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Single channel RC operated model planes

I was introduced to Radio control flying in the early 1960's.
Hitherto I had built simple free flight models with rubber power or small diesel and glow-plug engines. In New Zealand at the time and living with my wife and three girls, the hobby was still in its infancy. I built a successful free flight model which needed a mechanical shutoff valve for the engine. The valve restricted the engine run to about forty seconds. A flight longer than this would have resulted in a flyaway and lost model.

Our family moved to Fiji and I began to make models again however there was no hobby shop in the city of Suva where we lived so I had to import materials from England and Hong Kong.
One of the catalogs I received from Hong Kong illustrated a radio control unit with single channel capability. This meant that only the rudder movement could be used to control the plane.

A colleague in my office was also interested in the hobby so we built the model together. I had a diesel engine from England to use for power and once the model was built and all equipment installed we set off to test fly the plane. The model was called "Rhoma". It had a high wing, box section fuselage and was covered with doped tissue. First flights were conducted in field with high grass in case of a crash. The model being untested did in fact land badly on its first flight but survived with minor holes in the covering. We tried again and this time we were fortunate to have success. A new model will mostly need re-trimming before it flies in a stable fashion. We returned home and I set to work to adjust the rudder mechanism and add a small trimming tab on the fin in case the model tried to turn without a signal.

The single channel radio control unit was a forerunner to the equipment that has been developed in the intervening years. A single channel radio when keyed by a micro switch on the transmitter sends a carrier wave signal to the receiver in the plane. The receiver relays this impulse to a mechanical device called an escapement which is similar to a clock mechanism. A strand of rubber provides the power to the escapement.

Operating a single channel system requires the pilot to observe the model closely and make adjustments to avoid losing the model downwind. In Fiji the trade winds blow fairly steadily and if the model gains height it becomes harder to prevent the model from flying away and out of range of the radio. The switch control causes the rudder to turn in one direction and then on release it returns to neutral. The next signal operates the rudder in the opposite direction. Holding the key on, turns the model until it is released.

Eventually I moved to California where my first purchase was a four channel proportional radio and servos to move the controls. I built a P.51 for the equipment but found that I had to relearn how to fly with the new system. Crashes were frequent until I got the hang of it.

The hobby has arrived at a very high degree of sophistication with multi engined scale models and miniature jet engines. Every year the model fraternity hold the "Nationals" where experts from many countries compete. Radio systems are at the point where interference between operating radios is virtually unknown.

In my almost sixty years of building model planes, I have seen great developments. The hobby may go even further than it has so far. The US military is employing miniature unmanned aircraft to give advance notice of enemy movements and attack targets. What is next we will have to wait and see.

Learn more about this author, Archie Brown.
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