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Aircraft Auxiliary Power Unit starter

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Shaftdriver
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Aircraft Auxiliary Power Unit starter

This is an APU (Auxiliary Power Unit) developed for a Hansa HFB320 aircraft built in the mid 1960s. The APU is a gas turbine, and is the smallest gas turbine manufactured for this application, output power around 12kW. It is intended to generate power for some of the aircraft systems when the main engines are not running, and also compressed air to operate the cabin air conditioning on the ground.

This unit was removed from the aircraft, unfortunately minus its electric starter motor/generator. I dismantled the engine and repaired a few bits, repainted it, fitted it in a frame and made a new flange for a starter /generator from another turbine engine. I added some control electronics, and the engine has been started and run successfully in this configuration many times.

This winter's project is to replace the big lump of a brushed starter generator with a brushless motor and controller. Due to the large inertia of the turbine rotor, plus its gear train, it is convenient to be able to ramp the starter motor slowly - hopefully an ideal application for VESC ! Also, once the APU is up and running, the regenerative braking will recharge the battery.

I've only just started the required modifications - new motor mounting flange and spline adapter - so I just have pictures of the current configuration. The picture shows the unit out of the frame. The black section on the left is the compressor/combustion chamber/turbine, the yellow section is geartrain, fuel pump, tachometer generator and fuel control valve. The black lump on the right hand side is the existing DC motor/generator, to be replaced by a 6374 190kV outrunner.

I'm new to VESC tool, it has a pretty steep learning curve, which is not surprising considering it has been in development for years, and I'm only weeks into it...

2005-04-29 002.JPG

Snabelost
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Sound like a fun project!

What should you use the APU for when you are able to start it?

Shaftdriver
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It is a profound question....there is no specific use, it is an end in itself, rather than a means to an end. It will re-charge its own batteryfrown

RCMarmion

Snabelost
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That is good enough as an explanation :-)

velolac
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Hi,

Nice project. Are you able run the turbine with good efficiency at fraction of the previous load or working point? That sized motor is told to be around 3kW max, but for sustained use probably it is better to think of it like 1..1,5kW motor. Maybe it make sense to use a bigger motor and of course appropriate VESC for it.