What is the best design for cooling vents on a Sukhoi radial engine?

[Sopwith1]

Advice needed please with the design of cooling vents, louvres on the cowling of a radial engine. Plane is a Sukhoi, as per vid links below, 76 inch span 37cc petrol engined radio control. Cooling will be from cutouts in the cowl approx 20 x 80 mm with a flat plate louvre at the leading edge. Most flying will be low airspeed so airflow wil be mainly propwash.

What I would like your help with is the optimum size(how much protruding from cowl) and angle for a single flat plate, and how much more effective would this be if there was 2 or 3 louvres. If using 2 or more what is the best spacing.
Very much how long is a piece of string I know, but a ball park idea would be much appreciated. I've attached a couple of links showing the plane and style of flying.
many thanks
Robin

http://video.google.com/googleplayer.swf?docid=4995237916930599540&hl=en&fs=true

 

[tyroman]

Sopwith1,

A belated welcome to PF!

That is a brute of an RC plane! And whoever is piloting it is very skillful...

As far as an approach to answering your question, I would suggest experimentation. If cowls are cheap and available, louver one, mount it and fly the plane. To determine its cooling performance, instrument the plane with thermistors or thermocouples on the exhausts and feed the signals to an on-board memory chip. Some cheap home digital thermostat might be adapted to convert the analog signal to digital data. After a test flight, retreive and analyze the data to see if the louvers did the job. If not, change the louvering and try again.

Heck, with the power that plane has, you could probably mount a transmitter and get real-time data during a test flight.

And if that sounds crazy, what about servo-driven dampers on the louvers controlled by the thermocouple signals?