 The first B @-@ 29 was delivered to the USAAF on 1 July 1943 , and Groves met with Arnold later that month . Groves briefed Arnold on the Manhattan Project , and asked for his help in testing the ballistics of the Project 's proposed bomb shapes . Arnold and the head of the Ordnance Division at Los Alamos , Captain William S. Parsons , arranged for tests to be carried out at the Naval Proving Ground in Dahlgren , Virginia in August 1943 . No aircraft was available that could carry the 17 @-@ foot ( 5 @.@ 2 m ) long Thin Man , so a 9 @-@ foot ( 2 @.@ 7 m ) scale model was used . The results were disappointing – the bomb fell in a flat spin – but the need for a thorough test program was demonstrated . 
