A039

MAKE: SynchroLite ~ Power - Train (for 2 engines)

Power-train Extremes

	Maximum engine power	= 30 hp
	Maximum engine rpm	= 6200
	Maximum rotor disk radius	= 9 feet
	Maximum reduction	= 10:5 : 1 Will probably be less

Forward Slope of Mast

Forward angle for rotor shafts off of vertical: 5 degrees? [K-Max is ?]

Consider putting some (3 degrees) forward tilt in fuselage. This will probably result in; A leveler cockpit in forward flight. Landing with more rear leg contact befor front leg. More clearance between tail boom and blades. Maybe slightly less fuselage drag.

Shock Loading

If shock loading from single cylinder engine is causing early breakdown of overrunning clutch, gears or bearings etc. consider locating an elastomeric torque device inside the driven pulley's housing and or in the Inner Ring which is located between the overrunning clutch and the mast..

Soft-Start Idea August 30, 1999

As an alternative to brake band, Normal shoe brakes (go cart) could be located inside the end of the drum, or disk calipers on both sides of the drum.

Consider the idea of 2 Destaco (De-Sta-Co) toggle clamps, since they "lock" in position. They could actuate the band clutch devices via an adjustable spring. This spring would automatically set the time for getting the rotors up to full speed. If one was actuated slightly before the other it should not cause any problem. Occasionally the time to bring the rotors up to speed could be timed and if it differed from the recommended time the spring loading could be adjusted. This will allow the clutches to "lock" on or off. There should be a separate control for both systems, so that they are totally independent of each other.

Ratio Consideration August 28, 1999

It looks like the greatest reduction will be 10.5:1. Changed?

By going to a 22-tooth sheave on the engine the ratio will be reduced to 9.53:1.

The sun gear has gone down to 24 teeth from 26-tooth. This gives a 1/64" clearance over a 1.375" diameter mast and maintains a 3.5/DP wall thickness on the sun gear. It will also allow the planet gears to go to 22 teeth, which will take their bearings better and handle more horsepower. This will also result in an additional 5.7% speed reduction. If the mast is less than 1.375 at this location then there is even more reason to do this. If we are willing to stay with the 21 teeth planet then the ring gear can come down to 66 teeth; which was done.

Comparison: Centrifugal Clutch and Gears vs. Belt Drive w/ Soft-Start

Centrifugal Clutch & Gear

Compact

Automatic actuation

Belt Drive Soft-start

Non critical area

- 2 drives

Before freewheeling clutch

Can be visually inspected

Absorbs shock from 2-stroke

Engine Mounts

All the ultralight planes at the ultralight park have rubber (Lord) mounts for their engines. Also they drive the propellers via a v-belt.

The UltraSport 254's engine and transmission are hard mounted to the seat back.

June 3, 1999 Consider locating the mid/lower mount as low as it can go. This should then be in a location where there is more "meat on the seat/tube and also the coupling between it and the other 2 mounts will be longer.

Vibration:

On the Robinson R22 and the 2 Bells at BCIT the helicopter frame is isolated from the transmission by rubber mounts. On the Ultrasport 254 the power train is bolted directly to the fuselage.

Synchronized Timing of Engines

Should the engines, particularly on the one with gears for the primary drive have the engines timed to each other, so that they fire ate the same time or so that they fire opposite to each other?

May have to use ratchet type of overrunning clutch and fixed position soft-start.

Mount mechanisim on housing 0309.

This will allow the engines to fire at the half cycle of the other.

The ratchet should also eliminate thee need to case harden a portion of the shaft.

Summary of Kaman 1972 Transmission Design report

Using Kaman's algorithm for the SynchroLite, one primary and one secondary and 1/2 synchro will weigh in at 38 pounds, for a total transmission weight of 76 pounds. This might include mast.

Lead-Lag:

It is extremely probable that there is lead-lag between the 2 pair of rotors in forward flight. The teetering of the blades and the Coriolis effect will cause it. This problem may put excessive loading on the shafts, gears and bearings of the power train. It may also oscillate at 2-P which in turn will compound the problem. This lead-lag must be taken care of and it should also probably be dampened.

Can this be done with the torque of the masts?

Note that the v-belt takes some of the shock loading of the engines and power train

Mounting:

Mast is mounted firmly in the gearbox.

The power train is rubber mounted on the fuselage.

Mast Rotation

Port - Counterclockwise when view from plan view.

Starboard - Clockwise when view from plan view.

Danger re Loose Clothing or Objects June 1, 1999

There is a strong chance that loose articles of clothing, such as Snoopy's scarf would get caught in the belts and pulleys.

During flight, a hard object may "fly" into the belts and pulleys and destroy them.

Consider forming some light screening from the backboard back about 12 - 18". This will still allow air to get through, it will weigh very little and it will give "shape to the helicopter.

Or just screen off each belt, individually. This screen might be part of protection between belts and control rods.
Clutch - Soft-Start & Phase Lock

The purpose of the clutch soft-start is to allow the engines to be started while not connected to the rotors.

The purpose of the phase lock is to:-

A/ give positive locking to the clutch soft start, and

B/ cause the engines to fire in synchronization.

The soft-start brake band is applied when the collective is in the down position and the engines are running at a fast idle. When the rotors come up to the fast idle speed the phase lock is set . The engine torque is then increased to set the positive phase locks. Then the phase-lock is adjusted to cause the engines to fire together. This will probably necessitate a grip belt.

Phase lock could be worm gear type of arraignment. I LH & 1 RH.

See C092.doc re Conversation with Eagles Perch.

Re paying for designer looking at my secondary and synchro gearboxes.

Access to transmissions etc.

Consider having cover in back of seat.

Last Revised: July 10, 2000