Subject: Flying the DC-7
From: AAA-rotaryeng
Date: 3/5/2013, 8:12 PM
To: AAA-rotaryeng


Paul: Interesting ... talks a little about turbocompounding ...

This runs about 9minutes and should be viewed on a larger (than iPhone)
screen. Talk about pilot workload.


Sully and Jeff fly an old Eastern Airlines DC-7. Full screen is a must!

http://marcbrecy.perso.neuf.fr/DC7.html


Kevin Devore

 Paul,

 I passed the above info on to a good friend of mine and received this
 reply:

 Thank you for the tape of the DC-7, that brought back memories too. I was
 type rated Captain in both Constellations  and DC-7s. Another funny story
 about the first time that I flew a 7. With those damn Wright turbo
 compound 3350s in the B-29s, Connstellations, & DC-7s they all became the
 finest 3 engine aircraft in the world-at the time.

 I had to smile at his comments.

 Gary Knutson

 Yes I have heard that about the Connie but not the B29. It had a
 straight R3350 and not the turbo compound version. Although the B29 had
 its share of problems
 at first.

 The TC problem was; one exhaust valve would fail and take out the turbine.
 Especially if the flight engineer screwed up the mixture. Then the
 engine had to be shut down.

 The exhaust valve absorbs a tremendous amount of energy and is the
 Achilles heal of all aircraft engines.

 Here is a heat balance on the subject.

 This is the reason a rotary would be near twice as efficient and a lot
 more dependable. No exhaust valves.

 Paul Lamar

That's an interesting diagram that I hadn't seen before.  Thanks for
sending it.

Gary Knutson


This article has a lot more about that.

http://www.rotaryeng.net/sum-turbo-comp.html

And a video.

http://www.rotaryeng.net/Oxford-640-4802.wmv

Paul Lamar

Paul,

Did you ever run the turbo compound Mazda with the gearbox shown in the
pictures?  If you did, were the results published?  Looks like a neat
project but it probably consumed lots of time and money.

Gary Knutson


Not yet. The box cost a bunch. I spent so much money on that I had none left over for dyno time :) It is actually cheaper to use a turbo compound system from a mass produced truck engine. Detroit Diesel DD15.
Almost bolt on with a three rotor. You would no happen to have access to a dyno would you.

Paul Lamar