Sealing an ASW 28 canopy

[Bob Caldwell]

After seeing the thread about the PIK canopies I wanted
to ask if anyone had taken any extra ordinary steps
to seal an ASW canopy. To date all I have done is
to put some sticky back foam at the front near the
demist vent. It is pretty good but I suspect it can
be better. I have heard that it helps to run the same
foam all way around the fuse in the depression along
the canopy opening. Thoughts????

Bob

[bumper]

The Schleicher canopy fits tightly with a convoluted type interface. Before
adding any weather-strip or seal, try this experiment to see if there's any
room to do so.

Take very small bits of modeling clay (plasticene) and place them on the
sealing surfaces. Close and then re-open the canopy to test the clearance.

On my 26e, there's no room at all for any weather-strip. In fact, the little
bits of clay used in the above test lifted the canopy ever so slightly above
the fuselage at the forward lip.

all the best,

bumper
"Bob Caldwell" > wrote in message
...
> After seeing the thread about the PIK canopies I wanted
> to ask if anyone had taken any extra ordinary steps
> to seal an ASW canopy. To date all I have done is
> to put some sticky back foam at the front near the
> demist vent. It is pretty good but I suspect it can
> be better. I have heard that it helps to run the same
> foam all way around the fuse in the depression along
> the canopy opening. Thoughts????
>
> Bob
>
>

[John Sinclair]

I have had success in finding the tight spots in my
canopy/ fuselage fit by placing a strip of paper in
the seal area and then closing the canopy. Free sliding
paper = OK, dragging paper = tight spot. I sand down
the tight spots then put 3/16 X 3/8th open cell foan
all the way around. Good for a season or two, but the
shearing action at front and rear will eventually destroy
it and so you get to do it again.
JJ

At 05:48 08 August 2005, Bumper wrote:
>The Schleicher canopy fits tightly with a convoluted
>type interface. Before
>adding any weather-strip or seal, try this experiment
>to see if there's any
>room to do so.
>
>Take very small bits of modeling clay (plasticene)
>and place them on the
>sealing surfaces. Close and then re-open the canopy
>to test the clearance.
>
>On my 26e, there's no room at all for any weather-strip.
>In fact, the little
>bits of clay used in the above test lifted the canopy
>ever so slightly above
>the fuselage at the forward lip.
>
>all the best,
>
>bumper
>'Bob Caldwell' wrote in message
...
>> After seeing the thread about the PIK canopies I wanted
>> to ask if anyone had taken any extra ordinary steps
>> to seal an ASW canopy. To date all I have done is
>> to put some sticky back foam at the front near the
>> demist vent. It is pretty good but I suspect it can
>> be better. I have heard that it helps to run the
>>same
>> foam all way around the fuse in the depression along
>> the canopy opening. Thoughts????
>>
>> Bob
>>
>>
>
>
>

[Udo Rumpf]

Based on my experience, a negative pressure inside the cockpit will do the
trick.
This is base on having built two gliders and own an ASW24.
Providing the perimeter fit of the canopy is good, no edges of the
canopy frame are sticking out that is all that would be needed.
Case in point. When I picked up my ASW24 the canopy frame was covered
with foam tape and the front and rear edges were raise. I removed the
material made sure the canopy frame got back it's original fit.
Then I improved the exit ventilation at the tail. The Cockpit is now quite,
plus I stay cooler, due to better ventilation flow
Regards
Udo

[Eric Greenwell]

Bob Caldwell wrote:
> After seeing the thread about the PIK canopies I wanted
> to ask if anyone had taken any extra ordinary steps
> to seal an ASW canopy. To date all I have done is
> to put some sticky back foam at the front near the
> demist vent. It is pretty good but I suspect it can
> be better. I have heard that it helps to run the same
> foam all way around the fuse in the depression along
> the canopy opening. Thoughts????

Do you have a specific problem you are trying to cure, such as a whistle
from the back edge or cold air leaking in right at the front? Those are
places where my ASH 26 E has problems, generally only in winter flying.

The rear is easily solved by putting about 2 feet of thin open cell foam
weather-stripping on the canopy frame, usually renewing it in the Fall.

The front is much more difficult, due to the shearing action during
closing and canopy shrinkage in the winter. Most of the cold air on my
glider actually comes in the front vent, which is not fully sealed by
the vent flap. Taping over about 50% of the vent area and putting some
soft foam on the flapper valve to seal against the remaining area makes
a big difference. Again, I do this each Fall, removing the tape in the
late spring.

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Eric Greenwell
Washington State
USA

[bumper]

Udo,

Can you provide details of what you did to improve exhaust ventilation at
the tail?

thanks,

bumper
"Udo Rumpf" > wrote in message
...
> Based on my experience, a negative pressure inside the cockpit will do
> the
> trick.
> This is base on having built two gliders and own an ASW24.
> Providing the perimeter fit of the canopy is good, no edges of the
> canopy frame are sticking out that is all that would be needed.
> Case in point. When I picked up my ASW24 the canopy frame was covered
> with foam tape and the front and rear edges were raise. I removed the
> material made sure the canopy frame got back it's original fit.
> Then I improved the exit ventilation at the tail. The Cockpit is now
> quite,
> plus I stay cooler, due to better ventilation flow
> Regards
> Udo
>
>
>
>

[Udo Rumpf]

Bumper,
When I discovered no air was getting out through any of the tail assembly
in my 24, I simply made a 11/2" hole over the drain hole in the tail wheel
fender. Ahead of the fender is a bulk head that has a nice large opening.
The standard tail wheel leaves enough
clearance around the fender frame to allow air to be sucked out.
The only disadvantage would be if you land in a muddy field.
That is a trade off I am willing to make.
Regards
Udo

[bumper]

Udo,

Interesting, I'll have a look at my ASH26E.

Might it also be possible to include a check-valve sort of flap that would
allow exhaust but would prevent dirt from the tailwheel from entering the
tail boom?

bumper

"Udo Rumpf" > wrote in message
...
> Bumper,
> When I discovered no air was getting out through any of the tail assembly
> in my 24, I simply made a 11/2" hole over the drain hole in the tail
> wheel
> fender. Ahead of the fender is a bulk head that has a nice large opening.
> The standard tail wheel leaves enough
> clearance around the fender frame to allow air to be sucked out.
> The only disadvantage would be if you land in a muddy field.
> That is a trade off I am willing to make.
> Regards
> Udo
>
>
>
>

[Eric Greenwell]

Udo Rumpf wrote:
> Bumper,
> When I discovered no air was getting out through any of the tail assembly
> in my 24, I simply made a 11/2" hole over the drain hole in the tail wheel
> fender. Ahead of the fender is a bulk head that has a nice large opening.
> The standard tail wheel leaves enough
> clearance around the fender frame to allow air to be sucked out.
> The only disadvantage would be if you land in a muddy field.
> That is a trade off I am willing to make.

Wasn't air able to exit through the rudder horn and cable openings?


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Eric Greenwell
Washington State
USA

[Udo Rumpf]

> Wasn't air able to exit through the rudder horn and cable openings?

> Eric Greenwell
> Washington State
> USA

It appears the opening is plugged by excess assembly epoxy.


Udo

[Udo Rumpf]

> Might it also be possible to include a check-valve sort of flap that would
> allow exhaust but would prevent dirt from the tailwheel from entering the
> tail boom?
>
> bumper

I have given it some thought.
Installing a brush wiper at the front and rear to clean the rolling face.
of the wheel. Also a smaller wheel would allow a secondary fender.
The original wheel is about ~7". A 6" wheel would be large enough.
That would allow room for some sort of baffle.
Udo

[Eric Greenwell]

bumper wrote:
> Udo,
>
> Interesting, I'll have a look at my ASH26E.
>
> Might it also be possible to include a check-valve sort of flap that would
> allow exhaust but would prevent dirt from the tailwheel from entering the
> tail boom?

There appears to be plenty of exit area in the tail of my ASH 26 E
through the rudder horn fairings and openings in tail bulkheads. I
suspect restrictions, if any, are due to the engine box, or even just
stuffing the baggage compartment full with a down jacket, as I do.

Even so, my 26 has too much ventilation flow, so I've blocked off the
left side duct in the nose. I've heard of at least one pilot of an ASW
27 that made the nose intake hole smaller to achieve the same thing. My
guess is Udo's problem is specific to his glider, and not ASW 24 and
later models in general.

Craig Shaber had an exit (reverse NACA duct) installed in his ASH 26 on
the right side of the fuselage near the wheel doors, but I don't recall
if he thought it improved anything. Other pilots have done this to
various gliders, rather than trying to get the air all the way to the tail.

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Eric Greenwell
Washington State
USA

[Greg Arnold]

Eric Greenwell wrote:

>
> Even so, my 26 has too much ventilation flow, so I've blocked off the
> left side duct in the nose. I've heard of at least one pilot of an ASW
> 27 that made the nose intake hole smaller to achieve the same thing. My
> guess is Udo's problem is specific to his glider, and not ASW 24 and
> later models in general.

I would agree -- when I had a '24, I thought the ventilation was very good.

[CHo]

why not ask AS sending an email?
and you sure will get an answer
I always get a reply
:-) Chris CH
ASW27


"Udo Rumpf" > wrote in message
...
>> Wasn't air able to exit through the rudder horn and cable openings?
>
>> Eric Greenwell
>> Washington State
>> USA
>
> It appears the opening is plugged by excess assembly epoxy.
>
>
> Udo