the same yellow zinc chromate primer color worn by Fat Man. While many Manhattan scientists expected that the development of the means of delivery of the atomic bomb would be straightforward, Parsons, with his experience of the proximity fuze program, expected that it would involve considerable effort. The test program was initiated on 13 August 1943 at the Naval Proving Ground in Dahlgren, Virginia, where a scale model of the Fat Man plutonium bomb was developed. On 3 March 1944, testing moved to Muroc Army Air Field, California. The initial tests demonstrated that the Fat Man assembly was unstable in flight, and that its fuzes did not work properly. Production The shells of the pumpkin bomb were manufactured by two Los Angeles firms, Consolidated Steel Corporation and Western Pipe and Steel Company, while the 'California Parachute' tail assembly was produced by Centerline Company of Detroit. After initial development, management of the program was turned over to the U.S. Navy Bureau of Ordnance in May 1945. A total of 486 live and inert training bombs were eventually delivered, at a cost of between $1,000 and $2,000 apiece. All of the inert versions went from the manufacturers directly to Wendover Army Air Field, Utah, by rail, where they were used by the 216th Base Unit in flight testing of the bomb. Some test drop missions were flown by the 509th Composite Group's 393d Bombardment Squadron as training exercises. The bombs intended as live ordnance were shipped to the Naval Ammunition Depot, McAlester, Oklahoma, for filling with explosives. The Composition B was poured as a slurry, solidified in a drying facility for 36 hours, sealed, and shipped by railroad to the Port Chicago Naval Magazine, California, for shipment by sea to Tinian. Description The pumpkin bombs were externally similar to the Fat Man bomb in size and shape, and both had the same California Parachute square tail assembly and single-point attachment lug. The pumpkin bomb had three contact fuzes arranged in an equilateral triangle around the nose of the bomb while the atomic bomb had four fuse housings. The atomic bomb had its shell sections bolted together and sealed with externally-applied, sprayed-on liquid asphalt, but most if not all of the pumpkin bombs were welded, with a four-inch hole used for filling the shell. The Fat Man also had four external mounting points for radar antennas which the pumpkin bombs did not have.