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Old Sep 14, 2012, 02:05 PM
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Ben Buckle Super Scorpion

Hello

Is started to build a Ben Buckle Super Scorpion 66 and will in this context hear you all, what kind of engine would you recommend this model, electrical or fuel, and what type of engine

Michael
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Old Sep 14, 2012, 02:42 PM
Jack
USA, ME, Ellsworth
Joined May 2008
16,992 Posts
You going to make us dig all the info out the hard way?

Is this the plane?

http://www.benbucklevintage.com/inde...&products_id=5
Specifications:
Span: 1677 mm (66")
Engine Size: .20 - .30 2 stroke
Radio: 3 Channel

And are those it's specs?

Looking at the recommended 2 stroke motor the glow to electric conversion starts with fuel cu.in. disp. x 2000 = Watts of electric power. So with a .30 you want a 600 Watt power system. And those are input watts.

An average electric motor can handle 3 Watts per gram of motor weight so you a 200 gram motor.

Any idea of the prop size? That, and the battery voltage will decide the other details like the motor Kv and the like.

One of these two might be in the ball park for size and there is some prop testing info there too:

http://www.headsuprc.com/servlet/the...2-Sport/Detail

http://www.headsuprc.com/servlet/the...h-06%29/Detail

Jack
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Old Sep 14, 2012, 03:23 PM
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Chattanooga, Tennessee, United States
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The other way to look at it (rather than equating glow capacity with electric watts), is to get an idea of AUW... I imagine that this aircraft would be very light (~3lb or less???), and needs only to fly slowly... in this case a large diameter low pitch prop with perhaps as little as 300W behind it should do. 75W-100W/lb should be more than enough.
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Old Sep 14, 2012, 07:50 PM
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I had a similar plane called a Miss2 and more then 40 watts a pound is a waste of motor. To much power and it will brake the wing spar.The glow is spinning a small diameter prop very fast, a less than preferable set up for a plane such as the one in the pic. The fuel proofing will add allot of weight and that will diminish the flight performance as well.
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Old Sep 15, 2012, 07:39 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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If I needed the weight to help get the CG right I would use the 200 gram motor. And I would power it with a larger slower turning prop and not use full throttle just because it is there.

If the day comes when you get caught downwind in rising winds and have to claw you way back upwind slowly you'll be glad you had some power in reserve.

And then there are those doggoned magnetic trees that snatch out at you at the last second when you fly into a hole in the gravity while crossing a distant treeline...

Jack
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