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Which Propeller to choose???

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Which Propeller to choose???

Old 11-20-2007, 07:07 AM
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Default Which Propeller to choose???

Hi, can please anybody advise me Which propeller (size) to choose for my hand made plane.
It weight with all the servos, BUT WITHOUT THE ENGINE, around 1,5 kg (3,3 pounds).
The wing span is 1,10 meter (43 inch).
The engine is MAGNUM GP 40.

Thanks!
Old 11-20-2007, 08:45 AM
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Default RE: Which Propeller to choose???

Try a 9x7
Old 11-20-2007, 12:01 PM
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Default RE: Which Propeller to choose???

A 9x7 will be fastest, a 10x6 will be a little slower but have better accelleration and vertical pull. The 10x6 will use less fuel and make less noise.

Jim
Old 05-06-2008, 07:36 AM
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Default RE: Which Propeller to choose???

i would use a 10*6 on a 40 engine
Old 05-06-2008, 08:49 PM
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Default RE: Which Propeller to choose???

Or if you want slower flight with more pulling authority, you could try an 11-4 or 5.
Old 05-07-2008, 06:36 AM
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Default RE: Which Propeller to choose???

All these responses are correct. One additional note to the 11x4 idea, I'm restoring a 40-year old scale biplane right now and it will run on an OS-40LA. I'm planning to use an 11x5, both to keep the speed down and still maintain the capability of near-vertical climb, should anything "unkind" come up while flying.

An 11-inch prop will be putting nearly any .40 engine to some stress, so don't expect full RPM with a prop that long. But the sheer POWER available is awesome.

Dave
Old 09-27-2008, 03:19 PM
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Default RE: Which Propeller to choose???

FWIW. A crude rule of thumb, generated from reviewing a lot of R/C Report engine test data, is that a one inch change in diameter equals a 2 inch change in pitch. Using the same brand of props, a 9-8, 10-6, or 11-4 will all turn at about the same rpm. I have done it a few times and didn't really need to touch the needle valve.
Old 03-25-2009, 08:27 AM
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Default RE: Which Propeller to choose???

Hello guys

I would like to ask if some one knows what propeller should I use on a OS max FS81 a engine? , itĀ“s bolted on a fliton inspire 60 acro , and the engine turns a 2 bladed 14x6 APC , now the point is that I would like to use a 3 bladed prop , and the rule to follow is , either step down 1 in lenght , or 1 in pitch , in that case that would be either a 13x6 or 14x5 prop , is it that simple or am I missing something+ , besides , IĀ“ve checked master airscrew , but they donĀ“t have either of the ones I need , can some one help me out?

thanks

Peter
Old 03-25-2009, 05:07 PM
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Default RE: Which Propeller to choose???

Zinger has the biggest 3 blade selection http://www.zingerpropeller.com/3_bladed_Propeller.htm that I know of.
The picture shows the "Load" put on the engine for various prop sizes. It is a calculated value from the free ThrustHP program. In theory, two props with the same load will be turned at the same rpm by a particular engine. This is not perfect but it might help a little.

<< Edit: The load of a 14x5 three blade is 288120 >>
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Old 03-25-2009, 05:22 PM
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Default RE: Which Propeller to choose???

I love an 11x5 on my TT GP-42. It just woke that engine up on the H9 Ultrastick 40 and works great with the same engine on a 6.5 pound SPAD Debonair trainer.

It's not fast, but it pops right off the runway and climbs well for a heavy, lightly engined plane.

Jack

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