Subject: Flying the DC-7
From: AAA-rotaryeng
Date: 3/8/2013, 9:54 AM
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<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<http://www.rotaryeng.net/sum-turbo-comp.html

  And a video.


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

Paul,

Do you have a plan for dyno testing a turbo compound setup?  Are all the
parts and a suitable test engine available?  How about a exhaust system,
etc.

I do have access to a well instrumented and equipped test cell but my "run
time" is somewhat limited.  A test would have to be laid out and
documented and as much of the hookup stuff done ahead of time as
possible.  The facility is local (to me).

Let me know what you might have in mind.  It would be an interesting test!

Gary Knutson

I have a simple plan. Run 500 RPM increments for one minute each with out
the TC and measure and record the fuel flow and HP. Then repeat with the TC.

I have a stock 3 rotor but it is not complete and running. It has the
stock turbo's. It needs a Motec installed. We can get help on that because
Jim Medere of Racing Beat has done it several times.

I don't currently have a Motec. He sells them I think.

We can buy the DD15 TC system new for about $4000. I can rig a cog belt
drive from the DD15 gear box out put to the 3 rotor out put shaft if I have
dwg of the dyno bell housing bolt pattern. It would entail cutting slots in
a  stock Mazda bell housing for the belt to pass through. The belt HP would
be in the range of 30 HP plus or minus 20. The DD15 GB puts out 1800 RPM or
so max when the turbine is going 40,000 RPM. That means we would have to
step it up 1 to 3 or so.

I can fly up there and spend the time hooking things up.
I think the data output from the Motec would be all we need.
We would have to monitor engine temperature of course and RPM but even
that the Motec would know.

I would probably be cheaper for me to deliver the engine than crating and
shipping. Which would run about $1000 as I just had a 400 pound engine
shipped from Or and that is what it cost.

1500 miles at 20 MPG and $4 a gallon is $300 each way.

Paul Lamar

Let me know if this gets going.  I'll put some more in.

Van


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