Auxiliary power unit
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An auxiliary power unit is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft, naval ships and some large land vehicles. Aircraft
A Honeywell GTCP36 APU mounted in the tail of a business jet
The APU exhaust in the tailcone of an Airbus A380
The intake diverter of the Jumo 004, with pullcord starter handle for Riedel APU and its sparkplug access ports
The Riedel two-stroke engine used as the pioneering example of an APU, to turn over the central shaft of both World War II-era German BMW 003 and Junkers Jumo 004 jet engines (pullcord starter variant shown)
BMW 003
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The BMW 003 is an early axial turbojet engine produced by BMW AG in Germany during World War II. The 003 and the Junkers Jumo 004 were the only German turbojet engines to reach production during World
Auxiliary power unit
…APU-style starter for all three German jet engine designs to have made it to at least the prototype stage before May 1945 – the Junkers Jumo 004, the BMW 003 (which uniquely appears to use an electric starter for the Riedel APU), and the prototypes (19 built) of the more advanced Heinkel HeS 011 engine, which…
BMW 003 engine at the Luftwaffenmuseum der Bundeswehr. Airflow from L to R.
Preserved BMW 003 with Riedel flat-twin mechanical APU fitted