skylab payload shroud jettison tests

8/6/2019 Skylab Payload Shroud Jettison Tests

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SKYLAB PAYLOAD SHROUD

by Charles J. D a y eLewis Research CenterCleveland, Ohio 44135


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I11TECH LIBRARY KAFB, NM1. Report No. 2. Government Accession No.

NASA TN D-6913. .4. Title and SubtitleSKYLAB PAYLOAD SHROUD JETTISON TESTS

7. Author(s)Char les J . Daye

9. Performing Organization Name and AddressLewis Research CenterNational Aeronau tics and Space Admin istrationCleveland, Ohio 44135

2. Sponsoring Agency Name and AddressNational Aerona utics and Space Admini strationWashington, D. C . 20546

. . . ~~6. Abstract

Il11111 ISlllll l1111Ill3. Recipient's Catalog No.

5. Report DateAugust 19726. Performing Organization CodeI8. Performing Organization Report No.

E -677910. Work Unit No .

491-0111. Contract or Grant No.

13. Type of Report and Period CoveredTechn ical Note14. Sponsoring Agency Code

The s epa rati on concept of the Skylab Paylo ad Shroud is presented, and its behavior in threefull-scale jettison tests in vacuum is descr ibed. The shroud peta l a r res t ing mechanism isexplained, a s well a s the pri mar y and secondary data acquisi t ion syst ems. The first twotes ts demonstrated the need fo r so me st ructu ral design modif icat ions al though the sep arat ionproc ess was sat isfactory in each tes t . The third test, incorporat ing these design modif icat ions, was sat isfactory in al l aspec ts of shroud performa nce.

7. Key Words (Suggested by Aut ho r( 4 18. Distribution StatementSkylab prog ram Unclassified - unlimitedManned flight Payload shroud testing Space power facility

19. Security Classif. (of this report) 20. Security Classif. (of this page) 22 . Price'Unclassified I Unclassified 1 21 . NO. ";,'"; $3.00

IIIIIIIIIIII I I I I I I I I1 I I I I


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S K Y L A B P A Y L O A D S H R O U D J R T I S O N TESTSb y C h a r l e s J. Da ye

L e w is R e s e a r c h C e n t e rS U M M A R Y

Th re e full-scale jettison te s ts of the Skylab Payload Shroud were conducted invacuum to determine the adequacy of the sep aration concept. The te st chamber is 30.5meters (100 f t ) in diamete r by 3 7.3 'me ter s (122 f t ) tall. The test shroud is constructedof aluminum plate with tra ns ver se stiff ene rs. It is 6.6 me ter s (260 in. ) in diameter and17.1 met ers (56 f t ) long. The complete assemb ly has a ma ss of 11 068 kilogra ms(24 400 lb). The te st shroud used in these te st s is essentially identical to the productionunits.

The jettison tes ts were performed a t altitude, the chamber pr es sur e being 2 . ~ x I O - ~t o r r . N o aerodynamic heating was simulated, since in the mission, jettison oc curs es sentially in orbit. The prima ry data syst em consisted of 18 high-speed motion pictureca me ra s. The shroud separa ted into quadran ts, eac h of which was caught in a catch-net arr es tin g s yste m designed to prevent any damage to the quadran ts. N o difficulty inrea ssembly of the tes t shroud occurred afte r any of the test s.

The test resul ts , that is , center-of gravity velo citi es, outward rota tion , and longitudinal roll , fell well within the performance range established by Marshall Space FlightCenter and its contract or. In the first two te st s, a number of problem s in the sepa ra tion system and in pa rts of the stru ctur e occurred. These resulted in some designmodifications to both the test shroud and the production units. Following incorporationof thes e modifications, a third test demonstrated completely satisfactory jettison per formance. There were no misfirings or malfunctions in any of the firing systems.

INTRO DUCTlONThe Skylab mission re qui re s the largest, most ma ssive payload shroud eve r

launched. Mission succ es s, of course, depends on the succes sful jettisoning of thisaerodynamic fairing. Moreover, i n contrast to mos t other missions , this particularpayload shroud will not be jettisoned until the spa cecraf t reac hes orbital altitude. Thus,


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full-scale tests of the separation concept and jettison proc es s were c onsidered nec essa rto provide missio n anal yze rs with free-flight separa tion dynamics data for evaluation ofthe flight jettison itself. In addition, be cause of the pr es en ce of optical equipment andother experime nts inside the shroud, no free-flying pa rtic les or objects can be tolerated

This report presents a descrip tion and results of the Skylab Payload Shroud jettisontest program carri ed out at NASA Lewis Res ea rch Cen te r's Space Power Facility (SPF)located at the Ce nte r's Plum Brook Station near Sandusky, Ohio. The in-chamber tim eperiod extended f ro m mid-September 1970 to June 1971. The test program was carrie dout by S P F personne l at the r equ es t of the Skylab Air lock Module P ro je ct Office at theNASA Marshall Space Flight Center (MSFC) . The Skylab Payload Shroud was built fo rNASA by the McDonnell Douglas Corporation.

TEST ARTICLE AN D SEPARATION CONCEPTThe Skylab Payload Shroud is an aerodynamic fairing protecting the forwar d portion

of the Skylab clust er du ring launch and ascent to orbit . The shroud mounts on a s t ructure called the Fixed Airlock Shroud (FAS). Th is stru ctu re is mounted on the instr ume nunit of the S-IVB (Saturn V third stag e), which has been converted into an orbit al workshop. Inside the Payload Shroud, fr om the orbital workshop forw ard, a r e the airl ockmodule, the multiple docking adapte r , the Apollo tel escope mount and its deploymentassembly, and a number of ex periment s ca rri ed on thes e modules .

The Payload Shroud thu s is the sam e diameter a s the S-IVB stage, 6.6 m et ers(260 in .) . It is approximately 17 .1 me te rs (56 f t ) tall, is made of aluminum, and has ama ss of 11 068 kil ogr ams (approx. 24 400 Ib). It co ns is ts of two major p ar ts : a cylindric al section 8 . 8 me ter s (29 ft) in length and a conical section 8.2 me ter s (27 ft) inlength. An exploded view of the shroud is shown in figu re 1 and the te st shroud in theSP F assembly area in figure 2.

The Payload Shroud separ ate s into quad rant s. Figure 3 i l lustrates the separationmode a s the shroud is jettisoned fr om the Skylab cl ust er . The separa tion concept is thesame as that used in the A i r Force Titan IIIC universal payload fairing system (ref. 1) ,which has completed a number of successful launches. Th is separation concept us es thega s pres sur e generated by rapidly burning l inear explosive to ac t on a thrusting joint,sheari ng riv ets which hold the whole assembly together, and imparting the nece ssa rysepara tion velocity to the quadrants to jettison them well cl ea r of the spa cec raft . Across-s ect iona l view of the thru sting joint is shown in figure 4. Th is thrusting joint extend s the full length of the shroud . The linear explosive is contained within thestai nles s-st eel tube indicated on the sketch . Rows of po rt s in the tube as semb lie s allowthe ga s generat ed to expand into a bellows, which thr us ts against the piston on the adja

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quadrant, shearing the riv ets and separating the shroud. Figure 5 i l lustrate s theion of the joint. The amount of lin ea r explosive is twice that required to sh ear theets . The linear explosive is ignited by el ect rica lly actuated de tona tors at both of its

Burn time is roughly 2 to 3 milliseconds, and discerni ble movement of the sepa quadrant s occu rs within 8 t o 16 milliseconds. Details of thi s separa tion pro cess ,

s revealed in these tests, a re described herein.On each edge of e ach quadran t, then, the sep aration for ce s a r e tangent to the c ir nce of the shroud. They a r e thus at a 45' angle to the di recti on of movement of

For each quadrant, the vector su m of the se fo rc es produces the net accelting fo rc e on the quadrant in the direction of movement. Moreov er, becaus e the se

are com pres sive , they tend to cur l the shroud edges in, and flexing occur s. Thisan be seen in the films.

The Payload Shroud is held together not only by the shear r iv et s, but al so by dualat both the af t and forw ard ends of the cylindri cal portion of each se pa ra

joint. The pins a r e refe rred to a s "latchpins. ' ' Pr io r to jettison, the pins in theseare retr act ed by line ar explosive and detonator s, as in the separation syste m.

During launch and asce nt, the st ru ct ur al load of the Apollo tele scope mount (ATM)ca rr ied to the cylindrica l portion of the shroud through four linkages, known a s theM Support Assembly. These linkages a r e located a cr os s the four separation lines at

ard end of the cy lindr ica l half of the Payload Shroud, and a r e shown in figure 6 ., the Payload Shroud must sepa rat e not only fr om itself and its mounting on the

Airlock Shroud, but als o fr om the se linkages. Moreov er, it must do th is withoutshocks or vibration to the Apollo telesco pe. For the SP F tests, the

M was simulated by a light str uc tur e to which the ATM Support Assembly was atallowing flight-like operation of these jo ints in the ground te st s.

S pa ce P o w e r F a c i l i t y T es t A r t i c l e a n d D e v i a t io n s f rom F l i g h t A r t i c l eTh ree payload shro uds a r e being manufactured for the Skylab prog ram : One for the

one a s par t of the backup har dware; and one for ground testing both in the testsng described here in and fo r vibration-acoustic tes ting at the Manned Spacecraft Cen ter

A l l three shrouds are essentially identical; the test shroud a s received at S P Fthe other two in two minor aspects :

(1)The two dam per- arm connecting legs near the tip of the cone were re moved.r e used to connect damper a r m s from the tower at the pad, prior to launch. They

ese nt protrusions which could damage the arr es tin g system used to catch and stopjettisoning quadrants in t he ground tests at SPF. Their mas ses were replaced with

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(2) Separation se nso r breakwires, latchpin breakw ires, acce lerome ters, and associated wiring we re added to the unit fo r the SPF test program.

Objectives of the Space Power Facility TestsDetailed objectives and requi rem ents for the S P F Skylab Payload Shroud jettison

tests are given by McDonnell Douglas. Th is is the baseline document for thi s progra m,and its objectives may be summarized as follows:

(1)Demonstrate separa tion of the shroud quadrants(2) Demonstrate separation from the Fixed Airlock Shroud and the Apollo telescope

mount, and assess separation shock(3 ) Verify structural integrity due to separation loads(4 ) Ve r i f y separation performance characteristics(5) Ve r i f y containment of the ga se s generated by the linear explosivesSpecifically, it was predicted by MSFC and its contractor that the separation char

ac te ris tic s would fall within the performance lim its presented in table I . Also, a per-

TABLE I. - PREDICTED DYNAMIC PERFORMANCEOF SKYLAB PAYLOAD SHROUD JETTISON

I m/sec (ft/sec)

11.0

formance range was evolved fro m mission studies. This range is illustrat ed in figure 7, together with the shroud performance fr om the data of the thre e te st s performedat SP F. Any combination of yaw ra t e s and separation velocities falling to the right ofthe line labeled "no recontact - orbital mission'' repr ese nts acceptable performance.The second line, labeled "no recontact - ground test" represents the same performancespecification adjusted for gravity effects in ground t es ts at SP F. Thus, for the SPFtests to be considered successfu l, the data must indicate performa nce range s to theright of the latter line.

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TEST CON FIGURA TION AT SP ACE POWER FAC ILITYThe test configuration at SP F con sis ts of the test shroud and the test support equip

The test support equipment can be divided into three parts: (1) a structural /sy ste m fo r catching and holding the free-flying quadrants without damage;

2) the electrical/electronic sys tem for controlling the te st and collecting ce rtai n data;nd (3) the prime data system, that is , the high-speed motion picture c am er as .

D e s c r i p t i o n of Space Power Fac i l i t yThe Space Power Facilit y is essentially a very la rge vacuum chamber for the testf spacecraft and/or the ir sub sys tem s and components in a simulated space environ

In operation, the facility will provide a vacuum of fr om to torr. Thechamber itself is 30.5 meter s (100 t ) in diameter and 37.2 meters (122 ft) high,22 700 cubic meters (800 000 f t3) . Designed

o include the capability for ground testing of advanced nuclear-electric space powertest chamber is surrounded by a concrete shell 1.8 o 2.1 meters (6 t o 7 ft)

thickness. The facility is shown in fi gure 8, while a cross- sectio nal view through theis illustrated in figure 9 . The view shown in the photograph is from the

To the east of the domed test chamber enclosure is a high bay assemblyea ; to the west is a second high bay workshop called the d issa sse mbly area. The

is a concr ete s tru ct ure designed for the handling of radioactive ma ter ia ls and nuar power sys tem s subsequent to operation in the tes t chamb er.

Test ar t ic les are assembled i n the assembly area, moved to the test chamber, andcompletion of tes ting, moved to the disassembly a re a i f they a r e nuclear devices.

the installation, erectio n, tes ting, and remov al of te st ar ti cl es of la rge si zeght a r e the la rg e ch amber do ors (providing openings of 15.2 m (50 f t ) by 15.2 m

f t ) ) and th re e se ts of standard-gage rails which pas s f rom the apr on east of the asar ea , through the test cham ber, and into the disassembly area. Overhead

nes and other servic es are provided i n the assembly area, the test chamber, and thearea. Direc tly abutting the north side of the concre te te st cham

er enclosure is a te st contr ol cente r for facility operation, control of tests, and data

S t r uctura I l M e c h a n i c a l T es t S u p p o r t E q u i p m e n tThe stopping and catching of free-flying ob jects as large as the Skylab Payload

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Shroud quadrants without damage re qui re s a sizeable structural/mechanical sys tem .The test configuration in the SPF est chamber is shown in figure 10. Four free

standing towers tied together at the top supported four large catch-nets made of nylonwebbing mate rial . The catch-nets wer e laced to side fra me s of aluminum pipe. A typica l catch-net assem bly is shown in figu re 11. Horizontal movement of each catch-netwas controlled by three hydraulic cylinders mounted in the four co rne r towe rs along eacside of the catch-net ass emb ly. Each hydraulic cylinder was connected to a catch-netfr am e by 2.54-centimeter (1-in.) nylon rop es run through a fairlead and spliced to eyebolts on the fra me s. How these r opes we re led through the fairle ads on the supporttowers is shown in figure 12 . The catch-net f ram es are outside the picture ; the hydraulic cylinders are mounted horizontally behind the plate at the top of the pic ture . Thenets w ere placed such that free flight of each quadrant i n the horizon tal dir ect ion wouldbe 1.22 meters (4 f t ) . For a shroud quadrant of 2700-kilogram (5940-1b) m ass impinginon an arresting system at velocity of 6. 55 met er s per second (21.5 ft/s ec) , the peakstopping fo rce will be between 110 000 newtons (25 000 lb) and 134 000 newtons(30 000 lb), depending on the trav el of the arre sti ng s ys tem.

The catch-net fra me ass emb lies were supported vertically by brea kwires whosebreaking strength was slightly gr ea te r than the weight of e ach catch-net and fr am e. Whenthe shroud quadrants impinged on the nets , these w ire s broke , allowing the catch-netfr am e and the quadrant to move outward and downward. Ar re st ing of ve rtic al movement was provided by polyurethane closed-cell foam blocks arrang ed in stacks 3.661meters (12 ft)by 4.9 meters (16 ft) by 1.37 me te rs (4 5f t) high underneath each catch-net assembl y. Each sta ck was secured in place with rope and covered with cotton cloth.The Fixed Airlock Shroud Simulator on which the test shroud was mounted w a s itselfmounted on a structural steel base such that the aft (lower) edge of the shroud was approximately 2.75 meters (9 ft) above the chamb er floo r. Thus, each net-quadrant co m1 bination could free fall 1.37 meters (4 2 ft).

Inside the shroud was an interna l work tower extended up to the cone-cylinder int er face level. Th is tower supported four came ra s and served to arrest the fall of the ATMSimulator as the ATM Support Assembly joints separa ted during the jettison pro ce ss .

To prevent the shroud quadrant s fro m bouncing back out of the net s toward thecenterline of the tes t assembly, a re st ra int mechanism was devised, Inboard and aboveeach catch-net, a rope was suspended s o that the separa ting shroud quadrant would pa ssunder it. This rope was tied to one tower , passed through a fairlea d on the adjacenttower, over a No . 35 Bar ien t ratcheting sailboa t winch, and connected to shock cord pre tensioned to about 2670-newton (600-lb) load. First movement of the catch-net framepulled a pin, allowing the shock cord to relax and thu s pull the rope down. The winchprevented any slackening of the rope due to shroud quadrant impingement. Thesebounce-back re str ain t ro pes acted in about 0. 2 second after the pin w a s pulled, moving

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4.6 meters (1 5 f t ) . A typical bounce-back re st ra int r ope after triggering iswn in f igure 13 . Thus, after jettison , each quadrant was s ecure ly held by the catch-

it and the res tra int rope inboard of it .The principal elemen ts f or adequately minimizing the peak stopping fo rc es on thelying shroud quadra nts we re the hydraulic cylinder ass emb lies . A s noted pre

six of these connected to it by m ea ns of nylon rope s. Aatic of the circu itry used is shown in figur e 14. The cyl inders had a bore of1meter ( 2 ~ i n . )nd a maximum str oke of 1 . 2 2 meters (4 8 in . ) .The continuing outward motion of the shroud segments after net impact extends the

der shaf t. The piston thus dis places the incompressible hydraulic fluidthe accumulator, where the trapped nitrogen gas is compressed. The kinetic ener

y required to com pre ss the gas is the energy supplied by the moving shroud segment asdecel erates . The compression char act eris tics of the nitrogen gas closely approached

Use of the accumulator to dis sipate t he shroud segment energy has the following:(1 ) When the shroud impacts the net, the cylinder reaction force is a minimum.

s tends to decr eas e the initial decelerating force on the s hroud.(2) The accumulator precharge pres sur e is not cr it ic al when a range of jettison

is expected. If the shroud velocity were higher than predict ed, the cylinderuld simply strok e longer and thus co mp ress the ga s to a greater degree.

(3 ) No pretensioned spring s, and so forth, were required. P r io r to a test, theto the desired p re ss ur e and sealed.

The total trave l involved in stopping a free-flying shroud quadrant is the su m of thef the hydraulic p isto ns plus the st re tc h in the connecting rop e plus the outcomponent of the str etc h in the catch-net. The la tte r two a r e , of co urs e, ela stic ,

d will re tu rn some of t heir potential energy to the quadrant, which will bounce backh an equal kinetic energy. The cha ract er is tic s of each of the se components a s de

r e shown in figure 15 . For less than 689x10 3 newton-per-mete r (100-psi) prech arge, the hydraulic cylinder charac teristic moves to the

on figure 1 5 .T o es tim ate an expected bounce-back velocity, shroud quadrant bounce-back energy

equated to elastic energy sto red in the ropes plus the catch-net. The result indicatedce-back veloci ties between 3 . 0 5 and 3 . 9 7 met ers per second (10 and3 ft/sec) can be expected, depending on the pr eci se shape of the nylon st re ss -s tra in

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sta rtup of the ca mera , existed especially in the Mitchell reg ist er -pin cam er as . The refore , a slow-start device was used with the Mitchell came ras . This device utilized atime-delay relay and voltage spl itte r circui t, allowing the ca me ra to start slowly at abou60 fr am es pe r second for a period of 2 seconds, af te r which the camer a automaticallywas switched to f u l l speed of 500 fr am es per second. The slow-sta rt device was placedin line with the power le ads and w a s located inside each container housing a Mitchellcame ra. With this approach, no data were lo st due to film breakage.

The c am er a fie lds of view were illuminated by 1000-watt photographic flood la mps.Two to four such lamps w ere re quired for each cam er a, depending upon thei r locationand distance from the ta rg et s. The lights were manually turned on approximately1 minute before jettison and manually turned off approximately 2 to 3 minutes aft er jettison.

Since the,run tim es of the Mitchell and Fai rchi ld c am er as a r e 8 and 4 seconds, respectively, they were started automatically by the Discrete Events Programmer suchthat th er e would be no danger of missing the 1/2-second-duration shroud separati on.A l l 500-frame-per -second ca me ra s turned themse lves off upon running out of film. The1000-frame-per -second camera s were switched off by the Discr ete Eve nts Prog ramm er .Because of high power requirem ents during sta rtu p, the c am er as were sequentiallystarted in four group s of four c am er as each and one group of two ca me ra s. The ratioof starting cur rent to run curre nt w a s approximately 3 to 1.

A calibration run for each cam era was made pr ior to the first test. An aluminumrod graduated in 5.08-centimeter (2-in.) incr eme nts was suspended in each came ra' sfield of view along a line which the ta rg et portion of the shroud would follow during jettison. A ree l of film w a s then exposed and pr ocessed. This reel of film was retained andused a s the distance calibration in analyzing velocity data fro m the film s.

T es t C o n t r o l S y s t e mThe test control system is the equipment required to conduct an integrated s epa ra

tion test and data collection operation. The major el ements of the syste m include (1)theDiscrete Events Progra mme r, (2 ) the detonator circuits, (3 ) the camera and lightingcircui ts , (4 ) the instrumentation s ys tem , and (5) the FM and computer recording equipment. The system design used minimized the chance of inadvert ent operation by providing electri cal arm -sa fe switch feature s. In addition, the design provided for panel display of the s ta te of cri ti ca l components to aid in ana lysi s of possible sy stem malfunction.This latter feature is important because thes e components a r e located in the vacuumchamber and ar e not accessible f or checking while the chamber is evacuated.

ILiscrete Events Programmer. - The Discrete Events Pro gram mer , designed andbuilt at SPF, generated up to 12 discrete signals in a pres et sequence to command events

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occur. The time base was derived from the 100-hertz output of a crystal-controlledWWV. There we r e a total of 12 set and 12 reset thumbnail switch

s to provide the 12 sequenced events. The elapsed time (from progra mmer start coma given event to begin w a s selected by dialing its channel se t thumbnail switch,

ch was calibrated in 0.01-second units. The re se t time was selec ted in a like manA programmer abo rt feature was provided which stopped the timed event sequence

d reset the counter to z er o in the event a "go" condition was not pres en t when the firend came on. This ab or t signal w a s derived from the separation firing unit charge

so that the te st would be aborted i f any one of the units fa iled to charge proper2.5 seconds aft er charge command was given. The pro gramme r thumbnail

ect or sw itches were positioned pri or to beginning the test , and a clear plastic covera s insta lled to prevent accidenta l change of setting. The sequence of events used dur

the te sts is given in table III.

TABLE 111. - DISCRETE EVENTS PROGRAMMERSEQUENCINGEvent

Programmer start Camera groups 1 and 2 s ta r t Camera group 3 s ta r t Separation firing unit charge command Camera groups 4 and 5 s ta r t Test abort scan Separation firing unit fir e command System safe commands:

Latch firing unit panel safe Separation firing unit panel safe 117 volt and 28 volt safe Camera groups 1 to 5 and camera 19 stop

Computer stop

Time,sec05.00 5.50 8.00 9.00

10.5011.0020.00

30.00

Detonator circuits. - As noted previously, the Skylab Payload Shroud separationinvolves two different syst em s activated by linear explosive energy. Thus,

ar e two separate sets of detonators: one to activate the separatio n system itself,ne to re tr ac t the latchpins prior to separation. Thus, there wa s flight cabling runeach detonator in both sets to connectors at the base of the shroud. SPF circuitry

at these inte rface s; on jettison these connectors were pulled apart by lanyards .this arrangement, SPF provided two se ts of detonator ci rcu its : one to arm and

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fire the latchpin retra cto rs prio r to separation, and one to arm and fire the separationunits. These control circ uits provided separa te rela ys to arm the latchpin firing unitsbus and the separa tion f iring unit bus.

The latchpin firing un its were charged by applying 28 volts dc to the charge input.This charged a capac itor in the firing unit to 2300 volts. A 500/1 voltage divider fed a4.6-volt signal back to the control room, where elec tronic c ircu its evaluated the signaland turned on a light when the signal ro se above 4.0 volts. On the fire command,another electron ic cir cuit noted the sh arp de cre as e in capacitor voltage and turned on afi r e light. There was one charge light and one fire light for each firing unit. Provisionw as als o made for monitoring the state of pulse se ns or s (simulated detonato r-electr icalload) during checkout prio r to the actual test. For the latchpin system, charging andfiring w a s done manually; i f any malfunction was indicated, a hold could be initiateduntil a decision was made.

Similar circ uitry and operation applied to the sepa ration firing units, except thatthese operations were done automatically in the Discre te Events Prog ram mer. Thissystem included circuitr y for verification that all firi ng units were charged: i f this condition was not met, the automatic sequencing stopped and an abo rt existed. As with thelatchpin control system, provision wa s included for monitoring the state of pulse sen so rsduring checkout.

Cam era and lighting circui ts. - Cam era lights were turned on manually pr ior to thete st by panel controls. The cam era s were operated in five different groups (three acand two dc voltage driv es). Relays were provided to separatel y energize the ac and dcsupply buses. The cam er a run circuits als o provided for a 1-second timed pseudo-runfor use during checkout and testing. The IRIG A neon lamp cur rent was monitored foreach cam era to provide an indication back to the control cen ter that the time code information was being supplied to the camera.

Instrumentation sys tem . - The instrumentation system consisted of nine triaxialaccelerometers mounted on the Payload Shroud and ATM Support Assembly, latchpin andsepara tion breakw ires, and miscellaneous para me te r measuremen ts of the detonatorsystem.

Endevco 2261M piezoresistive accele rome ters were used on triaxial mounting blocksto provide shock data at nine locations on the separatio n points, pin-puller brackets , andATM support mounts. Seven of the acce le rom eter s were on two of the shroud quadrants.Cabling to these sensors , as well as to the breakwires, was by means of an umbilicalcable strung from the int erna l work tower to the center of gravity of the shroud. Excitation and conditioning for the acc eler ome ter channels were supplied from bridge conditioning equipment in the data room outside the test chamber.

Sixteen pin-puller breakwires were installed on the latchpin pullers to obtain verification that the pins were retr act ed. From these continuity loops, signals were derived

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which turn ed on 16 lights on the panel when the pins were re tra cte d. On the first test,eight breakw ires were installed to monitor separation. Four additional breakw ires wer einstalled for the second and third jettison tests.

~ ~ ~ ~ _ _M and computer recording equipment. - Three 14-channel_FM tape reco rder s wereused to reco rd test data. Two of these were used for 24 acc eler ome ter channels. Thethird recorded three accelerometer channels along with 60 channels of multiplexed back-up data. A l l rec orde rs were operated at 60 IPS (1.53 m/sec) . Each magnetic tape hadone channel of IRIG A recorded for time correlation, along with a 200-kilohertz reference signal for data processing uses . The multiplexed data recorded 10 channels pertape channel with l-kiloher tz bandwidth. The data include firing unit charge cur rent s,fire cu rre nts , capacitor voltage, b us voltage, and breakw ire data.

SHIPPING, ASSEM BLY, AN D INSTALLATION OF TEST SHROUDThe Payload Shroud for the S PF te s ts w a s completely assemble d in the cont rac tor's

plant. The final assem bly mode used was essentially the s ame a s that to be used at SPF,and the same a s that to be used with the flight shroud a t Kennedy Space Center . Following the initial fitup, during which no problems were encountered, the test shroud wasdisasse mbled into four cylindrical quadran ts and four conical quadrants. These eightpieces were shipped by truck t o SPF . A s each truck arri ved, the shroud segment w a soff -loaded onto a rai l road car .

In the SPF high bay asembly area, a stacking plate was mounted on an additionalflatcar, and leveled with jacks so that all the points on which the bottom edge of theshroud res ted were within *0.079 centimeter (*1/32 in. ) of a t rue flat plane. Figure 17illu stra tes the stacking plate in place on the rail road c a r . Suitable la ter al support forthe shroud segmen ts and inte rnal work scaffo lds was provided. Figu re 2 shows the conica l half of the shroud res tin g in place on thi s stacking plate.

In the reassembly sequence, the cylindrical portion of the test shroud was reassembled first, then removed from the stacking ring and placed on wood blocks on thefloor of the assemb ly ar ea . The stacking plate w a s then used to reassemble the conicalportion of the t es t shroud, and the conical portion was then mated to the cylinder in theassembly area to assure good alinement of the surfaces before final mating inside thechamber. A f t e r this check, the conical half was set aside, and the cylindrical h a l f wasrepositioned on the stacking plate and moved into the cham ber. It was then lifted overthe interna l work scaffold and mated to the FAS Simulato r. The laminated shi ms andtension cleats wer e then bolted in place. These flight components are illustrated in figure 18. The ATM Simulator was insta lled next. A t the sa me time, the conical half ofthe test shroud was returned to the stacking plate, and the separat ion syste m linear ex

13


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plosives were installed i n it, while those fo r the retracti ng pins w ere installed in thecyl indrical half. The con ical half of the test shroud was moved into the cha mber andlifted into place on top of the cylindr ica l half. The two hal ves were then bolted togethe rand the li nea r explosive fed through the separ ation s ys tem tubing on the cylindrical half.Pulse se ns ors wer e installed in place of detonators, and the test shroud was then readyfor a dry run checkout.Refurb ishment of the test shroud for the second and third tests was carrie d out inthe SPF assembly area. The separated quadrants w ere removed fr om the catch-netsand returned t o the assemb ly area. They were reworked and reassembled into the twoha lve s. Mounting on the test stand and final rea sse mbl y for t he second and third teststhen proceeded the same a s for the first test.

TEST PROCEDUREWhen all install ations and checkouts were complete, a pretes t review was held.

Following the revi ew, execution of the te st proc edure was initiated. Although the jettison test itself took less than a second, about 5 days "in test" were involved in runningeac h of the thr ee tests performed. A complete dry r un at vacuum was performed. Thevacuum chamber was returned to ambient pre ss ure , and film from all came ras removedand developed. Following cam era reloading, the dry run pulse sen so rs were replacedby the linear explosive deton ators. The chambe r was seale d, and pumpdown for the testitself was initiated. A l l operations fro m initial closing of the chambe r for the dry r unthrough return ing the chamber to ambient pres su re following the ac tual test were governed by a detailed checksheet te st procedure . All events were manually controlled upthrough the re tracti on of the 16 latchpins. Following an ar bi tr ar y hold after latchpin re tracti on, events through jettison were trig ger ed automatically upon sta rtin g the Dis cre teEvents Programmer.

A f t e r each test, upon opening the chamber, a safety inspection was made. A l l detonat ors were moved. Then a detailed inspection of the shroud quadrants , t he test supportequipment, and the surrounding a re a was perfor med. Detailed me asu rem ent s of the location of each quadrant in the polyurethane foam blocks were made , as well as theamount of extens ion of each hydraulic piston in the arr es ti ng sy st em . Any ano mal ieswere noted. Prepa rations for removing the shroud quadrants fro m the catch-nets wereinitiated. The shroud quadrants after jettison, in the catch-net sy stem, are shown infigure 19.

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TEST RESULTS The resu lts presented here a re those measure d fr om the data by S PF personnel.

xcept for observing that the major results of the jettison tests, that is , the separationSPF did not

empt to int erpret any of the test results as fa r as flight implications w ere concerned.s includes a number of even ts which occu rred in the first two tests, resulting in ar of des ign modifications to the test shroud and the production units. Those in

est ed in such asp ec ts of this test program should contact cognizant MSFC personnel.er pressure for all three tests was approximately 2X10-4 t o r r .

S e p a r a t i o n V e l o c i t i e s a n d Y a w R a t e sTable IV lists the cen te r -of -gravity separation velo cit ies , yaw rates, and roll rat es

or all three tests performed at SPF. From figure 7, it can be s een that while the mea sured yaw-rate range was lower than that predicted, the center-of-gravity velocity range

within the lower half of the range pred icted. Moreover , the measured ranges fellwithin the acceptable performance limits established by the MSFC Payload Shroud

TABLE IV. - SUMMARY OF SKYLAB PAYLOAD SHROUD JETTISONTEST RESULTSNorth South

Easti Test I Quadrant Ia I Quadrant I1 Quayr::t I11 I Quadrant IVCenter -of -gravity separa tion veloci ties, m/sec (ft/sec)1 5.32 (17.42) 5.30 (17.37) 5.25 (17.18) 5.28 (17.28)2 5.41 (17.72) 5.18 (16.95) 5.22 (17.10) 5.44 (17.80)3 5.05 (16.51) 4.75 (15.53) 5.05 (16.53) 5.00 (16.38)

I Yaw ra te s, r ad/sec (deg/sec)1 0.0925 (5.3) 0.1135 (6.5) 0.124 (7.4) 0.117 (6.7)2 ,228(13.1) .215 (12.3) .227 (13.0) .187 (10.7)3 .133 (7.6) .0750 (4.3) .147(8.4) .138 (7.9)

I Roll rates, rad/sec (deg/sec)1 0.232 (13.3) 0.263 (15.1) 0.326 (18.7) 0.241 (13.8)2 0 (0) ,0977(5.6) .195 (11.2) .248 (14.2)3 .138 (7.9) .0977 (5.6) .037 (1.9) .lo5 (6.0)

aContains spherical nose cap.

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contractor fro m mission considerations. Thus, f ro m this standpoint, all three testssuccessfully met MSFC requireme nts.

R o l l R a te sN o limiting specifications on allowable quadrant rol l rates were established for this

prog ram . Instead, MSFC and its contractor analyzed measured ro ll rates from thestandpoint of possible reconta ct of a quadrant aft co rne r with some part of the spacecraft. Quadrant ro ll rates measured in the jettison tests a r e shown in table IV. Themaximum SP F roll rate measured was 18.7 degree s per second and the minimum, zer o.MSFC- contractor analy ses of t hese data indicated that the range measured in the SP Ftests is acceptable.

A c c u r a c y of Phototo -op tic M ea su re m en tsCalibration. - The major s ource of e r r o r in calibrating the data cam er as was due

t o resolut ion limitations on the film of the m arked inc rem ents on the calibrat ion ba rs .The incre men ts when measured on a Vanguard film data analyzer were found to have amaximum disp ers ion of *2.4 percent of the value, over a cal ibra tion range of 1.22meters (4 f t ) .

Velocity calculations. - The quadrants did not sep ara te at precisely right angles toeach other, that is , at 45' to the data ca me ra s. In addition, quadrant flexing occurred.These observations are discussed lat er , in the section Traje ctor ies and Flexing ofQua dran ts. Because of the flexing, it was not possible t o measu re precisely the deviation of the quadrant "flightpath" fr om a t rue 45' angle to the data cam era s. For thefour cam er as photographing separation near the nose cap, this e rr or was estimated tobe a maximum of 6 perce nt; for the four ca me ra s photographing separation at the shroudbase, the er ro r was estimated to be 1 percen t. The difference is due to the fact thattrajec tories and flexing could be measured more accurately at the base, with the up-looking cam er as , than at the nose cone region.

Came ra film velocities. - The actual speed s (frames/ sec) of the fil ms in all camer as used in the tests wer e measured by using the IFUG A time code along the edge ofthe film. These speeds were used in calculating the tes t res ult s; however, since thefilm velocities could be determined very accur ate ly, the e r r o r involved in measuringthem was negligible compared to other sou rces .

Fr am e uncertainty. - In determining the number of f r ames of f ilm for a targetimage to tra vel a known distance, the re was a maximum of *1/2 frame uncertainty be

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tween data analy zers; this amounted t o a maximum of i2 percent for 0.305 meter (1 f t )of t ravel .

Total effect. - The total effect of these uncertainties on the s eparation chara cte ris ic s of table IV are given in table V.

TABLE V . - PHOTO-OPTIC MEASUREMENTACCURACY SUMMARY

Er ro r due to calibration bar:Nose cone ar ea ca mera sBase cameras

Er ro r due to variance in angle of flight:Nose cone area camerasBase cameras

Error due to uncertainty in determiningnumber of fr am es per distance traveled -nose cone area cam eras and base c amer as

Maximum er r o r in calculating tip velocitiesMaximum error i n calculating base velocitiesMaximum error in calculating center -of -

gravity velocities

I n i t i a t i o n of S e p a r a t i o n P r o c e s s

E r r o r ,percent

+ 2 . 4*2.0

*6.1 i l . 0*2.0

* l o . 5*5.0*7.2

The longitudinal sepa ration s yste m is fired at the aft end of e ach sep ara tion joint.t a nominal burn velocity of roughly 6100 met ers per second (20 000 ft/sec) for the

ine ar explosive, between 2.5 and 3.0 milliseconds ar e required for the explosive torn the enti re length of the sepa rat ion joint. Some tim e is then required for the ga s

enerated t o build up sufficient pr es su re i n the joint bellows to initiate sh earin g of t heriv et s holding two adjacent quadrants together. A t th is ti me , outward movement of thepayload shroud quadrants begins. This process is il lus trated by the data of table VI ,which correlates data from accele romete rs, breakwires placed ac ros s the separationjoints, and the high-speed c am er as . The data shown are from jettison test 3. Thesketch indicates the approximate locations,of the instrumentation along the s epa rat ionjoints. The acce lerom eter tra ce s showed an initial vibration or shock, followed by atime delay, followed by a lar ge r shock. The data shown are t imes measured to the lead

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1 0

TABLE VI. - SKYLAB PAYLOAD SHROUD ETTISONTESTS - ANALYSIS OF INITIATION O F

SEPARATION PROCESS, TEST 3Position along Accelerometer data Breakwires Cameras

separationjoint

Timea, msecA f t end 4.8 17.6Mid cylinderTop cylinder

5.05.7

15.014.7 ..

Bottom conicBiconic interface

6.26.3

10.911.1 .-Aft end0.I7.1 9.9 L

. . . 1 . *1 ~ *. . " -.--'lime s ar e averagea eiapsea rime s aIrer Iir e commana Ior ailfour separation joints.

ing edge of each of these indications. The column labeled "first vibration" is taken tobe an indication of th e pr og re ss of the explosive detonation fr om the aft end of the shroud(bottom in th ese tests) to the forward end. Note that the time taken is, on the averag e,2 . 3 milliseconds, about what would be expected. The column labeled "first shock" indicates the initiation of separa tion a s rive ts a r e s heare d, with the forward (top) end ofthe separa ting quadr ants moving out first. This a gr ee s with the yaw ra te s given intable IV . The ca mer a data in the la st column als o indicate the s am e thing. A slighttime lag between the tim es a s indicated by the acce ler om ete rs and first discerniblemovement a s indicated by the cam er as is to be expected, since the latter w ere dete rmined visually.

The breakwire ti me s noted in table IV indicate that the wi res broke upon detonationof the linear explosive, and not on the initiation of separation. These wi re s we re rat he rfine, somewhat britt le mat eria l furnished and epoxied in place by the MSFC contractor.

Trajectories and Flexing of Q u a d r a n t sIdeally, the shroud quadrant s sepa rate and follow tra jec tor ies a t right angles to each

oth er . With the test shroud orientation used in the SPF chamber, this would be nort h,ea st , south, and west. For the data came ra locations specified, th is would be exactly45Oto the optic axis of the cameras looking at ta rg et s on the si de s of the shroud. Th isdid not quite happen. None of the quadrants in any of the tests separa ted exactly along18


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its ideal trajecto ry. Figure 20 is illustrative of plots that were made of the motion ofthe lower co rn er of ea ch quadrant made from the 1000-frame-per-second uplookingcameras . It shows the horizonta l movement of the c or ne rs of quadrant I (east) andquadrant IV (south) in test 1. Meas urement of a stra ight line drawn through these pointsfor the edge of quadrant IV indicates a deviation of about 5.5' fr om the idea l path. Figure 2 1 is a map of where eac h quadrant cam e to r e s t in the polyurethane blocks. It indicates that quadrant IV in test 1 came to rest between 5 and 6' away from the idealpath. This is the maximum deviation which occurred.

Figure 20 also is ill us tra tiv e of the flexing of each separating quadran t. It can beseen that thi s flexing tended t o damp out after about 0.305 meter (1 f t ) of tra ve l. Thus,the SPF-m easured shroud velocitie s quoted in table IV were taken f rom the film whichcovered the second 0.305 me ter (1 f t ) of tra ve l. The maximum disp lacement of th isflexing observed (at the lower corn ers) wa s approximately 2.54 centimeter (1 in .) . Itis not known whether the displacements along the separa tion joints toward the forwar dend of the shroud were any great er than th is . Flexing along the joint could be observedin the film, but it was not possible to measur e it. This flexing of the shroud qua drantswas entirely e lastic in all three tests; there was no difficulty rea sse mbli ng the testar ti cl e afte r any of the tests.

L a t c h p i n P e r f o r m a n c eIt was mentioned that, in addition to the riveted separation joints, the shroud quad

ran ts a r e held together prior to jettison by eight linkages, essentially steel plates with ahole near each end, one on ei the r side of a separa tion joint. Through each hole passe sa pin which is retracte d prior to jettison. Thus, there are 16 latchpins. If at le as t onein each of the eight plates re tr ac ts , separation is possible. These pins a r e retracte d bya linea r explosive system the sa me a s that used for actual jettison. In the S PF tests,the pullers for these pins were f ired manually prior to initiating the automatic test se quencing. The MSFC requirem ent was that all 16 must re tr ac t before proceeding witha jettison test. This requirement was met in all three tests; that is , no latchpin failedto re tr ac t in any of the thre e tests.

La nya r d Disco nne c t sElec tric al power to both the latchpin retr act ion syst em and the se paration firing

systems is supplied from the spacec raf t to the Payload Shroud by cables which arejoined by connectors ac ro ss the FAS - Payload Shroud inte rfac e. Lanyard s are fixed

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23/41

thes e events, ana lyse s of them, and the resultant design changes are beyond the scopeof thi s rep ort . The following prob lems were observed:

(1)Oscillation of the forward nose cap caused recontact with the other three quadrant s, resulting in metal chips falling through the shroud inte rio r.

(2 ) The trans vers e member fastening the conical half of the shroud to the cylindrical half failed structurally.(3) A larg e number of sheare d rivet s on the separation rail flew free.

(4) On the second test the tubing containing the lin ear explosive burst at all fourelbows leading into the rail assembly at the aft end of the shroud.

No problems in the test shroud occurred in the third test.

PERFORMANCE OF TEST SUP POR T EQUIPMENTThe separating shroud quadrants moved out of the field of view of the data c ameras

almost at impingement in the catch-nets, and the ca mera showing the ove rall view wasnot cal ibra ted fo r making measur emen ts involving perf orma nce of the mechanical testsupport equipment. Thus , only qualitat ive information can be provided concerning th isequipment.

Post -tes t measure men ts and visual examination of the fil ms from the ove rall viewcamera led to the obser vations disc usse d in the following para grap hs.

Peak Stopping Fo rceThe total movement of all the hydraulic pistons was measur ed following each te st .3The overall range was from 0. 48 to 0.94 meter ( 18 3 o 37 in. ), depending upon the

cylinder position (the lower ones moved least) and the test. The overall average wasabout 0.76 meter (2.5 f t ) . Fro m these measur ements and from simple impulse theory,it was es timated that peak stopping fo rc es averaged about 116 000 newtons (26 000 lbf).

P e r f o r m a n c e o f P o l y u r e t h a n e BlocksA s discuss ed previously, bounce-back ve locities in the range 3.0 to 4.0 meters per

second (10 to 13 ft/sec) were expected. Visual study of the film s support the notion thatthe actual bounce-back velo cities in these te st s wer e much lower. The aft (bottom)edge s of the shroud quadrants have a rather wide flange attached to them, for mounting

21


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on the FAS Simulator, as indicated in figure 18. Thi s flange penetrated the polyurethane5blocks between 0.067 and 0.153 meter (23and 6 in.) , with the average estimated to be0.089 meter (3.5 in .) . Thus, apparently, the poor elasticity of the foam blocks reducedthe bounce-back to about half that expected. Consider ing the inexpensiveness of thefoam blocks, the ir ready availability, the fact that little engineering was required, andthe beneficial re su lt s obtained, the use of these blocks was one of th e mo re interesti ngas pect s of th is test program. The aft end of a quadrant res tin g in the cloth-coveredfaam block ass embly is shown in figure 22 . The energy absorption in the foam, ofcourse, was beneficial to the opera tion of the bounce-back re st ra in t rope shown in figure 13.

Catc h -Nets and TowersVisual study of the films indicated that once a jettisoned quadrant impinged in itscatch-net , the two moved outward and downward as a unit: that is , little or no sliding of

the quadrant relative to the net could be observed. Of course, after the breakwiressupporting the catch-nets ve rtically broke, they wer e unrestra ined i n vert ica l motion.Impact of the quadrants in the nets was sufficient to produce noticeable flexing of theside frame s. N o damage to the tes t shroud occu rred , although a fra me and a quadrantedge did touch in at l ea st one cas e. N o problems with the tower assemblies were encountered i n any of the tests.

Bounce-Back Rest r a nt SystemIn the first test, the rope shown in figure 13 struc k the spherica l nose c ap attached

to that quadrant. It slid off outboard of the quad rant , and the par ticu lar quadrant cameto rest leaning against the central struc ture . N o damage could be detected to the testshroud. In subsequent tests, the tension in the shock cord w a s increased somewhat, andall four mechanisms performed sa tisf acto rily. It should be noted that the winches wereobviously not designed fo r vacuum operation. To condition them fo r vacuum operation,they were dismantled, cleaned , and relubrica ted with vacuum oil. Th is did not appearto affect their operation.

Pr im ar y Data Sys temA s previously noted, 18 cam eras were installed a s the primary data s ystem for

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TABLE Vm. - CAMERA PERFORMANCEAND MEASURED FILM SPEEDS

Camera

Upper targetdata cameras

Lower targetdata cameras

Camera insideshroud

Upward-lookingcameras

Film speed, frames/sec495.0 496.0 494.0 499.0 498.0 495.0 495.5 509489.0 488.0 490497.0 478.5 433

(a) 495.0 496943.5 836.0 872 855.3 778.0 905 956.5 863.0 911 936.0 855.0 886

b870.6 893.0 822 1021.8 982.0 1010 1132.0 1037.0 1085 821.3 780.0 918

Overhead camera I (a) 497.0 I 501aCamera malfunction.bEstimated.

these tests. Thus, for the thr ee tests, a total of 5 4 camera runs were made, excludingcalibration and dry runs . In the first test, two cam er as failed to operate: the overheadcamer a and the one target c ame ra. There were no cam era malfunctions in either thesecond or third tests. A summary of ca mer a perform ances is given in table VIII.The film speeds shown wer e used in calculating the shroud separatio n velocit ies. Th er ewer e approximately 80 floodlights used in conjunction with the primary data camera system. The lam p envelopes we re exposed to the vacuum. In the third test, one of theseburned out. Th is was the only lam p failure which occurred; it did not affect the obtaining of photographic data.

CONCLUSIONSThr ee full-scale jettison tests of the Skylab Payload Shroud were conducted at the

23


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I I 11111 I I1 1111 III 11.11 I1 I11111 II,I. 1111 I 1 1 1 1 . 1 , I 11.1-, -..,

Lewis Research Center 's Plum Brook Space Power Facili ty. The following conclusionswere reached:

1. Skylab Payload Shroud quadrant s epa ratio n velocit ies and yaw and ro ll rates, asmeasured through the us e of high-speed motion picture c am er as , f ell well within theperformance envelopes established by MSFC and its contractor.

2 . A l l detonators, redundant or not, in both the latchpin retraction syst ems and theseparation syste ms fired in all th ree tests.

3 . Various problems o ccurring in the first tw o tests resulted in design modificationsto both the t es t shroud and the production units. No problems occurred in the third test.

4 . The structural/mechanical test support equipment, designed to catch and arrestthe free-flying shroud quadrants, functioned as designed. N o difficulty in refurbishmentand rea sse mbly of the shroud after the tes ts was experienced.

5. Out of 54 runs , two cam era malfunctions occurre d. There was no significant los sof data, however.

6. N o pro blem s of any significance occurr ed with the elect rica l /electronic control/data systems .

Lewis Research Center,National Aer onautic s and Space Administration ,

Cleveland, Ohio, May 8, 1972,491-01.

REFERENCE1. Burch, B. A . : Titan III-C Payload Fairing System Full-sca le Separation Te st. Rep.

AEDC-TR-68-247, ARO, Inc . (AD-846062L), Ja n. 1969.

24


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CD-11276-22

\ F i g u r e 1. - Payload S h r o u d major assembly breakdown.

2 5


28/41


29/41


30/41

304 -S t a i n less -st ee l tube, ,-Piston1 ,-Cylinder r'rI Fram e \I fI I r F r a m eit w3

CD- ,11278-22.II L B e l l o w s in s t a ll a t io n , b u t y l -I r u b b e r - c o a t e d w o v e n f a b r i ciI

L O . 318 -cm (0 . 125 - i n . 1 d i ama l u m i n u m w i r e

F i g u r e 4. - P a ylo a d S h r o u d ty p i c a l s e p a r a t i o n t h r u s t i n g jo i n t .

,c B e l l o w s

C y l i n d e r S e p a ra te d p o s i t i o n\\ r B elC y l i n d e r P i s t o n

CD-11279-22P o s i t i o n at e n dof p o w e r s t ro ke

F i g u re 5 . - P a y l o a d S h ro u d - a c t i o n of se p a ra t i o n sys t e m .

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m

j L a t c h p i nT en sio n l i n k 7 I\ \ I ,-Shim

\ -L a te ra l s u p p o r t

L P i n p u l l e r sC D-11280-22

F i g u r e 6. - P a y lo a d S h r o u d A T M S u p p o r t A ss e m bl y.

Pred icted da ta rangeT e s t d a ta r a n g e f o r t h e t h r e e t e s ts

a,c e3 .

0 1 2 3 4 5 6 7S h m u d q u a d r a n t c e n t e r - o f - g ra v i t y v e lo c i ty , m / s e cI ! I0 5 10 15 20S h r o u d q u a d r a n t c e n t e r - o f- g r a v i ty v e lo c i ty ,f V s e c

F i g u r e 7. - P e r f o r m a n c e e n ve lo p es a n d tes t d a t a ra n g e f o r S ky l a bP ay lo ad S h r o u d g r o u n d j e t t i s o n tests.

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._ ,

Figure8. - Space Power Fac i l i t y .

30


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St ee l l i n e r pae

1.83-111 (6.0-ft) /- Te s t ch a m b e r : d i a m e t e r ,30.5 m (100 ft); h e i g h t ,

.-n c l o s u r e d o o r: c l e a r- - C h a m b e r d o o r c l o s e d C h a m b e r d o o r area, 15.2 m b y 1 5 . 2 mc (50 ft by 50 ft). .

N A S A t r a n s f e r e n g i n e ,B r i d g e s f o l d ed d o w n

m e c h a n i s m8391-S

p u m p sF i g u r e 9. - C r o s s s e c t io n t h r o u g h t e s t c h a m b e r o f S p ac e P o w e r F a c il i ty .

31


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Wh)

F i g u r e 11. -T yp ica l ca tch -ne t assemb ly .

F i g u r e 10. - T e s t s h r o u d m o u n t ed i n Space Power F ac i l i t y chamber p r io r tos t a r t of t es t p rog ram.


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F i g u r e 12. - Fai r lead and camera mount ing on suppor t tower . F i g u r e 13. - T y p i c a l b o un c e -b a c k r e s t r a i n t r o p e - a f t e r t r i g g e r i n g .

WW


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-B l adde r - t voe ,- Oil r e t u r n v a lv e- .accumulator,-...-..-... - C h e c k v a l v e,

gaseous ,/' H y d r a u l i cn i t r o g e n1 f l u i d 7\A C v l i n d e r

CD-11281-22F i g u r e 14. - H y d r a u l i c c y l i n d e r s c h e m a t i c .

i

2

1

IF i g u r e 15. - C h a r a c t e r i s t i c s o f a r r e s t i n g m e c h a n i s m c o m p o n e nt s .

34


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I/ Topwalkwayw i t h h a n d r a i l 7I I,Camera r V i e w i n q a re a s/ ,rTelevision \I I ,I ( typicai)s o u t h w a l l II ! I i / ' l- 'I-Tower legsB a se o f s h r o u d

F i g u r e 17. - Stack ing p la te.

(8.0 R)' S h r o u d S i m u l a t o rF i g u r e 16. - Data camera locat ions fo r Sky lab Payload Shroud je t t ison tests.Ln


38/41

wQ,

A ft s h r o u d s u p p o rtf r a m e-,

\ \ ,.Sky lab Pay loadS h r o u dtcFA S S i m u l a t o ra n d t e s t

s u p p o rt s t r u c t u r e

C D-11283-22F i g u r e 18. - P a y lo a d S h r o u d m o u n t i n g o n te s t s u p p o r t s t r u c t u r e .

F i g u r e 19. - S h r o u d q u a d r a n ts after a test,


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000

Distance f rom re ference po in t , cmFigure 20. - M o v e m e n t o f a f t c o r n e r s o f two ad jacent quadrants a f te r je t t ison - view ing upward. Came ra speed, 870.6 f rames per second; data p i n t s a t two- f rame inte rva ls .

W4


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20. % cm (%1 in . ),1.91 cm test 1, \ -2.146 m (84- in. ), t e s t 3 (3/4 in. ), I / / 2

North CD -11284-22 F i g u re 21. - Posi t i on of sh ro u d q u a d ra n t l o w er e d ge s a f t e r t e s ts .

F i g u r e 22. - A f t ( l o w e r ) e d ge of s h r o u d q u a d r a n t i m b e dd e d i n p o l y u r e t h a n e block.38 X A S A - I . : ~ ~ ~ ~ . ~ ~ ~ ~ ,972- 3 , E-6779


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skylab payload shroud jettison tests

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