The questions of this thread should center around:

- Are high speed (50-80K RPM) alternators available

OTS?

- Can they be safely coupled to the turbo?  Possibly replacing the compressor section?  (U-joints are out!)
- Are high efficiency electric motors available OTS

that can be bolted to the e-shaft?

- Can this be done to recover some exhaust energy,

or is this a waste of time?

First, turbocharging does not increase efficiency.
However, a carefully designed system using a
turboalternator might increase the torque.

I'm not aware of OTS high speed alternators, at least
just yet, for the rotaries. Custom, they can safely be
coupled to the turbo. The compressor section can be
replaced too.

High efficiency brushless electric motors are
available.

Given the notorious inefficiency of the rotary engine,
any heat recovery would be of great value. A custom
turbo alternator has been done.

see Barber-Nichols site

http://www.barber-nichols.com/products/specialty_products/turbo_alternators/default.asp

To do this single design change in isolation would
make the engine prohibitively expensive. However, an
estimated 20-30% could be recovered assuming a base
efficiency of 40%.

However...one design takes the rotary engine and
eliminates the "bulkiness" of past and current designs
in RX-7/8 and other rotaries.

Almost all rotating parts are placed on the main
rotary shaft including a starter/alternator, a
compressor, and a flywheel in line with the rotary
engine! Intake and exhaust would be designed to assist
in cooling/heating.

The result is interesting since efficiency goes up as
weight goes down. With the above changes, and by using
other materials, the efficiency could reach 75% and
the weight could drop 50%. The gross increase in
power/pound would be a factor of 3 1/2, very
significant for airplane use.

Starter/alternators are already here and gives the
engine a bit more breathing room.

Instead of one turbo alternator, smaller multiple
turboalternators might be used for redundancy sake.
Also, there are scalability issues to address with the
larger the rotating parts.

David Mathes

"Given the notorious inefficiency of the rotary engine,"

It is not as bad as you think David. We are within
4% of a typical Lycoming BSFC. .47 for the rotary as opposed
to .45 for the Lyc. Sure people are claiming .38 but they
have no independent data to back it up. That is diesel territory.

What more than makes up for that is the ability of the rotary
to burn auto fuel. Most Lyc's now a days require 100 LL.
Typically there is a 50 cent a gallon saving or about
$2.50 verses $3.00 or about a 17% savings in favor of the rotary.

Paul Lamar

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