stab/elevator gap seal question

[Brad[_2_]]

I've heard that on some sailplanes, putting a mylar gap seal on the
top surface can cause handling issues. Anyone care to comment on that?
I've added a mylar seal and the safety tape to the top of mine, and it
does indeed add a small step just ahead of the elevator, despite my
best attempts at hiding the fwd bump with safety tape.

Thanks,
Brad

[[email protected]]

On Jul 20, 5:53*pm, Brad > wrote:
> I've heard that on some sailplanes, putting a mylar gap seal on the
> top surface can cause handling issues. Anyone care to comment on that?
> I've added a mylar seal and the safety tape to the top of mine, and it
> does indeed add a small step just ahead of the elevator, despite my
> best attempts at hiding the fwd bump with safety tape.
>
> Thanks,
> Brad

The problem usually noted is when the safety tape or the seal comes
loose and acts like a spoiler, affecting elevator control.
It is unlikely, but not impossible for this to make the glider
uncontrollable.
Schleicher requires safety tape on elevator seals to avoid the problem
of seal lifting. Interestingly, they don't require it on flaps or
ailerons(this from '27 maint book).
That bump you have will likely act as a useful turbulator.
Commonly zig zag tape is put an inch or 2 ahead of the hinge line to
help retain flow attachment when deflected.
FWIW
UH

[JJ Sinclair[_2_]]

On Jul 20, 2:53*pm, Brad > wrote:
> I've heard that on some sailplanes, putting a mylar gap seal on the
> top surface can cause handling issues. Anyone care to comment on that?
> I've added a mylar seal and the safety tape to the top of mine, and it
> does indeed add a small step just ahead of the elevator, despite my
> best attempts at hiding the fwd bump with safety tape.
>
> Thanks,
> Brad

The problem with adding mylar and transition tape is inadequate
adhesion between the wing & mylar and/or between the mylar and
transition tape. If I remember correctly, the guy that felt his Ventus
was uncontrollable near Uvalde had waxed his ship and then added the
transition tape over fresh wax. The tape lifted and believing the ship
was uncontrollable, he bailed out! I recommend the 10mm of the mylar
that will come into contact with the stab/wing/fin be sanded with 220
dry sandpaper and the coresponding 10mm area on the stab/wing/fin
also be sanded with 220 dry sandpaper. Wipe both surfaces with acetone
just before applying the mylar. Also, wipe the area where the
transition tape will go with acetone just before applying the tape.
Hope this helps,
JJ

[Brad[_2_]]

On Jul 20, 4:13*pm, JJ Sinclair > wrote:
> On Jul 20, 2:53*pm, Brad > wrote:
>
> > I've heard that on some sailplanes, putting a mylar gap seal on the
> > top surface can cause handling issues. Anyone care to comment on that?
> > I've added a mylar seal and the safety tape to the top of mine, and it
> > does indeed add a small step just ahead of the elevator, despite my
> > best attempts at hiding the fwd bump with safety tape.
>
> > Thanks,
> > Brad
>
> The problem with adding mylar and transition tape is inadequate
> adhesion between the wing & mylar and/or between the mylar and
> transition tape. If I remember correctly, the guy that felt his Ventus
> was uncontrollable near Uvalde had waxed his ship and then added the
> transition tape over fresh wax. The tape lifted and believing the ship
> was uncontrollable, he bailed out! I recommend the 10mm of the mylar
> that will come into contact with the stab/wing/fin be sanded with 220
> dry sandpaper and the coresponding 10mm area on the stab/wing/fin
> also be sanded with 220 dry sandpaper. Wipe both surfaces with acetone
> just before applying the mylar. Also, wipe the area where the
> transition tape will go with acetone just before applying the tape.
> Hope this helps,
> JJ

Thanks Hank and JJ,

My stab was recently waxed with the WX block and seal combo. The first
application of double sticky and safety tape pulled right off, just
like you said. I did a good acetone wipe and re-applied and now have
really good stick. For the wings maybe I will try that 220
grit........might be psychologically hard to do since I just spent a
bazillion hours sanding and re-painting and sanding and polishing the
wings!

Hey JJ................you wouldn't happen to have any LS type seat
backs in the corner of your shop would you? Or...........maybe I can
find one to use as a splash.

Brad