The Loon, also called the JB-2 or KUW-1, was an American copy of the German pulsejet-powered V-1 or "Buzz Bomb" of World War II. It was designed to carry a 2,200-pound high explosive warhead to a range of 150 miles and could be launched from the ground, ships, or aircraft. The air-breathing pulsejet motor is the long tube at the rear.
The development of the Loon came too late for use in World War II, and it was not used in combat. However, it provided invaluable experience to U.S. Navy and Army Air Force (and later, Air Force) personnel in the handling of missiles. The Loon was cancelled in 1950. This object was donated to the Smithsonian in 1965 by the U.S. Naval Supply Center.
More information: Loon Missile