Selecting a Motor/Battery Setup 

Here are some general guidelines for total watts:

70-90 watts per pound of aircraft - TRAINER/SCALE FLYING - 90-110 watts per pound of aircraft - SPORT/MILD AEROBATIC FLYING

110-130 watts per pound of aircraft - ADVANCED SPORT/AEROBATIC FLYING - 130-150 watts per pound of aircraft - EXTREME AEROBATIC/MILD 3D FLYING

150+ watts per pound of aircraft - ADVANCED/UNLIMITED 3D FLYING

So for an example - Let's say we have a 17oz plane that we want to pick a system for. Take the 17oz, divide by 16 to get pounds = 1.0625 pounds.

Now take the 1.0625 pounds and multiply by 150watts for Unlimited 3D Performance = 160 total watts minimum required for this model to acheive Unlimited 3D Performance.

So now you are looking for a motor that can at bare minimum deliver 160 total watts.

For the battery, you want to use an 11.1volt 3cell, take the 160 total watt number and divide by 11.1volts to figure out how many amps would be required of the motor/prop.,

when paired with an 11.1volt LiPo = 14.4amps. So now you know that when using an 11.1volt LiPo, you need a motor that can handle 14.4 amps on a continuous basis, handle 11.1volts and be capable of 160 total watts.

As for the ESC selection, you always want a good cushion in there so things run cool and nothing really gets stressed. Basically, you look at the max. burst rating for the motor in terms of amps, and add in some cushion.

Something equivalent to the Park 450 or Torque 20T-1030 in terms of specs. would do the trick. With a max. burst rating of around 18amps, a good bet for an ESC would be a 25 amp, that can handle a 3cell LiPo.

However, sometimes manufacturers list the ratings of their ESC higher than what they really are, so you need to take that into account also.

If the ESC is not rated high enough then it can burn up, or it can think the battery is dead as soon as your put any load on it and then shut the engine down.

November 2, 2007