The Murphy Builders Site

Roger,

254R's wings always felt very stiff to me too -- until they were
connected to the torque tubes and stick. When driven by the torque tubes
and stick, they feel fine. There's a lot of leverage in that linkage, so
what feels stiff at this point may be hardly noticeable when they're
hooked up.

Ron


Roger Cole wrote:

After covering the wing I checked the friction of the aileron torque
tube and found that it is too stiff. Is there any way of loosening
it without un-doing the wing?

Roger Cole
Murphy Elite #709
rcole927@earthlink.net

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Hi Roger
Sounds like yours is coming along well. I guess you're no worse off by
carrying on and doing something about it when you've finished and the
controls seem too stiff. Chances are they will be fine when it's all
connected up. I think I'd wait and see.
Nig
745E
(still finishing the second wing)

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
Roger Cole
Sent: 16 November 2007 02:00
To: Rebel Builders
Subject: [rebel-builders] Friction in aileron torque tube


After covering the wing I checked the friction of the aileron torque
tube and found that it is too stiff. Is there any way of loosening
it without un-doing the wing?

Roger Cole
Murphy Elite #709
rcole927@earthlink.net







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I have more friction in one wing than the other. The root cause seems to be
a torque tube that is slightly out of round. I tried polishing the delrin
bearing blocks and using various lubricants with little improvement.. I decided
that when the complete control system is hooked up it should be OK. A little
friction might be helpful. Rebel #200.

Norm Wandke



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Norm:

The following is worth just what it will cost.

The best one might hope for on this subject is a control system that is
frictionless. In other words, zero friction is good.

I should think that if you have any friction in the system you should do
your best to minimize it at this time. You mentioned that you think that one
tube is out of round. Can you measure the tube in several spots to determine
if this is true, and how much out of round it is?

Before you get to the point of not being able to work on this area, I would
try to run down what is going on.

I should think that in flight, the friction will be something that you will
have to fight forever.

There may be enough mechanical advantage on the torque tube from the air
loads on the flapperons that it easily over-rides any friction in the tube.
I don't know about that

Maybe some flying builders can shed more light on this.

But I do know that zero friction would be the goal.

Tim (you get what you pay for) Hickey
R 808.


----- Original Message -----
From: <Newcog@aol.com>
To: <rebel-builders@dcsol.com>
Sent: Friday, November 16, 2007 8:40 PM
Subject: Re: [rebel-builders] Friction in aileron torque tube

I have more friction in one wing than the other. The root cause seems to
be
a torque tube that is slightly out of round. I tried polishing the delrin
bearing blocks and using various lubricants with little improvement.. I
decided
that when the complete control system is hooked up it should be OK. A
little
friction might be helpful. Rebel #200.

Norm Wandke



************************************** See what's new at
http://www.aol.com




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Hi Tim
Yes you are of course correct!
However FWIW...
I sanded out the delrin on 119 and still it seemed like a lot of
friction. (Don't leave any grit behind)
My tube was oval by at least 0.040" as I recall and I never did manage
to reduce that much and I don't think it really matters much once the
tube is loaded and/or riveted together anyway.
Adding some "CROWN" brand silicone as recomended by Wayne (plastics
expert) helped a bit but it still seemed too tight and it got a bit
tighter after closing the wing. (See archives on caution not to use any
other brand of silicone.)
However it seems to be a non issue once I got flying. Note that unless
you go to ball bearings. the things are definitely going to have
noticeable friction with the flaperons down anyway but even that does
not seem objectionable to me. Perhaps partly because it is so effortless
to pick up a wing with rudder on a Rebel. Perhaps partly because I'm
used to heavier controls. Most pilots have commented on how stable the
Rebel is and how it does not need constant aileron corrections like the
cessna/zenith/grumman that they normally fly.
Ken

Tim Hickey wrote:

Norm:

The following is worth just what it will cost.

The best one might hope for on this subject is a control system that is
frictionless. In other words, zero friction is good.

I should think that if you have any friction in the system you should do
your best to minimize it at this time. You mentioned that you think that one
tube is out of round. Can you measure the tube in several spots to determine
if this is true, and how much out of round it is?

Before you get to the point of not being able to work on this area, I would
try to run down what is going on.

I should think that in flight, the friction will be something that you will
have to fight forever.

There may be enough mechanical advantage on the torque tube from the air
loads on the flapperons that it easily over-rides any friction in the tube.
I don't know about that

Maybe some flying builders can shed more light on this.

But I do know that zero friction would be the goal.

Tim (you get what you pay for) Hickey
R 808.


----- Original Message -----
From: <Newcog@aol.com>
To: <rebel-builders@dcsol.com>
Sent: Friday, November 16, 2007 8:40 PM
Subject: Re: [rebel-builders] Friction in aileron torque tube

I have more friction in one wing than the other. The root cause seems to
be
a torque tube that is slightly out of round. I tried polishing the delrin
bearing blocks and using various lubricants with little improvement.. I
decided
that when the complete control system is hooked up it should be OK. A
little
friction might be helpful. Rebel #200.

Norm Wandke

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The torque tubes tend to be out of round & I think I tweaked them to improve it but
never got to perfectly round.

There's a lot to be gained by spending time and getting the bearing mounts straight
and getting the bearings perfectly concentric with the tubes. The bearing mounts I
had to deal with left something to be desired (well, a lot...) as far as the three
flanges being planar and perpendicular to the torque tube bearing mount surface. I
spent time re-bending & tweaking the flanges so that all three sat in the same
plane and so that the bearing mounting face was at right angles to the mount
flanges. That makes a world of difference when you rivet the bearing mount to the
spar because the bearing mounts do not distort when the rivets pull them down.

If you do this then you should not need to sand/modify the Delrin/Acetal bushings
other than "breaking" the sharp edges.

It's also important to smooth the surface of the torque tubes. Use some fine
sandpaper/scotchbrite and smooth/polish the surface by rotating the tube against
the paper. You should finish with a close to polished finish and the tube will
rotate smoothly with little friction if the bearing (mount) is straight.

With the tubes & mounts cleaned up like this the torque tubes should spin freely by
hand without lubricant.

Cheers,

Dave

www.elite583.cjb.net


Newcog@aol.com wrote:

I have more friction in one wing than the other. The root cause seems to be
a torque tube that is slightly out of round. I tried polishing the delrin
bearing blocks and using various lubricants with little improvement.. I decided
that when the complete control system is hooked up it should be OK. A little
friction might be helpful. Rebel #200.

Norm Wandke

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--
David A. Ricker
Fall River, Nova Scotia
Canada






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