- Jul 18, 2005
- Abu Dhabi UAE
- 582 Commander Elite
- Total Flight Time
- Stopped counting years ago after 5,000
Could a tuned angular alignment of a U-joint help mask 2/rev rotor vibration?
(just thinking inside my small box)
Not in this case. They want to change the direction to a different angle, not a different plane with the same angle, as seen in the video. Even then, you can't have the input power on the tail rotor shaft because it is the part that would still have the variable speeds. You would have had to apply the power into the system between the U-joint and transmission to have constant RPM speeds at the input and output shafts.
They need a constant velocity U-joint to change the angle. They could use a very large rubber damper between the transmission and the U-joint, but they would have to mount the U-joint and shaft separately, and still the rubber damper would need replacing too frequently.
By fair the best solution would be a CV-type joint in place of the U-joint. Or, they should have designed the tail rotor shaft 90 degrees to the main mast.
I would have gone about it oppositely from what my experience I gained over the years, if I had to go to the trouble of angling the TR-shaft. The lower you place the tail rotor from the plane of the main rotor, the more unstable the aircraft becomes between minimum and maximum flight weights, and also each time to apply TR control input, because of the changing of thrust from the tail rotor. That is why I designed my latest UAV helicopter with the TR on the same plane as the main rotor.