The Auxiliary Power Unit (A.P.U.) was fondly referred to as the "Putt-Putt".
These are small gasoline engines that were aboard every B-29 aircraft.
The "Putt-Putt" provided extra power to start the 4 engines on a B-29.
The APU was the only means of supplying power to the radios on the stranded Kee Bird. The Air temperature
was somewhere between 50 to 60 degrees below zero.
The Kee Bird crew members built a small fire underneath the Putt-Putt to warm it up enough to where it might fire up.
The Kee Bird's Copilot (Russell S. Jordan) recalls in his story that when
the Putt-Putt finally started up on that frozen lake, it was the "sweetest sound he'd ever heard in his life".
The Putt-Putt enabled the Kee Bird crew to utilize their radio after they had crash
landed on the frozen lake. Each of the crew members agreed that the Putt-Putt
had saved their lives. Without it, radio contact would have been impossible. Without radio contact, the crew's rescue would have been impossible.
The following photos are of the Putt-Putt aboard the "FiFi", the only fully-operational
B-29 in existence. The "FiFi" is owned and operated by the Commemorative Air Force (formerly known
as the Confederate Air Force).
The Putt-Putt shown here is identical to the one aboard the Kee Bird.
You can click on each image for a larger version.