Home >> Hobbies >> Aviation

How to Find the Correct Motor for a RC Electric Airplane

Finding the proper electric motor for your RC airplane can be determined by the overall weight of the entire airplane, electrical components and all. You will also need to choose what type of electric motor to use. There are two types of electric motors brushed and the brushless. The brushed type motors are a little cheaper in cost but the brushless motors have more power and require a special electronic speed controller designed specifically for the brushless type motors. Another consideration is the type of battery you will be using for the airplane. Brushless motors require a higher output current to run them and need to use a Lithium Polymer, LiPo, type battery with high output current. Brushed motors run fine on Nickel Cadmium NiCad or Nickel Metal Hydride, NiMH, type batteries that are significantly cheaper but heavier than the LiPo type.

Things You'll Need

Postal scale (able to weigh in grams)

Instructions

- 1
  Decide on which of the motors to use, brushed or brushless. If money is an issue, then the brushed type motor is the least expensive choice. The batteries and speed controller will be less expensive as well. They can use either Nickel Cadmium, NiCad, or Nickel Metal Hydride, NiMH. The older NiCad holds more power but are a bit heavier. The NiMH batteries power falls off faster but is the lighter of the two.
- 2
  Choose the brushless motor if cost isn't a factor. The brushless motors put out more power than a motor of the same weight that is brushed. Remember that a brushless motor requires a electronic speed controller designed for a brushless motor. They will also need to use a Li-Po battery with an output within the voltage and current range of the motor you choose.
- 3
  Figure out the power loading in watts per pound. Use the formula. Power (Watts) = Current (Amps) x Voltage (Volts). Find the current and wattage and voltages for a specific combination of motors, batteries and propeller size using the calculation program.
- 4
  Using a postal scale weigh the airplane and electronics everything. Once you have all of the variables use the formula, Power Loading(Watts/Pound) = (Power (Watts) x 16) / Weight (ounces) to find the watts per pound. To take off you will need 50 watts per pound, to do aerobatics requires about 75 watts per lb. 100 watts per lb. will fly a wingless airplane.

Aviation