of spectral transmissivity, the reinforcedfilms were oriented for maximum and minimum transmissivity. Thesevalues were used to obtain the integrated transmissivity.

The results from the Eppley thermopile experiments tend to indicatethat the lower value of transmissivity be used for the transmission ofsolar energy. The measurements of room temperature emissivity alsoindicate that the lower or minimum value of transmissivity is the bestvalue for composite films. We suggest that the minimum va!ue be used asa representative value of composite film transmissivity.

The properties of G. T. Schjeldahl S-11, GT-lll, and GT-66 fabrics

are listed in Tables I and II and on Figures 7-12 and 27-29.

C. OTHER MATERIALS

As a service to marufacturers of balloon fabrics, Arthur D. Little,Inc. has performed tests to determine the thermal radiation propertiesof various reinforced and plain films. These properties are listed onTables I and II and on Figures 13-19 and 30-45.

As urethane rubbers have been considered for superpressure balloons,the transmissivity of two samples (.3 and 1 mil) was measured in anunstretched and stretched condition. In the solar spectrum, the trans-missivity was unaltered. However, the transmission of infrared wasgreatly increased (1.2 to 3.5 times the unstretched case).

--0

III

} + + )

II

VI. NOTES TO THE BALLOON DESIGNER

A. T EP-LAL RADIATION

'The sun and the earth and its atmosphere can be considered to be

black body radiators at 6,000*K and 300*K, respectively. A representa-tive value of the radiant energy radiation which is incident on thesurface of the balloon is 7.38 Btu mt2 rin - ' (2.002 cal cm-2min - I )

from the sun and 2.45 Btu ft - 2 min- 1 from the earth and its atmosphere.For a one million cubic foot balloon (modeled by a 1-4 foot sphere),.44 the solar radiation is assumed to contact an area equal to the projectedarea of 24,075 ft2. The earth radiation is incident on the total sur-face area of the balloon which is 48,308 ft2. The total incident radia-tion is 89,122 and 118,347 Btu/min from solar and earth radiant sources.

B. RADIATION ABSORPTION

Referring to Figures 1 and 2, a 1.5 mil polyethylene has an effectiveabsorptivity, cf, of .12 and .21 for solar and earth radiation band-

,J widths, respectively. This value of absorptivity is the ratio of energyI " absorbed by the balloon to the energy incident on its surface. There-

fore, the radiation absorbed by the balloon fabric is 10,694 Btu/min and

24,852 Btu/min for solar and earth sources. For a mylar scrim, GT-lIl,(a ff = .17 and .63), the absorbed energy is 15,150 and 74,558 Btu/min,

respectively.

C. RADIATION EMISSION

Balloons radiate thermal energy at rates proportional to the fourthpower of the absolute temperature of the fabric. The emissivity of the

balloon is equal to its absorptivity if the temperature of the fabricis equal to the radiation equilibrium temperature of the earth and itsatmosphere. Thus, a fabric w4ith high emissivity (mylar) floating insunlight is less affected by solar radiation than a polyethylene balloonbecause the proportion of total radiant energy wbich comes from the sunis less (16% for mylar, 29% for polyethylene). This equilibriumtemperature then, of a mylar balloon, tends to be less in sunlight thana polyethylene balloon. The ratio of absorptivity of sunlight and emis-sivity of energy is .57 for polyethylene and .25 for mylar. This ratiois useful for predicting radiation equilibrium temperatures. Becauseof the high value of emissivity, a reduction in the environmentalequilibrium temperature will reduce the gas temperature of a mylar: balloon more than that of a polyethylene balloon. This reduction ingas temperature will cause a mylar balloon to have less altitude

j. stability at sunset or over clouds or flying from land to water.

9iiltI~

C11

Cf'.4

00

*0 0t

900

00.*d **

01

LO ~LO ....

.90.9 :

. . . . . . -

05.7

0.3

0. . . . . . .

Li0.1

a 11 1 2

Wrag - Mcmns WwIergM - Kcrons

FIGURE 2 1 POLYETHYLENE .75 MIL FIGURE 3 5 RAVEN/VISQUEEN 1.5 MIL

D.90.9

(L7 0.7

0.0.6

qCC

'~0.4

0.3 ------- - - .0.3-L00.2

0

01230 1 2

Waveegh-w c~sWvlength - Mcrons

FIGURE 5 8 RAVEN/VISQUEEN 1.5 MIL ROLL 9996 FIGURE 6 10 RAVEN/VISQUEEN 1.5 MIL

0.7'

0-UII

1'

4-4

2z 3 01:

Wanyh -Mhcrons Wvidenth- Mcrvns

10 RAVEN/VISQUEEN 1.5 MIL ROLL 1500 FIGURE 7 23 S JELDAHL/GT 66 1.5 MIL R M, 9988

11C

0.94

LOLO

0.9 0.9

P-7 ~0.7Z=

U :E:0.6

~ 0.1

050.35 4-

i:040.24

0.3 0.1

U0

0 1230 1 2

Wowlenth - cronsWavelength - M cwns

FIGURE 8 23 SCHJELDAHL/GT 66 -. 25 MIL SCRIM, MAX FIGURE 9 24 SCHJELDAHL/S-11 .35 MIL S'

0.9 0.9.

0..8 -1- 0.

0.6-- ~0.6TlA

0.5~ 0.5

.4~~ -. - -4 .

0.3~ 0.3

-4- 7

0.13 - -- -- - 0.

00 -.-- I - -±--01230 1 2

Wavelength - Mcmns Wavelength - ?vVcmns

FIGURE 11 24 SCHJELDAHL/S-11 .35 MIL SCRIM, MAX FIGURE 12 24 SCHJELDAHL/S-11 .35 MIL SC~

12.

4-4 1

0.~

2 P 3Wwle~ -Mcn W~ah=Pcrn

24 SCHJELDAHL/S-11 .35MIL SCRIM, MIN FIGURE 0.23CjLALS1 .5MLSRM I

-4--'0.2

-0.1

Waniength ~ ~ ~ --- isWragh cn

-- 4-

12.5

0.4;

0.99

0.7

00.7

0.6

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00.45

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0.81

0

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03

2 4 6 a 10 12 14 16 is 2 4 6 a 10 12 14 16 IsWawlength -hcmns WaWouio - Mcrons

FIGURE 20 1 POLYETHYLENE .75 MIL FIGURE 21 2 VIRON/POLYETHYLENE 1I

1.0 1

0.9 i ~0.9 Ili ft

41 1

0.7 - ~0.74

0.6 ~0.36 Z Z -

0.5 0.2

0.1 -# 0.4

f ~02. 4 6I 0 1 1 6 1

Wavength- I.cron Wav it I itwn

FIGR23 0.AE/IQ N15MI OL28 IUE24 6 fAE/ISUE 1 4_MI R

0.1 014

z i

Sz

rL

wavel-4--h -4-con

2-4,

4 6 a 10 12 14 16 1 2D 2 4 6 1 10 12 14 16 18 2DWavelngth - Mcrons Waveength - M~crons

0.8.

6 RAEN/ISQBEN1.5MILROLL993 FIURE25 RAEN/VSOUEN .5 IL OLL999If I I I f I

14 ----

0.1 . . . .. . . ....

0.2 -4 -- :L

0.5 44-0.1T 0.

0.4 i 0.9

0.8.

0.3

020.62. .

0.1 0.1

2 4 6 8 10 12 14 16 is 2D 2 4 6 1 10 12 14 16 3i .Wavelength - Mcrons Wmveength - M.crons

FIGURE 29 24 SCHJELDAHS-11 N.35 MIL SRML MIN0 FIGURE 3 2 SCHEAHL 66AG .25EIL1

1.15

. . . . . . . . .

4 4 1 10 12 14 1 13W vln u

It GO

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Wrveength - Murons Wawfenph - Muons

E3 2 SCxELAHG 66ACE .E2FMI SCRI M AL FIGURE 3 7 SHEA SAC/MERF6LM..8 MIL RM U

. . . ...L

0.8 1 I

00.6.4-f

0.7 ~0.7

0.6 0.6

0.2t -.-4440.1 If[

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0.2 z0.7

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0 0

2 4 6 8 10 12 14 16 18 2D2 4 6 1 10 12 14 16 is

Wavelengthi - mcrons Wavelengthi - Mcrons

FIGURE 35 2 SEA SPACE/MERFAB SNL SCRIM, M N FIGURE 33 30 SEA SPACE/MERFAB LOADL WEE

1.0 ii it16iA1 1 1 4 1 1 1 il -l f f l i i i I i

:41

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G. 7 ... I

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0.2 . 0.>

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FIGURE 38 31 SEA SPACE/S -FAB FIGURE 39 32 SEA SPACrE/S-FAB SEAMED V

.0 . .. . . . . . . .

0.9:

0.7 ~0.7 4

060.6. i

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0

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FIGURE 41 33 WINZEN/POLYURETIHANE .3 MIL 07o ELONG FIGURE 42 33 WINZEN/POLYURETHANE .3

17

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ILL -1-H 1

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EA SPACE/S-FAB SEAMED WITH SCRIM, NUN FIGURE 40 32 SEA SPACE/S-FAB SEAMED WITH SCRIM, MAX

* , , , 1.0

491-

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6 8 10 12 14 16 15 2D 2 4 6 8 10 12 14 16 is 20

Wavelengt - Mvcrons Wavelength - Wicrns 'WINZEN/POLYURETHANE .3 MIL 507o ELONG FIGURE 43 34 SEA SPACE/POLYURETHANE 1. MIL 0%o ELONG

17

iti

~0.2

2 4 6 8 10 12 14 16 18 2DWwmowgh - Mains

FIGURE 44 34 SEA SPACE/POLYURETHANE 1. MIlL 100%0 ELONG

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REFERENCES

1. I. W. Dingwell, W. K. Sepetoski and R. M. Lucas, "Vertical Motion ofT High Altitude Balloons", Technical Report II, Arthur D. Little, Inc.,

for the Office of Naval Research, December 1963.

2. A. E. Germeles, "Vertical Motion of High Altitude Balloons",Technical Report IV, Arthur D. Little, Inc., for the Office ofNaval Research, July 1966.

3

I

II.1

34."1

I

[I

APPENDIX

FORTRAN LISTING OF COMPUTER PROGRAMUSED TO CALCULATE INTEGRATED ABSORPTIVITY

35

Zrtbur 0I.lit±Ic.Jinc.

FOR*LIST ALL*IOCS(CARD.TYPEWRITERKEYROARD,1132 PRINTER9DISK)C APPARENT HEAT TRANSFER COEFFICIENTS IN A TRANSPARENT SPHEREC REFLECTANCE VALUES MUST BE SMALL IF WAVELENGTH DEPENDENT

DIMENSION WL1C15O)vS(150)9TITLE(20)Clu374 13.0C2s14388*0SIGMAu5o6666E-12READ( 2.15)WLMINoWLMAX#T

15 FORMAT(3Fl0.4)DO 16 lx1,117

16'READC 2,15) WL1( I) S( 1)11 READ(2911O)(TITLE(J)sl11,18)110 FORMAT(18A4)

T READ12,515)WL#RtN515 FORMAT(2F10*49I5)

IF(WL) 1000*10009120120 IF(WL-s25)8098099080 ZIOTsol39641

NWL-1 17

T DO 6 l'2tNWL6 ZIO=ZIO+s5*(S( I )S(I-1) )*(WL1(1I)-WL1 (1-1))ZIOVSZIO

F IPRIN-1~J. GO TO 100

90 T=WLREAD( 2.15) WLM IN, WLMAXJ DWz (WLMAX-WLMIN 3*#OlW=WLM I N-DWNWL*101

DO 104 I-19NWLWO=WO+DWWL1CI)xWOS(I)uCl/((WO**5)*(EXP(C2/(WO*T))-1.O))

104 Z*Z+S(I)-- ZIOuDW*(Z-*5*(S( 1)+S(NWL)))

ZIOT=SIGMA*(T**4)ZIovu00OREAD(2915)WLLoRLREAD(2#15)WLU#RU

21 R1=RL+((WL1(I)-WLL)*(RU-RL)/(WLU-WLLi)45 S1=S( I)

St'I)=Sl*R1IF( -1) 17.17,107

107 ZIOV=ZIOV+.5*(SC1)+5(1-1))*(WL1(I)-WL1(m'1))17 1=1+1

1Ff I-NWL) 19919.20019 IF(WL1II)-(WLU+s0001fl2192192222 WLLxWLU

RL =RUREAD( 2,15)WLUtRU

36

GO TO 19200 IPRIN-2100 WRITE(39211)(TITLE(I)tI-1,1S)211 FORMAT(1Hl18A4)I

WRITE(39105)WLMINoWLMAXtT105 FORMAT(Y////2XtWAVELENGTH RANGE IS'.FSolt' TO',F5*19' MICRONS

1T-'.F5s1,' DEGREES KELVIN')WRITE(39106)ZIO

106 FORMAT(2X9'SPECTRAL INTENSITY OVER THIS RANGE IS 19F12*891 WATTSiPER SQ CM91)WRITEC391106)ZIOT

1106 FORMAT(2Xs0FROM A TOTAL OF '.F12*89' WATTS PER SO CM')GO T0L309403'.IPRIN

40 WRITE(3#109)ZIOV109 FORMAT(//2X9'INTENSITY AFTER ABSORPTION'9F12e8)44 READ(29515)WLtRoN30 WRITE(3918)WLsR9N18 FORMAT(14X92F10e4#l5932Xe'.')

WLO=WLROu RNOmNI

YL1RR*S( )

WRIE 3,wWL,,

31 WRTO(3090)N30 FRMu*AT(4X'RDS OU OF ODER'

330 L~ RA(i l)WLtR01363733W~LUWL(ol)W#9

NA2j0

R1uRO+(CWLU-WLO)*(R.RO)/(WL-WLO)IS1MS(I)GO TO 39

37 WLU=WLSi-Sf I)

GO TO 3938 WLUxWL

NA1wOR1=RSlS( 1-1)+( (WLU-WL1( [-1) )*f S(1)-Sf 1-1) )/(WL1(1I)-WL1( 1-1)))

j39 YUxS1*R1DL- WLU-WLL

37

ZsZ+. 5fDL* (YU+YL)GO TO(3119310)tNO

311 RR1U1omAR-R1*R1/(1.-AR)

RO. RR1SZZij+o*L(YIYI

112 h-mLwW

AT3 GO T/Z by11tN

ARZIZ/ZIOV

112 ITE( 52AWR=IT(3u51)A

WRITE(39152)ARWRITE(39151)AAA

1152 FORMAT(///12X#IMEAN REFLECTANCE- #F1O.4)151 FORMAT(12X,1MEAN TRANSMITTANCEs 19F1O.41153 F0RMAT(12X#IMEAN ABSORBTANCEu 9F10#4)

r154 FORMAT12Xt0EFFECTIVE ALPHAEPSILON-49F1O.4)1.155 FORMAT(12X96 MEAN EFF. ALPHA9EPSILONx',F10*4)

GO TO 111000 CALL EXIT

END

1 38

Security Classification

DOCUMENT CONTROL DATA -R&D(Security clessiflcation of title, body of abstract and indexing annotation must be entered Whon the overall report Is classified)

I 0R16,NATIN G ACTIVITY (Corporate author) 2a. REPORT SECURITY C LASSIFICATION

Arthur D. Little, Inc. None20 Acorn Park 2b couPCambridge, Massachusetts 02140 --

3. REPORT TITLE

THERMAL RADIATION PROPERTIES OF SOME POLYMER BALLOON FABRICS

4. DESCRIPTIVE NOTES (Type of report and inclusive detes)

Technical Report - 1967

5. AUTHOR(S) (Last nane. first name, initial)

t Dingwell, I. W.

a-* 6. REPORT DATE 7a. TOTAL NO. OF PAGES 7b. NO. OF REFSJune 1967 43 Two (2)

8A CONTRACT ORt GRANT NO. 9& ORIGINATOR $ REPCRT NUMSIEIES

Nonr 3164(00)b. PROJECT NO. Technical Report V1

C. 9b. OTHER RI PORT NO(S) (Any other numbers that may be assigniedthis report)

C-62944d.

10. A VA ILABILITY/LIMITATION NOTICES

Qualified requesters may obtain copies of this report from DDC.

I. SUPPL EMENTARY NOTES 12. SPONSORING MILITARY ACTIVITY

Part of a continuing series of Office of Naval Researchtechnical reports Physics Branch (Code 421)

Washington, D. C.13 ABSTRACT

As the absorption of solar and earth atmosphere thermal radiationis an important factor in the vertical motion of high altitude balloons,the thermal radiation properties of the thin films that compose balloonfabrics must be determined. This report presents the results of propertymeasurements made with spectrophotometer, emissometer, and thermal radia-tion measuring equipment. The films wh-kch-vere considered fa'l-l-ito ,three categorie,:

a. /Fclyethylenes,

b. .Mylar Composites

c. .Other Fabrics

/,

FORMD1473__ _ _ _ _ _ _ _DD I JAN 64


Security Classification14. KE WORDS LINK A LINK f LINK C

I ROLE WT ROLE WT nOLK WT

Balloon Materials

High Altitudej Spectral Radiation Properties

Absorptivity

Reflectivity

Emissivity

Transmissivity

INSTRUCTIONS1. ORIGINATING ACTIVITY: Enter the name and address imposed by security classification, using standard statementsof the contractor, subcontractor, grantee, Department of De- such as:fense activity or other organization (corporate authjr) issuing (1) "Qualified requesters may obtain copies of thisthe report.

report from DDC."2s. REPORT SECURTY CLASSIFICATION: Enter the over- (2) "Foreign announcement and dissemination of thisall security classification of the report. Indicate %hether"Restrictedreport by DDC is not authorized."ance with appropriate socurity regulations. (3) "U. S. Government agencies may obtain copies of2b. GROUP: Automatic downgrading Is specified In DoD Di- this report directly from DDC. Other qualified DDCrective 5200. 10 end Armed Forces Industrial Manual. Enter users shall request throughthe group number. Also, when applicable, show that optionalmarkings have been used for Group 3 and Gi )up 4 as author- (4) "U. S. military agencies may obtain copies of thisized. report directly from DDC. Other qualified users3. REPORT TITLE. Enter the complete report title in all shall request throughcapital letters. Titles in all cases should be unclassified.If a meaningful title cannot be selected without classifica-tion, show title classification in all capitals in parenthesis (5) "All distribution of this report is controlled. Qual-Immediately following the title. ified DDC users shall request through4. DESCRIPTIVE NOTES: If appropriate, enter the type of _"report, e.g., interim, progress, summary, annual, or final. If the report has been furnished to the Office of TechnicalGive the inclusive dates when a specific reporting period is Services, Department of Commer'ce, for sale to the public, indi-covered. cate this fact and enter the price, if known.S. AUTHOR(SY: Enter the name(s) of author(s) as shown on IL SUPPLEMENTARY NOTES: Use for addtional explana-

or in the report. Enter last name, first name, middle initial, tory notes.If military, show rank and branch of service. The name ofthe principal author is an absolute minimum requirement. 12. SPONSORING MILITARY ACTIVITY: Enter the name of

the departmental project office or laboratory sponsoring (pay6. REPORT DATE Enter the date of the report as day, ing for) the research and development. Include address.month, year; or month, year. If more than one date appearson the report, use date of publication. 13. ABSTRACT: Enter an abu-ract giving a brief and factual

summary of the document indicative of the report, even thoughs. TOTALwNUBER tOF PAGES:The totalpagecoUn it may also appear elsewhere in the body of the technical re-

should follow normal pagination procedutes, i e., enter the port. If additional space is required, a continuation sheet shallnumber of pages containing information, be attached.

7b. NUMBER OF REFERENCES: Enter the total number of It is highly desirable that the abstract of classified reportsreferences cited in the report. be unclassified. Each paragraph of the abstract shall end with: 8. CONTRACT OR GRANT NUMBER: If appropriate, enter an indication of the military security classification of the in-the applicable number of the contract or grant under which formation in the paragraph, represented as (TS). (S), (C), or (U).the report was written. There is no limitation on the length of the abstract. How-8b, Sc,& 8Sd. PROJECT NUMBER: Enter the appropriate ever, the suggested length is from 150 to 225 words.military department identification, such as project number,subproject number, system numbers, task number, etc. 14 KEY WORDS: Key words are technically meaningful terms

or short phrases that characterize a report and may be used as9o. ORIGINATOR'S REPORT NUMBER(S): Enter the offi- Index entries for cataloging the report. Key words must hecial report number by which the document will be Identified selected so that no security classification 4 required. Identi-and controlled by the originating activity. This number must fiers, such as equipment model designation, trade name, militarybe unique to this report. project code name, geographic location, may be used as key9b. OTHER REPORT NUMBER(S): If the report has been words but will be followed by an indication of tech,'z:al con-assigned any other report numbers (either by the originator text. The assignment of links, roles, and weights is optional.or by the sponsor), also enter this number(s).10. AVAILABILITY/LIMITATION NOTICES: Enter any lim-itations on further dissemination of the report, other than those


i thermal radiation properties of some polymer …i thermal radiation properties of some polymer...

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