Aluminum top Cobra trailer leaks - how frequent?

A few people told me that their Cobra trailers with aluminum tops
developed leaks. I wonder how frequent this problem is. Obviously
aluminum top is nice to keep it looking good, but one of the the
purposes of a trailer is too keep the glider inside dry. In New
England we sometimes get 4 inches of rain in a day. Thx, AK

I have a 1983 Cobra and a 2000 Cobra, both with aluminum tops. Neither
has any leaks, for what it's worth.

-John

On Mar 29, 6:59 am, AK wrote:
A few people told me that their Cobra trailers with aluminum tops
developed leaks. I wonder how frequent this problem is. Obviously
aluminum top is nice to keep it looking good, but one of the the
purposes of a trailer is too keep the glider inside dry. In New
England we sometimes get 4 inches of rain in a day. Thx, AK

I have a 2001 aluminum Cobra. No leaks.
Guy

On Mar 29, 6:59*am, AK wrote:
A few people told me that their Cobra trailers with aluminum tops
developed leaks. I wonder how frequent this problem is. Obviously
aluminum top is nice to keep it looking good, but one of the the
purposes of a trailer is too keep the glider inside dry. In New
England we sometimes get 4 inches of rain in a day. Thx, AK

I have an aluminum 2001 cobra, and have had several leaks. The major
problem is the seams around the tail doghouse. Artful application of
silicone sealer has stopped the leaks, but it took several tries. I'd
be curious to hear of better fixes. Obviously, drilling out all the
pop rivets and then reassembling it with new sealer would be best, but
that is a huge pain we'd all rather avoid.

Next time, I'm getting the fiberglass top.

John Cochrane

On Mar 29, 9:24*am, John Cochrane
wrote:
On Mar 29, 6:59*am, AK wrote:

A few people told me that their Cobra trailers with aluminum tops
developed leaks. I wonder how frequent this problem is. Obviously
aluminum top is nice to keep it looking good, but one of the the
purposes of a trailer is too keep the glider inside dry. In New
England we sometimes get 4 inches of rain in a day. Thx, AK

I have an aluminum 2001 cobra, and have had several leaks. The major
problem is the seams around the tail doghouse. Artful application of
silicone sealer has stopped the leaks, but it took several tries. *I'd
be curious to hear of better fixes. Obviously, drilling out all the
pop rivets and then reassembling it with new sealer would be best, but
that is a huge pain we'd all rather avoid.

Next time, I'm getting the fiberglass top.

John Cochrane

Well, even the fiberglass top can leak a little. When I put my plane
together the other day
there was a string of mud spots on the leading edge of my wings near
the root end. Those
parts of my wings are under the passive vents installed in the
trailer, so I'm getting some
moisture in through or around those vents.

-- Matt

On Mar 29, 6:24*am, John Cochrane
wrote:
On Mar 29, 6:59*am, AK wrote:

A few people told me that their Cobra trailers with aluminum tops
developed leaks. I wonder how frequent this problem is. Obviously
aluminum top is nice to keep it looking good, but one of the the
purposes of a trailer is too keep the glider inside dry. In New
England we sometimes get 4 inches of rain in a day. Thx, AK

I have an aluminum 2001 cobra, and have had several leaks. The major
problem is the seams around the tail doghouse. Artful application of
silicone sealer has stopped the leaks, but it took several tries. *I'd
be curious to hear of better fixes. Obviously, drilling out all the
pop rivets and then reassembling it with new sealer would be best, but
that is a huge pain we'd all rather avoid.

Next time, I'm getting the fiberglass top.

John Cochrane

Don't laugh . . . but, Capt. Tolley's Creeping Crack Cure (really!) is
some amazing stuff. See: http://www.captaintolley.com/

It's water thin, so wicks in using capillary action, dries clear so no
mess. Fairly benign stuff but sure works well. I once did a test to
see if it would also seal fuel. To make the test as difficult, I
drilled a small hole in the bottom of a plastic polyethylene bottle,
and then made a one inch cut from the hole with a razor. Applied a
drop of Tolley's and waited 24 hours. Thin filled the bottle with
100LL avgas . . . no leaks after several days. Did the same with
MoGas, no leaks. Since the stuff is designed to seal water leaks in
small voids, I'm real sure it'll fix your trailer leak in the overlap
seams.

bumper
Minden, NV
On a non-related note . . . just 2 days left to order MKIV and QV at
old prices.

On Mar 29, 8:59*am, mattm wrote:
On Mar 29, 9:24*am, John Cochrane
wrote:



On Mar 29, 6:59*am, AK wrote:

A few people told me that their Cobra trailers with aluminum tops
developed leaks. I wonder how frequent this problem is. Obviously
aluminum top is nice to keep it looking good, but one of the the
purposes of a trailer is too keep the glider inside dry. In New
England we sometimes get 4 inches of rain in a day. Thx, AK

I have an aluminum 2001 cobra, and have had several leaks. The major
problem is the seams around the tail doghouse. Artful application of
silicone sealer has stopped the leaks, but it took several tries. *I'd
be curious to hear of better fixes. Obviously, drilling out all the
pop rivets and then reassembling it with new sealer would be best, but
that is a huge pain we'd all rather avoid.

Next time, I'm getting the fiberglass top.

John Cochrane

Well, even the fiberglass top can leak a little. *When I put my plane
together the other day
there was a string of mud spots on the leading edge of my wings near
the root end. *Those
parts of my wings are under the passive vents installed in the
trailer, so I'm getting some
moisture in through or around those vents.

-- Matt

This might also come from the even worse problem of metal-top (all)
trailers -- condensation.

Any day the 5 am temperature goes below the dewpoint (most days in the
spring), the glider inside the trailer will be sopping wet. It dries
out by noon if you have a good vent. But your beloved glider is
spending 4-5 hours a day covered in water.

I've attacked this successfully with a dehumidifier, but that needs
power which we don't have at my current airport.

The new insulated tops might help. Has anyone noticed a big
difference?

John Cochrane

On Mar 29, 1:50*pm, John Cochrane
wrote:
On Mar 29, 8:59*am, mattm wrote:



On Mar 29, 9:24*am, John Cochrane
wrote:

On Mar 29, 6:59*am, AK wrote:

A few people told me that their Cobra trailers with aluminum tops
developed leaks. I wonder how frequent this problem is. Obviously
aluminum top is nice to keep it looking good, but one of the the
purposes of a trailer is too keep the glider inside dry. In New
England we sometimes get 4 inches of rain in a day. Thx, AK

I have an aluminum 2001 cobra, and have had several leaks. The major
problem is the seams around the tail doghouse. Artful application of
silicone sealer has stopped the leaks, but it took several tries. *I'd
be curious to hear of better fixes. Obviously, drilling out all the
pop rivets and then reassembling it with new sealer would be best, but
that is a huge pain we'd all rather avoid.

Next time, I'm getting the fiberglass top.

John Cochrane

Well, even the fiberglass top can leak a little. *When I put my plane
together the other day
there was a string of mud spots on the leading edge of my wings near
the root end. *Those
parts of my wings are under the passive vents installed in the
trailer, so I'm getting some
moisture in through or around those vents.

-- Matt

This might also come from the even worse problem of metal-top (all)
trailers -- condensation.

Any day the 5 am temperature goes below the dewpoint (most days in the
spring), the glider inside the trailer will be sopping wet. It dries
out by noon if you have a good vent. But your beloved glider is
spending 4-5 hours a day covered in water.

I've attacked this successfully with a dehumidifier, but that needs
power which we don't have at my current airport.

The new insulated tops might help. Has anyone noticed a big
difference?

John Cochrane

Somehow, we don't seem to suffer from this problem much in southern
Arizona - perhaps that's because our dew point is often way below
freezing (it's about 20 F today at El Tiro) - check our weather
site.....

http://www.mike-the-strike.net/Soari...ast/ElTiro.htm

May I suggest changing your gliderport rather than your trailer!

Mike

On 3/29/2010 1:50 PM, John Cochrane wrote:


Well, even the fiberglass top can leak a little. When I put my plane
together the other day
there was a string of mud spots on the leading edge of my wings near
the root end. Those
parts of my wings are under the passive vents installed in the
trailer, so I'm getting some
moisture in through or around those vents.

-- Matt

This might also come from the even worse problem of metal-top (all)
trailers -- condensation.

Any day the 5 am temperature goes below the dewpoint (most days in the
spring), the glider inside the trailer will be sopping wet. It dries
out by noon if you have a good vent. But your beloved glider is
spending 4-5 hours a day covered in water.

I've attacked this successfully with a dehumidifier, but that needs
power which we don't have at my current airport.

The new insulated tops might help. Has anyone noticed a big
difference?

John Cochrane


If the 5 am air temperature goes below the dewpoint, you will have fog.
If your trailer is well ventilated (has a fan), you may get air inside
the trailer that is below the dew point. I wouldn't think an insulated
top would help. If the trailer is not well ventilated, however, it
would seem that an insulated top would help get the air inside the
trailer warmer than the dew point, and thus would help keep it dry.

Compare this situation with radiation of heat to space at night. If you
leave your glider tied out at night, it radiates heat, the fiberglass
can get below the dew point, and you can have water on the glider in the
morning. The same thing can happen to a metal trailer -- if the metal
ends up below the dew point, there will be water on the metal (both
inside and out). An insulated top should help here, because there is no
exposed metal inside the trailer.

This raises another question -- should trailers have fans? My aluminum
Cobra does not, and it (and the glider) always has been dry inside.

On Mar 29, 5:29*pm, Greg Arnold wrote:
On 3/29/2010 1:50 PM, John Cochrane wrote:





Well, even the fiberglass top can leak a little. *When I put my plane
together the other day
there was a string of mud spots on the leading edge of my wings near
the root end. *Those
parts of my wings are under the passive vents installed in the
trailer, so I'm getting some
moisture in through or around those vents.

-- Matt

This might also come from the even worse problem of metal-top (all)
trailers -- condensation.

Any day the 5 am temperature goes below the dewpoint (most days in the
spring), the glider inside the trailer will be sopping wet. It dries
out by noon if you have a good vent. But your beloved glider is
spending 4-5 hours a day covered in water.

I've attacked this successfully with a dehumidifier, but that needs
power which we don't have at my current airport.

The new insulated tops might help. Has anyone noticed a big
difference?

John Cochrane

If the 5 am air temperature goes below the dewpoint, you will have fog.
* If your trailer is well ventilated (has a fan), you may get air inside
the trailer that is below the dew point. *I wouldn't think an insulated
top would help. *If the trailer is not well ventilated, however, it
would seem that an insulated top would help get the air inside the
trailer warmer than the dew point, and thus would help keep it dry.

Compare this situation with radiation of heat to space at night. *If you
leave your glider tied out at night, it radiates heat, the fiberglass
can get below the dew point, and you can have water on the glider in the
morning. *The same thing can happen to a metal trailer -- if the metal
ends up below the dew point, there will be water on the metal (both
inside and out). *An insulated top should help here, because there is no
exposed metal inside the trailer.

This raises another question -- should trailers have fans? *My aluminum
Cobra does not, and it (and the glider) always has been dry inside.

We're big believers of solar fans here in the soggy SouthEast US.
Typical
summertime dewpoints are in the '70Fs. I've seen several planes that
didn't
have solar vents (or whose vents had failed) that remained parked for
a while.
The gelcoat on the leading edge of the wings and the bottom of the
fuselage just
rots away over time (that's where the dew collects). The entire plane
can get
furry from mildew. My plane needed quite a bit of work before I would
buy it --
it needed the leading edges redone. There's a plane in the shop
getting a
complete refinish because of the same problems.

-- Matt