ENGINEERING RESEARCH INSTITUTE THE UNIVERSITY OF MICHIGAN ANN ARBOR Quarterly Report ATMOSPHERIC PHENOMENA AT HIGH ALTITUDES (November 1, 1956 to January 31, 1957) F, Lo-\Bartman W Jo Wilkie V, CO Liu Approved: L. M. Jones Department of Aeronautical Engineering Project 2387 DEPARTMENT OF THE ARMY PROJECT NOo 3-17-02-001 METEOROLOGICAL BRANCH, SIGNAL CORPS PROJECT NO. 1052A CONTRACT NO. DA-36-039 SC-64659 March 1957

i The University of Michigan T Engineering Research Institute TABLE OF CONTENTS Page ABSTRACT iii LIST OF ILLUSTRATIONS THE UNIVERSITY OF MICHIGAN PROJECT PERSONNEL 1. INTRODUCTION 2. GRENADE EXPERIMENT i) v I. 2.1. 2.2. 2,,~o 2.4. 2.5. 2.6. 2.7. 2.8. 2.9. 2.10. PRE-FIRING OPERATIONS AT FORT CHURCHILL PERFORMANCE OF AEROBEE SM1:01 PRELIMINARY RESULTS OF THE GRENADE EXPERIMENT IMPACT PREDICTION FOR AEROBEE SM1:01 DOVAP TELEMETER RECORD DATA REDUCTION DISCUSSION OF GRENADE INSTALLATION DIFFICULTY GRENADES MISFITS OF PARTS TRANSPORTATION AT CHURCHILL ON AEROBEE SM1:01 4 I 1] E 13 13 II =I L v L L L L I L L 5 5 5 II L L 3. AIR SAMPLING 3.1, RESIDUAL GAS IN BOTTLE B-15 3.2. GROUND-AIR SAMPLE ADMITTED TO BOTTLE B-15 3..3o COMMTS 34. E HIGH HELIUM CONTENT IN 13-1X 3.5. CONDENSABLES 356. BOTTLE B-10 15 13 14 14 16 16 17 4, RESEARCH INVESTIGATIONS - PROGRESS REPORT 'ON RAREFIED GAS-FLOW RESEARCH 5. LABORATORIES VISITED 6. FUTURE PROGRAM 17 IS IC 6.2. 6.3. GRRENADE EXPERIMEiT AIR SAMPLING, RESEARCH INVESTIGATIONS 2C 23 23 7. ACKNOWLEDGMENTS ii

The University of Michigan T Engineering Research Institute ABSTRACT Aerobee SM1:01 was successfully fired at Fort Churchill. The data reduction on this flight was begun. Air sample bottle B-15 and control samples associated with bottle B-15 were analyzed. Various repairs were made to the analyzer. A new method of attack for solving rarefied gas-flow problems is being developed; the results of a sample calculation using this method are presented. iii

The University of Michigan T Engineering Research Institute LIST OF ILLUSTRATIONS Figure Page 1 Placing Aerobee SM1:01 on scales (in preparation for making weight and center of gravity measurements). 2 2 Aerobee SMl:01 being raised up into launching tower. 3 5 Aerobee SM1:O1 leaving Aerobee launcher (1/100-second exposure). 5 4 DOVAP telemeter record for Aerobee SM1:01. 9 5 Drag coefficient of a flat surface for specular reflection. 20 Table I Weight and Center of Gravity Information for Aerobee SM1:01 2 II Grenade Ejection and Detonation Data from 6.9 In./Sec Recording of Aerobee SMl:01 DOVAP Telemeter 10 III Summary of Results 15 iv

The University of Michigan Engineering Research Institute THE UNIVERSITY OF MICHIGAN PROJECT PERSONNEL Both Part Time and Full Time Allen, Harold F., PhoDo, Research Engineer Bartman, Frederick Lo, MoS,, Research Engineer Billmeier, William G., Assistant in Research Chapelsky, Orest, Assistant in Research Finkbeimer, Richard Go, Electronic Technician Gleason, Kermit Lo, Instrument Maker Harrison, Lillian M,, Secretary Kakli, M. Sulaiman, M.S., Assistant in Research Jew, Howard, M.A., Research Assistant Jones, Leslie M.o BS,, Project Supervisor Liu, Vi-Cheng, Ph.D., Research Engineer Loh, Leslie T., MS,, Research Associate Malkani, Sundru J,, MoSc,, Assistant in Research Otterman, Joseph, PhoD,, Research Associate Prince, Milford Wo, Machinist Schumacher, Robert Eo, BoS,, Assistant in Research Stohrer, Albert W., B.S., Research Associate Taylor, Robert No, Assistant in Research Titus, Paul A,, BoSo, Research Associate Wenk, Norman Jo, BoS., Research Engineer Wenzel, Elton Ao, Research Associate Whybra, Melvin Go, MoAo, Technician Wilkie, Wallace Jo., MSoEo,, Research Engineer Zeeb, Marvin Bo, Research Technician v

The University of Michigan T Engineering Research Institute 1. INTRODUCTION This is the seventh in a series of quarterly reports on Contract No. DA-36-039 SC-64659. The purposes of the contract are: a. to adapt the rocket-grenade experiment for use in the Arctic during the International Geophysical Year, b. to collect and analyze upper-air samples, and c, to engage in the general investigation of problems relating to upper-air research. 2. GRENADE EXPERIMENT 2.1. PRE-FIRING OPERATIONS AT FORT CHURCHILL The pre-firing operations conducted up to November 1, 1956 are described in the last quarterly report, No. 2387-19-P. On November 1, 1956, the total weight and center of gravity of the missile were determined. Figure 1 shows the missile being placed on the scales. The missile as weighed was complete except for fuel, oxidizer, helium, grenades, and Prima-cord detonator block. Table I contains a summary of weight and center of gravity information for Aerobee SMl:Ol. The total length of the missile was 210.7 inches, the forward 70,15 inches consisted of the nose cone, grenade section, and instrumentation section, and the rear 140.56 inches was the standard AJ 10-25 Aerobee power plant and tail cone. The missile was placed in the launching tower on November 9, 1956. Figure 2 shows the missile as it is being raised up into the tower. The first vertical check was held the same day. In this check everything worked properly except the transmitter for the AN/DRW-3 cut-off receiver. The transmitter malfunction was corrected and a second vertical check was successful in all details on November 10, 1956. At this time the final firing schedule was set up; however, the exact firing time could not be set because of the heavy cloud cover. On November 11 at about 4 p.m. examination of weather charts revealed 1

L - The University of Michigan T Engineering Research Institute Fig. 1. Placing Aerobee SM1:01 on scales (in preparation for making weight and center of gravity measurements). TABLE I WEIGHT AND CENTER OF GRAVITY INFORMATION FOR AEROBEE SMlOl After All Before After After Grenades Firing Burnout Ejected Dry weight of missile (power plant, tailcone, and fins), lb 287 287 287 Payload (nose cone, grenade section, instrumentation section, wiring, antennas, and Prima cord), lb 220 220 130 Helium, lb 5 -- Aniline, lb 181 4 4 Oxydizer, lb 497 - - Total, lb 1190 511 412 Center of gravity (inches from nose tip) 113.5 81,4 90..................... i.................0 2

The University of Michigan Engineering Research Institute ri:,_ - -t!-E,..:~;;: --:itiS::::..:.. bO o'Ofq.:.........::::W:::::.:i~7::j:j::g.............. r -: r-4 x E i. i-......EiiN.............. -E~l;~lEE00E~id;:i:. _...:- -:>0.-. ii —:.:....::.j:,-..Er 3~-. 33::-i-f003 3.................33 3-333. 5w8igg:i.gi005:0,........i0,; 2s..................................i '. i i-i:iE:-:0_ _ -_<~Je~ c it.Q'*.* * _iiii_ i: saa 1 _LSS: _0 E__r,.,,.,,,j,,,_ z~h _ S.,,,,:r: '''' ' -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:i i;, tt 3_ 3

The University of Michigan * Engineering Research Institute that the sky would begin to clear sometime during the early morning hours of November 12. It was decided to schedule the firing for about 4 a.m. of November 12. The pre-firing operations proceeded smoothly except for some difficulty in grenade loading. Grenades No. 8 and 18 could not be threaded completely into their sockets. The grenade that was first tried in the No. 8 position was removed and successfully inserted into another position. This indicated that the thread at the bottom of the grenade mortar was at fault rather than the thread on the grenade itself. Another grenade was then tried in the No. 8 position, but also could not be threaded completely into the socket. Moreover, in attempting to force this grenade into position, it was jammed into the socket. At this time it was decided that an attempt to remove this grenade forcefully might result in shearing the shear rivets at the bottom of the grenade. If this happened, the grenade would become dangerous to the grenade loading personnel, and therefore it was decided to leave this grenade as it was, A similar situation was encountered in the case of grenade No. 180 Because of its short lanyard, grenade No. 18 is potentially more dangerous in the case of sheared rivets than the other grenades. Accordingly it was decided to leave this grenade as it was, At the time of grenade loading it was not certain that these two grenades were threaded far enough into their sockets to enable the microphone plug to mate with its jacko Because of this uncertainty and because grenade No. 18 was designed to explode within the nose cone, thereby destroying all unejected grenades, another short lanyard grenade should have been installed in position Noo 17. However, under the pressure of the situation, this was not done. (See 2.7 for further discussion of this difficulty.) At about 4 p.m., the sky began to clear and helium pressurization was begun. Except for a hold due to the failure of the radar-transmitter motor-generator set and some difficulty with the Twin Lakes ballistic camerashutter operation indicator, the remainder of the firing operations proceeded without difficulty. 2 2o PERFORMANCE OF AEROBEE SMI: 01 The missile was fired at 5-47:47 aomo on November 12 (see Fig. 5). The performance of the booster and Aerobee sustainer motors was about normal, -although the burning time of each of these units was longer than usual. Booster burnout (from booster separation) occurred at 2.729 seconds after lift time and the sustainer motor burnout (from launch station maximum radial velocity) occurred at 36.2 seconds. The normal burning times for booster and sustainer motor are 2.5 seconds and 34 seconds, respectively. Preliminary data from radar and DOVAP are the following: 4

The University of Michigan Engineering Research Institute Fig. 30 Aerobee SMI:Ol leaving Aerobee launcher (/lOO1-second exposure). 5

The University of Michigan Engineering Research Institute Maximum velocity, 3250 ft/sec (DOVAP-initial data) Peak altitude, 222,700 ft (Radar plot) Peak time, 135 seconds (DOVAP). The predicted performance of Aerobee SM1:01 was: Maximum velocity, 4200 ft/sec Peak altitude 274,530 feet. The discrepancy between the predicted and actual performance of Aerobee SM1:01 has not been completely resolved as of this dates however, it appears that the low maximum-velocity and low peak-altitude of Aerobee SM1:01 was due to the drag of the DOVAP antennas. This drag was not allowed for in predicting the peak altitude of Aerobee SM1:01. 2.35 PRELIMINARY RESULTS OF THE GRENADE EXPERINT ON AEROBEE SM1:01 All the grenade-experiment instrumentation on Aerobee SM1:01 appears to have worked very satisfactorily. Before firing, all equipment was operated on external batteries, then transferred to internal batteries without difficulty All monitor signals were normal. The program timer started at booster separation and went through its timing sequence properly. Sixteen grenades were ejected at the proper timeso The two grenades which failed to eject did so because of the loading difficulty described above. DOVAP cycle counts were recorded at all stations,.starting shortly after the missile left the tower and continuing on to what appears to be the impact time. DOVAP telemetering worked very well. The telemetering record will yield the grenade explosion times and all the details of the timer operationn The missile-borne flash detectors whose signals were transmitted by the DOVAP telemeter, appear to have worked as desired. The tracking radar ground station and DPN-19 missile unit performed very well; a plotting board record which covers the complete trajectory was obtained, Although the range-safety officer did not find it necessary to cut down the missile) it appears that the AN/DRW 3 cut-off receiver was working properly and would have performed the cut-off function properly. The ground equipment of the Signal Corps Engineering Laboratories worked very wello All nine microphones in the sound-ranging array received each grenade signal. The microphone signals, ground flash detector signals 6

The University of Michigan Engineering Research Institute and DOVAP telemetry signals were successfully recorded on one oscillograph record at Twin Lakes, along with range-timing signals. The ground meteorological data necessary for the grenade experiment were also recorded by SCEL personnel at the Twin Lakes site. Pibal wind observation runs and highb-altitude radiosonde runs were made by personnel of the White Sands Signal Corps Agency group at Fort Churchill. The pibal wind observations provided data used to set the tower tilt for the desired rocket trajectory. The high-altitude radiosonde runs were made at approximately 3525 a.m., 5:15 a.m., and 8:15 am. of the firing dayo On these runs, data were recorded of 34000 ft, 62000 ft, and 102000 ft, respectively. The meteorological data from the last run will cover the low altitude range of the data from the grenade experiment. ~2.4. IMPACT PREDICTION FOR AEROBEE SM1:O01 The impact prediction work for Aerobee SMl:01 was carried out by personnel of the Meteorological Branch, Fort Churchill Division, White Sands Signal Corps Agency. Their data are summarized in "Meteorological Report for Aerobee SM1:01," by Lloyd White. The desired trajectory for Aerobee SML.:Ol was due south from the launcher over Twin Lakes. Impact was desired to be south of Twin Lakes. The trajectory was planned so the grenade ejections would be made on the upleg of the trajectory as directly as possible over the Twin Lakes sound ranging array. The rocket ballistic factors, unit wind effect, tower tilt effect, and coriolis displacement were calculated by the WSSCA personnel. Because of low ceiling and poor visibility all pibal wind observation balloons were not tracked to 200 feet as desired; however, three of the runs did obtain this altitude. On the basis of the data obtained, the tower tilt was set at 60 miles east and 141 miles south. With this tower tilt and the prevailing winds, the rocket impact was predicted to be 21 miles due south of the launcher (azimuth 180~ ) The actual impact was 33 miles from the launcher at 200 degrees azimuth. Although the trajectory was a suitable one in that it satisfied the technical requirements of the grenade experiment, the fact that the impact prediction was in error was of some concern to the range-safety officer. In his words, z.While well within the range limitations or boundaries, this impact too closely approached the boundary." Because of the concern of the rangesafety officer, an attempt will be made to determine the reason for the error in predicted impact. 1, See "Report on the Pre-IGY Firings Conducted at Ft. Churchill, Manitoba, Canada," Jan. lO, 1957, by Jack Siwert, Capt. Ordnance Corps., RangeSafety Officer, Ft. Churchill IGY Rocket Project. 7

The University of Michigan * Engineering Research Institute 2.5 -DOVAP TELEMETER RECORD The DOVAP telemeter record for SMl:Ol has been received from BRL. This record is a real time oscillographic recording (6.9 in./sec paper speed) of the first 205 seconds of rocket flight. Figure 4 is a photograph of a portion of this record, showing the sequence of events covering the one.Second interval during which grenade No. 3 was ejected and detonated. The legend indicates the meaning of the telemeter signals. The times Tl, T2, T4m and T5 were easy to read; however$ the time T3 is not indicated with the desired clarity. The signal at this pon int idicates qualitatively whether or not the grenade ejection switch has operated; however, the exact time is difficult to determine. This time sequence of events for all eighteen grenades is given in Table IIo The times T4 are of primary importance to the grenade experimento It is believed that these times are accurate to ~ 0.001 second. T2-T1 is the time interval between the time at which current is applied to the stepping relay and the time at which current is applied to the grenade squibo This time interval is approximately the same for all grenades. The time interval T5sT1 during which current is applied to the stepping relay, is the time during which the timer microswitch is actuated by the grenade firing camo This time interval depends on the width of the notch in the cam and on the motor speeds The relatively large value of 0270 second for the first grenade indicates that the motor was operating at a lower than normal speed at this time. The time interval T3-T2 tells how much time elapsed between application -of current to the squib and the operation of the ejection switch. The time interval T4-T3 between operation of the ejection switch and the grenade flash is an indication of how far the grenade traveled before it was detonated. Since the accuracy of the time T3 is somewhat poor, the time T4-T2 is also given for reference. Consideration of these three intervals indicates that grenades 1, 2, 5, 10, 135 and 16 probably did not travel the full length of lanyard before they were detonated. This recording of the DOVAP telemeter data was made with the use of a wide-band discriminator capable of resolving a 50 Kc subcarrier deviated plus and minus 40%. The discriminated signal was filtered by a 3 Kc low-pass filter and recorded on film using a galvanometer having a 600 cps damped frequency response. The tie delay of this combination to a pulse modulation sinal with 5 microsecond rise time has been measured to be 160 microseconds. The limiting factor in the time accuracy of the determination of grenade flash time from this recording is the paper speed of 6.9 in./sec. Accordingly a request has been made to have the first 100 seconds of this record played back at a paper speed of 20 inches per seconds The signals will be read againo It is hoped that a greater reading accuracy will be obtained. 8

1 -------- - - - - - IT"UTTIMTRITTIV I "TMITIIITTTMITI-TIITIT"I-"MITIITI I III M JI II 11TIT111-111 I I-1111T M I'M I'll IIIIII I M 1.1 III II rlyr-117MIJIMT-1-1-1 IT 48. 625'8 sec.. 01-sec. timing pulses. 49. 6258 sec. Grenade #3. Time after rocket lift. Il I I _~r. - _~~~~~I IA IIIII ---nL....... 0 o.. 3 2) 2 3 1 I 5 1. Stepping-relay current applied. 2. Current applied to grenade squib. 3. Grenade ejection switch operates. 4. Flash from grenade explosion. 5. Stepping-relay current removed. 48. 701 sec. 48. 716 sec. 48. 765 sec. 48.789 sec. 48. 936 sec. rm:3 Go 3" goQ MD u, %A Ir n =1 c+ c+ I I f Fig 4 DOVAP telemeter record for Aerobee SM1:O Fig~ 4~ DOVAP telemeter record for Aerobee SMl'0!. 1 ' ' -4

The University of Michigan Engineering Research Institute TABLE II GRENADE EJECTION AND DETONATION DATA FROM 6.9 IN./SEC RECORDING OF AEROBEE SMISO1 DOVAP TELEMETER Grenade T1 T2 T3 T4 Ts T2-T 1 T3 -T2 T4-T3 T4-T2 T5-T1 Nimber (sec() ( ) (sec.) (s (sec) (sec) (se) (sec) ) ( se) (sec) I (sec) 1 41.o790 41.o802 41.854 41,871 42.060.012.052.017.069.270 2 45.229 45.243 45 300 45330 45.452 o014.057.030.087.223 3 48,701 48.716 48,765 48.789 48.921.015.049.024.073.220 4 52,1 94 52.208 52,272 52.514 52.398.014.064.042 o106.204 5 55,658 55.671 55.722 55,777 55.869.015.051.055.106.211 6 59.091 59.105 59.156 596207 593519.014.051.051.102.228 7 62571 62 6271 628 62.626 62.687 62 783.01.0 42 o061.103 o212 8 66,067 66.082.. 66.271.015 - -o 204 9 69.536 69.604 69.653 69 750 - -.049 - 214 10 72.979 72.992 73.031 735071 75.205.013.039.040.079.226 11 76.469 76.484 76.554 76.589 76.688.015.070.035.105.219 12 79-972 79o985 80.052 8o.o081 80.173.013 047 o049.096.201 13 83.442 835455 83.496 83,660.0153 -.041.218 14 86.891 86.904 86.950 860999 870118.013 o046..o49.095 o227 15 90. 382 -90 394 90.1445 90. 499 90.598.012.051 o 054.105.216 16 935.889 93.902 93.955 93.963 9 4.093.013 o053 o008.061.204 17 7659737872 97 975865 78 970424 970 04716 o80 052 o098.215 18 100.820 100.832 - 101.048.012 -- - -.228 NOTES: T1 = Time at which stepping relay current was applied. T2 Time at which current was applied to the grenade squib. Ts = Time at which grenade ejection switch operated. TT4 Time of the flash from the grenade explosion. Ts i= Time at which the stepping relay current was removed,. All times are given with respect to the time of rocket lift. Accuracy of reading flash time is + 0.001 second. 10

The University of Michigan Engineering Research Institute An examination of the full 280 seconds of the telemetering record is desired to check for possible malfunction of the equipment after grenade ejection. Accordingly a request has also been submitted for a playback of the complete DOVAP telemeter record at a paper speed of 4 inches per second. 2o6. DATA REDUCTION The work on the DOVAP trajectory for Aerobee SMI:01 did not start during this quarters Neither the cycle count films nor the ground station coordinates had been received, although they were expected to arrive early in February, 1957. 2,7. DISCUSSION OF GRENADE INSTALLATION DIFFICULTY During the loading of the rocket with grenades, difficulty was encountered with grenades No. 8 and No. 180 The grenade in mortar No. 8 did not seat properly and another was substituted which also did not seat properly. The threads seemed unusually tight, making the grenade difficult to seat or to removeo The loading personnel surmised, incorrectly, it turned out, that the grenade was installed into the mortar socket sufficiently far to make the necessary electrical contacts. Number 18 grenade gave similar difficulty. After all eighteen grenades were in place the nose cone was installed and the tower was cleared of personnel to permit pressurizing the helium tank, the last operation before firing, Consultation by the loading personnel with personnel more intimately acquainted with the grenade and mortar assembly brought to light the fact that electrical contact had not been made on grenades Nos. 8'and 18. Pressurization of the rocket had already started and it seemed advisable to continue with the firing preparations with two doubtful grenades rather than risk the possible adverse effects of de-pressurizatiot for the sake of removing or examining these grenades. The rocket was launched successfully with sixteen grenades firing as plannedo As predicted, grenades Noso 8 and 18 did not fire. Several factors contributed to the malfunction of grenades 8 and 18o The aluminum castings from which the grenade bulkheads were made did not possess the machinability which was claimed for them. As a consequence the threads were not as smooth as desired. The grenade installation wrench was too long to be used conveniently in the tower and was shortened in the field. This field modification necessitated leaving off the torque handles. With the torque handles off, the person installing the grenades lost his previously acquired sense of feel of the limiting torque to be appliedo Since the lack of torque handles would indicate an apparent torque higher than actual, it is 11

The University of Michigan Engineering Research Institute quite possible that these two grenades would have seat.ed properly if an addi-' tional safe amount of torque had been applied. The most important factor, however, was the lack of proper organization of field operations. Personnel were presen t at the launching site who knew the grenade rocket assembly intimately and who could have taken the necessary action immediately. In this case such action would have been to determine if the grenades were impossible to seat properly and it so, to remove them from the rocket and fly without them. The following actions have been undertaken to prevent any such occurrence againt 1. Tighter specifications on materials and inspection of grenades and mortars o 2. Redesign of installation wrench to facilitate reading proper torque limits under tension of field conditions. 35 Arrangement of field operations so that a person with intimate knowledge of the grenade and rocket assembly will have excellent coaunication with those installing the grenades. 2.8. GRENADES Two grenades were fired at Churchill from individual mortar tubes as reported in the last quarterly report. In addition sixteen grenades were fired successfully from the rocket as reported elsewhere in this report. Counting 46 previous grenade launchings attempted with 44 successes, the total launchings attempted is now 64 with 62 successes for an indicated reliability of this grenade lot of 97%o Two grenades in the rocket which were improperly installed and which were specifically predicted by number as unlikely to be fired were not counted in arriving at this reliability figure. If only those grenades fired at Churchill are considered the reliability figure is 100%. 2.9. MISFITS OF PARTS For the November firing at Churchill.The University of Michigan provided the complete warhead for the Aerobee rocket plus the handling of the subcontract for the reconditioning of the rockets and for the notch antenna installation. Prior to the arrival of the various rocket components at Churchill, no attempt was made to mate all these components. Despite the fact that these conponents were all supposed to be jig.-fitted before shipment from the factory_ difficulty was encountered in attempting to mate physically major components. Such mating was impossible in at least one case due to substantial -misalignment of screw holes. 12

The University of Michigan T Engineering Research Institute Further, it was necessary to manufacture some electrical and mechanical parts in the field which could not be prefabricated without having the rocket present. Because repairs are difficult or often impossible in the field where facilities and materials are limited, it is desirable to complete all fabrication work and all possible inspection and repair work before the rocket and instrumentation leave the States. To avoid these difficulties in IGY firings, the Aerobees will be shipped to Ann Arbor for pre-fitting of components prior to shipment to Churchill. 2.10. TRANSPORTATION AT CHURCHILL Although transportation at Churchill normally would not be considered a proper subject for this report, the lack of adequate transportation at Churchill definitely interfered with the operation of preparing and firing rockets. For the IGY firings it is planned to take a vehicle to Fort Churchill for the use of University of Michigan personnel. 3. AIR SAMPLING During the quarter the final run on upper-atmosphere sample bottle B-15 was made. The apparatus was prepared and ground-air samples were made and analyzed in preparation for the analysis of upper-air sample B-10. The effects of coolants on various samples were investigated. Difficulties with breakage in the fractionating column and failure and replacement of the charcoal oven were encountered. 3.1. RESIDUAL GAS IN BOTTLE B-15 Results of the analysis of bottle B-15 were reported in the previous quarterly report. Following these analyses a series of tests was undertaken, designed to show any discrepancies in the results arising from the steel sample bottle or its connecting tubing. First, approximately 8097 of the bottle gas was pumped into the system. This gas consisted of residual gas not previously transferred, plus any gas which may have leaked into the bottle or any gas which may have outgassed from or permeated through the walls of the connecting tubing. Included are the soft-glass-to-hard-glass graded seal, the glass-to-Kovar seal, and the copper tubing and its flare-fitting connection. An analysis was made of this extremely small sample. The helium content was quite different from the samples previously examined, i.e., the

The University of Michigan ~ Engineering Research Institute samples B-15, runs 1-2-,3 and "residual" in Table III, 352o GROUND-AIR SAMPLE ADMITTED TO BOTTLE B-15 After a short pumping, 0.021 cc of gas from ground-air sample No. 13 was introduced into the bottle. This sample was toeplered out the same day in a manner similar to the pumping of the original sample. This gas was then analyzed, and the results are indicated under 13l*X in Table III. It will be noted that the helium content as compared with normal No. 13 ground-air samples is 10322 times higher. The neon content is near normal, and the oxygen content is very low. The bottle was flushed with No. 13 ground air, pumped for about 2 hours by the system mercury-diffusion pump to a good vacuum. A second sample of gas from ground-air sample No. 13 was introduced into the bottle. This sample was then toeplered out as before, and preparation for analysis was made. The oxygen cell was operated, and this sample showed even less oxygen than the first sample. At this point a system breakage necessitated admitting air. The control ground air was lost, so no further analyses were made. In the table, the data obtained are listed under 13-2XL -5.30 COM TS With these data~;certain conjectures can be made. First, consider gas cleaned up on the copper filament. Metal surfaces within the bottle appear to react readily with the oxygen in the air sampleo It therefore appears unlikely that the upper-atmosphere sample contained appreciable oxygen. This seems to be consistent with the results of analyses made previously by both Dr. Paneth at Durham and our own control samples over several years. If a gas other than oxygen is assumed, it must then be a gas which will react readily with either the hot copper filament or the equally hot copper oxides which form on the filament. The most likely gas appears to be hydrogen, which would then reduce the copper oxides on the filament to form water. Actually, the filament appears to be cleaned up slightly when operated with the upper-atmosphere samples in the cell as might be expected with hydrogen. It ls hoped that the gas from one of the samples can be examined with a mass spectrometer to verify this deduction. The gasg whatever it may be, can be assumed to have (1) been present in the upper air, (2) leaked in or outgassed from the bottle, or (5) leaked in or outgassed from the connecting tubing.

i TABLE IIISUMMARY OF RESUTS m vr........... Condensable Matter.. Quantity Before Oxidation After Oxidation SampleRHGas upper air Ne upper air Gas-*oV s Vs Sample RunGs before pper air Gas bLosa- *Vol. Lost *Vol. L"s%.*Vol' Lost *Vol. Lost He ground air Ne ground air on Filament Oxidatione gr d ar e grod air Liquid N2 Dry Ice Liquid N2 Dry Ice. (cc NTP) _______ (%)._ 1 I ) 1 (f) Ground Air 13 1 0.0089 Calibration Run 19.6 --- - 13 2 0,0042 " " 13 3 0.0074 " " 0 -_ o.95 -._ 13 4 0.0106 " " 18.7 ---.- -- 0.8o8 13 5 0.0074 " 19.08 -- - -- 1.8 17 1 o0007 " " 19.0 --- - - 0.62 17 2 0.0087 18.4 -- -. --- 0.5 16 1 0.005 " 6" 17.4 -.- - --- o5 Upper Atmosphere B-15 1 0.0082 1.64 1.12 23.2 2.9 -- - B-15 2 0.0061 1.64 1.14 23.7 -- — _ - 2.2 B-15 3 0.0036 1.67 1.13 24.2. — --- 2.0 B-15 Resid.al 0.0018 5.25 1.22 25.6 5.3 -- 5.4 0.78 B-10 1 0.0102 1.52 1.13 36.0 2.3 -- 12.0 10.0 Ground Air Introduced into B-15 153 X 0.0053 1.52 1.06 2.8 -- - - 1.0 13 2X 0o0049 - - 0.35 -- - -0.5 Leaked or Outgassed Material B-10 not open Connecting tubes only. 0.0001285 7.75 0.214 0 63 04. *Measured with McLeod gage. -4 ar r 3 o -I w -9 * I go M r+ 0D I

The University of Michigan Engineering Research Institute Later checks have shown that no gas is cleaned up from a small sample collected for 48 hours in the connecting tubing. Possibility (2) is being considered. There is some possibility of hydrogen permeation of the steel bottles. This will be investigated further during the coming quarter. 35.4 HIGH HELIUM CONTENT IN 13-1X Ground air from No. 13 sample was introduced into the bottle in an attempt to discover whether or not any separation of the upper-atmosphere sample gases occurs in the bottle. It was surprising to find a high helium content in the extracted gases, The explanation of this effect is not immediately apparento However, in preparing the system for opening bottle B10O, a check analysis was made of gases collected over a two-day period in the connecting tubings, Although the sample was very small, the results of the analysis are considered reliableo The gases contained a large proportion of helium compared to ground air. From these data it seems likely that any increase in helium in Bottle B-15 residual, after toeplering and while still attached to the system, was due to helium permeation of the connecting tubingo This helium leakage is not high enough to account for the amount of helium in 135-1X The same checks will be run on B-15 with No. 17 ground air to further clarify this point. Although the helium content in the connecting tubing is increased, it should be noted that the sample is very small. If the whole sample of B-10 were contaminated with the gas collected during two days, the He upper-air He ground air ratio would be changed less than 2%, and B-15 changed less than 2.6%. The pumping time is only about 7 hours; consequently, the error from this source is less than 1% on each bottle and is not considered significant. 3.5. CONDENSABLES Some data were collected showing the amount of sample reduction when a trap cooled to various temperatures. In addition, this cooling was done both before and after removing gases on the hot filament. It should be noted that several gases have sufficiently high boiling points to be condensed at the temperature of liquid nitrogeno In all cases, the trap volume comprised only a small portion of the total volume containing the sample. It is estimated to be on the order of a few percent. The results appear in the table and no comments will be made on them at this time. All readings are based on the change of pressure in a fixed volumeo The pressures were measured with a MeLeod gage. I I i 16

- The University of Michigan * Engineering Research Institute During this period several breaks occurred in the capillary-tubing fractionating column, Delays were encountered while the breaks were repaired. One piece of capillary, which was particularly persistent in its breakage, was finally replaced before the work could be continued. The charcoal oven also caused delay. The heating element burned out, and it became necessary to construct a new oven before proceeding with the analyses. The apparatus is now working well, and bottle B-10 analysis should be completed during the next month. 306, BOTTLE B-10 Preparations were made for opening B-10. Prior to the opening several checks for system tightness were made. Breakage on the column caused the loss of some ground-air samples. Ground-air sample. No. 16 was analyzed once before breakage and loss. Ground-air sample No. 17 was analyzed as a control. Results are noted under 17-1 in the table. The upper-atmosphere sample B-10 was then opened. To date only one run has been completed on this sample. The helium and neon ratios appear to be slightly lower than B-15. The results are listed under B-lO-1 in the table. An additional control sample was run. The results are given in 17-2 in the table. We have now analyzed gas from bottles with 1- and 2-inch orifices. From the data now available, it may be concluded that the separation shown is not caused by either supersonic velocity at sampling or by the dynamics of the sampling orifice, 4. RESEARCH INVESTIGATIONS - PROGRESS REPORT ON RAREFIED GAS-FLOW RESEARCH One of the drawbacks of; the aerodynamic methods of upper atmosphere measurements is the lack of satisfactory theory of predicting the aerodynamic effect of flow around a body in the rarefied gas, such as atmospheric air at an altitude of 100 Km. The properties of the atmosphere at this altitude can be characterized as a medium with a mean free path comparable in order of magnitude to the size of.the body about which the aerodynamic effect is of in terest. Results of low-densit wi tests crresponding to these flow conditions have been meager and perhaps unreliable due to unresolved experimental difficulties involved in the tests. 17

The University of Michigan * Engineering Research Institute The classical theoretical analysis of the problem boils down to the solution of Boltzmann's collision equation. Attempts have been made along this line for solving various rarefied gas problems by Chapman, Enskog, Grad, Uhlenbeck, and Change to mention a few. However, due to the immense mathematical difficulties involved, only modest success has been achieved. Satisfactory results have been obtained mostly in the field of diffusion problems such as those described in the treatise by Chapman and Cowling (The Mathematical Theory of Non-Uniform Gases, Cambridge University Press, 1952, 2nd ed.). The present approach offers a new line of attacko The general principle of which can be briefly described. When the mean free path of the medium is much larger than the characteristic size of the object, the so-called free molecule flow region prevails in which collisions between the molecules of the medium may be neglected as compared with those with the object. The theory of free molecule flow has been well developed except for the uncertainty concerning the nature of reflection of the gaseous molecules from the solid surface of the object. As far as this interaction is concerned, at least two different types of mechanisms of reflection are possible, depending on the state and nature of the surface? the kind of gas, the density of the impinging stream, and the respective temperatures of the gas and the solid surface. These are specular reflection and diffuse reflection. In specular reflection, the component of the molecular velocity tangent to the surface remains unchanged but the component normal to the surface reverses its sign. In the diffuse reflection, the molecules are reflected from the surface in an absolutely random manner, all traces of their past history having been lost, they obey a cosine law similar to that of a surface emitting radiant energy. The incident molecules usually make several collisions in the interstices of the surface during which time they can exchange momentum and energy with the surface. Review of progress in recent research concerning the interaction between gaseous molecules and the solid surface is given by Schaaf (Heat-Transfer Symposium, University of Michigan Press, 1952). It can be said that the free molecule flow theory, which describes the characteristics of flow in extremely rarefied gas, will be established once the uncertainty of this interaction phenomenon is cleared. The attempt, initiated here, is made to take collisions into account so as to obtain a better approximation to the aerodynamic effect of the flow for which the characteristic size of the object is not entirely negligible compared to the mean free path of the medium. It can be considered as a second approximation to the aerodynamic force, while the result of the free molecule flow constitutes the first approximation for which the effect of molecular collisions has been neglected. It is plausible. to assume that the chance that a reflected molecule collides n times near the object is obviously less than if it collides m times, if n >m. Thus we start the analysis by taking into account those molecules that collide once in the gas near the object. This is here con 18

The University of Michigan E Engineering Research Institute sidered as the second approximation. Theoretically speaking, the nth approxinmation can be obtained by calculating the effect of n collisions. In the scheme of successive kinetic calculation, we define D as the-correction term to the first order of approximation 9f the aerodynamic force (the free molecule flow theory)o In obtaining D(1; we take into account the contribution to the aerodynamic force on the object due to the collisions between the incident and reflected molecules in the first roundo As a sample to test the workability of the basic idea just described, we chose a very simple model which consists of a flat plate moving in a direction normal to its plane in a monatonic gas of hardy spherical molecules. Specular reflection is assumed. The results of the calculation of the drag coefficient of the flat surface at various ratios of mean free path and plate diameter are plotted in Fig. 5. The results presented here are considered preliminary because they are obtained on the basis of very crude assumptions concerning the molecular behavioro Nevertheless, the results of the sample calculation already indicate that the present idea is promising when considered as a working model for solving rarefied gas-flow problems. A technical report dealing with the present method of attack on the rarefied gas-flow problems will be issued as soon as sufficient sample calculations are completed. 5. LABORATORIES VISITED During this quarter, visits were made to the following places. a.) Fort Churchill, Manitoba, Canada b ) Air Force Cambridge Research Center c ) Evans Signal Laboratory do) Defense Research Board, Ottawa, Ontario. 60 FUTURE PROGRAM During the nxt quarterlwork on the project will include the fol: lowing: 19

The University of Michigan E Engineering Research Institute CD - K= 1.67 K=: 0 I2 3 4 MCO Fig. 5o Drag coefficient of a flat surface, CD =..drag CD n= a2 L i a2 P V2 200 for specular reflection. 4LM mean free path K = - Knudsen number, plat e 2a plate diameter 6 1o GRENADE EXPEERIM T ao ) Data reduction for Aerobee SM1:01. b ) Re-design of Aerobee instrumentation for IGY grenade experiments. co) Construction of a prototype "modular" instrumentation section. d ) Analysis of Aerobee SM1:01 rocket performance. e.) Rehabilitation of Aerobee rockets by the Aerojet-General Corporation. f.) Construction of Aerobee instrumentation for IGY grenade experiments. go) Analysis of method of impact prediction. 20

The University of Michigan T Engineering Research Institute 6.2. AIR SAMPLING Bottle B-10 will be analyzed and the analysis of control samples will continue. 6,3. RESEARCH INVESTIGATIONS The method of attack on rarefied gas-flow problems introduced above will be applied to other sample problems. 7. ACKNOWLEDGMENTS Thanks are due to the Meteorological Branch, Evans Signal Laboratory, for cooperation and financial support. Thanks are also due for the great help at Fort Churchill of: a.) Col. L. G. Smith, IGY Rocket Project Officer; b.o) The Interservice Support Coordinating Group; c.) Major M. Gunne for Canadian Logistic Support; d.) The Fort Churchill Section of WSCCA for Radar Tracking, Range Safety Impact Prediction,and Communications; e.) BRL, DOVAP, and Ballistic Camera Groups; f ) Commander Diehl and the Aerobee launching Team; go.) The field crew of NMAMAI h.) The field representatives of the Aerojet-General Corporation. The assistance of the grenade-loading crew provided by the National Northern Fireworks Co. is greatly appreciated. 21

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