Not a good idea to use a u joint at one end and a flex coupling on the other end. the angle on the front u joint need another u joint to match that angle only opposite. say -3 degrees front needs a +3 degrees on the back. as a u joint turns the shaft speed increases and decreases because of the angle of the joint. the front will speed up you need another joint in the rear to slow it back down. have you ever driven a car with a bad driveline angle it vibrates under acceleration but not under decal. that's what may happen.
Just my uneducated opinion
Thanks but don`t give me too much credit here. The Swift`s designer, John Uptigrove is a REAL licensed Professional Engineer who knows how to do stuff.I'm happy to see some discussions about the Swift. I've followed the project for many years now. I really liked it instantly and I honestly think it will be the kit I'm buying. Only positive thing with the years of waiting is that I have been able to put away the needed funds... but it really is a long waiting.
But I must admit that I'm a bit worried about being one of the first builders. Not that I'm afraid of some glitches in the build instructions or such. What I'm thinking about is possible weaknesses that result in catastrophic failures in the air, like failures of rotorhead or rotorblades.
Wish I were like Bryan Cobb or other skilled forum members, judging every part/design in terms of safety and constructing new ones where appropriate.
But then again, people in the experimental community have jumped on new designs all the time. Mini-500, Helicycle, Rotorway, Mosquito, Safari...
This will explain it better than words;I stand corrected, it would appear there is only 1 "U" joint and it connects the shaft directly to the transmission. I don't know why you would use a "U" joint there and not some kind of CV joint.
Bryan,Thanks but don`t give me too much credit here. The Swift`s designer, John Uptigrove is a REAL licensed Professional Engineer who knows how to do stuff.
I can only speak from what I see on certified helicopters and what has worked. The star plate has had success but required revisions on Robinsons. The 2-yoke U-joint was problematic on Hillers but it made a 30 degree change in direction. The Brantly has a 12" short shaft at the front with a Morflex at both ends. Mine never had any issues and had flown 2700 hours without being changed. As far as I know, the Lovejoy type is not used on certified helicopters but the Helicycle uses it and doesn`t have issues???
I copied the Brantly setup on my Mini-500.
I'm sure it has a clutch. With no rotors installed there is little resistance so any clutch drag will move the system.Watching the engine start again, I noticed that the tail and main rotorhead started to spin just as the engine fired. Would that indicate direct drive without a clutch (not talking about the clutch for autorotation)?
I have no knowledge to base any opinion.Thanks, that makes sense.
What's your overall impression of the Swift? A part from the U-joint already discussed.
At least they designed their own. Not like others that take someone else's design, make a few little modifications and then have the nerve to exclaim it is now their design.