Page 75 - Apollo Moonships

The lunar spider 73
RCS FUEL TANK
Each RCS fuel tank had a volume of 1.9 cubic feet and contained 104 pounds of Aerozine 50.
RCS HELIUM TANK
Each RCS helium tank had a capacity of 910 cubic inches and carried 1.03 pounds of gas.
XIDIZER TANK
pacity of the RCS
er tanks was 2.38 cubic housed 208 pounds of
en tetroxide.
36 cubic feet 2011 pounds 3217 pounds 3.35 cubic feet 6.5 pounds 67.3 cubic feet 7513 pounds 11993 pounds 5.9 cubic feet 51.2 pounds
1 cubic foot
ASCENT ENGINE
The rocket engine that propelled the lunar lander ascent stage developed 3500 pounds of force in the vacuum of space and was fed by a fuel tank and an oxidizer tank mounted along the sides of the midsection. This power was enough to lift the moon into the ascent stage and propel it into the lunar orbit at 6500 feet per second. The engine was designed to be very reliable (if it failed, the astronauts could never take off from the moon), so it was built to be simple and functional. The engine, for example, could be shut down and restarted 35 times but was not throttleable (produce the same thrust all the time) and had no gimbal capabilities. Instead, it was tilted 1.5° upward from its centerline. Before the initial engine starts,
the propellant tanks must be pressurized with gaseous helium. The gas was stored in two spherical tanks placed in the aft equipment bay.
The ascent engines mounted on each lunar lander were never tested before being used on the moon because their propellant was so corrosive that it destroyed many of their critical components.
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ASCENT ENGINE PROFILE Manufacturer:
Length:
Diameter:
Weight (dry):
Nominal thrust:
Engine start to 90% of rated thrust: Engine shutdown to 10% of rated thrust: Restart capability:
Fuel flow rate:
Oxidizer flow rate:
Engine life:
Bell Aircraft/Rocketdyne 47 inches
31 inches
180 pounds
3500 pounds–force 0.310 seconds 0.200 seconds
35 times
4.3 pounds per second 6.9 pounds per second 460 seconds
1 Pressure transducer
2 Oxidizer line
3 Fuel line
4 Injector 9 5 Thrust chamber 10
Propellant valve assembly Throat
Oxidizer inlet
Fuel inlet
Nozzle extension
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DESCENT ENGINE
The descent engine was more sophisticated and powerful than the ascent engine. It was throttleable and had a gimbal ring and actuators to provide vector thrust along the pitch and roll axes (it moves +6° and -6° from center along the X and Z axes). The engine developed a nominal thrust
of 9,900 pounds, but it could also be operated between 6,800 and 1,280 pounds. The engine was designed with throttle and gimbal capabilities to efficiently perform its primary task: provide the LEM with a controlled descent down to the moon’s surface and the ability to perform necessary maneuvers so astronauts could choose the right landing
site. Four cylindrical, 67.3 cubic-foot titanium tanks—mounted in the center compartment of the cruciform inner structure of the descent stage—fed the engine. Two of them contained fuel, and the other two contained oxidizer. In order to force fuel and oxidizer into the engine’s thrust chamber, the propellant tanks were pressurized
by one tank filled with supercritical helium (a condition in which fluids act as gases and liquids at the same time due to the pressure and temperature to which they are subject).
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DESCENT ENGINE PROFILE Manufacturer:
Length:
Diameter:
Weight (dry):
Nozzle expansion area ratio: Nominal engine thrust (full throttle): Minimum engine thrust (low stop): Gimbaling capability:
Restart capability :
Thrust (throttleable):
Engine life:
Space Technology Laboratories 95 inches
63 inches
348 pounds
47.4 to 1
9900 pounds-force 9900 pounds-force
±6° along X and Y axis 20 times
1280–9900 pounds–force 910 seconds
1 Oxidizer shutoff valves
2 Fuel shutoff valves
3 Solenoid 9
Gimbal ring Oxidizer flow valve Fuel inlet line
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4 Thrust chamber
5 Throttle valve actuator
6 Fuel flow valve
10 Oxidizer inlet line 11 Heat shield
12 Nozzle extension
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