HP required is proportional to the cube of top speed while cooling
air flow only increases with the square of speed. That is the
fundamental problem cooling an aircraft engine running flat out.
That is also why we offer an Everett Hatch Memorial Fund $500
prize to the first NA 13B averaging  over 200 MPH in a sanctioned
cross country race of at least 100 miles.  If your cooling system
works well enough for this I would consider the problem solved.

Tracy claims his RV4 goes 214 MPH which should be sufficient.
However he has declined in the past to enter the  annual Sun 100 race
at Sun & Fun in April. :) How about this year Tracy?

Paul Lamar

2003 (next S'n F) may be the year I'm ready to try it.  Main reason I
haven't been ready in the past is no time to review race course and
landmarks for turns.  Very important if you hope to have any chance of

doing

well.

Tracy

wmd wrote:

So if one wishes to take full advantage of the engines potential horsepower,
cooling systems
need to be designed for that level of power output but available cooling air
lags behind and engine can only be run at somthing less than full power ?
Would an even larger radiator take care of the problem ?

bd

Short answer is yes. The long answer is a larger opening and duct
feeding air to the rad with a cowl flapped exit.
There is a phenomena called external diffusion. When the exit air is
blocked off by the cowl flap the increased pressure in the system
is transmitted all the way out to the opening. This in turn
causes the excess air to by pass the opening actually resulting
in less drag. This is handy at cruise speed to minimize the cooling
drag. At top speed the cowl flap should be partially open and 
at climb speed fully open. So far I have been unable to convince
anyone flying a rotary to implement this configuration.


Paul Lamar
 
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