DESIGN:UniCopter ~ Power Train
For much information on K-Max transmission see:OTHER: Helicopter - Outside - Intermeshing - Kaman - K-MAX ~ Transmission
For information on the Revolution Gears see;B011.html ~ Revolution
For general information on power trains see:Mechanics
Also see;OTHER: Mechanical - Bearings ~ Transmission
The transmission is one single unit. The X-over synchronization portion also serves as the final reduction.
This drawing is item 0814 and it is only conceptually correct.
Engine Induced Rotational Acceleration and Deceleration:
The firing of the engine's cylinder(s) will result in rotational acceleration and deceleration. Engines with fewer firings per revolution of the crankshaft, in other words fewer cylinders and 4-stroke vs. 2-stroke, will result in greater acceleration and deceleration. This 'jarring' must be isolated from the power train. Attaching a flywheel to the engine would help but this will add unnecessary weight and not reduce the shock on the engine's components. It appears that the best arraignment is one of placing a device with spring and damper between the engine and the power train. The Rotax 912 has a dog clutch and friction clutch in its gearbox. I believe that one or more of the Hirth's gearboxes have a doughnut type of device. The Robinson uses V-belts.
Using the Robinson V-belt style of soft start pluse a feleable coupling.
Consider having the transmission as a totally sealed unit (with the possible exception of changing oil). Maintenance to the power train could only be done by authorized representatives, or perhaps on an exchange basis. Sensors could be located within the transmission to record specific past activity.
It appears, from a comment The book 'Whirlybirds' that needle bearings are a no-no in transmissions..
Oscillation during Autorotation:
If the drive train between the two rotors is too complex, or too light, there may be the opportunity for an oscillation to start between the two rotors that could destroy the drive train and craft.
Consider having a slip fit spline on one end of the shaft between the primary and secondary gearboxes. This will allow for thermal expansion and eliminate the need for a coupling.
Being an Absolutely Rigid Rotor the primary reasons for in-plane vibration have been eliminated.
See: UniCopter Pusher Propeller
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Last Revised: July 7, 2005