Boost-Protective Cover (BPC)The boost-protective cover protects the command module from aerodynamic heating during boosted flight and from heat and soot from the launch escape and Jettison motors of the launch escape system. It is made of ablative cork and Teflon-impregnated glass cloth supported by glass honeycomb in the upper portion. It is jettisoned with the launch escape system at 268,000 feet altitude less than three minutes after liftoff.
Launch Escape System (LES)
Apollo Spacecraft (without Boost Protective Cover)
The launch escape system is 33 feet tall and consists of an escape motor, pitch control motor, tower jettison motor, tower release mechanism, canard subsystem and Q-ball assembly. It weighs about 8,500 pounds.
The launch escape motor is 26 inches in diameter, 15 feet, 3 inches long and burns about 4,700 pounds of solid propellant to provide 155,000 pounds of thrust.
The pitch control motor is nine inches in diameter, 22 inches long, and burns solid propellant.
The tower jettison motor is 26 inches in diameter, 47 inches long, uses solid propellant and develops about 33,000 pounds of thrust. It removes the LES after the second stage ignition.
The tower release mechanism consists of four explosive bolts which separate Just before the Jettsion motor or escape motor ignites to detach the LES from the command module.
The canard subsystem is mounted in the pitch control motor housing near the top of the launch escape system. Each of two wing-like canard surfaces is about 18 inches wide and 24 inches long. The aerodynamic surfaces are deployed by explosives 11 seconds after the escape motor fires during an abort. They stabilize the command module blunt end forward prior to drogue chute deployment.
The Q-ball assembly is at the top of the launch escape system and contains pressure sensors to determine flight angles of attack and dynamic pressures during launch or launch abort.
Command Module Guidance and Navigation System
The system consists of inertial, computer and optical subsystems. During this unmanned mission the optical subsystems, telescope and sextant, will be inactive.
A control programmer will perform tasks normally done by the astronauts.
The computer will be activated to determine spacecraft velocity and attitude and reentry angle.
Command Module Attitude Control and Stabilization System
The system, composed of 12 small rocket engines installed in independent, identical sets of six, provides onboard propulsion for positioning reentry into the Earth's atmosphere. Fast acting valves enable the engines to be fired in short bursts to 30 per second to position the spacecraft precisely during reentry. Thirty bursts (pulses) per second is about the rate a spark plug fires in an automobile engine operating at 3,000 revolutions per minute, or about 70 mph.
Thrust: 93 lbs. per engine Length: 11 inches Diameter: 5 inches Weight: 8.3 lbs. Propellants: Monomethylhydrazine (fuel) and nitrogen tetroxide (oxidizer). Combination is storable and hyper- golic - 270 lbs. on this mission. Components: Ablative thrust chambers, feet acting valves, and detachable nozzle extension. Pulse frequency: 30 cycles per second Earth Landing System (ELS)
Besides the sequence controller, the Earth landing system consists of two nylon conical ribbon drogue parachutes 13 feet in diameter; three ringslot nylon pilot chutes, seven feet in diameter; and three ringslot, nylon main chutes 83.5 feet in diameter.
At 24,000 feet altitude, after reentry, a barometric switch activates pyrotechnics which jettison the apex heat shield to uncover the parachutes.
Two seconds later the drogue chutes are deployed by mortar to stabilize the spacecraft blunt end forward. The drogues are reefed for eight seconds, then fully opened by reefing cutters.
The pilot chutes are deployed about 10,350 feet, pulling the three main parachutes from their containers. The main chutes also are reefed for eight seconds until cutters permit the large canopies to open fully.
The VHF recovery and survival antennas and a flashing light are deployed after the main chutes disreef, the survival and recovery beacons begin operation before touchdown.
If the spacecraft lands with its apex end in the water, the control programmer will signal a pump one minute after splashdown to inflate one of three flotation bags. five minutes later, if the spacecraft is still not upright a second pump inflates another bag, and if necessary five minutes later the third bag will inflate.
When upright, other aids, such as the HF transmitter and flashing light begin operation.
Power Supply System
Power for the spacecraft will be furnished by two of three fuel cells carried in the service module. Maximum gross power of these two units is 2,840 watts (29 volts). The cells weigh 240 pounds each and use oxygen and hydrogen as reactants. A total of 672 pounds of liquid oxygen (in two tanks) and 60 pounds of liquid hydrogen (in two tanks) will be carried. The third fuel cell will not function during this mission.
Service Module Main Propulsion System (UPS)
This system provides thrust required for large changes in spacecraft velocity after launch vehicle separation.
In orbital missions the SPS will be used for orbital changes and retrofire, and on a lunar Journey will provide midcourse corrections and velocity changes for entering and leaving lunar orbit.
Two electrically operated servo-actuators provide the SPS engine with the capability of gimballing action. SPS propellants (fuel and oxidizer) are kept to the bottom of the tanks for proper flow into engine pumps by maneuvers performed by the SM reaction control system.
During this flight the restartable engine will be fired four separate times for a total of 5 minutes and 25 seconds.
DESCRIPTION:
Engine Thrust 21,500 pounds Engine is capable of operating for 12 and a half minutes in various time increments involving up to 50 separate periods of operation. Propellants 7,500 lbs. of UDMH (fuel) 15,180 lbs. of nitrogen tetroxide (oxidizer) Height 12 feet 7 inches Weight 770 lbs. Service Module Reaction Control System
Sixteen small rocket engines are used to carry out ullage requirements, perform stabilization maneuvers during flight and to separate service and command modules prior to reentry. They are arranged in clusters of four.
FUNCTION: Positioning of SM, ullage requirements for SPS propellants, separation SM/CM DESCRIPTION: Number 16 clustered in four quadrants Propellants Nitrogen tetroxide and hydrazine 50-50 UDMH - (838 lbs. carried on this mission) Size 14 inches long, largest diameter six inches Weight 5 pounds Thrust 100 lbs. (each engine)
Copyright 1997, 1998 by John
Duncan |
