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[rebel-builders] Rebel control stiffness in cold weather

Posted: Sun Feb 19, 2012 5:37 pm
by Ken
I've seen this a few times on other aircraft especially after heavy rain
or poorly lubed controls. Condensation can do it. I fly all winter here
and have never seen it on my rebel though. I have noticed that the
elevator cable tension reduces when very cold since the aluminum
fuselage shrinks more than the steel cables. Should the elevator freeze
solid, note that the trim tab will work in reverse. Wayne (one of our
resident plastic authorities) says to use 'Crown' brand silicone on the
delrin. He has posted that all the other products including other brands
of silicone caused issues when used in his business. I did not think
that delrin absorbed as much moisture as nylon?? Pulleys like to freeze
up as well if not full of dry grease.
Ken

Walter Klatt wrote:
I did some high flying today in the mountains, where the OAT was down to -6
C for an extended time. I noticed a slight stiffness in my controls, both
elevator and flaperons. I have never noticed that in the past. Hard to
believe, but have probably never flown in that cold before. Normally, don't
go up there except in the summer when I am doing XC trips, and the temps are
still always above freezing, even up at 10,000 feet. And in the winter, I
usually only fly in good weather, when again the temps are well above
freezing. So this may well have been the coldest weather my Rebel has seen.
When I came back down to sea level and warm temps (+14 C), the controls were
back to normal.



Just wondering about you guys out east and in the interior of BC. You must
do a lot of flying in the cold. Is this normal to feel some stiffness in the
controls in cold weather?



Does the delrin absorb some moisture and then freeze and expand in cold
weather? I do not lubricate these joints, but was thinking of trying some
Boeshield on them. It is supposed to displace moisture, and is used in
commercial aircraft, and is also popular in the marine industry because it
prevents corrosion. Is there any other lubricant that can be used with
delrin?



Walter





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[rebel-builders] Rebel control stiffness in cold weather

Posted: Sun Feb 19, 2012 5:37 pm
by Walter Klatt
Thanks, Ken, will have to check out that Crown stuff. Have been researching
on the internet to see what is compatible with delrin. They say not to use
oil based products. However, one popular product, Tri-Flow is said to be OK
to use with delrin.

I am guessing that the delrin must have absorbed moisture over time. I do
live in a damp climate. And when it was exposed to freezing temps, it
swelled a bit. So was thinking of finding something that can displace water,
and maybe dry it out again.

Worked as a good auto pilot, though. The controls just stayed where I set
them...

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ken
Sent: October 12, 2009 5:02 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Rebel control stiffness in cold weather

I've seen this a few times on other aircraft especially after heavy rain
or poorly lubed controls. Condensation can do it. I fly all winter here
and have never seen it on my rebel though. I have noticed that the
elevator cable tension reduces when very cold since the aluminum
fuselage shrinks more than the steel cables. Should the elevator freeze
solid, note that the trim tab will work in reverse. Wayne (one of our
resident plastic authorities) says to use 'Crown' brand silicone on the
delrin. He has posted that all the other products including other brands
of silicone caused issues when used in his business. I did not think
that delrin absorbed as much moisture as nylon?? Pulleys like to freeze
up as well if not full of dry grease.
Ken

Walter Klatt wrote:
I did some high flying today in the mountains, where the OAT was down to
-6
C for an extended time. I noticed a slight stiffness in my controls, both
elevator and flaperons. I have never noticed that in the past. Hard to
believe, but have probably never flown in that cold before. Normally,
don't
go up there except in the summer when I am doing XC trips, and the temps
are
still always above freezing, even up at 10,000 feet. And in the winter, I
usually only fly in good weather, when again the temps are well above
freezing. So this may well have been the coldest weather my Rebel has
seen.
When I came back down to sea level and warm temps (+14 C), the controls
were
back to normal.



Just wondering about you guys out east and in the interior of BC. You must
do a lot of flying in the cold. Is this normal to feel some stiffness in
the
controls in cold weather?



Does the delrin absorb some moisture and then freeze and expand in cold
weather? I do not lubricate these joints, but was thinking of trying some
Boeshield on them. It is supposed to displace moisture, and is used in
commercial aircraft, and is also popular in the marine industry because it
prevents corrosion. Is there any other lubricant that can be used with
delrin?



Walter





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[rebel-builders] Rebel control stiffness in cold weather

Posted: Sun Feb 19, 2012 5:37 pm
by Garry Wright
Have never noticed a difference in FOKM.

G

Walter Klatt wrote:
I did some high flying today in the mountains, where the OAT was down to -6
C for an extended time. I noticed a slight stiffness in my controls, both
elevator and flaperons. I have never noticed that in the past. Hard to
believe, but have probably never flown in that cold before. Normally, don't
go up there except in the summer when I am doing XC trips, and the temps are
still always above freezing, even up at 10,000 feet. And in the winter, I
usually only fly in good weather, when again the temps are well above
freezing. So this may well have been the coldest weather my Rebel has seen.
When I came back down to sea level and warm temps (+14 C), the controls were
back to normal.



Just wondering about you guys out east and in the interior of BC. You must
do a lot of flying in the cold. Is this normal to feel some stiffness in the
controls in cold weather?



Does the delrin absorb some moisture and then freeze and expand in cold
weather? I do not lubricate these joints, but was thinking of trying some
Boeshield on them. It is supposed to displace moisture, and is used in
commercial aircraft, and is also popular in the marine industry because it
prevents corrosion. Is there any other lubricant that can be used with
delrin?



Walter





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[rebel-builders] Rebel control stiffness in cold weather

Posted: Sun Feb 19, 2012 5:37 pm
by David A. Ricker
Might just be that the thermal coefficient of expansion (TCE) (or
contraction in the cold...) is enough to tighten up the clearances on
the bushings the torque tubes run in enough to make them feel tighter.
The Delrin would have about 4x the TCE of aluminum.

Don't know about the fit in your plane but in our Elite project it took
a lot of effort to make the aileron torque tubes run freely and not bind
so if they were a bit tight anyway and cooled down it might bind and add
feel to the control stiffness.

FWIW, water absorption over 24 hours is about 1/4 the value for Nylon 6.

Dave


Walter Klatt wrote:
I did some high flying today in the mountains, where the OAT was down to -6
C for an extended time. I noticed a slight stiffness in my controls, both
elevator and flaperons. I have never noticed that in the past. Hard to
believe, but have probably never flown in that cold before. Normally, don't
go up there except in the summer when I am doing XC trips, and the temps are
still always above freezing, even up at 10,000 feet. And in the winter, I
usually only fly in good weather, when again the temps are well above
freezing. So this may well have been the coldest weather my Rebel has seen.
When I came back down to sea level and warm temps (+14 C), the controls were
back to normal.



Just wondering about you guys out east and in the interior of BC. You must
do a lot of flying in the cold. Is this normal to feel some stiffness in the
controls in cold weather?



Does the delrin absorb some moisture and then freeze and expand in cold
weather? I do not lubricate these joints, but was thinking of trying some
Boeshield on them. It is supposed to displace moisture, and is used in
commercial aircraft, and is also popular in the marine industry because it
prevents corrosion. Is there any other lubricant that can be used with
delrin?



Walter





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[rebel-builders] Rebel control stiffness in cold weather

Posted: Sun Feb 19, 2012 5:37 pm
by henri monnin
Hi David, I flew my Rebel on skies last