Hurant Karibian wrote:

  In over 5000hrs of operating 3350 compounded engines
in Connies and DC-7 I had one exhaust valve failure. I
found the civilian flight engineers didn't have near
the knowledge of that engine and how to operate it
that we learned in the military. Karibian

That is a record.

As a passenger, I have flown a lot of miles on turbo compound powered
airplanes and I have never had to duck from flying valves. Turbo compounding
is a point design situation, unsuitable for variable load operations such
as cars. It has the potential for improved econmy in near steady power
situations like aircraft, but if you want more power, increase the size of
the engine for a better trade for power to weight and complexity. The weak
link is probably turbine temp, and the rotary is a downer in that regard.
I understand that there was at least one DC7 with little airfoil shaped
holes - you think your muffler has got it bad - try 50,000 rpm turbine
blades glowing yellow, _ Vance

Ah but we have a very simple solution for both the exhaust temp problem and the point
design car engine problem. Still secret :) Perhaps I'll tell you when I get back from Japan.
Making the rotary engine larger is not trivial. Much much easier to apply turbo 
compounding to get both more power and less fuel burn.

BTW the RX8 side exhaust port engine has cooler exhaust. By how much I don't know
yet.

Also the solution to the airfoil shaped holes in the fuselage was an armored 
steel ring around the later exhaust turbines. All current turbo fan engine 
have something similar to deal with a thrown fan blade only in this case 
the ring is Kevlar.

Paul Lamar
 
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