Piston-engine on-board APUs?

The C-124 had two: one in each outboard nacelle just aft of the powerplant firewall. It was a V-2, 4 cycle engine with its own oil supply.

Martin Mars.

WIX responses to exactly the same Q: http://www.warbirdinformationexchange.org/phpBB3/viewtopic.php?f=3&t=45170

Wasn’t Vespa and Lambretta scooter engines originally designed as APU for some Italian aircraft?

The Jumo engines on the Me 262 had a two-stroke ‘starter’ engine built into their nose cones.

I can remember two that preceeded the C130.

The first one that comes to mind was ZA947, the BBMF Dakota. I used the APU on a number of occasions. This was a delightful unit mounted in the rear fuselage opposite the Elsan. comprising of a small petrol engine connected to an lecky genny, it worked wonderfully to re-charge the batteries, vitally important when we were doing a lot of ground movements at low power as the main DC genny’s wouldn’t come on line until 1200+ rpm. The APU could be elect started remotely from the cockpit, elect started on its own starter panel, or in the case of flat batteries, there was a lawn-mower type pull cord. It never failed to start easily, and coped easily with the loads we placed on it. The only concern was ensuring there was sufficient airflow (rear cabin door and para door open) as the air-cooled engine generated a lot of heat.

The second application I remember vividly were the two V4 petrol engined APU’s installed in the wing centre section of Philippine Mars.

I was once told that the Scott twin-cylinder boxer engine had been used as an APU power supply during WWII, but I cannot remember what it was installed in.

camlobe

Going back a bit further the DH91 Albatross 4 engined airliner of 1937/8 had a Stanley auxiliary motor mounted behind the radio operators compartment to provide power for starting and emergency operation of the radios. This was only fitted to the Atlantic version and not to the Imperial Airways European type.

Lancaster MARK X’s had the American B24 APU fitted postwar… Not sure if the Canadair Argus had an APU as well??

Beverly

It was not large, built much earlier, believe it or not the Fiat CR-42 had an on board Garelli engine to drive a compressor.

The B-24 had such an an APU. For spec see http://www.jdsqrd.com/plane.htm

Tim

The Lancaster i believe had a Triumph 500 cc engine. Which later was used a a racing motor cycle engine by Triumph’s GP.

Dave

Short Sunderland

Pete

The Catalina is one that immediately comes to mind…