According to Wikipedia's Jet Propulsion Laboratory:
During JPL's Army years, the laboratory developed two deployed weapon systems, the MGM-5 Corporal and MGM-29 Sergeant intermediate range ballistic missiles. These missiles were the first US ballistic missiles developed at JPL.7 It also developed a number of other weapons system prototypes, such as the Loki anti-aircraft missile system, and the forerunner of the Aerobee sounding rocket. At various times, it carried out rocket testing at the White Sands Proving Ground, Edwards Air Force Base, and Goldstone, California. A lunar lander was also developed in 1938-39 which influenced design of the Apollo Lunar Module in the 1960s.6
6Launius, Roger (2002). To Reach High Frontier, A History of U.S. Launch Vehicles. University of Kentucky. pp. 39–42.
7Keymeulen, Didier; Myers, John; Newton, Jason; Csaszar, Ambrus; et al. (2006). Humanoids for Lunar and Planetary Surface Operations. Jet Propulsion Laboratory, National Aeronautics and Space Administration. Pasadena, CA: JPL TRS 1992+ Humanoids for lunar and planetary surface operations
Question: What did JPL's 1939 lunar lander look like and what practical aspects of landing on the Moon did this engineering design address?