Prop tachometer - a rev counter for model aeroplanes

prop tachometer elektor may 1982 — 5-39 As aeromodellers will know, it is necess- ary to match a particular propeller with any given engine. Each propeller has a specification, indicating the optimum efficiency relative to its "speed" (rpm). Therefore a way of measuring its speed is essential. When an engine is being tuned it is also very useful to be able to check the rpm relative to any adjust- ment made. A mechanical method would prove costly and rather com- plicated to make. The only sure way to achieve a high standard with a relatively low cost is to use an electronic circuit. The speed of the propeller can be deter- mined with the aid of opto-electronics. An analogue indication can be provided by means of a moving coil meter or, if digital is preferred, by using a digital display. Which method used will deter- mine the cost. rev counter for model aeroplanes Modellers tend to be rather slow in getting into electronics. This could stem from the fact that balsa wood and elect...