LEM gear

Glenn

Why did the Apollo LEMs have a four leg landing gear instead of a three leg landing gear?

I saw some old photos of LEM concepts using a three gear setup and it got me wondering why they went to a heavier 4 gear setup.

Thanks,
Glenn

FredGarvin

I found this just snooping around:

"Apollo LEM landing gear design freeze:

MSC Director Robert R. Gilruth reported to the MSF Management Council that the LEM landing gear design freeze was now scheduled for August 31. Grumman had originally proposed a LEM configuration with five fixed legs, but LEM changes had made this concept impractical. The weight and overall height of the LEM had increased, the center of gravity had been moved upward, the LEM stability analysis had expanded to cover a wider range of landing conditions, the cruciform descent stage had been selected, and the interpretation of the lunar model had been revised. These changes necessitated a larger gear diameter than at first proposed. This, in turn, required deployable rather than fixed legs so the larger gear could be stored in the Saturn V adapter. MSC had therefore adopted a four-legged deployable gear, which was lighter and more reliable than the five-legged configuration."

This is from a site that appears to have a pretty good chronology of the design process:

http://www.astronautix.com/craft/lmlggear.htm

Hope this helps.