Radio-controlled helicopters are a fun and interesting hobby for enthusiasts of all ages. While flyers may know a lot about how helicopters work, the radio control is still a mystery.
When talking about helis, RC generally means radio-controlled, not remote-controlled. While remote-controlled helicopters do exist, they don’t allow for as much freedom when flying. The biggest difference between radio-controlled and remote-controlled vehicles is that remote-control requires a wire that connects the controller and the vehicle, while radio control is always wireless.
Radio-controlled helicopters usually come with a handheld device including channel controls and a radio transmitter. The transmitter usually includes a battery that is a power source for the controls and signal transmission. The helicopter itself contains a receiver that reads signals from the transmitter. Crystals inside both the transmitter and reciever vibrate at a high frequency when powered. The transmitter uses this radio frequency to send a signal to the receiver in the heli, allowing for wireless operation.
Just as local radio station have designated frequencies, radio control frequencies are also assigned by the FCC. The frequencies are carefully chosen to ensure that there is no possibility of interference with public service frequencies used for air traffic control or emergency services. The specific frequencies vary by country, but in the United States, most RC helicopters operate between 72 MHz or 75 MHz.
Heli motion is controlled by channels, which are segments, or bands, within a frequency. Small fixed-pitch helicopters require four-channels to operate the throttle, elevator, aileron and rudder, while micro helicopters can often use two. Collective-pitch models usually need six channels; one each for the throttle, collective pitch, elevator, aileron, rudder and gyro gain. Each RC heli must operate on a different channel or interference will occur, resulting in erractic control of the vehicle, and many heli transmitters are advanced enough to “search” for available open channels in their frequency.
The radio is argued to be the most important part of an RC helicopter. Understanding how and why your heli can fly while you are on the ground can be valuable knowledge, especially in situations where channel interference is affecting performance.
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