The new Swift - video of engine start

Looking at the video and other pictures that just came out recently, I'm curious. Although it is a super slick looking machine, given the cabin layout, if one needs to auto, will you be able to see where your going to land given how the front console is laid out. Kind of reminds me of the rotorway scorpion cabin layout. Maybe they are going to incorporate some chin bubbles but wonder why the would not have considered this already in their molds. Does no one else see this or am I missing something.

Just curious.
 

bryancobb

Junior Member
What`s Up With The Swift`s Drive?

What`s Up With The Swift`s Drive?

I see a 4-star flex plate is expected to carry 180 Horsepower and within 2 feet I see THREE different types of flex joints...

A steel universal...a 4-star-a-la-Robinson...and a Lovejoy

 
Bryan,

Interesting! What's your take on that, is it just a cheap/unorthodox design but functional (safe) or is it questionable?
 
u joint setup

u joint setup

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.

Doug

Just my uneducated opinion
 

Jason O

Junior Member
I don't think we can see the other end "U" joint so we don't know what the matching angle is. It would appear that the belt is the main drive. One way goes to the tail rotor and the "U" joint way goes to the rotor transmission. I would be stunned if the designers of the a helicopter did not know about the angular acceleration and deceleration of a U Joint.

FWIW
Jason


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.

Doug

Just my uneducated opinion
 
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...
 

bryancobb

Junior Member
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...
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.
 

DennisFetters

Gold Supporter
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.

Jason
This will explain it better than words;

www.youtube.com/watch?v=5aCK4Bob6a0


You have to give people a chance to make mistakes while they learn, and correct them. All new designs have some things the designer try's, but then learns that was not such a good idea.
 

HighAltitude

in transition
I have to laugh at this thread. Being a raised on a farm, the video Dennis posted was basic knowledge for water pumping engines, tractor pto drives, and harvesting machinery. One trip to town to pick up a new pto driveline at the driveline shop teaches all these lessons. (I was that annoying kid that asked why they welded on balancing weights, why the u joints had to be aligned, etc.)

It comes down to torsional vibrations and a design that controls them. A selection of a lovejoy vs u joint isn't as important as the equal angles and the torsional vibrations, as the video attempts to demonstrate. I can't imagine the compromises when setting up a heli drive system but I would trust the designer rather than forum members throwing out engineering opinions from their couches.
 

DennisFetters

Gold Supporter
As it's set up now, the constant input speed is at the drive belt and sprocket, and the spraque clutch needs to be in the sprocket as well. That means with the angle on the U-joint feeding the main transmission, there will be torsional vibration created from the offset U-joint going into the main transmission. But, there will be feedback throughout the drive system. As I see the system in the pictures, it will be trouble. But then, I'm not privy to the full design.

They won't be able to tell much until they put on the main blades and run it under power.

The only solution I see is to loose the U-joint and put a CV joint in it's place. I'll bet money that in time that is what they will do.
 
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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.
Bryan,

Fair enough, you might not be a "REAL licensed Professional Engineer". But non the less, I have followed your work with the Mini-500 with great interest and I'm very impressed :). And the point I'm trying to make is that I don't have the smallest of ability to judge if a new design is safe like you are doing. But I think that goes for most of the people who builds kit helicopters or airplanes.
 
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)?
 

DennisFetters

Gold Supporter
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'm sure it has a clutch. With no rotors installed there is little resistance so any clutch drag will move the system.
 

DennisFetters

Gold Supporter
Thanks, that makes sense.

What's your overall impression of the Swift? A part from the U-joint already discussed.
I have no knowledge to base any opinion.

To design and build any helicopter on your own is a great and challenging accomplish.

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.
 

Jincamty

Magic free zone
Could a tuned angular alignment of a U-joint help mask 2/rev rotor vibration?

(just thinking inside my small box)
Cheers Cam.
 

Hawk

Newbie
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.

Sure does ! Reminds me of the theft of the control system design of the CH-6 from Augusto Cicare and called it his own and then patent it here in the USA... and then attempt to sue everyone and their brother for his STOLEN design patent infringements!!!
 
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