This week in history -- March 26, 1949: YB-36D first flight Published March 28, 2013 By AFNWC Historian Air Force Nuclear Weapons Center KIRTLAND AFB, N.M. -- Early versions of the B-36 were criticized for insufficient performance. On Oct. 5, 1948, Convair proposed that the problems could be addressed by fitting two pairs of turbojets in pods underneath the outer wings, similar to those fitted underneath the inner wing of the Boeing B-47 Stratojet. The turbojets would be used for takeoff and for short bursts of speed during the bombing run, and would have only a minimal effect on range. The changes resulted in the B-36D version. Conversion of a B-36B to D configuration was authorized Jan. 4, 1949. The prototype B-36D was obtained by converting a B-36B.The modification was sufficiently successful that the Air Force contracted for additional bombers as B-36Ds during FY 1949, and opted to modify existing B-36Bs to D configuration. The first true production B-36D flew July 11, 1949. The first B-36Ds were accepted by the Air Force in August 1950, and were initially sent to Eglin AFB, Fla. for testing. By June 1951, 26 B-36Ds had been delivered. The last B-36D was accepted in August 1951. Eighty-one B-36Ds were delivered; 22 built as B-36Ds from the start, and 59 others were converted from B-36Bs.