0627 was a BT-1 converted to the XBT-2, the progenitor of the Douglas SBD Dauntless. Its first flight as the XBT-2 was on 22 April 1938. It was assigned to NACA's Langley Memorial Aeronautical Laboratory in February 1939 for full-scale wind tunnel tests. The XBT-2 had the characteristic perforated flaps, but here they appear to have been replaced. Photo by: Carl Mydans / Life

Despite its shortcomings, the Northrop BT-1 dive-bomber did see carrier service. The type was retired from the fleet by April 1941. BuNo 0631 lasted as a trainer until 1944. Photo by: Carl Mydans / Life

Some 56 examples were built of the Northrop BT-1 dive-bomber. Low-speed handling issues and the lack of wing folding made it unsuitable for carrier use. The reworked BT-2 became the SBD Dauntless as Northrop became the El Segundo division of Douglas. Photo from: US Navy - National Naval Aviation Museum