This engine is a six-cylinder, inline, liquid-cooled engine which produced 120 hp at 1,350 rpm and was manufactured by the Union Gas engine Company of Oakland, CA. It was adopted by the U.S. Navy to power its "D" class airships. This particular engine was one of two that powered the Navy's D-6 (S/N A5972) which was built by Goodyear in 1920. D-6 was 198 feet long and had a top speed of 56 mph. It was unfortunately destroyed by fire in 1921.
This engine is located in the Military Hangar near the de Havilland Beaver display.