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

Single Blade Props

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Old 12-12-2002, 11:23 PM
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JIMESTES
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Default Single Blade Props

Any one tried these and what does it buy you as far as rpm how about power.
later Jim
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Old 12-13-2002, 01:22 AM
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PAINLESS
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Default Single Blade Props

Single blade props are more efficient than 2, 3 and 4 bladed props because there are no tip vortex for the blade to run thru from the proceeding blade.

I think the FIA control line world speed record is held by a single blade prop on a .15 engine at 209 mph.

The trick would be finding the right pitch and diameter, or is that radius. You would need to fab a u-shaped bracket that the propshaft passes thru and can be filled with lead to balance.
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Old 12-13-2002, 04:26 PM
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banktoturn
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Default Single Blade Props

I think that, for a high speed plane, the blades don't really go through that much junk from the other blades. I think the main efficiency gain is from the fact that getting rid of the other blades allows you to go to a larger diameter. This assumes that you aren't running into problems with tip speed, which would limit the diameter, but this doesn't usually happen with our planes.

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Old 12-13-2002, 11:46 PM
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BruceDana
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Default Single Blade Props

I posted this in the Warbird thread a few days ago...

A quote from the Bolly websight (who makes props for R/C, UAV, Ultralights, ...) so they know a little bit about propellor theory:

"Contrary to popular belief, multiple-blade propellers do not operate in severely disturbed air from the previous blade (when in forward flight). The reason multi blade propellers often appear inefficient is the need to use considerable lower diameter propellers (in comparison to 2 blades), for the same horsepower available. Diameter for diameter a well designed 4 blade prop will in some circumstances perform better than the equivalent 2 blade propeller."
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Old 12-15-2002, 03:59 AM
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Default Single Blade Props

The Bolly people say it better, and with more authority than I can, but I would add one qualification. For "extreme speed prop planes", the goal is often to choose the propellor that will give the highest straight line speed, which means that you are power limited, and need high pitch. This often forces the props to be chosen with smaller than ideal diameters, since power goes up dramatically when you try to spin a higher diameter prop. This sounds to me like exactly the situation where a high-pitch, single bladed prop with slightly larger diameter might outperform a two bladed prop, which would need to have a smaller diameter.

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Old 02-27-2003, 10:54 AM
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bobbdd
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Default Single Blade prop

I hate to sound like an old biddy, but be carefull makeing, your own prop. those things go fast, and what seems quite strong in your hand, might fly apart at 12000-14000 RPM.
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Old 03-06-2003, 09:27 PM
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Default one blade props

does anyone have pic.. or a web. site?
slingshot396@aol.com
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Old 03-07-2003, 02:46 AM
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I don't know of anyone addressing one blade props
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Old 03-07-2003, 02:50 AM
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Default 1 blade prop

thanks anyway, bobbdd
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