V-22 Rotor Question

Literature mentions that the 3-blade V-22 rotor hub is attached to the rotor
shaft by a means of gimbal or universal joint. Gimbal and universal joints
do not transmit a constant velocity when the hub and shaft axes are not
aligned.

Does anyone know if the V-22 uses a gimbal joint or if it actually uses a
Constant Velocity Joint?

Thanks.

Dave J.

It could be two universals close together?
But then it would need a supporting bearing/structure at the rotor end
aswell. ?
Hmmm...
A CV makes more sence.

Cam


"Dave Jackson" wrote in message
news:aW6xc.702485$Ig.509981@pd7tw2no...
Literature mentions that the 3-blade V-22 rotor hub is attached to the
rotor
shaft by a means of gimbal or universal joint. Gimbal and universal
joints
do not transmit a constant velocity when the hub and shaft axes are not
aligned.

Does anyone know if the V-22 uses a gimbal joint or if it actually uses a
Constant Velocity Joint?

Thanks.

Dave J.

Cam

Two universals will only provide a constant velocity on the output shaft if
the axes of the input and output shafts are parallel. For instance, when
these two shafts are parallel but not aligned, the first universal will put
a varying velocity into the connecting 'shaft' and the second universal will
remove this varying velocity.

I think that the hub and shaft axes on the V-22 are not always aligned and
therefore a double universal joint will not provide constant velocity.

Dave J


"Cam" wrote in message
...
It could be two universals close together?
But then it would need a supporting bearing/structure at the rotor end
aswell. ?
Hmmm...
A CV makes more sence.

Cam


"Dave Jackson" wrote in message
news:aW6xc.702485$Ig.509981@pd7tw2no...
Literature mentions that the 3-blade V-22 rotor hub is attached to the
rotor
shaft by a means of gimbal or universal joint. Gimbal and universal
joints
do not transmit a constant velocity when the hub and shaft axes are not
aligned.

Does anyone know if the V-22 uses a gimbal joint or if it actually uses
a
Constant Velocity Joint?

Thanks.

Dave J.

True, I had forgoten about that (parallel in/out shafts)

But does that mean a tractor or four wheel drive suffer from alternating
velocities on the front wheels when cornering?

Cam

"Dave Jackson" wrote in message
news:Cynxc.674680$Pk3.470737@pd7tw1no...
Cam

Two universals will only provide a constant velocity on the output shaft
if
the axes of the input and output shafts are parallel. For instance, when
these two shafts are parallel but not aligned, the first universal will
put
a varying velocity into the connecting 'shaft' and the second universal
will
remove this varying velocity.

I think that the hub and shaft axes on the V-22 are not always aligned and
therefore a double universal joint will not provide constant velocity.

Dave J

Are you folks sure the V22 is using a universal joint like what we find on
an automotive drive shaft? I would thing that that would be a very arcaic
way to transfer power. Modern front wheel drive cars us a CV (constant
velocity) joint in place of the old standard universal joint. I'm not
saying that a CV joint fully eliminate the problems you're talking about
with universal joints but they do work significantly smoother at higher
angles.

Some general links with pictures of what I'm talking about a

http://volksweb.relitech.com/tech/cvjoints/cvparts.jpg
http://volksweb.relitech.com/tech/cvjoints/cvfrnt.jpg

Just a thought!
Fly Safe,
Steve R.


"Cam" wrote in message
...
It could be two universals close together?
But then it would need a supporting bearing/structure at the rotor end
aswell. ?
Hmmm...
A CV makes more sence.

Cam


"Dave Jackson" wrote in message
news:aW6xc.702485$Ig.509981@pd7tw2no...
Literature mentions that the 3-blade V-22 rotor hub is attached to the
rotor
shaft by a means of gimbal or universal joint. Gimbal and universal
joints
do not transmit a constant velocity when the hub and shaft axes are not
aligned.

Does anyone know if the V-22 uses a gimbal joint or if it actually uses
a
Constant Velocity Joint?

Thanks.

Dave J.

Cam opined

True, I had forgoten about that (parallel in/out shafts)

But does that mean a tractor or four wheel drive suffer from alternating
velocities on the front wheels when cornering?

Yes, and for sharp turns, it is quite noticeable.

"Dave Jackson" wrote in message
news:Cynxc.674680$Pk3.470737@pd7tw1no...
Cam

Two universals will only provide a constant velocity on the output shaft
if
the axes of the input and output shafts are parallel. For instance, when
these two shafts are parallel but not aligned, the first universal will
put
a varying velocity into the connecting 'shaft' and the second universal
will
remove this varying velocity.

I think that the hub and shaft axes on the V-22 are not always aligned and
therefore a double universal joint will not provide constant velocity.

Dave J





-ash
Cthulhu for President!
Why vote for a lesser evil?

Cam wrote
But does that mean a tractor or four wheel drive suffer from alternating
velocities on the front wheels when cornering?

Steve's post covers the front wheel drive.
To elaborate a little, The FWD has 2 CV joints; usually a Tripod joint at
the 'differential' and a Rzeppa joint at the wheel.

Dave J

"Steve R." wrote
Are you folks sure the V22 is using a universal joint like what we find on
an automotive drive shaft? I would thing that that would be a very arcaic
way to transfer power. Modern front wheel drive cars us a CV (constant
velocity) joint in place of the old standard universal joint. I'm not
saying that a CV joint fully eliminate the problems you're talking about
with universal joints but they do work significantly smoother at higher
angles.

Some general links with pictures of what I'm talking about a

http://volksweb.relitech.com/tech/cvjoints/cvparts.jpg
http://volksweb.relitech.com/tech/cvjoints/cvfrnt.jpg
"Cam" wrote
It could be two universals close together?
But then it would need a supporting bearing/structure at the rotor end
aswell. ?
Hmmm...
A CV makes more sence.
"Dave Jackson" wrote
Literature mentions that the 3-blade V-22 rotor hub is attached to the
rotor
shaft by a means of gimbal or universal joint. Gimbal and universal
joints
do not transmit a constant velocity when the hub and shaft axes are not
aligned.

Does anyone know if the V-22 uses a gimbal joint or if it actually uses
a
Constant Velocity Joint?

There are all FAR to mathematical for me but there are a few
pictures that I liked too The unicopter link in particular
has a lot of diagrams.

google [v-22 gimbal] returns:

http://rotorcraft.arc.nasa.gov/publi...ree_AHSF02.pdf
Which says:
"The V-22 hub comprises three composite arms, or yokes,
connected to the shaft by a constant-velocity joint."

There is no detail of the CV joint in this document but tehre seem
to be other documents on the same site.
e.g.
rotorcraft.arc.nasa.gov/publications/files/Acree_AHS01.pdf

Note that the google results contain an incorrect space
where in the URL displayed after the summary text.


Google [v-22 "constant velocity joint"]
http://rotorcraft.arc.nasa.gov/resea...amdetails.html
"Gimbaled hub with constant velocity joint (spherical bearing
and elastomeric torque links)"


http://www.unicopter.com/1301.html
Much *detail* and many ##-DIAGRAMS-##
"(Somewhat similar to the V-22 tilt-rotor)"


http://www.aero.polimi.it/~quaranta/...RF-2000-60.pdf
"Significantly,
it considers the gimbal joint, that links the hub to
the mast in order to allow the fapping motion of
the overall hub, and thus implementing a constant
velocity joint, and the swashplate, with all the re-
lated components that are required to transmit the
pitch controls to the rotor blades."


http://pcwww.liv.ac.uk/eweb/fst/publ...SSLA_feb11.pdf
"In contrast, the homo-kinetic, constant velocity joint,
featured on the V-22, requires that the drive
component be connected after the gimbal springs
eliminating cyclic variation of the rotor angular velocity."

Thanks for the web sites.

The actual operation of the V-22 CV joint and whether it transmit a true
constant velocity still remains a mystery. Both Bell and Sikorsky have
patents on differing ideas for CV joints but I don't know if they have
implemented them.

The implication of a true CVJ in a rotor-head is interesting, because it
should eliminate the Corollas effect and thereby eliminate a primary source
of lead/lag.

Dave J


"AnyBody43" wrote in message
m...
"Steve R." wrote
Are you folks sure the V22 is using a universal joint like what we find
on
an automotive drive shaft? I would thing that that would be a very
arcaic
way to transfer power. Modern front wheel drive cars us a CV (constant
velocity) joint in place of the old standard universal joint. I'm not
saying that a CV joint fully eliminate the problems you're talking about
with universal joints but they do work significantly smoother at higher
angles.

Some general links with pictures of what I'm talking about a

http://volksweb.relitech.com/tech/cvjoints/cvparts.jpg
http://volksweb.relitech.com/tech/cvjoints/cvfrnt.jpg
"Cam" wrote
It could be two universals close together?
But then it would need a supporting bearing/structure at the rotor end
aswell. ?
Hmmm...
A CV makes more sence.
"Dave Jackson" wrote
Literature mentions that the 3-blade V-22 rotor hub is attached to
the
rotor
shaft by a means of gimbal or universal joint. Gimbal and universal
joints
do not transmit a constant velocity when the hub and shaft axes are
not
aligned.

Does anyone know if the V-22 uses a gimbal joint or if it actually
uses
a
Constant Velocity Joint?

There are all FAR to mathematical for me but there are a few
pictures that I liked too The unicopter link in particular
has a lot of diagrams.

google [v-22 gimbal] returns:

http://rotorcraft.arc.nasa.gov/publi...ree_AHSF02.pdf
Which says:
"The V-22 hub comprises three composite arms, or yokes,
connected to the shaft by a constant-velocity joint."

There is no detail of the CV joint in this document but tehre seem
to be other documents on the same site.
e.g.
rotorcraft.arc.nasa.gov/publications/files/Acree_AHS01.pdf

Note that the google results contain an incorrect space
where in the URL displayed after the summary text.


Google [v-22 "constant velocity joint"]
http://rotorcraft.arc.nasa.gov/resea...amdetails.html
"Gimbaled hub with constant velocity joint (spherical bearing
and elastomeric torque links)"


http://www.unicopter.com/1301.html
Much *detail* and many ##-DIAGRAMS-##
"(Somewhat similar to the V-22 tilt-rotor)"


http://www.aero.polimi.it/~quaranta/...RF-2000-60.pdf
"Significantly,
it considers the gimbal joint, that links the hub to
the mast in order to allow the fapping motion of
the overall hub, and thus implementing a constant
velocity joint, and the swashplate, with all the re-
lated components that are required to transmit the
pitch controls to the rotor blades."


http://pcwww.liv.ac.uk/eweb/fst/publ...SSLA_feb11.pdf
"In contrast, the homo-kinetic, constant velocity joint,
featured on the V-22, requires that the drive
component be connected after the gimbal springs
eliminating cyclic variation of the rotor angular velocity."

Coriolis effect has to do with dissimetry of lift (advancing blade vs.
retreating blade) not blade velocity. On an articulated rotor head, lead/lag
will remain, so CV joints are moot in that regard.

Bob