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Explain prop sizes to me please

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Old 01-09-2006, 07:37 PM
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lynntonyd
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Default Explain prop sizes to me please

I have my first electric plane ready to go. Its a GP Yak 55 flightflex model that I added a Dymond Typhoon 6 brushless outrunner to. It is listed as 34.5" wingspan and 14-16 oz in the specs. I have a 3 cell 1800mah battery which is a bit big I know. I need to know what prop to use. I bought a bunch so I could play around. The plane is a 3D machine but I can't do any of that. I have been flying glow engines all year and I am pretty good with my trainer and can do basic loops. rolls etc. I'm looking for a prop that won't fly 180 mph or kill the battery in 2 minutes. I want to fly slow and keep the plane in the air. I then plan to learn aerobatics with no fear of crashing my big balsa plane! Here is what I have:

11 x 4.5 (Came with the plane) a 9x4.7 a 9x3.8 and a 10x3.8. I bought a bunch because they are cheap so what the heck. I know kind of what the numbers mean. The large # is the diameter and I guess the second number is the angle? The 3.8's seem much more "flat" than the others.

BUT what does that do in the air? My intuition is that a smaller angle would make less drag and spin faster, maybe give less thrust?

Which one would you use first and why? Then which ones would you move to when I get used to the plane?

Thanks for your input!
Tony
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Old 01-10-2006, 12:35 AM
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jdetray
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Default RE: Explain prop sizes to me please

Hi Tony-

The second number in a propeller specification is its pitch, which is related to blade angle. To quote [link=http://avstop.com/AC/FlightTraingHandbook/BasicPropellerPrinciples.html]an informative web site[/link]: "The pitch in inches is the distance which the propeller would screw through the air in one revolution if there were no slippage."

- Jeff
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Old 01-10-2006, 11:09 AM
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tf2psycho
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Default RE: Explain prop sizes to me please

i would go with the 11 x 4.5 or the 10x3.8 but i still have to build her
the 11x8 gws slo fly prop worked great on my 15oz 3d yak54f running a 3 cell 1320
thinking about using the 11x8 with park400 and 25 amp esc ,1320li po for the yak55
i think this plane should be great for you i bet you will be prop hanging on your first flight
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