What is wrong with these cooling system

designs?

Paul,
 If the question wasn't rhetorical, there is no

diffuser prior to the face of the heat exchanger.
The turbulent entry and "dead" corners will reduce
the effectiveness of the heat exchanger. Better

would be to angle the heat exchanger and use the

wedge style feed with a diffuser tapered to meet the
intake.

Bill Jepson

You also get a B Bill :)  To be fair there is some
subtle factor that just
recently crystal clear to me again. Hint it affects
air cooled engines as well.

Paul Lamar

Robert LeClercq wrote:

Has no one noticed the frequently discussed worm drive
hose clamps.
Robert

Good point Robert. Constant torque hose clamps and silicon rubber hose
should be used.
Still not what I had in mind.

Paul Lamar

Tony Snow wrote:

OK Paul, I'll take a shot at it...

A good cooling design must have a good route for the expanding heated air

to

get away from the exchanger.

Tony Snow

Absolutely true but that is still not the major problem here.

Paul Lamar

Tony Snow wrote:

One more time...

Quoted from Paul Lamar 10/7/04:

A novice would get the impression from all this discussion that the rotary
is hard to cool. It is no more difficult than any other liquid cooled
aircraft engine. Things must be done right. IMHO few have done them right
so far. This is the list.

A: A ram air scoop is required. No NACA scoops.

B: An adequate volume of core is required. 600 to 800 cubic inches.
Maybe less if all other criteria are satisfied.

C: A proper diffuser. A wedge shaped diffuser is about all that
is practical for a rad of the proper proportions. A K&M type diffuser
is too long to be practical.

D: Cold air must be available for the rad. Don't heat the air before
it goes through the rad. A one degree F increase in the air temp is
a 1% reduction in cooling capacity.

E: Keep the core thickness less than 2 inches thick. A too thick core
will not pass enough air at low speeds.

F: Last but by no means least make sure the back of the rad is
completely unobstructed. The minimum distance for the obstructions is
50% of the core's longest dimension. Given the constraints of a typical
cowl that means dump the hot air directly over board though a large hole
in the wall of the cowl. Don't try to use and exit duct the wall of which
is too close to the back of the rad.

I have yet to see a cooling system that meets all six of these criteria.

Paul Lamar

Now, with this in mind, I would say that the shape of the inlet for the
cooling are will not deliver a smooth airflow with a sufficient pressure
gradient across the radiator core to the exhaust.  That is my final answer.
Sorry If I wasted your time.

LOL  Tony Snow

If I said anything more I would be giving the problem away.
I want to see if somebody can figure it out.

Paul Lamar
 
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