You may well be right Mike. Do you have a scanner. Can you scan that
pressure plot on the RV4? Are you going to use the stock air intakes
or are you going to place a water rad intake below the spinner?

Same question for Ken.

Paul Lamar

Paul,

Mike Wills wrote:

  The pressure distribution diagram that I'm refering to appeared in an
article of Sport Aviation a few years ago. It was written by an aero
engineer and was a computer model of Steve Barnard's RV6A (not an RV4, but
close as I can get). The guy has done similar articles on Nemesis and some
WW2 era fighters. I had to borrow the magazine to read the article as I
didnt have a copy. I think Ken can tell you what issue since he put me onto
it in the first place.

  I'm going to build my own cowl with an under the spinner inlet. I
remember talking to Alan Tolle and Everett Hatch about the cowl design on
their airplanes a few years ago at Copperstate. They sealed the radiator
and oil cooler exits to the cowl and then pressurized the entire cowl as a
pressure plenum. I remember thinking at the time it sure seemed like a poor
choice from the drag standpoint. But it sure is a lot easier than trying to
build a smooth inlet duct from the bottom front of the cowl to an oil
cooler in the top rear of the cowl. Cant argue with success - to my
knowledge Alan's RV3 remains the fastest 13B powered RV around so the
cooling drag must not have been too bad. This is the approach Ive decided
to take.

Mike Wills

The cowling on the RV4 is a lot higher than the RV6. I think there is
enough slope on the cowling so the pressure may not be as low.

Allan had a lot of problems with cooling on the ground as radiant heat from
the exhaust was seen by the radiators. I was there when Allan had to shut the 
engine off before the Sun 100 race. Nearly did not get it started again when it
was time to race.

Paul Lamar
 
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