Page 73 - Apollo Moonships

The lunar spider 71
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QUADRANT III
This quadrant houses descent engine electronics, an oxygen tank, and two helium tanks.
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QUADRANT II
This quadrant included landing radar electronics, a scientific equipment package, and a water tank.
LANDING GEAR ASSEMBLY LEM/SLA interface
Outrigger
Deployment and downlock mechanism
Crossmember assembly
Sensing probe
LANDING GEAR
Side frame Secondary strut Primary strut
Footpad
The landing gear of the Lunar Excursion Module (LEM) was designed to satisfy several requirements, such as maximum weight, freight capacity, or the ability to be retracted to reduce its size during the Saturn V launch. One of the most critical was the impact attenuation, because the landing gear could be able to preserve the integrity of the LEM to enter into contact with different types of lunar terrain: from a loose powdery dust into the ship could sink (regolith) to a very slippery or hard soil. Having in mind these considerations, engineers built the landing gear using a four-leg configuration with the same number of cantilevered assemblies. Each assembly comprised several struts, trusses, a footpad, and a deployment and downlock mechanism. The primary and secondary struts were piston-cylinder-type tubes that mounted inside a compressible aluminum-honeycomb cartridge with high shock-absorb capabilities. The design of the struts not only provided the impact attenuation required but also saved weight because
a thick-walled tube was not necessary. The material was also used on the footpad attached at the end of each primary strut. The footpad was 31 inches in diameter, enough to ensure minimal penetration of the LEM into the regolith or another loose terrain. The innovative landing gear was also resistant and could remain undamaged even in the event that the LEM bounced two or three times against the lunar ground. However, this never happened because the LEM astronauts were highly trained to set the vehicle down very softly.