Paul,

Thanks for your book how to cool your wankel. Most interesting, a  good
reference source..

I do have a question about horizontally mounting and ducting a heat
exchanger under the engine. (pusher) using a K&L diffuser. I am  also  considering
direct exhaust into the airstream under the cowl  with a cabin adjustable
louver cowl flap for the exit air. Were those  louvers, shown off the shelf
items or were they custom made??

In your book, the drawings of K&L diffuser and pictures of your heat
exchanger test rig, seem to indicate that the intake air is direct, not being
expanded, at all, before going through the heat exchanger.

Stated earlier in the book, however was the necessity to expand the
incoming air so as to decrease the velocity and increase the pressure as it goes
through the heat exchanger and likewise constrict the flow to increase the
velocity and decrease the pressure as it leaves the cowl.

With the K&L is it beneficial to use a K&W diffuser to the entrance  of the
K&L, or a diffuser of any type, or is this unnecessary?

Additional question. With the K&L diffuser, does the air source   have to
be in line with the device, or can the air be fed from the sides of the
plenum, before the tapering starts? I am considering armpit scoops, one from
each side feeding the diffuser. will I get more turbulence than desired. Will
feeding the diffuser in this manner (from both sides of the before
diffuser  plenum) screw up the airflow? Or do we know?



Thanks


Stay Cool,

Rich

As there are some heating and cooling adjustable louvers sets that
can be bought from Home Depot and HIVAC suppliers.
http://www.atlantasupply.com/wall-register-vents.htm
Use two or more and cut away what you don't need.

A constant area duct feeding the K&L diffuser works fine. Just keep it
as short as possible. Putting a K&W diffuser ahead of it is of unknown
benefit if any.

What works best on a rear engine is a P-51 type scoop with a boundary
layer bypass.

Arm pit scoops will work but you will have to use boundary
layer bypass channels on the fuselage sides I suspect. Using two
for one core is indeed problematic as the air could go in
one wide side and out the other :) You might have to partition
the K&L diffuser in that case. You would also have more internal skin
friction in the ducts.

With a rear engine a quick and simple set up very well might
be about the same drag. Fly it and then you can adjust the
cooling and the drag only to what you need. You could also
use an electric screw jack to adjust it in flight.

Paul Lamar


I use one of these for my trim, I'm looking at using the
same type for my cooling flap.

http://www.firgelliauto.com/default.php?cPath=110

Brian Trubee