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Old Sep 14, 2006, 03:35 PM
skyking1231 is offline
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Question

E props vs Gas or nitro props ???


I have always wondered about this. They usually say "not intended for gas engines " or something like that on propellers desinged for Electric applictions.

How come ? Some of these electrice motors are spinning the props at lot faster and in many cases with a lot more power than a gas engine.
Is it because engines maybe have alot more torque ?? Or different foil shapes b/c usually elec's are runing at higher RPM's ?


Can you run a prop desinged for gas engine on an electric motor ? Or is it just sucky...not as efficient ??

I saw a 8x6 3 bladed prop that may suit one of my planes really well. but It is for gas applications. on an elec...I am not sure what the results will be?
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Old Sep 14, 2006, 03:54 PM
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Well, im no expert on this but I would say that a gas engine creates a lot more stress on a prop driving it.(bang rotation bang....etc etc) Electric motors are much more smoother in putting the energy into the prop.
Old Sep 14, 2006, 05:09 PM
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Quote:
Originally Posted by skyking1231
I have always wondered about this. They usually say "not intended for gas engines " or something like that on propellers desinged for Electric applictions.

How come ? Some of these electrice motors are spinning the props at lot faster and in many cases with a lot more power than a gas engine.
Is it because engines maybe have alot more torque ?? Or different foil shapes b/c usually elec's are runing at higher RPM's ?


Can you run a prop desinged for gas engine on an electric motor ? Or is it just sucky...not as efficient ??

I saw a 8x6 3 bladed prop that may suit one of my planes really well. but It is for gas applications. on an elec...I am not sure what the results will be?
I always use gas props on big electric 3Ds since those props have better thrust in slow flight.

However, for fast flying electrics, I always use electric props since they are somewhat more efficient.

Slimer props aren't sucky...
Old Sep 14, 2006, 05:45 PM
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I guess a "slimer" is supposed to be a gas plane ??
Old Sep 14, 2006, 05:54 PM
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Franck has it right.

mw
Old Sep 14, 2006, 06:55 PM
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Yes. Slimers are glow powered models. They get the name from the slime you have to wipe off the plane and your hands before going home. Not that there's anything wrong with that...........

Glow props are built heavier and so they weigh more than an E-prop. The hub is also thicker. There's no reason you can't run a glow prop on an E-plane if it's not too thick to fit on the adapter. It's just more bulk to spin.
Old Sep 14, 2006, 07:05 PM
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Yes - slime is the reason that I fly only electic!!!

But have you seen the weed-wacker motors (50cc+) in the bigger models. Those motors are quite clean and excellent except for one thing. That cheap tree-sawing sound!
Old Sep 14, 2006, 07:41 PM
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I gave up using electric props for any larger planes as they are a lot more fragile than glow props. If your plane just drops on it's nose when a gust of wind gets under it's tail while sitting on the bench you may get one blade broken off. Also, any ground strike will see you putting on a new prop and the way I fly it gets expensive. For slow flyers you pretty much have to use them as they are generally more effecient than glow props and lighter but the slow fly props are usually not as brittle.
Last edited by batman; Sep 15, 2006 at 05:46 PM.
Old Sep 15, 2006, 06:24 AM
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There are factors in props...

1/. Intended RPM. wildly differnet in many electric setups, espc slofly.

2/. Vibration: Glo engines kick once per rev. Electric motors push up to 24 times per rev.

3/. Mass. Glo engines NEED a flywheel.

4/. Efficiency. Glo engines usually have power to waste

Put all that together and yiu end up with glo engines swinging strong heavy props with no particular attention to blade profile, usually in te 8K -20K reve range.

Electrics can be lighter, less stiff, and have thiner blades of more blade area especially if designd for sub 5000 RPM.

Even tow 'electric' props with te same writing on them can be wildly different..add glo props in and there is another dimension altogether.

Moral: Try em all and use the one tbat suits YOU. I have found APC electrics to be my 'standard' and I don't deviate unless there is good reason. They seem to work best FOR ME.

Wood props if thin enough section also work well. I seldom have any geared setup runing at more than 7000 RPM tho.
Old Sep 15, 2006, 11:42 AM
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One day I hope the technology will allow me to convert my 1/4 scale P-47 to electric. I know iT will be very expensive...but for now it is not possible to get a 25 pound airplane in the air on elec's. Right now I have a chainsaw engine in it.

Thanks evryone for the info.
Old Sep 15, 2006, 12:06 PM
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duplicate deleted.
Old Sep 15, 2006, 12:08 PM
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Quote:
Originally Posted by skyking1231
One day I hope the technology will allow me to convert my 1/4 scale P-47 to electric. I know iT will be very expensive...but for now it is not possible to get a 25 pound airplane in the air on elec's. Right now I have a chainsaw engine in it.

Thanks evryone for the info.
It certainly is possible right now. All elements exist commercially. It's just very expensive.
Old Sep 15, 2006, 02:01 PM
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Quote:
Originally Posted by skyking1231
One day I hope the technology will allow me to convert my 1/4 scale P-47 to electric. I know iT will be very expensive...but for now it is not possible to get a 25 pound airplane in the air on elec's. Right now I have a chainsaw engine in it.

Thanks evryone for the info.

http://www.hackerbrushless.com/motors_c50quad.shtml

Right in line with my motto; If you've got the budget, we've got the technology.

Steven


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