Converting a gas-engine ("nitro") model plane to electric power is a straightforward process. You need basic knowledge of model planes, power-to-weight ratios and center-of-gravity (COG) balance points. Electric motors weigh less than gas models because they have fewer parts. The battery packs, however, are fairly heavy. This means everything will need to be in a slightly different location within the fuselage than the old engine was in order for the balance point to be correct.
Things You'll Need
- Electric motor
- Electronic speed controller
- Battery pack
- Double-sided foam mounting tape or mounting screws
- Balancing jig
- Hobby-sized or jeweler's screwdrivers
- Measuring tape
- Marking pen
- Balancing weights
Remove the old gas engine from the plane.
Remove the parts associated with the gas engine, including the servo and push rods, fuel tank, fuel lines and fuel pump, if any.
Remove any balancing weights that were used, as the new motor, battery pack and ESC will cause the plane to balance at a slightly different point.
Determine the longitudinal center point of the aircraft, and make an indicator mark at that point. Find the COG balance point, and mark that as well. Normally, this is somewhere between the midpoint and forward edge of the wings. If you do not have a balancing jig, simply pick up the plane with one to three fingers (depending on the size of the plane) under each wing. Placement of your fingers from should be from a few inches to about a foot (again depending on the size of the plane) away from the fuselage. When it is balanced, it will be reasonably level from front to back.
Place the new electric motor, ESC and battery pack temporarily within the fuselage. The battery pack, as the heaviest item, should be placed as near the COG as possible. The motor needs to go as far forward as possible. Pick up the plane and again check the balance point. Move the various new components forward or backward as needed to come as close to neutral balance as possible.
Install the new components with double-sided foam tape for the ESC and battery pack holder. The motor can be mounted with either foam tape or screws, as indicated by the size and type of motor you chose. It is important to center the motor precisely from side-to-side for proper and safe operation of the propeller. Make sure neither the motor nor its ESC or battery pack interfere with any push rods or servos for operation of wing flaps, ailerons or elevator.
Double-check the balance once again. Any minor variations from neutral can now be fixed with the addition of balancing weights placed opposite the direction of tilt, i.e., in the nose if the plane balances tail-heavy; in the tail if it balances nose-heavy.
Consult the instructions that came with the new motor or consult your local hobby shop to determine if you need a different size or pitch of propeller than the original. This is quite likely.
Tips & Warnings
- Depending on the size and type of plane, you may find it necessary to remove all the operating hardware for the control surfaces and start anew in order to correctly place the new motor.
- The front bulkhead MAY need to be modified to assure proper placement of the shaft leading to the propeller.
- Consult your local hobby shop for the correct size and power of engine for the type and size of plane you have, and the correct electronic speed controller (ESC), used by electric motors instead of a servo motor. Be sure to obtain an ESC with enough ports for the control surface servos as well.
- An incorrectly matched motor and propeller can cause safety hazards.
- If the prop is too large for the motor, insufficient power to maintain lift will be a problem, resulting in a possible crash or failure to take off.
- If the prop is too small for the motor, there can be extreme vibration, possibly resulting in shearing of the prop shaft. This would cause the prop or broken pieces thereof to become missiles.
- Photo Credit avion modele reduit image by jerome scalvini from Fotolia.com
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