Item 1011

DESIGN: UniCopter ~ Power Train - Assembly - Lateral Engine - w/ Belt

For use with Rotax 912 and 914.

Drawing:

 Possible Disadvantages:

Is there room for the aft air cleaners?. Consider leaving the forward intake manifold as is, with the air cleaner pointing to starboard, but replacing the aft one with the opposite handed one so that the air cleaner point to port, aft of the transfer drive.

Interference between crankshaft and driver sheave. Consider reducing the diameter of the sheave slightly and redesigning the engines gear housing so that there is an 'external slot' into which the rim of the sheave and belt can go. If possible use wider, stronger green belt. Or, since a new housing is required, consider shorting the crankshaft and bushing.

Will have to lower the engine by an inch or two so that the forward air filter misses the starboard final pinoin.

 Advantages:

Engines torque should offset some of the rotors" torque in pitch, with changes in power. The helicopter wants to pitch up with increased power, therefor the CW rotating crankshaft should be pointing out on the starboard side.

Has two gear reductions plus Goodyear Eagle, but one gear is spur and Eagle has low power loss.

The pilot and the engine can be closer to each other, longitudinally.

 Notes:

Get engine as far forward as possible, for center of gravity and smallness of fuselage. Take pilot back one inch and bring radiators etc. forward.

Can move the engine to starboard one or two inches, if required to give more room for the Eagle Pd belt. The weight of the transmission will offset the side shift of the engine's weight.

Ctr. to ctr. distance in drawing has been opened from 27" to 29" but the angle has not yet changed from 18º. Can the 29" be reduced a bit?

Drive Train:

When standing on the starboard side and looking to port, the XZ plane of the rotors is rotating CCW and an increase it torque wants to drive the tail down. The X-shaft is rotating CCW when view from the starboard side. The engine's prop flange is pointed to starboard and it is rotating CCW when view from the atarboard side. The engines crankshaft is therefor rotating CW when view from the starboard side.

Components:

Engine:

Reduction - Primary: Approximately 2.58:1 Rotax's standard gearing.

Torque spike absorption: Rotax's standard device.

Reduction - Secondary: 1.06:1 Goodyear Eagle 1012

Reduction - Final: 2.66:1 Spiral bevel gears at both rotors

Soft start clutch: Beefed up SCM axle clutch 0751. Located inside the driven sheave.

Overrunning clutch: Located inside axle clutch and X-shaft. 0260

X-shaft: Second pinion at rotor brake end should maybe float on shaft ???

Rotor brake: (on other end of X-shaft from soft start clutch). Must default strongly to normally off.

 Notes re Primary Spur Gears:

XXX.

 Notes re Secondary Belt & Sheave:

XXX.

 Notes re Final Spiral Bevel Gear Sets:

Two 81-degree, custom spiral bevel gears. See B301. I think that these gears are applicable to Assemblies 0925, 0946 and 0999. Except the ratio has been changes to 2.66:1

 Center of Gravity of Engine:

 

X = -10.0"

Z = +12.39"

Y = +2"

Back to top | UniCopter Home Page

Last Revised: January 6, 2002