Starting in November 1943, the Army Air Forces Materiel Command at Wright Field, Ohio, began Silverplate, the codename modification of B-29s to carry the bombs. Test drops were carried out at Muroc Army Air Field, California, and the Naval Ordnance Test Station at Inyokern, California. Groves met with the Chief of United States Army Air Forces (USAAF), General Henry H. Arnold, in March 1944 to discuss the delivery of the finished bombs to their targets. The only Allied aircraft capable of carrying the long Thin Man or the wide Fat Man was the British Avro Lancaster, but using a British aircraft would have caused difficulties with maintenance. Tests were carried out with modified Lancasters at Enstone Airfield, but Groves hoped that the American Boeing B-29 Superfortress could be modified to carry Thin Man by joining its two bomb bays together. Arnold promised that no effort would be spared to modify B-29s to do the job, and designated Major General Oliver P. Echols as the USAAF liaison to the Manhattan Project. In turn, Echols named Colonel Roscoe C. Wilson as his alternate, and Wilson became Manhattan Project's main USAAF contact. President Roosevelt instructed Groves that if the atomic bombs were ready before the war with Germany ended, he should be ready to drop them on Germany.