It's an interesting idea, Nigel - but i don't buy it!
The cam mechanism is extremely large compared to the piston - bad for packaging.
The resulting torque curve can be optimised, but sinusoidal motion is generally best for 4-strokes.
Apart from removing piston side forces (which is good), there is no reason efficiency would be any different from ANY engine with a 3:1 mechanical gearing.
For heavy duty diesels the last thing you want to do is to force the gearbox to handle higher torques! This is why hub reduction is so favoured, to keep diff sizes down.
Finally for a helicopter weight is king, and i just don't see any real reason that they can make any weight reduction claims. The ideal is that you put the reduction gear as close to the rotors as you can. I suspect time will put this into the interesting distraction category...
Mart
Last edited by Graviman; 23rd May 2006 at 11:28.