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Oct 18, 2004, 09:22 AM
Quit Chucking My Wood
rthorne's Avatar

Scale Conversion: Watts to Weight Ratio?

I'm in the process of determining which motor/battery combo to put in an HF Model ASW28 3 meter bird. I'd like to run an AXI 2826/10 or /12 with a 3s2p 2200 lithium pack

I'm not looking for a rocket ship, just something to get it up in the air a couple of times so I can thermal around.

I was thinking that 50 watts per pound ought to handle it.

Whats the wisdom of this group think?


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Oct 18, 2004, 01:20 PM
Registered User
Lenny970's Avatar
I've converted several (3.5-6.6 meter) scale sailplanes to electric. I generally design the power system for about 75 watts per pound. This gives a strong, not rocket ship climb rate. I'd guess the typical climb angle would be around 30 degrees. I'm sure you could safely use something less than 75, but 50 watts per pound sounds a bit low to me.

Good luck,
Oct 18, 2004, 02:36 PM
Quit Chucking My Wood
rthorne's Avatar
Hi Lenny:

Thats what I needed to know.

I have a AXI 4120-18 on a Hanger 9 Funtanna with 6s2p 2200 irate cells. However, I think the motor is too big as well as the batteries from a weight stand point.

What do you recommend for a motor and/or gear box combination to put in a 80 to 90 oz scale bird?\

Oct 20, 2004, 08:05 AM
Gustavo Exel
gustabmo's Avatar
Originally Posted by Lenny970
I'm sure you could safely use something less than 75, but 50 watts per pound sounds a bit low to me.

Are you speaking motor input or output watts ?
Oct 20, 2004, 09:30 AM
Registered User
Andy W's Avatar
We use input watts..

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