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

Small diameter props and large spinners

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Old 03-19-2007, 10:22 AM
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still4given
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Default Small diameter props and large spinners

Hi Guys,

I've got a question for you go fast types. Our club is having a for-fun pylon race in which we have to use 40 size war birds and .55 max motors. I have selected to use a Spitfire with a Jett SJ50. A 2 3/4" spinner mates perfectly with the front of the fuse and the SJ50 seems happiest with a 9" prop so I'm wondering if using a large diameter spinner causes any loss of thrust with these smaller diameter props.

Along the same line of thinking, I may run a Corsair as well with a Magnum .52XLS. I'm wondering if using a large spinner might help divert some of the thrust around the large round cowl on the Corsair.

Any and all thoughts on this matter will be quite welcome.

Blessings, Terry
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Old 03-19-2007, 11:04 AM
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evan-RCU
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Default RE: Small diameter props and large spinners

Yes you'll loose some thrust but not as much as if you mismatched a smaller spinner to the larger front of your fuselage.

Yes it will cut down the drag on your Corsair.

Try larger diameter lower pitch props too you'll be surprised at how fast they can be on this type of pylon racers, they accelerate out of the corners better and by the time the high pitch proped planes catch you, well they won't you'll be through the next corner by then....
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Old 03-19-2007, 11:15 AM
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daven
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Default RE: Small diameter props and large spinners

Terry,

I ran Jett .50 and spitfire (kyosho) at our warbird races for a couple of years. The only plane that was faster was a WM Mustange with an OS. .91 FX and Ultrathrust muffler.

I tried all of the props, and the best combo I came up with was a standard APC 10x7 sport prop.
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Old 03-19-2007, 01:39 PM
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Default RE: Small diameter props and large spinners

I have a WM Dago Red and that has a 3.25" spinner, and I'm using a 10 X 8 std. APC sport prop on a Webra .50 (slightly modified internally, and U-T muffler) and it hauls it along quite well (126 if you believe radar guns)

Everyone who sees it can't believe it performs so well with only 3 3/8" of prop sticking out either side of that big spinner. Main reason why is because that's the most effective part of the blade...the hub area, or probably the center third of the prop doesn't contribute all that much toward forward motion.
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Old 03-19-2007, 02:36 PM
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Default RE: Small diameter props and large spinners

Hi Guys,

Thanks for all the kind advice. I will stick with the 2 3/4" spinner on the Spitfire then. I may try an even larger one on the Corsair along with a 10" prop. I just need to make sure the engine gets enough cooling air.

Blessings, Terry
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Old 03-20-2007, 09:10 AM
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Default RE: Small diameter props and large spinners

Terry,

After you get a few flights on the plane, try the 10x7 Dave noted. Sometimes that prop can really amaze folks. And considering you have an extension at the muffler, it will really bite into the tuning range nicely.
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