Traction drive transmission research
Join Date: Apr 2003
Location: Vancouver, BC, Canada
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Flight Safety,
Thanks for the information on friction drives. It's an interesting idea and it maybe applicable to applications where the mentioned features of 'quietness' and 'smoothness' are critical. However, I think that it will not be the answer for helicopter transmissions.
The weight to power ratio is probably the most important prerequisite for helicopters. It is doubtful that anything is going to outperform the planetary gear arrangement. The unit can be small because there are many teeth transmitting the load. (I.e. more planets = smaller gearbox.) As mentioned by Nick, if helical gears are used then the loads can be even greater and any noise is even less. High ratios can be easily accomplished by side-by-side gear sets. Gears, including the ring gear, appear to be available from Rush Gear Inc.
If a right angle transmission is required, another high performer is the aerospace spiral bevel gear. Arrow Gear has this catalog that shows in-stock (low price) gears.
slowrotor,
Here is a bunch of boring stuff on a single stage planetary gear for an ultralight helicopter, if interested.
Thanks for the information on friction drives. It's an interesting idea and it maybe applicable to applications where the mentioned features of 'quietness' and 'smoothness' are critical. However, I think that it will not be the answer for helicopter transmissions.
The weight to power ratio is probably the most important prerequisite for helicopters. It is doubtful that anything is going to outperform the planetary gear arrangement. The unit can be small because there are many teeth transmitting the load. (I.e. more planets = smaller gearbox.) As mentioned by Nick, if helical gears are used then the loads can be even greater and any noise is even less. High ratios can be easily accomplished by side-by-side gear sets. Gears, including the ring gear, appear to be available from Rush Gear Inc.
If a right angle transmission is required, another high performer is the aerospace spiral bevel gear. Arrow Gear has this catalog that shows in-stock (low price) gears.
slowrotor,
Here is a bunch of boring stuff on a single stage planetary gear for an ultralight helicopter, if interested.
