Hi Paul,

 I read your book on cooling wankel engines this
 weekend.  What a wonderful
 resource.  Thank you for writing that.  It was
 worth every penny.

 I am probably going to end up with a Mistral engine.
 I just feel good about
 it and what I have learned about the company and their
 product.  There are
 risks going with a new company.  But the old piston
 technology is probably
 equally risky for many reasons  (elimination of leaded
 fuels, noise
 complaints about old technology aircraft,  and most
 important, the inherent
 inferiority of piston engines compared to wankel with
 regard to reliability
 - even though Mistral is new and did have that accident
 with the exhaust
 which I looked into).

 For my kitplane (Foxtrot) it looks like the cooling system
 will probably go
 underneath the engine, per your Kay & London solution
 concept. But there is
 a lot of stuff that I have to think out down there.
 Whatever I do,  I'm
 going to figure out how to beautifully integrate the
 cooling into the
 airframe so it ends up stunning and low drag, but also
 state of the art for
 all systems.

 The Foxtrot airplane which we are building seems to have a
 fairly flat
 surface under the cowl, which would probably be conducive
 to K&L radiator
 concept.  But the cowl is also very wide because it
 was designed for an IO
 540 and also to make the cockpit wider for comfort.
 So there will be a lot
 of thinking going on as we get more into the project and
 figure out how to
 integrate the radiator with all the other stuff we want in
 the aircraft.  We
 of course don't know what brand or type of radiator we will
 use or how we
 will build the scoops and ducts so they don't affect the
 airframe and fit
 into the cowel.

 Learning the basic concepts about the size of the air
 intake, expansion
 after the air enters to reduce the air speed, developing
 pressure to get
 through the radiator, and then making sure the air exhaust
 doesn't develop
 drag were very powerful ideas.  I need to read it
 again.  Thank you for
 writing it down for people like me.  We're going to
 think everything out to
 make sure we get an excellent solution for our airplane.

 I was confused about the water manometer.  Of course
 we don't need it very
 soon.  But it seems like something important to
 measure performance.

 I'm thinking about a lot of other stuff for the
 airplane.  But one
 additional area is noise reduction.  If you have any
 pointers there it would
 be great.  I remodel buildings and I always add noise
 reduction systems
 (mass loaded vinyl, disconnect between components,
 etc.)  So I want to add
 that to my airplane, where it's more complicated but very
 important.  I've
 done the preliminary research but if anybody in your
 network knows some
 practical stuff about this it would be great.

 Your books was great and worth every penny.  Thank
 you.

 Bob Mayer

 San Francisco

 Thanks for the testimonial on the book. I can help you out
 in the
 Foxtrot installation for free using Rhino 3D but I need
 some dimensions
 of the firewall and the cowling.

 Mistral latest installation uses the bottom radiator
 configuration.
 Here are some pictures from the Aero show in
 Friedricshaven.
 An endorsement on what we came up with a decade or so ago
 :)
 Top heat exchanger is oil. Bottom is water.

 Paul Lamar


Looking at the picture of the Mistral Alternator belt, I'll bet it's not an
afternoon job to change out the drive belt!  Unfortunately, some
engineers and designers never get involved in the servicing of their monsters.

Joel
Over the Hill Materials Engr.

I am sure they will change that sooner or later :)

Paul Lamar


Paul,
As another reader of your book and copious other notes I am wondering why
you haven't commented on Mistral's arrangement of putting the oil
heater in front of the water heat exchanger.   Oil at 210F plus from
engine enters the heat exchanger and lets say lowers 20 degrees in exit
oil temps.  This lowers the delta T through the second heat exchanger
and added restriction lowers the over all mass flow.  To be fair water
is more efficient at exchanging heat than oil.  However to work the
surface area of both will have to be radically increased.  That may be what
we are looking at.  What am I missing?

Doug

Good question. Gordon and I had a discussion about that at
Aero. I am willing to give him a bit of slack as they are
about to try it out in Deland on the Maule :) We shall see.
BTW a lot of gyro's get away with it as well,

Paul Lamar