Paul,

   Has anyone ever tried and electric turbo-compound?  If the turbine
   drove a
   DC generator and you had the DC motor driving the crankshaft, which
   could be
   built into the flywheel, I think you might have a simpler and more
   efficient
   system.  You would get rid of the gears, the fluid couplings and
   probably
   the starter motor as well.  The new hybrid cars are using the flywheel
   pieces already.  The DC generator could have individually controlled
   windings so you could vary the load on the turbine at a given rpm.  You
   could also run at higher voltage to reduce the weight of the system.
    What
   do you think?

   Steve Brazil


   Yes Caterpillar and John Deere were working on that but no
   production hardware
   as far as I can find. What do you want to do with 37Kw of electrical
   power? Might
   be useful for a UAV or hybrid. If the generator is 80% and the motor
   is 80%
   the overall is 64%. Not good.

   Paul Lamar ...No rotor no motor.


Not just the efficiency issue..  A 50hp motor is going to weigh enough
to not make it practical for a normal, useful airplane - even if it's
made from unobtainium...  And the generator is going to weigh
essentially the same amount.  Fine for a fixed installation or maybe a
tractor or locomotive.

Here's an article that says you're looking at something like 75lb/hp,
but maybe as low as 30lb/hp..

http://www.1911encyclopedia.org/Electric_motors

I'm sure they can beat these numbers by a wide margin.  Even so, all of
the hybrid cars are heavy for their total horsepower, even ignoring the
batteries and considering the fact that they build them with lighter
materials than a regular car.  The manufacturers are getting adequate
performance by building cars how we already build airplanes - light and
low drag.

I did ponder the idea of including a large alternator in the turbo
compound to drive an airframe deice system..  No need for a motor for
that portion of the recovery.


Matt-



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