Saturn IB/V Instrument Unit

8/6/2019 Saturn IB/V Instrument Unit

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S A T U R N49

i n s t r u m e n t u n i t- L -

G E O R G E C . M A R S H A L L S P A C E F L I G H T C E N T E R / H U N T S V I L L E . A L A B A M A



i n t r o d u c t i o n

This brochure provides some basic, general information about the lnstrumentUnit, a very important part of the Saturn IB and Saturn V launch vehicles. Theselaunch vehicles are being developed primarily for the Apollo program for mannedlunar exploration but will also be used for future space missions.

The lnstrument Unit development is based on rather novel design concepts. Forexample, there is only one type of lnstrument Unit with almost identical instrumentsserving two dif fere nt launch vehicles-the Saturn IB and the Saturn V. The differe ntcomponents of the lnstrument Unit are being developed as "building blocks" toallow the lnstrument Unit to meet various missions by allocation of the requiredbuilding blocks. However, many mission variations can be achieved by changingthe program for the digital computer.

The IU may appear as a rather small part of a very large launch vehicle, but thi ssmall size is by no means a scale for i ts importance. I n fact, it is considered the"brain" or "nerve center" of the vehicle and contains most of the instruments and

systems for navigation, guidance, control (auto pilot), range safety, telemetry, track-ing, and others.

FRITZ H. WEBER

C h i e f / P r o j e c t E n g i n e e r

l n s t ru m e n t U n i t



S AT U R NI B / V I U

A S T R I O N I C SS Y S T E M

1 S T R U C T U R A L

2 E N V I R O N M E N T A L C O N T R O L

3

SlA N D



s c o p e . . .The Saturn 18 and Saturn V Instrument Units are briefly described. Since both

vehicles use almost identical astrionics systems, only minor differences will exist.To accomplish t b A p o l l o mission, the astrionics system performs the followingfunctions:

a guidance and control during all phases of flighta command and sequencing of vehicle functionsa insertion into earth orbita injec tion of S-IVB, IU, and spac ecraft into lun ar transfe r trajec torya stabilization of the S-IVB, IU, andLEM during turnaround of the command module

and service modulea execution of maneuvers to remove the S-IVB and IU from the spacecraft orb it path



-4

INSTRUMENT UNIT



s t r u c t u r a l s y s t e m . . .

The struc'tural system is designed for a field splice conn ectionto the S-IVB stage and flight separation from the spacecraft.Characteristics of this system are a 660 cm diameter cylinderand a honeycomb structure of aluminum alloy for strength andlight weight. It is fabricated in three sections for ease of handling.

CONTROL RESPONSIBILITY I P & VE LABORATORY



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e n v i r o n m e n t a l c o n t r o l s y s t e m . . .

An active environmental control system is provided forequipment cooling during ground operations and flight. Coolantis pumped through cold plates and ducts in the ST-124-M in-ertial platform, digital computer, and data adapter.Functions and characteristics:

seventeen cold pla tes around periphery of structure provide forequipment mounting and coolingcoolant is 60 percent methanol and 40 percent water by weightcoolant flow rate is 2.7 kilograms per minute per cold plateeach plate can dissipate approximately 420 watts

heat removal is through a heat exchanger with water boiloff

*CONTROL RESPONSIBILITYI P & VE LABORATORY



g u i d a n c e a n d

c o n t r o l s y s t e m s . . .The guidance and control systems solve guidance equations

and control the attitude of the Saturn IB/V vehicle. The systemhas the capability of accepting guidance commands from thespacec raft. Some IU components, such as the data adapter, fun c-tion in both the guidance system and the control system, b ut aredescribed only in the system which is most applicable.



ST-124-M STABLE PLATFORM

PLATFORM SERVO AMPLIFIER

POWER SUPPLY

DIGITAL COMPUTER

DATA ADAPTER



INFO

g u id a n c e s y s t e m . . .

6 TA E l L U E D

P L AT F O R M

S V S T C M

,-IO N T R O L

COMPUTER - A D A P T E R

T OS TA G E S

The Saturn guidance system instruments the equations for specific missionssuch as launch into ear th orbit, rendezvous, reentry, escape trajectories, and deter-mination of position.

The ST -1 24 4 inertial platform system provides:

a the inertial reference for vehicle guidancea the mechanics for pitch attitude programinga platform gimbal positions for attitude and steering error computationsa velocity information for computing vehicle position and velocitya azimuth alignment information

The system is comprised of an inertial platform (three or four gimbal configura-tion depending on the particular mission requirement) platform electronic assembly,platform ac power supply, and air bearing supply.

The digital computer determines velocity and position, attitude errors and de-rived vehicle heading, computes thrust termination and reignition signals; and pro-vides commands to guide th e vehicle to cutof f conditions. It conducts those requiredorbital operations, such as orbital checkout of the space vehicle. Characteristics ofthe d igit al compute r are: serial machine, random access magnetic core memory,micro-miniature packaging techniques, triple modular redundancy in the centercomputer, and multi ple duplex memory modules for high re liability.

The data adapter is the input- output un it that accompanies the digital computerand provides an interf ace with nearly all components of the astrionics system. Thedata adapter has a digital section that buff ers digita l quantities and an analog sec-tion that converts analog to digital quantities and digital quantities to analog.

CONTROL RESPONSIBILITY I ASTRlONlCS LABORATORY



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The attitude control system mixes signals from th e digital com puter, data adapter,

rate gyros, and lateral control accelerometers to provide control signals to he vehicleengines. This system has the capability of accepting manual con trol commands fromthe astronauts.

The control computer, an analog device consisting of electronics required forattitud e control, instrumen ts and solves the vehicle thrust vector equation; controlsthe engines about the yaw, pitch, and ro ll axes; and con trols the engines about theyaw, pitch , and roll axes; and contro ls the S-IVB auxiliary propulsion system.

The rate gyros supply the con trol computer with data of the a ttitude rate changeof the vehicle. The gyro ou tputs are also used to detec t excessive angular rates forthe emergency detection system.

The control signal processor contains the electronics associated with the rategyro package.

*CONTROL RESPONSIBILITY/ ASTRlONlCS LABORATORY



l o c a t io n of c o m p o n e n t s ...T Y P I C A L S AT U R N I B / V I N S T R U M E N T U N I T

RADAR ALTIM ETER

AROD COMPUTER

MINITRACK ROD CHANNL REC

D COMMAND LOGICPOWER CONV

OD POWER AMPLIFIER

OD OSC 8 FREQ SYN

COMMAND TRANSMITTER

LOCITY EXTRACTION

DACCO OLANT AROD DRIVER 8 MODULATOR

RETURN COOLING SYSTEMRADAR ALTIMETER UXlLlARY POWER

ANTENNA DISTRIBUTOR



AUXILIARY POWERDISTRIBUTOR.. . . . ....................+:...................+..::.: .:. R F ASSY FI T M s MODEL 245 MULTIPLEXER

:=.:: .:............. 1 MEAS RACK(5) \ \ POWER DISTRIBUTORMODEL 270 MEAS RACK SELECTOR

MEAS VOLTAGESUPPLY

56 VOLT POWERSUPPLY

T M CALIBRATOR

LEMETERANTENNA

\TM POWER DIV\ M RF COUPLER

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REMOTE DIGITALSUB-MULTIPLEXER(3)

ED S DISTRIBUTOR

I ST-1244AZUSATRANSPONDER

L AZUSA RI FILTER iIRSUPPLY

MINITRACK TRANSMITTER8 BATTERY

ADAPTER

MNTRACKANTENNA

COMMAND RECEIVER



m e a s u r i n g a n d

t e l e m e n t r y s y s t e m s ...During launch and orbital phases of vehicle flight, para meters

such as temperature, pressure, and vibration, are measured byappropriate transducers. Signals in the inertial platform, digitalcomputer, and other pertinent equipment are measured to m onitorvehicle operations. The combined measuring and telemetry sys-tem mea sures physical quantities and signals; the data is trans-mitted to ground stations to provide information for checkoutduring flight, and to verify commands received by the vehiclefrom ground stations.



M E A S U R I N G R A C K

T Y P I C A L T R A N S D U CE R S

M O D U L E



m e a s u r i n g s y s t e m . . .

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GS E- O N T R O L

The measuring system includes electrical pick-offs, transducers, signal condi-tioners, and a measuring distributor. All measurement signals in this system areconnected t o the measuring distributor and are directed to preassigned telemetrychannels. Printed circuit plug-in boards are used i n the distri butor to pro-vide flexibility.

Transducers are electromechanical devices that convert physical quantities suchas pressure and temperature into el ectrical signals. The transducers are designedfor accuracy and reliability.

Measuring racks contain signal conditioning modules that adapt the outp uts oftransducers and some electrical circ uits to th e electrical inp ut requirements of thetelemetry system. A regulated power supply in each rack provides power for themodules.

The RACS (Remote Automatic Calibratio n System) is used for cal ibrating selected

measurements during ground checkout. The measuring rack selector provides ameans of decoding a signal from the ground station du ring prelaunch to select thesignal conditioning modules for calibration.

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s u e MULTIPLEXERS

D I G I T A L D A T A



ABU HA1UHY

t e l e m e t r y s y s t e m . . .

The telemetry system modulates radio frequency carriers with signals from themeasu ring system, which are in analog or digit al form and require differint band-widths. For the most efficient use of the available telemetry frequency band, different

modulation techniques are applied to transm it the variety of signals.A D A P T E F

r SSIFM (Single SidebandIFrequency Modulation) system transm its vibration and acous-tic data that have wide frequency response (30 Hz to 3000 Hz) requirementsPAMIFMIFM (Pulse Amplitude ModulationIFMlFM) or FMIFMIFM systems transmitanalog data that have narrow frequency response requirementsFMIFM system transmits analog data th at have m edium frequency response require-mentsPCMIFM (Pulse Code ModulationIFM) system transmits digital data

D D A SA D I G I TA L

D A T A

The TM calibrator function s as calibration control and reference signal sourcefor the telemetry system for p reflight and inflight calibration.

A N A L O G

D A T A

V I B R AT I O N

D A T A

*CONTROL RESPONSIBILITYI STRlONlCS LABORATORY



C-BAND RADAR

RADAR ALTIMETER

AZUSA TRANSPONDER MINITRACK



r a d i o f r e q u e n c y s y s t e m s . . .

A D A P T E R:I

The radio frequency (RF) systems are available as required for various missionsto provide tracking and command. With the exception of the radar altimeter, theonboard equipment is connected through RF links with the corresponding.groundequipment.

The radar altimeter provides altitude data to supplement ground station trackin gwhen the vehicle is not covered by land-based stations.

The azusa transponder is part of a system to measure slant range and directionfrom the ground station to the vehicle.

The C-band radar transponder aids the radar ground stations in measuring range,azimuth, and elevation.

AROD (airborne ran ge and orbit determinatio n) is a doppler and range trackingsystem. However, the conventional procedure has been reversed.; the transmi tterand receiver are on board the vehicle, while the transponders are located at variouslocations on the earth.

The Minitrack beacon provides information for c omputing the vehicle orbit.The IU command system provides a means of receiving digital data or commands

from a ground station. The information is supplied to the digital computer throughthe data adapter. Prior to execution, all data or commands are transmitted t o theground station for verification.

The principal functions of the IU command system are to initiate closed-looptests in the vehicle, to provide ground computed orbital data to th e digital computer,if desired, and to aid in an emergency situation.



BATTERIES SWITCH SELECTOR

5 VOLT POWER SUPPLY 56 VOLT POWER SUPPLY



e l e c t r i c a l s y s t e m . . .

A D A P T E R

C

The electrical system of the IU generates and distributes all power required foroperation of components during flight and controls the operation and sequencingof various functions during checkout, countdown, and flight. Connection to groundsupport equipment is provided through the umbilical for prelaunch checkout.

The power distributor is the junction where the power is routed to various com-ponents through the IU network cables.

The measuring voltage supply provides a calibration voltage for the measuringsystem as a reference for different types of sensing equipment. The 56-volt powersupply provides dc power to the platform electronics assembly.

Two auxiliary power distributors, which handle only circuits under 10 amperes,supplement the main power distributor.

The control distributor receives commands from the switch selector and central-ly controls the sequencing of equipment and dist ribution of power through contac-tors within the power distributor.

Switch selectors provide the communications link between the computer-dataadapter and t he control d istributor in the IU and each stage. The digital computercontrols th e mode and sequence of funct ions i n all stages through the switchselectors.



POWER DISTRIBUTOR CONTROL DISTRIBUTOR

AUXILIARY POWER DISTRIBUTOR



e l e c t r i c a l s y s t e m (c o n t in u e d ) . . .

The emergency detection system (EDS) senses certain malfunctions in thestages and determines when these malfunctions are of a critical nature through cir-cuits in the EDS distributor, which is the interface box between the stages and thespacecraft. An emergency signal is transmitted by the distributor to the EDS'displaypanel in the spacecraft. The emergency conditions can result in:

an automatically initiated abort when the time interval between sensing of an emer-

gency condition and the required action is too short for human interventiona manually initiated abort when this time interval is sufficiently long for humanevaluation and reaction

IPrimary power is supplied by alkaline electrolyte batteries with silver oxide and

zinc as the active plate material. The nominal output is 28 volts at a relatively high i1

current rate. The batteries are activated by filling each cell with potassium hydroxidein water.

*CONTROL RESPONSIBILITYI ASTRlONlCS LABORATORY



c o n c l u s i o n . . .

Many additional pages can be filled with vital and in teresting information on thelnstrumen t Unit. For example:

the advanced design techniques used in the circuitry and packagingthe very high precision of the gyros and accelerometers of the stabilized platform

a miniaturization used in the digital computera redundant modular circuit s used to improve reliability

Note that the very high reliability.requirements as a consequence of the "manrating" place considerable emphasis on:

a design practicesa parts and com ponents qualification

environm ental, pefiormance, and other tes t programsa inspection and quality control, etc.

All these efforts required to develop the lnstrument Unit and its componentsand to provide the flight units are shared by a team of government and industrygroups.

One should realize that only a few years ago programs like the Saturn were onlywishful dreaming. Today, advanced technology and engineering have made thesedreams become a reality.



ASTR

S AT U R NI B / V l u

IONlCS SYSTEM(color schematic)

S T R U C T U R A L

E N V I R O N M E N TA LC O N T R O L

6 U l D A N C E& C O N T R O L •M E A S U R I N 6

& TELEMETRY

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MODE

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S P A C E C R A F T

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DIGITALl C O M P U T E

r - - - - - - .

l ROPULSION 8. - - - - - - a

- - - - ---.PROPULSION I.------a

.I GSE

Saturn IB/V Instrument Unit

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