 Testing began with scale models at the Naval Proving Ground in Dahlgren , Virginia , in August 1943 . Modifications began on a prototype Silverplate B @-@ 29 known as the " Pullman " in November 1943 , and it was used for bomb flight testing at Muroc Army Air Field in California commencing in March 1944 . The testing resulted in further modifications to both the bombs and the aircraft . 
