APS Engine

On my final visit to Glenn, there was a Lunar Module Ascent Propulsion System (APS) engine in the auditorium. It had been taken out of storage for the 40th anniversary of the moon landing.

APS engines are fairly rare; I've only seen them at the Cernan Earth & Space Center, the USSRC, and the Smithsonian (although the latter looks unlike the others I've seen), and there was a bare APS thrust chamber at Michigan Space & Science Center (now at the Air Zoo).

I was most excited by the fact that this engine is displayed on its side, allowing inspection of the interior of the thrust chamber and the injector; all the other APS engines are displayed in the traditional "thrust chamber opening down" position.

The sign on the side of the pedestal reads

Lunar Module Ascent Engine

This is an engineering model of the 3,500-pound thrust ascent engine. The engine was not gimbaled and it performed at full thrust. The engine remained dormant until after the ascent stage separated from the descent stage. The propellants used were helium-pressurized Aerozine 50 and nitrogen tetroxide.

Technically, of course, the ascent engine remained dormant until just before the ascent stage separated from the descent stage, because it was the firing of the ascent engine which effected the separation :-)

After GRC's on-site visitor center closed in 2009, this artifact was not among those moved the the Great Lakes Science Center. This engine is among the artifacts in GRC's "Celebrating Apollo" travelling exhibit, and I have additional photos of this engine from when the exhibit was hosted at the EAA Aviation Museum.