This is a cutaway of a two-chambered liquid-fuel rocket engine for the U.S. Navy's Lark surface-to-air missile. The larger chamber produced 400 pounds of thrust. The smaller chamber produced 220 pounds for a combined thrust of 620 pounds. The Lark motor was among the earliest regeneratively-cooled types in the U.S. and was developed by Reaction Motors, Inc.
The Lark had a range of 38 miles. It was designed in late 1944 as a defense against Japanese Kamikaze attacks in the Pacific Theatre but its development was slow. The Lark did not become operational but served as an important post-war test vehicle and saw service up to 1953. This object was donated to the Smithsonian by the Reaction Motors Division of the Thiokol Chemical Corporation in 1985.
Gift of Thiokol Chemical Corporation, Reaction Motors Division