Re-curving mylar on a glider

My top surface mylar seems to have lost some of it's curvature, because
it doesn't quite touch the aileron and flaps when they are in positive
positions. Does anyone know a way to put the curve back into the mylar
without removing it? It's so well adhered and smoothly installed, I'd
like to leave it on if at all possible, but I think it may be degrading
my climb while thermalling. The mylar is almost 12 years old.

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Eric, I would think that mylar that is 12 years old would have lost its
flexibility. It gets pushed up with upward aerleron or negative flap
settings and tends to stay there or very slowly flex back down to "neutral".
So going to positve settings will be difficult.

I don't know how you could put "life" back into the old plastic, but I would
be interested to hear.

BT

"Eric Greenwell" wrote in message
news:JfBYg.3919$5v5.3761@trndny08...
My top surface mylar seems to have lost some of it's curvature, because it
doesn't quite touch the aileron and flaps when they are in positive
positions. Does anyone know a way to put the curve back into the mylar
without removing it? It's so well adhered and smoothly installed, I'd like
to leave it on if at all possible, but I think it may be degrading my
climb while thermalling. The mylar is almost 12 years old.

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Eric,

The Mylar is originally curved by passing the strip through a set of curved,
heated rollers. Complicated enough, all by itself (g) . . . to do the chore
with the Mylars still attached to the plane is beyond my admittedly limited
experience.

bumper

"Eric Greenwell" wrote in message
news:JfBYg.3919$5v5.3761@trndny08...
My top surface mylar seems to have lost some of it's curvature, because it
doesn't quite touch the aileron and flaps when they are in positive
positions. Does anyone know a way to put the curve back into the mylar
without removing it? It's so well adhered and smoothly installed, I'd like
to leave it on if at all possible, but I think it may be degrading my
climb while thermalling. The mylar is almost 12 years old.

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

After 12 years the adhesive tape used to hold the seal in place has
deteriorated to the point that your original seal installation may be
unsafe. I've seen approx. 10 years seal installations where the adhesive is
about to release the seal. A small tug on the seal itself and the seal may
slip away from the adhesive. A lost seal inflight is something we all must
avoid at all cost. Control surfaces can stop working after a total or
partial separation.

I think 7-8 years is max any seal installation should be trusted because of
the potential loss of adhesion.
Also,the seal itself has deteriated from UV ( why it has lost the heat
induced curvature) and although is safe with regard to its physical
intregrity, new ones would look a whole lot nicer and a new seal with new
adhesive, a lot safer.

I think seal installations on gliders can be potentially the weakest link in
our sport. A failed seal can kill you and we should all be aware of time
limiations.

This winter I am reprofiling my wings and quess what, my seals will be
replaced after 5 years.


bob fidler
"Eric Greenwell" wrote in message
news:JfBYg.3919$5v5.3761@trndny08...
My top surface mylar seems to have lost some of it's curvature, because it
doesn't quite touch the aileron and flaps when they are in positive
positions. Does anyone know a way to put the curve back into the mylar
without removing it? It's so well adhered and smoothly installed, I'd like
to leave it on if at all possible, but I think it may be degrading my
climb while thermalling. The mylar is almost 12 years old.

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Bob:

Are you doing the reprofiling yourself or having it done?

Ray Warshaw
1LK

Bob Fidler wrote:
After 12 years the adhesive tape used to hold the seal in place has
deteriorated to the point that your original seal installation may be
unsafe. I've seen approx. 10 years seal installations where the adhesive is
about to release the seal. A small tug on the seal itself and the seal may
slip away from the adhesive. A lost seal inflight is something we all must
avoid at all cost. Control surfaces can stop working after a total or
partial separation.

I think 7-8 years is max any seal installation should be trusted because of
the potential loss of adhesion.
Also,the seal itself has deteriated from UV ( why it has lost the heat
induced curvature) and although is safe with regard to its physical
intregrity, new ones would look a whole lot nicer and a new seal with new
adhesive, a lot safer.

I think seal installations on gliders can be potentially the weakest link in
our sport. A failed seal can kill you and we should all be aware of time
limiations.

This winter I am reprofiling my wings and quess what, my seals will be
replaced after 5 years.


bob fidler
"Eric Greenwell" wrote in message
news:JfBYg.3919$5v5.3761@trndny08...
My top surface mylar seems to have lost some of it's curvature, because it
doesn't quite touch the aileron and flaps when they are in positive
positions. Does anyone know a way to put the curve back into the mylar
without removing it? It's so well adhered and smoothly installed, I'd like
to leave it on if at all possible, but I think it may be degrading my
climb while thermalling. The mylar is almost 12 years old.

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Bob Fidler wrote:
After 12 years the adhesive tape used to hold the seal in place has
deteriorated to the point that your original seal installation may be
unsafe. I've seen approx. 10 years seal installations where the adhesive is
about to release the seal. A small tug on the seal itself and the seal may
slip away from the adhesive. A lost seal inflight is something we all must
avoid at all cost. Control surfaces can stop working after a total or
partial separation.

Inspecting the seal fairing tape (leading edge of seal) before every
flight and replacing it once a year goes a long way towards keeping
seals safe. Agree though that the seal adhesive is life limited,
particularly in Arizona where it dries up.

I know of no way to restore the seal curvature but I did learn along
time ago not to tie the glider out with the elevator up as the seal
takes a set.

Andy

bumper wrote:


The Mylar is originally curved by passing the strip through a set of curved,
heated rollers. Complicated enough, all by itself (g) . . . to do the chore
with the Mylars still attached to the plane is beyond my admittedly limited
experience.

I am interested in finding out more about this roller process?
Any pictures or detailed descriptions available?
For my projects in the past, I successfully made my own curved Mylar
strips in 5ft sections

Udo

Bob Fidler wrote:
A lost seal inflight is something we all must
avoid at all cost. Control surfaces can stop working after a total or
partial separation.

Bob, I have heard this before, but I dont understand where the problem
would be (Other than the leading edge of the seal lifting ahead of the
control surface).Didnt most of these ships come from the factory
without seals, I know mine did.I have read stories on the Yahoo user
groups for the ASW20 about seals departing the plane inflight and other
than being a bit distresing, didnt cause any control issues.I have
flown ships with and without seals and I didnt notice any difference
..What have you encountered?

"Eric Greenwell" wrote in message
My top surface mylar seems to have lost some of it's curvature, because it
doesn't quite touch the aileron and flaps when they are in positive
positions. Does anyone know a way to put the curve back into the mylar
without removing it? It's so well adhered and smoothly installed, I'd like
to leave it on if at all possible, but I think it may be degrading my
climb while thermalling. The mylar is almost 12 years old.

Eric, I replace my seals on a much more frequent basis, I would say
that you have definetly gotten your moneys worth at 12 years.I dont
know if this is commonly accepted or not but I know of some pilots who
just wait till the seals make noise at high speeds before they replace
them.Not to worry, you can make your own seals at home in a few
evenings and they are rather inexpensive.
K Urban

About a year ago, one of my soaring buddies had a elevator seal become
separtated from the horizontal approx. 1/2 the length of the elevator behind
the safety tape. He had no idea of exactly what was his problem other than
is elevator had a small feedback of a minor flutter and it was almost
ineffective. I believe the safety tape remained intact but the major portion
of the seal behind the safety tape was raised into the slipstream. His
elevator lost the major part of its control and for a time he thought
bailing out may be an option. He did land safely but the experience was one
he would have rather avoided. I was flying that day and recall his
distressed comments while trying to deal with the issue. The point is: this
could have been avoided with understanding these seals need to be maintained
and time can deteriorate the adhesion properties of the seal.

The older the seals are, the more dangerous they become.

bob fidler
"KM" wrote in message
ps.com...

Bob Fidler wrote:
A lost seal inflight is something we all must
avoid at all cost. Control surfaces can stop working after a total or
partial separation.

Bob, I have heard this before, but I dont understand where the problem
would be (Other than the leading edge of the seal lifting ahead of the
control surface).Didnt most of these ships come from the factory
without seals, I know mine did.I have read stories on the Yahoo user
groups for the ASW20 about seals departing the plane inflight and other
than being a bit distresing, didnt cause any control issues.I have
flown ships with and without seals and I didnt notice any difference
.What have you encountered?

"Eric Greenwell" wrote in message
My top surface mylar seems to have lost some of it's curvature, because
it
doesn't quite touch the aileron and flaps when they are in positive
positions. Does anyone know a way to put the curve back into the mylar
without removing it? It's so well adhered and smoothly installed, I'd
like
to leave it on if at all possible, but I think it may be degrading my
climb while thermalling. The mylar is almost 12 years old.

Eric, I replace my seals on a much more frequent basis, I would say
that you have definetly gotten your moneys worth at 12 years.I dont
know if this is commonly accepted or not but I know of some pilots who
just wait till the seals make noise at high speeds before they replace
them.Not to worry, you can make your own seals at home in a few
evenings and they are rather inexpensive.
K Urban

IThere have been several accidents resulting from seals coming loose,
and causing a "spoiler" effect on the control surface. One is here

http://www.ntsb.gov/ntsb/brief.asp?e...07X04237&key=1

I think there was at least one Grob crash in Germany. Some manuals
specifically state there has to be tape on the elevator.

So, yes, this is a serious issue. Since hearing of the first crash,
"check condition of mylar and hold-down tape" has been part of my
critical assembly check.

John Cochrane BB