Hi,

I have a Slow Stick with the stock motor and ESC and really enjoy it. My question is I also have a "Piece O Cake" type gas plane with an OS 25 or 30 size engine with a 72" w/s and was wondering if anyone could please tell me what size electric motor I should buy to pull this around the park and can I use the ESC out of the Slow Stick?

Thanks for your help.

Mike Atkinson

[email protected]

I can say with confidence that you won't be able to re-use any of the components in the Slow Stick on the much larger and heavier Piece O' Cake. A plane of a certain size and weight requires a certain amount of power to fly. The amount of power is proportional to the plane's size and weight.

Since power is derived from Volts and Amps, a bigger plane needs more Volts and Amps. Your Slow Stick flies on about 8.4 Volts and 8 Amps, has a wingspan of about 36", and weighs about 12 ounces. The Piece O' Cake has a 72" wingspan, and weighs about 24 ounces. It's going to need about twice as much power because it weighs about twice as much.

You can double power by doubling Volts or Amps, and keeping the other the same, but it's easier to increase both.

The Piece O' Cake should do well on 8-10 cells with a Speed 400 or Speed 480 motor.

Great,

Thank you for the information. I thought the speed 400 might be a little too weak but if not then all the better.

Thanks again

Mike

You'll definitely want to gear it down, and run a big prop. Maybe use a Speed 480 on 10 cells.

Hi Matt,

Thanks again for the info. Can you suggest how best to do the gear down for the motor? I have never been able to find anything that tells you how to select the best gear system for a given motor/gear combination.

Thanks

Mike

Finding the right gearbox/prop combination is tough to do analytically. You need to find a combination that allows the motor to run at its most efficient power level, while giving you adequate thrust and pitch speed for the airplane.

I normally either run the numbers in a calc program like P-Calc at www.flydma.com, or Motocalc, or I just go by what someone else has done in the past.

Off the top of my head, I think a 3:1 gear ratio and a 10x7 prop is a good combination on a Speed 480.