B-29’s had APUs?
It was a large portable generator they had in the plane.
Yes, they were used on takeoff and landing.
Darryl Greenamyer’s crew had jury-rigged a gravity feed for the fuel tank, because the pump wasn’t working. While doing taxi testing, the fuel tank fell and threw gasoline on the APU. The guy in the rear of the plane was away for a critical moment, and the rest is (tragic) history.
Perhaps the saddest epilogue to the “Kee Bird” story was a post from a Norwegian helicopter pilot that I read on an aviation page years ago. He said that he regularly flew supplies and heavy cargo to various points around Greenland, and that the plane’s crash site was less than fifty miles from the coast...it would have been no issue to dismantle the plane into its main subsections, helicopter them to the coast, and ship them out on an oceangoing barge.
The guys that rebuilt the Plane put one in there.