The Murphy Builders Site

Turns out things are not as rosy as it seemed, and it's time for the next
two (4, 6...?) steps back. When I got the control column fully reinstalled
yesterday (first time in a couple years) I found way too much friction in
both aileron and elevator.

Some disassembly to isolate the aileron/roll problem shows the right wing is
fine. However, the left wing torque tube, which has always been stiff, is
worse, so much so that the flaperon, once raised, will not fall on its own.
(It's fine when disconnected from the push-pull -- no friction in the
hinges.) There's even an audible squeal coming from inside the wing,
presumably the Delrin bearings. I've read recommendations of using (only)
the Crown silicone lube in the archives but, even after cutting an access
port to reach the wing torque tube bearings, I'm not sure I could apply it
where it needs to go, or if it would do the job.

Even with both wing torque tube horns disconnected at the wing roots, there
is still too much friction in the overhead torque tubes at the torque tube
hanger, quite a bit more than I remember from when it was last hooked up to
the column two + years ago. The SS AIL-26 bearings which butt up against the
hanger are not moving, which is correct, I think...? I'm wondering if the
(captive, unreachable) connecting bolt across the hanger may be too tight?
Accommodating the angle change there has been a plague for many, I know.

The essence of difficulty in solving the roll problems is I have two places
with too much friction, and neither is easily accessible. I sure hope I can
fix both the aileron/roll issues without having to pull the left wing off.
Too much elevator friction in the control column bearings too, but at least
there is access to that.

Experience suggests this stuff will turn out to be not as difficult as I
imagine now, but it certainly is discouraging. Suggestions appreciated.

Ron
254R

Ron

Don't get too picky. What seemed like a lot of friction during build
turned out to be a non issue in flight to me. With flaperons down things
definitely stiffen up but it is still not an issue at all.

I had to sand all the large delrin bearings quite a lot to get things as
loose as I wanted. I did not find that the Crown silicone made all that
much difference but you can spray it in through a #30 rivet hole and it
is worth trying. Unfortunately it may cause paint adhesion difficulty if
it runs outside the wing.

The other thing was that my tubes were not perfectly round. Massaging
them gently in a vice seemed to help a little. Any chance you can remove
the end horn to see if the binding is from too thick of a 2" washer?
Probably not likely but we can hope. Opening the wing would be a pain.

For the control column you may find that the brackets are simply out of
alignment.

Ken

Ron

Don't get too picky. What seemed like a lot of friction during build
turned out to be a non issue in flight to me. With flaperons down things
definitely stiffen up but it is still not an issue at all.

I had to sand all the large delrin bearings quite a lot to get things as
loose as I wanted. I did not find that the Crown silicone made all that
much difference but you can spray it in through a #30 rivet hole and it
is worth trying. Unfortunately it may cause paint adhesion difficulty if
it runs outside the wing.

The other thing was that my tubes were not perfectly round. Massaging
them gently in a vice seemed to help a little. Any chance you can remove
the end horn to see if the binding is from too thick of a 2" washer?
Probably not likely but we can hope. Opening the wing would be a pain.

For the control column you may find that the brackets are simply out of
alignment.

Ken

If it makes you feel any better, my control stick bearings are fine but my
elevator horn is kind of stiff, no matter what order I torque the blocks
in. I'm thinking the floor they bolt to is so thin that they can torque it
enough to cause drag. I might consider it a poor man's auto pilot but for
you...you probably have a real one installed already!

Original Message:
-----------------
From: Ron Shannon rshannon@cruzcom.com
Date: Wed, 21 Apr 2010 12:13:22 -0700
To: rebel-builders@dcsol.com
Subject: [rebel-builders] control friction


Turns out things are not as rosy as it seemed, and it's time for the next
two (4, 6...?) steps back. When I got the control column fully reinstalled
yesterday (first time in a couple years) I found way too much friction in
both aileron and elevator.

Some disassembly to isolate the aileron/roll problem shows the right wing
is
fine. However, the left wing torque tube, which has always been stiff, is
worse, so much so that the flaperon, once raised, will not fall on its own.
(It's fine when disconnected from the push-pull -- no friction in the
hinges.) There's even an audible squeal coming from inside the wing,
presumably the Delrin bearings. I've read recommendations of using (only)
the Crown silicone lube in the archives but, even after cutting an access
port to reach the wing torque tube bearings, I'm not sure I could apply it
where it needs to go, or if it would do the job.

Even with both wing torque tube horns disconnected at the wing roots, there
is still too much friction in the overhead torque tubes at the torque tube
hanger, quite a bit more than I remember from when it was last hooked up to
the column two + years ago. The SS AIL-26 bearings which butt up against
the
hanger are not moving, which is correct, I think...? I'm wondering if the
(captive, unreachable) connecting bolt across the hanger may be too tight?
Accommodating the angle change there has been a plague for many, I know.

The essence of difficulty in solving the roll problems is I have two places
with too much friction, and neither is easily accessible. I sure hope I can
fix both the aileron/roll issues without having to pull the left wing off.
Too much elevator friction in the control column bearings too, but at least
there is access to that.

Experience suggests this stuff will turn out to be not as difficult as I
imagine now, but it certainly is discouraging. Suggestions appreciated.

Ron
254R




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I wish I was just being picky, but at present, I'd be reluctant to fly the
aileron function myself, much less have to explain the squeal to an
inspector. I've thought hooking up some electro-mechanical device to
exercise the flaperons up and down around the clock to see if it might
eventually break in. :-/

If it makes you feel any better, my control stick bearings are fine but my
elevator horn is kind of stiff, no matter what order I torque the blocks
in. I'm thinking the floor they bolt to is so thin that they can torque it
enough to cause drag. I might consider it a poor man's auto pilot but for
you...you probably have a real one installed already!

If it makes you feel any better, my control stick bearings are fine but my
elevator horn is kind of stiff, no matter what order I torque the blocks
in. I'm thinking the floor they bolt to is so thin that they can torque

enough to cause drag. I might consider it a poor man's auto pilot but for
you...you probably have a real one installed already!

Ron

Don't get too picky. What seemed like a lot of friction during build
turned out to be a non issue in flight to me. With flaperons down things
definitely stiffen up but it is still not an issue at all.

I had to sand all the large delrin bearings quite a lot to get things as
loose as I wanted. I did not find that the Crown silicone made all that
much difference but you can spray it in through a #30 rivet hole and it
is worth trying. Unfortunately it may cause paint adhesion difficulty if
it runs outside the wing.

The other thing was that my tubes were not perfectly round. Massaging
them gently in a vice seemed to help a little. Any chance you can remove
the end horn to see if the binding is from too thick of a 2" washer?
Probably not likely but we can hope. Opening the wing would be a pain.

For the control column you may find that the brackets are simply out of
alignment.

Ken

Hey Ron.

Try loosening all of the bolts that hold the delrin bearings in place and
let them find their natural location. Study what needs to be done and shim
using half washers as needed. A couple/few thin shims may take care of your
problem.

Eric
N645E

Hey Ron.

Try loosening all of the bolts that hold the delrin bearings in place and
let them find their natural location. Study what needs to be done and shim
using half washers as needed. A couple/few thin shims may take care of your
problem.

Eric
N645E

Eric, that may help with the right control column (elevator) bearing,
where
I have put in floor brackets to make the control column removable, but
friction in the left wing internal torque tube bearings is the main
problem,
and of course, I can't get at them without cutting some significant holes.
It may come to that eventually, but I'll try to get some of the Crown
silicone lube on them, and anything else I can think of, before doing
major
surgery.

I have now measured aileron (roll) friction as follows, in both cases
using
a digital fishing gauge pulling at the top of the (shortened) stick with
no
grip, at approx. 12.5" above the stick pivot:

1) With both wings disconnected at the wing root torque tube horns,
friction
in just the inside torque tube setup averages roughly 1 lb. 2 oz., and
increases slightly out near the stops. There is no appreciable friction in
the inside push pull tube bearings or bell cranks, so the great majority
of
that is probably at the hanger bolt and possibly a little in the guide
pin/bolts, which are still inserted in the wings, of course. Not good.

2) With both wings connected via their respective wing root torque tube
horns, the friction averages about 3 lb. 6 oz. for right aileron (left
aileron falling) and about 4 lb. for left aileron (left aileron rising).

These numbers are probably not real precise, but are certainly in the ball
park of repeatable scientific data, and certainly not good. The "squeal"
from the left wing torque tube bearings seems to come randomly from either
or both bearings, though always on the flaperon down motion and none on
the
upward motion.

Again, to repeat, there is no significant friction in the right wing, and
the left wing flaperon hinges are free and quiet when tested alone with
the
flaperon push pull disconnected, so the left flaperon hinges are not
contributing. The left wing torque tube bearings are stiff by themselves,
i.e., when disconnected from the fuse, etc. The spacers at the wing root
horns seem to fit well, so I don't think they are contributing to any
binding by spreading the horns apart or pulling them together out of their
natural positions.

I'm going to proceed incrementally, trying to lube places I can get to
first, like the guide pin bolts and hanger bolt -- to the extent I can get
something in the latter. Suggestions? Then will try to find some of the
Crown silicone lube and find some way(s) to get it to the left wing torque
tube bearings.

Does anyone know where I can get single cans of the Crown silicone lube?
All
I've found so far are 12-can case lots, at $70-80 ea. Thanks.

Ron
254R


On Wed, Apr 21, 2010 at 9:40 PM, Eric Fogelin <elist@whidbey.com> wrote:

Hey Ron.

Try loosening all of the bolts that hold the delrin bearings in place and
let them find their natural location. Study what needs to be done and
shim
using half washers as needed. A couple/few thin shims may take care of
your
problem.

Eric
N645E

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Ron
I had a problem with one wing. I loosened all the bolts holding the delrin
bearings with no apparent effect. I didn't have any crown lubricant but I
had a can of Rustcheck. One squirt and no more friction.
Dale

Eric, that may help with the right control column (elevator) bearing,
where
I have put in floor brackets to make the control column removable, but
friction in the left wing internal torque tube bearings is the main
problem,
and of course, I can't get at them without cutting some significant holes.
It may come to that eventually, but I'll try to get some of the Crown
silicone lube on them, and anything else I can think of, before doing
major
surgery.

I have now measured aileron (roll) friction as follows, in both cases
using
a digital fishing gauge pulling at the top of the (shortened) stick with
no
grip, at approx. 12.5" above the stick pivot:

1) With both wings disconnected at the wing root torque tube horns,
friction
in just the inside torque tube setup averages roughly 1 lb. 2 oz., and
increases slightly out near the stops. There is no appreciable friction in
the inside push pull tube bearings or bell cranks, so the great majority
of
that is probably at the hanger bolt and possibly a little in the guide
pin/bolts, which are still inserted in the wings, of course. Not good.

2) With both wings connected via their respective wing root torque tube
horns, the friction averages about 3 lb. 6 oz. for right aileron (left
aileron falling) and about 4 lb. for left aileron (left aileron rising).

These numbers are probably not real precise, but are certainly in the ball
park of repeatable scientific data, and certainly not good. The "squeal"
from the left wing torque tube bearings seems to come randomly from either
or both bearings, though always on the flaperon down motion and none on
the
upward motion.

Again, to repeat, there is no significant friction in the right wing, and
the left wing flaperon hinges are free and quiet when tested alone with
the
flaperon push pull disconnected, so the left flaperon hinges are not
contributing. The left wing torque tube bearings are stiff by themselves,
i.e., when disconnected from the fuse, etc. The spacers at the wing root
horns seem to fit well, so I don't think they are contributing to any
binding by spreading the horns apart or pulling them together out of their
natural positions.

I'm going to proceed incrementally, trying to lube places I can get to
first, like the guide pin bolts and hanger bolt -- to the extent I can get
something in the latter. Suggestions? Then will try to find some of the
Crown silicone lube and find some way(s) to get it to the left wing torque
tube bearings.

Does anyone know where I can get single cans of the Crown silicone lube?
All
I've found so far are 12-can case lots, at $70-80 ea. Thanks.

Ron
254R


On Wed, Apr 21, 2010 at 9:40 PM, Eric Fogelin <elist@whidbey.com> wrote:

Hey Ron.

Try loosening all of the bolts that hold the delrin bearings in place and
let them find their natural location. Study what needs to be done and
shim
using half washers as needed. A couple/few thin shims may take care of
your
problem.

Eric
N645E

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