Centaur AC-6 Press Kit

8/8/2019 Centaur AC-6 Press Kit

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NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WO 2-4155* * S WASHINGTON, D.C. 20546 ELS. WO 3-6925FOR RELEASE: FRIDAY PM ' SJuly 30., 1965

RELEASE NO: 65-235

CENTAUR (AC-6)TEST FLIGHT

SCHEDULED AUG. 4

The hydrogen-fueled Centaur launch vehicle will be test-flown from Cape Kennedy, Fla., by the National Aeronauticsand Space Administration no earlier than Aug. 4.

The vehicle development flight, designated Atlas-Centaur6 (AC-6), will be a full-scale simulated mission to determineCentaur's capability to inject a Surveyor spacecraft on alunar-transfer trajectory.

Surveyor is being developed by NASA to soft-land onthe Moon and conduct lunar surface studies in support offuture manned Apollo missions.

The AC-6 mission, sixth in a series of eight scheduledCentaur development flights, will be a further step in qualifyingthe Centaur vehicle for operational lunar and planetary spacemissions. The flight is designed to obtain data on severalnew Atlas-Centaur features and to continue evaluation ofother components and systems tested during previous missions.

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The AC-6 vehicle will be flown along a simulated lunartransfer trajectory. Full lunar transfer energy for thismission is a velocity of about 34,000 feet-per--second,or 23,700 miles-per-hour at spacecraft separation.

Following separation from Centaur, the Surveyor modelwill continue on a highly elliptical Earth orbit with anapogee of about 515,000 miles and a perigee of 100 miles.An orbit will be completed about every 32 days.

AC-6 will test several new development features of theCentaur vehicle, including a Centaur propellant utilizationsystem to provide maximum use of available propellants; anup-rated Atlas propulsion system--used on other Atlas launchesbut not with Centaur--which develops about 389,000 pounds ofbooster thrust; and a smaller volume liquid oxygen tank inthe Centaur stage which matches the volume of the liquidhydrogen tank more accurately than earlier vehicles and thusprovides more payload capability.

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-3-Centaur's guidance loop will be "closed" for the AC-6

flight;guidance steering signals will be utilized forvehicle steering. The guidance system, located on theCentaur staLg, will generate pitch and yaw steering signalsto the autopilots for flight control from booster engine cutoff(BECO) plus eight seconds to termination of the Centaur retro-maneuver.

Another area of major interest on AC-6 is Centaur'slaunch-on-time capability. Since future engineering andscientific Surveyor spacecraft will be launched toward theMoon on one-burn, direct ascent missions, only certainperiods, or "launch windows," are available. This is aperiod during which a vehicle must be launched from Earth tointercept a body in space. -

For AC-6, a six-day period has been selected closelyapproximating the period a Surveyor would be launched with aprime objective of landing on the Moon. Tne only realdifference between the simulated AC-6 mission and an actualSurveyor mission is that the latter would takeplace aboutsix hours earlier to obtain daylight photo coverage at launch.

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Centaur, employing liquid hydrogen and liquid oxygen,is being developed as a high-energy second-stage vehicleThis propellant combination providesabout 35 per cent more energy than vehicles using conventionalfuels. In addition to its mission of launching Surveyor towardthe Moon, the Centaur upper stage will be combined with aSaturn 1B vehicle for other planetary space missions.

Centaur is being developed for NASA's Office c SpaceScience and Applications under technical direction of NASAtsLewis Research Center in Cleveland. Centaur launches areconducted for Lewis by NASA'SGoddard Space Flight Center's (Green-belt, Md.) Launch Operations at Cape Kennedy.

Centaur and its Atlas booster are built for NASA byConvair Division of General Dynamics, San Diego, Calif. Thesecond stage hydrogen-oxygen engines are provided by Prattand Whitney Aircraft Division of United Aircraft Corp., WestPalm Beach, Fla., under technical direction of NASA'sMarshall Space Flight Center, Huntsville, Ala. which used thesame engine in the second stage of the Saturn I vehicle.Honeywell Inc., St. Petersburg, Fla., provides Centaur'sall-inertial guidance system. More than 300 other contractorsthroughout the U.S. are contributing to the project. 3(END OF GENERAL NEWS RELEASE - BACKGROUND INFORMATION FOLLOWS)

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TECHNICAL BACKGROUNDAND FLIGHT HISTORY

AC-6 is the sixth of eight scheduled engineeringdevelopment flights to qualify the Centaur vehicle foroperational space missions. Once operational, Centaur'sprimary mission will be to place the instrumented Surveyorspacecraft on the Moon and conduct surface studies.

The Centaur vehicle accomplished the first known successfulflight of a vehicle using liquid hydrogen as propellant Nov.27, 1963. Liquid hydrogen also has been tested successfullyin the Saturn I vehicle. Saturn V will use hydrogen enginesto propel American astronauts to the Moon. Liquid hydrogenalso is used in NERVA -- Nuclear Engine for Rocket VehicleApplications -- the Joint NASA-Atomic Energy Commissionprogram to develop nuclear rocket technology.

Since the initial flight success of Centaur, threedevelopment test vehicles have been launched: June 30 andDec. 1l , 1964, and March 2, 1965.

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-6-The June 30 mission accomplished five of six primary

objectives. A premature shutdown of the second stagehydrogen engines resulted in a shorter-than-planned burningperiod.

The December 11 flight successfully accomplished allprimary objectives. These included the first use of Centaur'sinertial guidance system to perform several in-flightmaneuvers in addition to steering the Atlas-Centaur vehicle.

An attempt last March 2 to test the Centaur with a dummySurveyor model on a simulated lunar trajectory--similar tothe objectives of the upcoming AC-6 mission--failed when theAtlas-Centaur vehicle settled back on its launch pad shortlyafter liftoff and burned, resulting in destruction of thevehicle and damage to Launch Complex 36-A.

Centaur project officials traced the March 2 failure toa fuel valve in the Atlas booster which closed after liftoff,shutting down the flow of propellants to the Atlas boosterengines and subsequently terminating thrust. Although thisproblem had never occurred during more than 200 NASA and AirForce Atlas launches, the fuel valve has been redesigned.

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A full-scale Centaur stage is now mounted in a SpacePower Chamber at NASA's Lewis Research Center in Cleveland.This vacuum facility, previously used for testing of full-scale aircraft and their propulsion systems, as well as forProject Mercury spacecraft tests, is capable of simulatingspace conditions at an altitude of 100 miles. It permitscomplete Centaur systems testing up to engine ignition.-

A new ground-test facility, called a Combined Systems TestStand, was built for NASA by Convair in San Diego, Calif.This facility, now being used to test the AC-7 vehicle,permits complete pre-launch ground tests of Atlas-Centaurand Surveyor prior to shipment to Cape Kennedy, this eliminatingmany similar tests currently required after the vehicle iserected for launch.

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NASAC-65-1283

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4 * SEOUENCE OF EVENTSNOMINAL .lTrfUDE, SURFACE RANCE, VEL FT/SECENT TIME, Sku STATUTE Ml SIATUTE MI

LFTOFF 0 0002 BOOSTER CUTOF. (BECO) i 142 36 50 81003 AND BOOSTER JETTISON3 jSTTISON ;NSL6.ATION PANELS 172 5S 93 89004 JETTISON NOSE FAIRING * 197 70 133 97005 SUSTAINER ENGINE CUTOFF (SECO) 235 92 202 11,25o6 ATLAS-CENTAUR qEPARATIOW 237 93 20e 11.250

2 7 CENTAUR FNGINE START 243 96 220 11,2008 CENTAUR 'NGINE CUTOFF 678 135 1740 34,5509 SPA(..,CRAFf zFPARATION 748 108 2180 1 34,70010 STAr- REORIENTATION 7 108 2200 |34,70011 Et-:) REORIENTATIOI 953 188 3480 I 34,30012 START RETRO-THRUST 953 188 3480 34,300jf FIGURES SNOWN ARE t.VROX IMA - 3UT TYPICAL OF POTENTIAL TRAJECTORIESi 1 FOR Ae-6, D0RNOING ON DAY OF LAUNCH.


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LAUNCH VEHICLE-9-

Total liftoff weight: 303,000 poundsTotal liftoff height: 113 feet

Atlas-D Booster Centaur StageWeight 263,000 pounds 40,000 poundsHeight 75 feet (including 1i3 feet (with noseinterstage adapter) fairing)Thrust 389,000 pounds at sea 30,000 pounds atlevel altitudePropellants Liquid oxygen and RP-1, Liquid hydrogen anda kerosene-like fuel liquid oxygenPropulsion MA-5 system, built by Two RL-10 enigines byRocketdyne Div., North Prat and Whitney AircraftAmerican Aviation, Inc. Div., United Aircraft Corp.Speed _500 mph at BECO, 23,700 mph at injection7,700 mph at SECOGuidance Pre-programed auto- Honeywell Inc. all inertialpilot through BECOContractor GD/Convair GD/Convai3

AC-6 consists of a modified Series D Atlas boostercombined with a Centaur second stage. Both stages are 10feet in diameter, connected by an interstage adapter. Thereare no internal braces in Atlas or Centaur; both maintaintheir rigidity through pressurization.

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The Atlas first stage, 75 feet in length including theinterstage adapter, is referred to as a one and one-half stageconfiguration since the booster engines are Jettisoned afteruse. Atlas employs conventional kerosene as a propellant andliquid oxygen as the oxidizer.

Using an MA-5 propulsion system, built by RocketdyneDivision of North American Aviation, Inc., Atlas developsabout 389,000 pounds of thrust. For the AC-6 mission, Atlaswill be equipped with uprated booster engines developing about165,000 pounds of thrust each, a sustainer engine with 57,0O0pounds and two vernier engines developing 1,000 pounds each,

Following first stage flight, the Atlas and Centaur areseparated by a flexible linear-shaped charge which severs theinterstage adapter. Eight retro-rockets mounted on the aftend of Atlas are fired to increase the separation rate.

The Centaur upper stage, 48 feet long including the nosefairing, is a space vehicle powered by two high-energy Prattand Whitney RL-10 engines rated at 15,000 pounds of thrusteach. Centaurts tank is constructed of Type 301 stainlesssteel, the same material used for the Atlas tanks. Paylcad,guidance and electronic equipment packages are mounted on theforward bulkhead of Centa. "s hydrogen taik.

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To minimize the boiloff of liquid hydrogen, which ismaintained at -423 F. degrees, external thermal insulationfiberglass panels are mounted on the hydrogen tank. The fourpanels weigh about 1,250 pounds and are jettisoned after thevehicle leaves the Earthts atmosphere.

AC-6 will be the first mission to test fully the Pro-pellant Utilization System. The system will be flown closed-loop: i.e., it will determine proper utilization of liquidhydrogen and liquid oxygen to insure that Centaur uses allavailable propellants, thus attaining maximum energy necessaryto inject a payload on an intercept trajectory with the Moon.

A nose fairing, constructed of honeycombed fiberglass,surrounds the payload and equipment mounted on Centaur andprovides thermal and aerodynamic protection during flightthrough the atmosphere. The nose fairing weighs about 2,000pounds and is jettisoned shortly after the insulation panels.

The Centaur stage of the AC-6 vehicle will be eqiAppedwith a smaller-volume liquid oxygen tank to achieve greaterpayload capability.

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Centaur's high-energy propulsion system has been designedwith a re-start capability: i.e., the vehicle and its payloadcan be flown into a low Earth orbit, coast until its targetis in a favorable position, then restart its engines andachieve a lunar or escape trajectory. Although current Sur-veyor spacecraft will be launched toward the Moon on a single-burn, direct ascent trajectory, Centaurts multiple short capa-bility will be tested during later Centaur development missions.

PAYLOAD CONFIG~tfATION

The dnmmy payload for AC-6 is a Surveyor dynamic modeldesigned to simulate the dynamic-response characteristics ofthe Surveyor spacecraft.

The model consists of a spaceframe supplied by HughesAircraft Co., El Segundo, Calif., contractor t;o NASA's JetPropulsion Laboratory at Pasadena for the Surveyor project,and a retromotor simulator assemoly built by Gener Dynamics/Convair.

The spaceframe is similar to that of a real Surveyorspacecraft, except for certain reinforcing structures whichare deleted. Dummy masses are mounted on the spaceferaine tosimulate the mass properties of those items they replace.

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K-13-The simulated planar antenna, solar panel and mast

assembly are similar in appearance to their Surveyor counter-parts, but are not operational. A simulated Surveyor landinggear is incorporated.

Mounted on a mast above the spaceframe is an oarni-directional antenna, which is used with the S-band trans-ponder. The transponder is required for post-separationtracking by the Deep Space Network.

The dryimainc model is instrumented with temperature sen-sors, accelerometers, microphones, position potentiometersand strain gages, all designed to monitor its behavior duringthe Atlas-Centaur boost phase.

The S-band transponder n the dynamic model permitsground tracking following separation fzn Centaur. The trans-ponder power supply is designed for 20 hours of operation.

The purpose of the retromotor simulator is to simulatethe Surveyor retrorocket engine, which will later be used todecelerate operational spacecraft for landing on the Moon,

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The dummy retromotor simulates the mass, moment ofinertia and center of gravity of the Surveyor retromotorand also carries the telecommunications system.

The dummy retromotor is mounted on the spaceframe inmuch the same manner in which the actual Surveyor retro-rocket will be attached to Surveyor. However, since it doesnot have to be separated from th e spacecraft, as in the caseof Surveyor, the assembly is attached with non-explosive bolts.

The dynamic model weighs about 2,100 pounds. ActualSurveyor spacecraft will weigh approximately 2,250 pounds.

DISTRUMENTATION AND TRACKING

AC-6 will be heavily instrumented. The telemetry willradio data measurements from Centaur for about three andone-half hours, or until its battery power is depleted.

Measurements on the upper stage will send informationon engine performance, guidance system and autopilot opera-tion, and structural behavior. Booster stage measurementsrelate primarily to engine function and guidance systems,plus standard vibration, bending and temperature data.

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A number of measurements will be made on the Surveyordynamic model, with particular emphasis on aerodynamic heat.-ing effects during boost flight and separation of the space-craft from Centaur.

AC-6 will be tracked during powered flight and portionsof its orbital flight to obtain performance information.

Atias-Centaur power flight tracking down the EasternTest Range will be accomplished by C-band radar and AzusaMark II/Glotrac systems by stations at Cape Kennedy, Antigua,Grand Bahama, San Salvador and Bermuda.

Separation, reorientation and retromaneuver data w.ll bereceived downrange by Air Force Eastern Test Range (AFETR)ground stations extending from Cape Kennedy to Pretoria,South Africa, and two telemetry ships on station in theSouth Atlantic.

Following injection into orbit, an S-band transponderattached to the Surveyor model will be tracked by stationsof the Deep Space Network until depletion of its batterypower, estimated at about 20 hours.

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-16-A C-band transponder on the Centaur stage will be tracked

by Air Force Eastern Test Range radar tracking stations for atleast 3 and one half hours after liftoff.

MISSION DESCRIPTION

Liftoff. For the firsttwo, seconds the Atlas-Centaurvehicle rises vertically, then for thirteen seconds rollsfrom a fixed launcher heading of 115 degrees to the desiredflight plane azimuth of from 93 degrees to 111 degrees de-pending upon launch time.

T plus 15 seconds. The vehicle begins pitching over tothe programmed flight trajectory. This gradual pitchovercontinues throughout the Atlas-powered phase of the flight.

T plus 142 seconds. Booster engine cutoff (BECO) by asignal issued by Centaur guidance when an acceleration levelof 5.7 G's is sensed. This is followed by jettisoning of thebooster package 3.1 seconds later. The sustainer engine con-tinues to pror--l the vehicle.

T plus 172 seconds. The four fiberglass insulationpanels surrounding the Centaur stage are jettisoned.

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T plus 197 seconds. The fiberglass nose fairing whichprotects the payload during flight through the atmosphere isjettisoned.

T plus 235 seconds. The Atlas Sustainer Engine Cutoff(SECQ) occurs at fuel depletion at an altitude of about 90miles.

T plus 237 seconds. Following SECO,Atlas and Centaurare separated. Eight retrorockets mounted on the aft end ofAtlas increase the rate of separation.

T plus 243 seconds. Centaur hydrogen engines are ig-nited for a planned burn of ;'35 seconds. Second state ig-nition occurs at an altitude of about 95 miles. DXring Cen-taur's powered flight, the vehiclets propellant utilizationsystem will be flown closed loop: i.e., the system will de-termine proper distribution utilization of available liquidhydrogen and liquid oxygen to insure that Centaur uses allpropellants, thus obtaining maximum energy necessary to in-ject a payload on an intercept trajectory with the Moon.AC-6 will be the first mission to full-test the system.

T plus 678 seconds. Second stage ignition terminates.

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-18-T plus 748 seconds. The Surveyor model will be separated

from Centaur by firing three squibs which release latches onthe payload adapter. Three spring-loaded cylinders thenforce the Centaur and model apart. Separation occurs at avelocity of 34,700 ft. per second or 23,700 mph

Tplus 753 econds. Since future Surveyor operationalspacecraft will be oriented with respect to the Sun and thestar Canopus, the Centaur vehicle must be separated suffi-ciently from the spacecraft to preclude Surveyor's starseeker from locking onto the launch vehicle erroneously.This will be accomplished by:

1. Rotating Centaur 180 degrees by its attitude controlsystem.

2. Blowing residual propellants through Centaur'sengines to apply retro-thrust. This "retrowaneuver" lastsabout 15 minutes.

The successful execution of the retromaneuver willseparate Centaur and she dynamic model sufficiently. However,the dynamics. model being flown on AC-6 will not be equippedwith a star seeker, nor will it have any mid-course maneuvercapability as will future Surveyors.

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-19-Following separation, the dynamic model will continue

in its elliptical orbit around Earth. The Centaur vehiclealso will circle Earth, but in a shorter orbit than the model.

CENTAUR DEVELOPMENT TEAM

The Centaur program is directed in NASA Headquartersby the Office of Space Science and Applications. Dr. HomerNewell is Associate Administrator for Space Science andApplications. Vincent L. Johnson is Director, Launch Vehicleand Propulsion Programs. R.D. Ginter is Centaur ProgramManager.

Project management is assigned to NASA's Lewis ResearchCenter. Dr. Abe Silverstein is Director of Lewis. Bruce T.Lundin is Associate Director for Development. David S. Gabrielis Centaur Project Manager.

Centaur launches are conducted for Lewis by GoddardSpace Flight Center's Launch Operations, Cape Kennedy.Robert Gray is Chief, GSFC Launch Operations.

Convair WD.vision of Geniral Dynamics Corp. is primecontractor for the Centaur vehicle,; including the Atlasbooster. Grant L. Hansen is Centaur Program Director andVice President, GD/Convair.

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Centaur AC-6 Press Kit

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