William wrote:

Paul, some comments on NACA's and the exiting of air on canard

airplanes.

A builder friend of mine has an E-racer, with an IO-540 supercharged

engine

in it that he has sorted out the cooling through the use of many

pressure

measurements as he made various changes. It now works very well.

He is using 2 NACA scoops on the top of the fuselage, and has dams on

the

edges.

He has read many papers on exhaust augmentation, and has designed and

tested

several versions. His current version (pictures attached) works very

well.

In the course of testing before he had the exhaust augmentors, he would
often find that air was *going in* the exit holes on the back of the
cowling.

He can now taxi around all day, with the augmentors keeping enough air

flow

to keep the engine cool, and when flying he gets between 7-8" of water
pressure differential across the engine (top deck to bottom deck).

Bill Schertz
KIS Cruiser # 4045

Would you ask him at what speed he measured that pressure drop?

BTW For further reading on NACA ducts the trick is to use the key word

"submerged"

in the NASA search engine.

I did that and came up with a gold mine. I have edited out the transonic
and supersonic studies.

There are also many papers on  thrust augmentors but I have not come up
with the proper key words yet.

Paul Lamar

At fast taxi on the ground (no ram air) he gets about 1.5" pressure drop,
which is sufficient for cooling on the ground.  When at 200 knots he gets 8+
" differential.

He estimates that at ~150 knots it is 5-6" water pressure differential,
hasn't written those values down.

Bill Schertz
KIS Cruiser # 4045

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