01/31/2009. Remarks by Johan Visschedijk: "Originally produced as a B-29B-55-BA by Bell at Marietta, near Atlanta, Georgia, this example was converted to a flying engine test laboratory. The test engines where fitted to a rig in the bomb bay (in this case an Allison J35) that could be lowered in flight. Note the feathered propellers, indicating the aircraft flew on jet propulsion only. Also tested were the General Electric J47 and J73."