Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

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Old 09-03-2002, 03:28 AM
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Jim D
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Well, my Shrike 15 Norvel 25BB combo has made it's first flights. I started with an APC 9x6 to keep it slow and get a feel for it. Even with that, it's making passes around 120MPH (covering our 500ft runway in about 3 seconds). I was actually shocked at the speed on a 9x6. Now the questions start:

-I seem to keep setting the high end richer and richer as it really unloads on a pass. I'm way richer on top than what I would normally set an engine. Is this normal with flying speed and really unloading the engine?

-What prop is the best speed fit for the little Norvel 25. It was turning the APC 9x6 14.2k on the ground set pretty rich. I would say it's probably unloading in the 16-17k range now.

-Would a pipe give more back pressure and help keep the engine from going too lean? It was sagging on extended vertical lines.

Help a speed newbie out here. BTW: the light little Norvel 25 helped keep the weight down enough that it glides fairly nice for landing. It's a good combo. And the little Norvel seems like a stout engine.
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Old 09-03-2002, 12:56 PM
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I think Norvell recommends a 9x4 prop for the bushing 25 engine. Thats what I use on mine and see between 16 and 17k on the ground with 15% fuel.

Remove the baffle from the muffler and drill out the outlet to .25" diameter, it has a little resticter cast in there. This should get you another 500 rpm.
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