by przybylski » Sun Nov 15, 2009 4:23 pm
I have never heard of a commercially made model engine which was fitted with the gearbox necessary for counter-rotating props. This would add a lot of weight, and in a small engine, there would be no advantage.
OS of course, did at one time offer a factory fitted gear reduction unit on their 61, but this still only involved one propeller. The advantage there, lay in the fact that the engine was able to turn a larger, higher pitched prop. DuBro and Byron also made these reduction units, although these were belt drive, not gears. In the early 1960's, a modeller in England made a scale C/L Fairy Gannet (won the Scale event at the British Nats with it) and it DID have counter-rotating props, although from memory he used 2 engines to drive them. I think he had an OS Max 35 driving the front prop, and a Max 15 on the rear. The model and the gearbox were descibed in AeroModeller magazine around 1962. BOB