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Old Oct 07, 2012, 11:50 AM
The Luftwaffle
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United States, FL, DeLand
Joined Sep 2012
1,143 Posts
Question
O.S. 91fx prop sizes???

I hav an O.S. 91fx, an original one from before the backplate fix. It has the original backplate but the needle assembaly from an O.S. 46la. (What? It works.) I have been using a 14-8 prop, and I have tried a few others but they just made it deadstick. I am looking for a good prop to 3d a plane on, not a speed prop like the 14-8. What other prop sizes would work with this setup?
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Old Oct 09, 2012, 11:10 AM
Ron - AMA 1025
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USA, FL, Largo
Joined Aug 2005
301 Posts
14x8 is heavy for this engine, I would use a 14x6 APC.
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Old Oct 09, 2012, 05:36 PM
The Luftwaffle
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United States, FL, DeLand
Joined Sep 2012
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I find that suprising that It is too heavy, It has been running that same prop for four months no problems.
I once tried a 14-4W And it didn't run good at all.
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Old Oct 09, 2012, 05:45 PM
Ron - AMA 1025
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USA, FL, Largo
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There is a big difference between a 14x4, 14x6 and a 14x8. A 14x8 is the equivelent to a 16x6, which is more a 120 size prop. The normal prop to run on a 91 size is a 14x6. Depending on the type of plane it is on, a 13x7 or 8 for more speed, a 15x5 or 6 for more pull.
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Old Oct 09, 2012, 05:50 PM
The Luftwaffle
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United States, FL, DeLand
Joined Sep 2012
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I might try it on a 14-6, But it runs suprisingly good on a 14-8 wood prop. However, something like a 15-5 or a 15-6 would be better for my u-can-do 3D 60 size. I worry about flying the wings off of it with my 14-8
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Old Oct 09, 2012, 05:52 PM
Ron - AMA 1025
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USA, FL, Largo
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I've had and flown most all of the Ucandu's, and the last thing you want is a heavy pitch prop, go with the 14x6, the engine and plane will be much better.
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Old Oct 09, 2012, 06:18 PM
The Luftwaffle
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United States, FL, DeLand
Joined Sep 2012
1,143 Posts
OK next time I go to the hobby shop i will get one. Thanks.
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