There is still the PSRU requirement due to the  engine still
  running at 6000 RPM where Tracy's box looks like overkill and timing
 belts
  at
  125 HP start getting bulky  and at 3 to 1 the large sheeve is also pretty
  large. Might be that a rotrax 914 gearbox  could be adapted to Jeff's
 psru
  plate and spacers.

  george grimes

  The torque pulse amplitude is the same for one rotor or two rotor.

  To scale the gear box down is a technical risk.

  Paul Lamar

 Paul, very good observation. Makes me wonder if a four rotor firing at 90
 degree intervals might be able to use Tracy's gearbox after running FEA on
 the thrust bearings.

 george grimes

 Probably. The gear set is normally used with a 650 ft pound Ford Power
 Stroke Diesel pick up truck engine and diesels are known for their sharp torque
 pulses.


 BTW In fact the Renault aircraft diesel would destroy constant speed props
 in a
 heart beat.

 That is probably why the Continental two stroke aircraft diesel engine
 never
 made it out of the prototype stage. I don't know how the Junkers Jumo ever
 lasted in 1935 or the Packard diesel before that. The props had to be
 cannon proof.

 Hope springs eternal :)

 Paul Lamar

 I am using a Hirth G40 gear box, which is rated for up to 140hp and is
 available with a wide range of ratios. Never had any issue with it on the
 ground. It also is available with damper or centrifugal clutch.


I have no business interest in this gear box, but it has been serving me
well so far, which I can not necessarily say for the Rotax C box.

Richard Sohn
N2071U

Richard you and Jeff should get together and combine resources.

Paul Lamar