For twenty or so pounds you can reduce your fuel
burn 10 or 20 %.

Get an e-turbo and take off the compressor.
You may save the weight of a muffler.

Hook them e-turbo generator to a 30 HP DC electric motor on
the prop shaft and viola you have an electric  turbo compound engine.

The e-turbo was designed to allow diesel engines to accelerate faster
with out generating smoke. DC motors will work as generators.

Paul Lamar


This makes perfect sense to me and fits what I think the rotary can
really do well, paul will disagree but, a generator. Unlimited revs no
harmonics, no redrive or vibration harmonics etc.etc.aluminum endplates.
Electric motors with a small battery to allow a safe return and a
blowdown turbine capturing all that hot exhaust and making good use of
it generating power. Put the engine where you want it and the radiators
the same. Electric motors where they work the best. Have you seen this
18 motor plane with 300% cruise efficiency?  Plus a prop on an electric
motor can be very light as there are no power pulses, the motors are
perfectly balanced and put out 100% torque at every rpm 95 % efficient.
Electric motors with ic generators will revolutionize aviation in a few
short years and the rotary is the perfect generator, maybe..

ray atkinson


The problem is the efficiency chain. any time you convert energy from
mechanical to
electrical and back there is a loss. Motors and generators have wire
that carry the current
that generates the essential  magnetic fields. Wires have resistance so
heat is generated.
Heat is energy. Lets say the generator is 90% efficient and the motor is
90% efficient.
90 times 90 is 81. So you just lost 19% of your recoverable energy, Gear
boxes are
over 95% efficient. The biggest problem with the electrical turbo
compound used by
F1 cars is heat generate by the electronics.. Then of course you have
all that extra
weight. not to mention cost. F1 cars are cost no object. It will be
interesting to see how
much Mazda wants for the FI style turbo compound RXx

Paul Lamar



Provided that
1/ Turbo lag or any sort of weak dynamic response is no big problem for
an airplane,

2/ It is much easier to handle clean and cool air than hot exhaust gasses,

I thought of using la large standard turbocharger to compress as much
air as possible from the exhaust gasses energy.

Of course one part of this compressed air flow should feed the engine.

But  the  rest  of  this  compressed  air flow is free for any other
usage… Including electric energy production from a turbo
expander.(See attached file: Cool air E-turbo.png)

A quite simple “Diverter-throttle” would feed the engine with the
required airflow, and the rest to the turboexpander.

The large enough turbocharger should not require a waste gate and would
muffle the exhaust sound.

Philippe Dejean (from France)

That is a really great idea Philippe. Solves a lot problems with a gear box
and an electric configuration. Thanks for sharing it you could easily get
  patent on that idea.. Next time I am in  France I am going to look
you up.

Paul Lamar


Thank you for the positive comment.

About, the patent, I am not used to such a procedure, and I am very
doubtful about the fact I could be the first to think to this rather
simple arrangement...

For the turbo expander, I first thought that a Procharger type
compressor fed backwards could do the Job, but If the stator
probably could work properly, I don't think that the impeller would be
efficient as a turbine in the reverse direction...
Further investigation needed, as well as for the large turbocharger
choice (lots of parameters to take into account,
including altitude).

The "diverter-throttle" seems quite easier to design. A pressure
balancing chamber should help to reduce the efforts and instability of
the moving part (see sketch).
A further development would be close loop controlling the throttle
through engine inlet pressure.


Philippe Dejean

That is always the way it is with me too. It is so simple and so obvious
I wonder why
no one thought of it before.

For a mechanical TC version the high pressure air could go through a low
temperature
turbine and then be geared back to the e centric shaft. The low
temperature turbine could
be much larger in diameter with much higher torque. About the size of a
flywheel.

Cheaper than a high temperature turbine.

Great idea. Thanks.

Paul Lamar



Of course you are right about the efficiency Paul, but I am thinking that really pushing the engine, and extracting the max from the exhaust, plus no gearbox and super light props and electric motors allows a smaller lighter motor to do the job with a small battery to get back to an airport when things quiet down too much. There is so much energy in the exhaust and it seem like the way to extract it is via a generator. Am I on track with the exhaust containing the same potential energy as the engine itself and what per cent would be recoverable via a blowdown turbine and generator? The main thrust of my argument is to allow generators and electric motors to absorb all the power without any harmonics or out of balance spinning parts. Perfectly balanced at 10000rpm at the engine and 20-50000 at the blowdown turbine working together seamlessly.

ray atkinson

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