This is a recording.
Again the fundamental problem is: NACA ducts are not designed to work with
heat exchangers. The boundry layer is not the problem.
A P51 style duct is called for on pushers for feeding heat exchangers.
Paul Lamar
a word about recorded messages:
Greg's plane comes off the runway like it was catapulted and continues to accelerate then it hits
a point where the drag of the (3) P-51 scoops just stops the acceleration and no amount of more
applied power will budge it. He and anouther pilot that has flown it agree there is a need for a
bit more prop but both agree the drag is kiling the performance.
...Chrissi
Cozy Mk-IV 13B-turbo
www.CozyGirrrl.com
Chrissi@BlueMountainAvionics.com
Really? Have you tried 2000 HP? Perhaps you need to squirt some of that
hot air aft and gain a bit of thrust :-)
I don't buy that Chrissi. Not all P51 duct systems are created equal.
Here is a picture of a liquid cooled engine powered airplane with P51 duct that
is just about the fastest canard in the world. Right behind Klause.
236 MPH. No were near 2000 HP. Just 250 HP like Greg's airplane.
Paul Lamar
Paul, Regarding your recorded message, there are hundreds of EZs flying successfully with NACA flush
inlets - a baffled air cooled engine with finned cylinders is a heat exchanger. A properly designed
flush NACA inlet can recover 85% of the available pressure as compared to a free air ram inlet of same
size.
That being said, I am using a downdraft ram air inlet on my Velo project and expect it to get as fast as
other fixed gear Velocitys.
Greg is flying without wheelpants or gear leg fairings, has a way too lumpy cowl with too much inlet
area, has a 3" exhaust pipe sticking out perpendicular to centerline just in front of the prop and has
not corrected any of the obvious things he could to make it go faster. He could easily speed up that
Cozy by 25 mph with minor expense and some labor to recowl. He must be too busy with the Blue Mtn
Avionics to play with the Cozy.
Herb Sanders
Yes and I have also said over and over again the pressure drop through a
air cooled engine is way less than a real heat exchanger such as
an oil cooler or a water radiator. Glance at the fin spacing for example.
Besides that many don't cool all that well.
Water cooling aircraft engines is a whole new ball game and not easy.
Why handicap yourself by using s NACA scoop that the inventors say
should not be used with oil coolers and water radiators. How specific
to you want them to get? It is too easy to build static pressure in the
radiator scoop to 80% of dynamic pressure. In a case like that
the air will simply refuse to go into a NACA duct.
Paul Lamar
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