Electric Power for Radio Control Model Airplanes
Electric RC planes power a revolution in the model aircraft hobby
Modelers have enjoyed flying practical radio control model aircraft since the mid 1960s. Most of these models were gas powered, fairly large size and flown outdoors. There has always been a desire to fly smaller RC airplanes indoors. Radio control gear until quite recently was too large and heavy for practical indoor flight. Fortunately, that has changed forever due to the widespread use today of electric power for RC models. Pilots can easily obtain affordable and well flying electric RC airplanes for any phase of flight, from large aerobatic aircraft to the smallest of micro indoor flyers.
Pietenpol Air Camper in flight
Several technical leaps allowed this evolution to occur. The first was the introduction of lightweight brushless electric motors. In the past modelers adapted “can” style electric motors for RC airplanes. These motors used brushes to apply electrical current to the rotating armature. While inexpensive, these brushed motors did not provide much power and tended to wear out quickly. Modelers were forced to build their aircraft as light as possible to have any type of effective flight performance and employed geared solutions for the propeller to try and overcome the low power of the motors.
The Robin can be flown indoors or outside
This situation changed with the introduction of brushless electric motors. Brushless motors have no internal metal to metal contact as the brushes to commutators did on the earlier motors. Thus, brushless motors tend to last a very long time. Brushless motors, due to their advanced technology, provide much more thrust as compared to brushed motors. Brushless electric motors are small and lightweight enough that the RC modeler will have no difficulty selecting an installing a motor that will provide all the required power for their model.
The ParkZone Cessna 210 weighs a mere 18 grams
The real challenge facing electric RC airplane pilots remains with the batteries. Lithium polymer (lipo) batteries, are the standard today for lightweight electrical power. Modelers still need to retain an awareness of the danger of fire from lipo batteries. There is a good discussion on the RC Groups forum regarding lipo battery safety.
Lightweight lipo batteries
Miniature lipo batteries are the key technology for the new generation of micro indoor electric RC models, such as the 4-Site and Pietenpol. These tiny one cell batteries come in various sizes, from 70 milliamps (used in the 18 gram ParkZone Cessna 210) to the 120 and 150 milliamp batteries used in the Finch or Extra 300. These smaller lipo batteries are safe and easily recharged at your flying site.
Build a Finch from free CAD plans here!
Electric RC flight has opened up the world of practical indoor RC model airplane flight. Previously, the heavier NiCad rechargeable batteries and geared motors made it challenging to build and fly micro indoor RC planes. It was possible to get something airborne, but you had to use fairly large wings to get these aircraft to fly. A good example of this is the generous wing area of the Blackburn. With today’s micro RC gear anyone who puts in the effort can produce an indoor flyer with great flying characteristics.
Blackburn monoplane in flight
Model weight is still the most critical factor to successful indoor flight. Use every technique at your disposal to produce a lightweight aircraft. As you design the plane, employ the technique of “building in lightness” as you prepare the plan. Carefully select the balsa, using a lighter grade for the tail section to keep the center of gravity at the correct location. To save weight on the Blackburn and Chickadee, I covered just the upper surfaces of the wing and tail.
Ready to fly electric model planes
The various manufacturers of ready to fly indoor RC model planes use foam for the construction material. The injected foam technique is suitable for these mass produced models, but is not common for original design use. Home built RC models typically use Depron flat foam for construction. In many instances modelers use foam formers and ribs to mimic balsa construction techniques.
Electric RC airplanes can be found with modelers everywhere these days. Electric motors start instantly, operate with minimum maintenance and are quiet and clean running. These inherent positive characteristics are ideal for indoor RC model flight. The only item that needed to be developed was lightweight micro RC gear, and that is now readily available. Whether you chose a RTF indoor model or one built from plans, anyone can join in the fun of indoor RC model flight year round.