Piston-engine APUs

[b29flteng]

C-97As had a piston powered APU. Later versions had a turbined powered APU.

[JohnB]

Think we can push the first APUs to pre-W.W.II. Thinking about it, you'd expect the large flying boats, having to operate independantly, to have them. Regards,

I'd guess the Boeing 314 flying boat also had one....which leads to the question, did the Boeing B-15 feature one?

Likewise, the DC-4E might of had one, and did the Douglas B-19 (the "Douglas Flying Behemoth") have one?

[Jack Frost]

All of the C/KC-97s all originally had a 2 cylinder, 4 cycle Apu that looked alot like the one in the large photo a few posts ago. I don't remember the horsepower of the engine but the output was 28v DC at 125 amps. It would crank an engine but it was really straining and wouldn't be able to do it without draw on the ships battery too as well as reduce to only essential electrical load. It was located on the right side of the lower forward cargo compartment right across from the Forward Entry Door. It was hot and noisy and vibrated alot..
Starting in 1957 they were all replaced by a Solar Turbine apu which increased the output to 600 amps @ 28 volts. A great improvement since the heater ground blower could be used without any external power. Nice in the artic!

Since the L models were all converted from G models, if they didn't already have the Solar APU, they got it then.

Jack
Ex-KC-97 Standboard Pilot

[Taigh Ramey]

I have been in Switzerland for about a month doing maintenance and flight training on two Beech 18's (Canadian 3NM's) and a DC-3 (ex C-47).



Check out what they are using for ground power













Its a homelite 28 volt APU exactly like the ones used in every B-17 and B-24 throughout WWII. The thing had been sitting idle since last October and fired right up. Pretty cool.