Paul,
Are those pictures of a Lancair 320? Cowl does look smaller than a Legacy.
On a Legacy (designed for a IO550) we will have to move the prop forward for
CG due to our lower weight. The mustang style scoop is the way to go, but
you need to put the oil cooler in it as well to get the max benefit. Then
the entire nose section gets rebuilt for lower drag. While changing body
parts to add the lower scoop, there is a large edit to do to the lower rear
fuselage and trailing edge wing intersection that has a great reduction in
drag. Biggest issue is getting the oil and water lines back there.
Larry Childs

We never got that one to cool. The P51 scoop adds a lot of drag.
Better to use an airplane with more frontal area and put the cooling in the
cowl.

Here is another one. But it is not a retract. Some sort of Lancair I think.
This did not cool either. Those were in the days before I wrote my book. The
cores are too thick and not enough frontal area on the cores.
The cores need to be big and thin.

Paul Lamar


Paul,
When you study the p51 air system, a lot of the radiator assembly was
actually tucked up in the fuselage, and the scoop on the bottom fed a
divergent duct that spread up into that aft area of the fuselage. It then
exited through a variable outlet cowl flap. The system works well when the
correct formula's are used.
That is the correct way to get a large area thin radiator into a bottom
scoop. The Legacy with the lower rear fuselage done the same way would give
the same thing as well as being able to install the "beluga butt" at the
same time. I can see where the ones installed in just the scoop didn't
work..... of course this means major structural mods to the aft fuselage.
Larry Childs

Actually the Germans did some research on cooling diffusers and the P51
version was flawed. They wrote a book called aerodynamics of propulsion.
I used a lot from that book to write my book. It is about $300 used.
David Lednicer turned me on to that book.

The other necessary book is compact heat exchangers written by some Stanford
professors  under contract with the US Navy. Took ten years and tons of
money. That is still in print. It is the bible of heat exchangers. I also
used a lot from that book to write my book.

Since I wrote the book in 2007 anybody that has followed the suggestions in
the book has had no problems cooling their Wankel. Some say too cool.

I'll send you a copy.

After the war the P51 diffuser  was corrected.
The H.E. core on the P51 was 11 inches thick as I recall and that is not
optimum.  The scoop adds to the frontal area while the cooling system under
the cowl does not.

You notice most of the unlimited racers remove the  P51 scoop.

Do you have scale 3 view of the Legacy. I have it for the GlasAir.

Paul Lamar


Paul,
The only mustang to race with an alcohol boil off system in recent history
is Galloping Ghost...... and I watched her crash in front of the grand
stands.....

All current fast Mustang racers (Voodoo and Strega) have modified belly
scoops still in place. We also don't need that core thickness as we don't
try to make 3500 to 4000 hp!
Larry Childs

So did I. Horrible. Dave kept his patient alive until she got to the
hospital. The hospital said she was too far gone. The whole side of her body was
missing.

Paul Lamar


One radiator installation I've read about that is supposed to be pretty
efficient is putting them in the inboard leading edge of the wing. The
Fairey Firefly MkIV did this and other good performing liquid cooled
airplanes like the Mosquito did it too.  It adds little frontal area and the
airflow in that area is pretty chopped up anyway so the wing can be a bit
less than perfect and the radiators are getting a bit of prop blast.  It
would look good if artfully done and I like it structurally better than
Spitfire style radiators. A clean installation on something like a Lancair
would look good and be easily maintainable.
https://aircraft.desktopnexus.com/wallpaper/1772027/

Steve Brazil

Old tech Steve. Modern heat exchangers are much lower drag.
They have large frontal area with thin core sections located in properly designed
diffusers. You need a copy of my book. How to Cool Your Wankel :-).

When are you coming down to see our time to climb project at SZP?
I'll try to be in Lancaster Fox Field for the LA airs show on the 18th.
We can get together then.

Paul Lamar

The Rotary Engine free News Letter. Powered by Linux.
If you want off the list PLEASE let me know and I will remove  you. ACRE NL
web site. http://www.rotaryeng.net You Tube http://tinyurl.com/beqqxas
Copyright 1998-2016 All world wide rights reserved.