Although experiments with rotary winged aircraft may be traced back to Leonardo da Vinci, successful flights were not achieved until the 1930s, and it was not until 1941 that the first practical, full size helicopter was built by lgor Sikorsky. Model enthusiasts are notably quick to emulate full-size aviation achievements, but were not as successful with rotary wing aircraft, and it was not until 1968 that the first fully controllable R/C model helicopter appeared, built by Dr. Dieter Schluter of West Germany.

Many modellers were convinced that the single rotor autogiro would be an easier subject to tackle than the helicopter and were conducting their experiments along these lines, but in fact the first really successful British R/C autogiro, a semi-scale model of the Wallace Autogiro, was first flown in 1978, ten years after the first appearance of the R/C helicopter. Designers and manufacturers the world over were quick to take advantage of Schluter's success and, In the early 1970s, model helicopter kits were on sale in the model shops.

In order to appreciate the reasons for the slow development of the model helicopter, at least a few of the problems which faced the pioneers must be considered. These problems were many and complex, for instance in order to achieve fight with any heavier-than-air machine, the lift force generated by its airfoils must overcome the aircraft's weight. In the case of a conventional aircraft this is achieved by its forward speed through the air which flows across its airfoil-sectioned wing, causing a speeding-up of the air, and there by a reduction in pressure, over its upper surface. At the same time, pressure increases across its under- surface of the wing.

The helicopter generates lift by the movement of its main rotor blades through the air as its rotor turns. The blades have to be moved at high speed and at a comparatively high angle of attack in order to produce sufficient lift to raise the model into the air. Weight is critical and experimenters who discovered that their chosen engine had insufficient power to produce the required lift were faced with a vicious circle. Fitting a larger engine to increase the available power also meant an increase in the weight to be lifted.

Bigger engines require more fuel and more weight! Increasing the angle of the rotor blades in the airflow produces more lift, up to a point but this also increases the drag of the blade, which now requires more power to move it at the required speed. All problems were eventually overcome and the fully controllable R/C model helicopter had arrived.
There were, however, no short cuts in its development: engines, drive gears, rotor blades, control methods, etc all had to follow a similar design to full-size helicopter and be built to the same exacting standards or perhaps closer to the mechanism design of the full-size helicopter.

So how difficult is the model helicopter to control in fight? Well, it has been described as similar to balancing a steel ball on a knife edge whale riding a bicycle! more on that when you visit Model Aeronautics for Dodos by following the link in my resource box.