Saturn IB-Saturn v Instrument Unit Technical Facts - [PDF Document] (2024)

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furth er information contact:Cape Kennew: J, F. Harroun

305-784-9 783

In Houston: A . S . Cella713-NU 8-3300, ext. 371In Washington(Bethesda):E. B, Evans

SATURN IB - SATURN V INSTRUMEN

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IIThe Saturn family has sys tem litarg rocket pro-

gram s, such a s Redstone, Thor, Jupiial guidance platform canbe traced from4theearlier Pershing,tone vehicles; the telemetrysystem evolved from a design first, and a portion of the t rackingequipment was developed initially forgram. Adding the human elementrequired new syste ms for longer

and more varied missibns and anvovei

Although the Saturn I ser ies ofi

there ar e onlyia few identical compo!Each of the labt fiveSaturn I vehicP

computer sim ila r to those in th

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Saturn IB

a completely new design incorporSaturn IF3 missions. The d e s ig nremain nearly identical for hot11 programs after velopment tests a r ecompleted.

The IU was designed and developed by NASA's George C. Marsh allSpaceFlight Center (MSFC). In the Saturn IB program, IUresponsibility is being trans-fe rr ed gradually to IBMrs Feder alSys ivision with ove ral l responsibilitybeginning with the fifthflight IU. Work on the fi rs t ight models is the responsi-bilityof MSFC, with the actua l assembly being done in IBM1s Huntsville,Alabama,facility. Testing is performed by IBM personnel,

IBM ' s contr act calls for fabrication and assembly, completesystem testing,and integration and checkout of the IU with thelaunch vehicle at the Kennedy SpaceCenter.

cluded in the contract a re req uirements for the computerprogram smissio n conditions and predicting vehicle perfo rmance,operating

automated checkout equipment on the ground, and for reducing andanalyzing environ-ment and performance data during and after theflight.

SATURN IBI VEHICLE - OVERALL Vf

Thelrange of capabilities and missio ns planned fo r the SaturnIB launch14vehicle is *fleeted in the design of the navigation s ystem s. This flexibility to me etIi1new missiop assignments requiresa gene ral purpose launch vehicle digital computer

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(LVDC), which generates stee rin g signals under ~otr t r ninternally-stored+program. Different missions can be controlled bydifferent LVDC programs. The

vehicle engine actuators ar e controlled by a separa te flightcontrol computer system ,including an analog computer, rate g yros,and control acc eler ome ters .

Fo r attitude control, the cu rr en t attitude of the vehicle iscompared with thede sir ed attitude, which is stor ed in the LVDC'sprog ram . Attitude correctionsigna ls, o r ste erin g commands, ar e the difference between the existing attitude a n dthe desiredattitude.

These s teering commands ar e combined with signal control sensorsin the flight control computer system to generate the controlcommand for the engineactuators. Gimballing the engines changes thed irection of the vehicle. During theS-IB burn , pitch and yawcontrol acceler omete rs provide late ral acceleration datato theflight control computer s o that stabl e flight is assured.

In guidance and control ter ms , each Saturn IB vehicle is a sepa rat e entity.Long bef ore each flight, NASA plans the missi on.Fro m this mission definition, IBM

op the mathem atical equations to be us ed by the guidance computer and\ IBM converts thes e equations into computer pro grams.

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Using a cbmputer complex installed a t the D M untsville, the mis -ision is simuldted to check out the progr ams and verify that,for any foreseeable s et ofE

conditions, t* LVDC will continuously determ ine vehiole sta tusand determi ne thei

L optimum path t o its destination.

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STAGE DESCRIPTION:*kr "The IU consists of six major subsystems:struct ure, environmental control,

guidance, flight contr ol, instrumentation, and elec tricMountedon the struct~1r:ll ing inner sur fac e is the ele ctron icequipment used

to navigate the vehicle, Inexsure environmen t and perfo rmance,and comnlunicatethese data to the ground. Supporting this equipmentis an environmental controlsy st em for heat dissipation, a supplyof nitrogen gas for the guidance pla tfo rm' sgas bearings, and anelectrical system.

STRUCTURE:The structure section is 2 1 . 7 feet in diame ter andthr ee feet high. Assembled

vehicle, it becomes a load-bearing part which supports both thecompo-nents within the IU and the weight of the spacecraft.

It is manufactured in three 120-degree segments of thin-wallaluminum alloyded over a c or e of aluminum honeyco inch thick o ra s thick. An aluminum alloy channel ring, e top and bottomedge

I of each segment, provides the sur face for mating the IU, theS-IVB stage, and thekets on the insid the

e environmental nts not requiring

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The segments ar e a l ignc r l ;rnd joinner and outer surf aceof c :~ch oint.

A spring-loaded umhilicnl door in the st ruc tur e provides amea ns f or serv iceconnections between the IU a n d ground supportequipment. A la rg er ac ce ss door. boltedin place, permits pc rsnn ~~ clo cntcr the IU following its mating to the launchvehicle

Despite its s iz e anti the st re ss es that must be withstoodduring launch, the/ complete str uc tu re, pr ln r to eqolpmentinstallation, weighs a little over 500 pounds.

ENVIRONMENTAL CONTROL:The cold plates of the enviro nmentalcontrol sys tem provide a m eans of

mounting and cooling the complex electro nic componentsstage,both on the launcl~ing ad and during flight.

eri ods of operation in a typical Saturn IB missi on, coupledwithYI

ace , req uir e special provisions for heat tran sfe r anddissipation.\!A c $ 4 ~s (1 6 in each stage) abso rb heal from theelectronic components.d The heat i s conducted through the smoothsur fac e of the cold plates to a coolant mix-aI tu re much likeantifreeze---GO?: methanol, 40's water , Cooling is a function ofthe

+d . 'contact ar ea Between the component and the cold pla te.Since the I,VDC, the launchvehicle data ddapter (LVDA) flight control computer, and the ST-124M inertialguidance pla tfo rm generatethe mo st heat, the coolant actually pa ss es through these

ii components ibstead of ex trac ting the heat viaconduction.

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Saturn IB - Saturn V Instrument Unit Technical Facts Page G/f-~LJI ; I?A w;bj&hii&

/ In the vacuum of s pa ce, the war med coolant, af terleaving-the cold pla tes,"*. - *% ii1 is routed through a devicecalled a sublimatbr. Water, from a res er vo ir in the IUii( issupplied to the sublinlator where i t i s exposed through a porousplate to the low

tem per atu re and pr es su re of outer space. The water freezes, blocking the pore s inthe plate. The heat from the coolant, transf err ed to the plate, is abso rbed by the ice,

\converting it dir ectly into water vapor (a proc ess calledsublimation).

This system is self-regulating: A sen sor constantly monitorsthe temperatu re.If the coolant requ ires chilling, this s ens orcontrols a valve which div erts varying

through the sublirnator/heat exchanger. If no cooling isrequired

e environmental control system provides a supply of

/ pressurized gaseous nitrogen to one side of the diaphragm inthe coolant and water9 es er vo ir s, sin ce in the weightlessperio d of flight, without som e form of artif icia lpr es su re ,these liquids would dispe rse into droplets. Gaseous nitrogen alsois pro -

bearings of the ST-124M platform. A pump to ci rcu late thecoolant,ry valves and tubing to control its flow, complete theequipment of the

environmental control sy s em .

GUIDANCE AgD FLIGHT CONTROLIJThe IU'$ guidance and flightcontrol sy ste ms con trol the flight of the Saturn IBito meetmissi$n require ments . Completely self-contained, these system smea sur egacc eler atio n apd vehicle attitude, deter mine velocityand position and the ir e ffe ct on

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the mission, calculate and issue control commands to ineactuators to place thevehicle in a desi red position. The majoryste m are: an inertialplatform, n digita l guidance computer , ananalog flight Zontrol computer, a dataadapter, control rat e gyrosand control acceleromete rs,

Pr io r to liftoff, ia~aneh aram ete rs a r e fed into the LVDC.About five sec on dsbefore liftoff, the inert ial guadance platformand the LVDC a r e released f ro m groundcontrol. Previouslyaligned to the launch azimuth, the guidance platform sensesandnieasures the vehicle's acceleration and attitude as the vehicleascends into theatmosphere, and i t sends these: measurements tothe LVDC via its interface, the

The LVDG integrates these rr~easurementswith t nce launch todetermineelative to st art ing point and destin

de correction signals in order fovelocity and altitude for itsmission.

'Shese attitude corr ect ion signals, ra te gyro outputs, andcontrol acce leromet er out-puts a r e sen t to the analog flightcontrol computer. Based on the data received fro m

e gyros and accelerometers, the flight control computer issuestheactual control conn~~~~rnds.

Each mission ha s at le as t thick phases: atmospheric poweredflight; boost periodafter initial ehtry into space, and thecoasting period.

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vehicle a re grea tes t during atmospheric boost because of theimpactr e on the vehicle1s sur face s, During this portion of theflight,

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Saturn LB - Saturn V Instrument Unit 8the guidance and flightcontrol system s a r e concerned primar ily with vehicleintegrity,and so it is programmed to sust ain an attitude tominimize vehicle loading.

After f i r st stage separation the prograiixs ara'd&sf.gnedto optimize the path the"4, *

vehicle takes to achieve the desired mission.During this phaseof powered flight, guidance is accomplished by a s er ie s of

repe tit ive computations. Approximately once every two secondsduring flight, theguidance computer dete rmines vehicle position,vehicle conditions required at the endof powered flight (velocity,attitude, etc.), and gene rates the attitude cor rect ionsignalsnecessary to accomplisli the desi red end result . This isknown amode, o r "closed loop guidance. "

Twenty-five times a second, attitude correction signals a r egenerated by the mostrec ent solution of the guidance problem. TheLVDC , hrough the LVDA, sends thesesignals to the flight controlcomputer where control commands ar e generated to st ee rthevehicle along the desi red flight path.

To ens ure reliability, crit ical circuit s in the LVDC and LVDAa re provided intripl icate. Each of 3 identical circ uits producesan output which is then "vatedl'upon. In cade of an er ro r inthese outputs, the majority rul es so that a randomfailure isiguored. In addition, the computer memory is duplexed, so that i fan err oris found in one port ion of the memory, the output isobtained from the other memory,

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and then the ,cor rect information read back into both memoriesto cor rec t the er ro r.6

01 To ensurd the accuracy of the position data originating inthe inert ial equipment,I

glts bearing4 a r e provided for the gyros and pendulums of theST-124M ine rt ia l

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Saturn IB - Saturn V Instrument Unit Page 9

guidance platform t o redu ce friction in these-components to aminimum. The beari ngsI e 'r"' * i

are 'Yloatedflon a thin film of dry, pressurizednitrogenxsupplied at a controlled pres -su re , tem peratu re, andflow rate from reserv oir s in the IU.

In addition to the guidance computations, other functions a r eperformed by theLVDC, an d it s input/output device, the LVDA.During pre-la unch , they conduct te stpr og ra ms ; during launchphase they dire ct the sequencing of events via the IBM-developedswitch s ele cto r (one in each stage ), such a s engine ignitionand cut-off,stage se parati ons, and check to se e that the vehicleis performing normally. Duringea rth orbit , they determineattitude control, conduct tes ts, and control the transmis-sion ofdata.

INSTRUMENTATION:P 1 Measuring se ns or s, o r transduce rs, a relocated throughout the vehicle to

0 onitor the vehicle environment and sy st em st performance.Approximately 300 suchi easurements a r e made by various sen sors, Acoustic transducers monitor soundlevels, res ist or o r thermistor transducers monitor temperature environments;\ pre ss ure sar e measured by Bourdon-tube o r bellows transducers;force-balance,o r piezoelectric accelgrometers me asure forcelevels a t critical points, and flow

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me te rs de termine r at es of liquid flow.I

iSignal c$nditioning modules modify the se v ariou s tr ans ducer outputs to af voltage. The different types of data requir edifferent mode s of

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Saturn PB - Saturn V Instrument Unit

transmis sion, and the telemetry porti bandfrequency modulation,frequency -modulated frequency fio8ulation and pulse-code-modulatedfrequency modulation.

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Each type of information is routed t o the app ropriate telemetr y equipment bythe measuri ng distrib utor s. For maximumutilization of the tran smi ssio n equipment,multiplexing isemployed on most telemetry channels. Measurements from differentsenso rs a re transmitted to eart h. The information transmitted overany channel is ase ri es of meas urements made at different pointswithin the vehicle, so that a la rgeamount of data can be s en twith a minimum of co mmu ni~ ati on quipment.

To furth er inc rea se the amount of data which can be handled,the LVDC-.

sequences the transmis sion of certain measurem ents. Forinstance, during ret ro-frocket firing, when flame interfer es withtelemetry +ransmissions, signals a re auto-

matically recorded on tape and transmitted late r.

eking sys tem s a r e used to determine vehicle position and thedatato provide traj ecto ry information. Transpon ders in the IUincrease

curacy of the ground-based tracking syst em s, Puls es ofradio-transmitted by the ground stations interroga te the vehiclein flight.

I .The airborne1 ransponder answ ers with a pulse, o r ser i esof pulses, frequency-or-time-displackd fro m the incoming pulse tominimize interference. The ground station

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Saturn IB - aturn V Instrument Unit Technical Facts Page 11-vOneC-band transponder is used to t~ i' ck ing ndependent ofvehicle

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attitu de along with a sing le AZUSA transp onder. The C -b adtracking system pro-vides orbi tal tracking data for both real timeand post flight trajec tory ana lysis. TheAZUSA sys tem provides real time tracking data for range safety impact predictions,and forpost-flight trajectory analysis.

A radio command link is used to communica te with the LVDC fromtheground. Examples of mes sag es include: updating data from theLVDC; commands

to per for m the updating, commands to per form tes ts, specialsubroutines; a com-mand to telemeter certain sectors of thecomputer memory; and a command to relayto the ground a partic ularadd res s in the computer memo ry. Message s can be addedo rdeleted as necessary.

ELECTRICAL:Ele ctr ica l power during pre-launch is furnishedfrom ground so urc es through

) the IU umbi lical connection. At approximately 20 to 30seconds pr io r to lift-off, a/ signa l from the Launch Control Center tran sf ers power to four 28-volt alkaline silve r-t zincbatteri es in the IU. Each batte ry has a capacity of 350 amperehour s. IU power

1 < < . eis designed for F. 8 hours of mission life. Loadsa r e partially distributed ove r thefour batteries 4 qualize thebattery drain, and to provide a redundant power sour ce

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Fto the componerits in the event of bat tery fai lur e.iTwospecla1 power supplies ar e provided: The 5-volt ma st er m easuringI

Svoltage supply cionverts the 28 Vdc main supply to ahighly-regulated 5 volts dc to be

-more -

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used a s a r efer ence and supply voltage for t ponents of themea sur ing sy st em ;the 56-volt power supply provi des the regulated 56-volt dc requi red f or operation ofthe guidance andcontrol s ys te m' s ST-124M iner tial guidance plat form.

The switch selec tor s in each vehicle st age provide a me ansof controllingthe sequencing of events taking place in that sta ge.Each sele ctor can issue up to112 different 28 volt commands to thevarious elec trica l circui ts in the Saturn. Theguidance system'sLVDC and 1,VDA control these , selecting the appropriate circ uitsas the miss ion progr esses .

The emergency detection equipment monitors thrus t f or bothpowered s tage s,guidance computer status, angular attack rates,attitude error, and angfe of attack.It dete cts abnor malconditions affecting the safety of the cre w. Where tim e isinsufficient for the crew to re act , the automatic abort will beused. If the crew canre ac t, the eme rgency detection system willprovide an indication, "manual abort, lwhich the crew ca n use i fdeemed nec essary.

ASSEMBLY OPERATIONS:Assembly of an IU4 begins with the arri valof thr ee curved stru ctu ral segments

aa t IBM's Huntsville, Alabama, facility.

iThe three: segments---each weighing approximately 175pounds---are placed on1a cir cul ar assembly fixture and arranged for alignment and splicing. Following this,

prote ctiv e rin g8 a r e bolted to the top and bottom of theassemb ly to stiffen the struc-tu re s o that i t can be movedabout without disturbing the alignment. Holes ar e cutthrough thest ruc tur e to mount vehicle antennas.

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Transducers to mensure temperatu d thi rm al conditioning panelsa r emounted to the IU's inner skin, and a frame-like, cablc trayto ca rr y the electricalcables is installed around thc top of thestructure. Components a r e mounted on thether ma l conditioningp:tnels. and the thermal conditionil~p, ys tem 's pumps ,accumu-

( la tors (stor age tanks). heat exchangers, and plumbing a r einstalled. A gaseous/i nitrogen supply systcxm for the ga s bearings of the iner tial guidance platform is

attached. Finally, ducts , tubing, and elec tric al cablescomplete the assembly of theIU. The assembled TCi wcighsapproximately 4000 pounds.

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Saturn IB - Saturn V Instrument Unit Technical Facts Page 1.1ag";computer con t s the te st in riccordance with 3 tes t firocedureprovided on a magnetic

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nd test resul ts a r e displayed on thc operator's console andrecordedon magnetic tape o r on -line pri nters . Pre-launch ,launch 2nd flight opera tion s a r etested, using computer siinul;~te d nputs to represc:it sihq als which a r e pres entduringflight.

Electro-m agnetic compatibility (EMC) te st s arc3conducted uponcompletion ofsystems checkout.

After EMC tests are completed, the water and waterimethanolcoolant solu-nmental control system is drai~ied, nd the gaseousnitrogen is

a i r benrln g sup111~'. Cert ain equipinent (the ST-124M inertialthe LVDC :tnd the LVDA) is removed and packaged separ atel yfor

unch si te . The asse mble d IU , with oth er componentsattached. i sping c ar ri er . Accelerome ters ar e mounted atsensitive points withine s tr es se s experienced during shipment.The unit is flown to the

VEHICLE INTEGRATIQN A T CAPE KENNEDY:I

Upon ar ri va l a t the Kennedy Space Center , the IU is checkedto verify that1no damage ha4 occ urr ed during shipment. Mechanicalalignment of the IU and plat-Itform mountin4 surfac es i s verifiedin the receiving ar ea .i1i

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Saturn IB - aturn V Lnst i -unl rXntUnit Technical Facts Page15

S-IB LAUNCH COMI ' I iEXThe IU is moved to t h ~:111nchad andraised to its position on the forward

sk ir t of the S-IVB and fastct,,, ~n to lace. Componentsremoved before shipment arereinstalled at this time. \ L , i ~ , .r and water/metl~anola r e supplied to the environmentalcontrolsystem from s t B t , v i c c b clu~pment n the l:~unch ower, andgaseous nitrogen issupplied to the high p~ ,c ss ur c toragespheres of the ai r bearing supply. At this tune,the IU syst ems ar e function:~lly-tested o verify operational status. Test sinclude"flight readiness, " "plug-in" (uml)ilicals connected),"plug-drop" (umbi1ic:ll droppedduring test to verify satisfa ctoryt ran sfe r from ground to vehicle power), and, finally"countdowndemonstration" (dress-rehearsal of terminal countdown terminatedinsimulated abo rt just pr io r to lift-off).

As the termina l launch countdown ne ar s T-10 hours, thepre-launch te stbat ter ies a r e removed, and the flight batteries installed and connected. The serviceplatf orms andcomponents1 handling equipment ar e removed f rom the inte rior oftheIU, nd, aft er a final check to ensur e that the are a is clear,the access door is boltedin place and the IU service a rm isretracted into the gantry.

i ] As the launch countdown pr ogre sses , a beam of light froma precisely-located, [ theodolite hut on the ground pa ss esthrough a sma ll hole in the IU and into a windowI{

in the guidancejplatform. The light beam is reflected back tothe theodolite fr om arpair of platform prism s. Each pri smreflects a different portion of the frequency

tspec trum , andft his "color code1' is used to align theplatform to its launch azimuth

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p ri o r to the flight. An acquisition light go cen ter whenthe$2

platform i s prop erly aligned. Computer-derived launch azimuthsignals a r e thenused to r elin e the position of the platformwith res pec t to a fixed ground referenoe.

With the launch azimuth est ablish ed, and the required missionparameter ssto red in the LVDC memory, th e IU is ready forflight.