View Full Version : Cobra trailer aluminum vs fiberglass top
I am interested in the pros and cons of aluminum vs fiberglass top for Cobra trailers.
Tom
Craig Funston[_3_]
July 12th 18, 05:47 PM
On Thursday, July 12, 2018 at 9:13:33 AM UTC-7, 2G wrote:
> I am interested in the pros and cons of aluminum vs fiberglass top for Cobra trailers.
>
> Tom
I have the fiberglass top. It will need refinish sometime soon due to gelcoat chalking, etc. Wish I had the aluminum top. They seem to be holding up to the elements better.
ymmv
Craig
Alex[_6_]
July 12th 18, 05:47 PM
PRO Aluminum
Aluminum Cobra trailers are almost maintenance free. You can store them outside for decades and after a cleaning they shine like new.
CONTRA Aluminum
If you bend or dent anything the repair will always be visible.
If stored outside in cold condition, serious amounts of dew will collect on the inside, if you don't buy the optional insulation.
After 20 years the sealing of the overlapping aluminum plates will become brittle and start leaking.
Custom sizes can be ordered to your needs. (extra long Arcus trailer is a real improvement over the smaller fiberglass version. Also the JS1 with 18/21 meters really benefits from the wider version available in aluminum)
The aluminum version is more expensive
PRO Fiberglass
It looks more streamlined
It's a bit cheaper
The double walled versions basically have a very effective insulation per design (no dew on the inside).
Easy to repair
CONTRA Fiberglass
Stored outside the paint quality degrades quickly. Even with regular polishing and waxing the paint will start showing first cracks and yellow patches after a couple of years. This drawback could probably be mitigated by replacing the gelcoat type paint with something more durable.
Size limited by the available molds: single, double (and 18m ?).
Alex[_6_]
July 12th 18, 05:49 PM
Update:
the custom sizes are of course pro aluminum and not contra as listed.
On Thursday, July 12, 2018 at 9:49:55 AM UTC-7, Alex wrote:
> Update:
>
> the custom sizes are of course pro aluminum and not contra as listed.
Thanks!
Tom
Nick Kennedy
July 12th 18, 06:48 PM
I've seen gliders stored in fiberglass top trailers that look like they have suffered long term UV damage. Not sure if the fiberglass lets UV through but that's what I've seen. My Aluminum top cobra is probably 26 years old and still looks good. And the plane inside looks good.
Whichever you don't buy will turn out to be better. :) I bought a fiberglass Cobra 26 years ago for my ASW 24 because I didn't want to deal with leaks between aluminum panels. Later Cobras seem to have a layer that prevents UV from penetrating the trailer. And minor encounters with tree branches, etc., are shrugged off as scratches rather than as unsightly dents.
But...the gel coat did deteriorate. Worse, the top cracked, I believe because of flexing from buffeting on the highway, and eventually leaked anyway! Yes, it was repairable (thanks, UH & P3) but an aggravation.
A couple of guys here have gone aluminum recently and that's probably the way I'd lean, but obviously whatever you do will be a compromise.
Chip Bearden
I have had both, the fiberglass top is way heavier. I can barely push it around by myself even when empty. But both have or will have finish issues and it will cost alot more to refinish the aluminium than the fiberglass. In all considerations if I was buying new Id probably go with th aluminium top.. but just barely :)
CH
On Thursday, July 12, 2018 at 9:22:31 PM UTC+1, wrote:
> I have had both, the fiberglass top is way heavier. I can barely push it around by myself even when empty. But both have or will have finish issues and it will cost alot more to refinish the aluminium than the fiberglass. In all considerations if I was buying new Id probably go with th aluminium top. but just barely :)
>
> CH
At the 2018 BGA conference exhibition I asked the 2 Cobra representatives which trailer top they would buy for themselves and without hesitation they said "the metal top but with with insulation".
Roy B.
July 13th 18, 12:55 AM
I have both: Metal top in the US and fiberglass in South Africa. The metal top seems to be easier to clean and keep clean. Also, the front door on the fiberglass top does not latch well or consistently. I have seen several of those blow open on the road. The metal top front doors don't seem to have that problem. But I don't think that there is a real big difference.
ROY
On Thursday, July 12, 2018 at 4:55:10 PM UTC-7, Roy B. wrote:
> I have both: Metal top in the US and fiberglass in South Africa. The metal top seems to be easier to clean and keep clean. Also, the front door on the fiberglass top does not latch well or consistently. I have seen several of those blow open on the road. The metal top front doors don't seem to have that problem. But I don't think that there is a real big difference.
> ROY
Thanks for all the replies. I have decided to go with the insulated Aluminum top.
Tom
OHM Ω http://aviation.derosaweb.net
July 14th 18, 10:39 PM
On Thursday, July 12, 2018 at 6:55:10 PM UTC-5, Roy B. wrote:
> I have both: Metal top in the US and fiberglass in South Africa. The metal top seems to be easier to clean and keep clean. Also, the front door on the fiberglass top does not latch well or consistently. I have seen several of those blow open on the road. The metal top front doors don't seem to have that problem. But I don't think that there is a real big difference.
> ROY
As a bit of an aside, I installed a second latch on my (aluminum top!) Cobra trailer forward hatch/door to prevent the dreaded "door bent back at 180 degrees from 60MPH (96KPH)" syndrome. Here is the latch I used; https://www.westmarine.com/buy/southco-marine--flexible-t-handle-latch-black-front-mount--15112527?recordNum=9. Latch picture can be found at; http://aviation.derosaweb.net/asw27/documents/Trailer/
I've never been able to find an aluminum trailer with the factory insulation package. Can anyone direct us to pictures and insulation specifics? My concern is it would be "delicate" and have a tendency to "pick".
If you were going to add insulate to an older trailer, what specific product would you use?
On Sunday, July 15, 2018 at 3:08:29 AM UTC+1, wrote:
> I've never been able to find an aluminum trailer with the factory insulation package. Can anyone direct us to pictures and insulation specifics? My concern is it would be "delicate" and have a tendency to "pick".
>
> If you were going to add insulate to an older trailer, what specific product would you use?
I looked at one several years ago and the insulation on that one appeared to be black "rubbery" expanded foam - not polystyrene foam. I have the same decision to make and will ask Spindelberger to send a sample.
bumper[_4_]
July 16th 18, 04:49 PM
On Sunday, July 15, 2018 at 9:32:46 AM UTC-7, wrote:
> On Sunday, July 15, 2018 at 3:08:29 AM UTC+1, wrote:
> > I've never been able to find an aluminum trailer with the factory insulation package. Can anyone direct us to pictures and insulation specifics? My concern is it would be "delicate" and have a tendency to "pick".
> >
> > If you were going to add insulate to an older trailer, what specific product would you use?
>
> I looked at one several years ago and the insulation on that one appeared to be black "rubbery" expanded foam - not polystyrene foam. I have the same decision to make and will ask Spindelberger to send a sample.
There are a number of self adhesive foam insulations available that are reasonably priced. I've also used the reflective "bubble wrap" stuff with 3M 77 or 90 spray adhesive (though that isn't so suitable for trailers). It doesn't need a high R value as it only needs to prevent condensate on interior surfaces. This stuff on Amazon looks interesting:
https://www.amazon.com/Noico-waterproof-insulation-Self-adhesive-Deadening/dp/B07CZ2DHV3/ref=sr_1_20?ie=UTF8&qid=1531726529&sr=8-20&keywords=self+adhesive+foam+insulation
bumper
On Monday, July 16, 2018 at 11:49:50 AM UTC-4, bumper wrote:
> On Sunday, July 15, 2018 at 9:32:46 AM UTC-7, wrote:
> > On Sunday, July 15, 2018 at 3:08:29 AM UTC+1, wrote:
> > > I've never been able to find an aluminum trailer with the factory insulation package. Can anyone direct us to pictures and insulation specifics? My concern is it would be "delicate" and have a tendency to "pick".
> > >
> > > If you were going to add insulate to an older trailer, what specific product would you use?
> >
> > I looked at one several years ago and the insulation on that one appeared to be black "rubbery" expanded foam - not polystyrene foam. I have the same decision to make and will ask Spindelberger to send a sample.
>
> There are a number of self adhesive foam insulations available that are reasonably priced. I've also used the reflective "bubble wrap" stuff with 3M 77 or 90 spray adhesive (though that isn't so suitable for trailers). It doesn't need a high R value as it only needs to prevent condensate on interior surfaces. This stuff on Amazon looks interesting:
> https://www.amazon.com/Noico-waterproof-insulation-Self-adhesive-Deadening/dp/B07CZ2DHV3/ref=sr_1_20?ie=UTF8&qid=1531726529&sr=8-20&keywords=self+adhesive+foam+insulation
>
> bumper
1/16" of an inch seems awful thin. Wonder what is the thickness of the Spindelberger insulation?
Martin Gregorie[_6_]
July 16th 18, 08:30 PM
On Mon, 16 Jul 2018 12:07:43 -0700, bensoaring wrote:
>> https://www.amazon.com/Noico-waterproof-insulation-Self-adhesive-
Deadening/dp/B07CZ2DHV3/ref=sr_1_20?
ie=UTF8&qid=1531726529&sr=8-20&keywords=self+adhesive+foam+insulation
>>
>
> 1/16" of an inch seems awful thin. Wonder what is the thickness of the
> Spindelberger insulation?
>
The web page says 1/6" (4mm) thick.
A clubmate had good anti-condensation results from lining a trailer with
3mm (1/8") polystyrene wallpaper underlay held on with contact cement, so
this stuff, which looks to be a lot more resistant to water penetration
as well as 33% thicker and denser than the polystyrene should be better.
--
Martin | martin at
Gregorie | gregorie dot org
On Thursday, July 12, 2018 at 12:13:33 PM UTC-4, 2G wrote:
> I am interested in the pros and cons of aluminum vs fiberglass top for Cobra trailers.
>
> Tom
My experience, having owned both, is that the current production glass to Cobra trailers keep the glider cooler and drier than metal top trailers.
Neatly done repairs are much easier in glass. I am experienced in both.
When the finish deteriorates, my opinion is that it is easier to refinish the glass trailer. This involves surface sanding to get a clean, slightly roughened surface, followed by a couple light coats of spray filler to clean up surface defects, orbital sand with 220 grit, and then spray with acrylic urethane.
The metal trailer, if the paint is bad, requires stripping to bare metal, etch, conversion coat, epoxy prime, then paint with AU.
FWIW most of the damage to either is meaningfully reduced by simply getting them out of the weather. This also keeps the glider cooler which slows aging.
In my view the dominant consideration is how well the trailer protects the glider that costs somewhere between 8 and 20 times what the trailer does.
UH
krasw
July 17th 18, 10:38 AM
I haven't ever seen metal top Cobra that requires painting. I have never seen glass top that doesn't.
Ken Payne
July 17th 18, 11:37 AM
At 09:38 17 July 2018, krasw wrote:
>I haven't ever seen metal top Cobra that requires painting. I have never
>seen glass top that doesn't.
>
Do Cobra offer a paint finish on their fiberglass tops. If not why not?
On Tuesday, July 17, 2018 at 11:45:05 AM UTC+1, Ken Payne wrote:
> At 09:38 17 July 2018, krasw wrote:
> >I haven't ever seen metal top Cobra that requires painting. I have never
> >seen glass top that doesn't.
> >
>
> Do Cobra offer a paint finish on their fiberglass tops. If not why not?
Very good question!
Craig Funston[_3_]
July 17th 18, 07:27 PM
On Tuesday, July 17, 2018 at 11:00:30 AM UTC-7, wrote:
> On Tuesday, July 17, 2018 at 11:45:05 AM UTC+1, Ken Payne wrote:
> > At 09:38 17 July 2018, krasw wrote:
> > >I haven't ever seen metal top Cobra that requires painting. I have never
> > >seen glass top that doesn't.
> > >
> >
> > Do Cobra offer a paint finish on their fiberglass tops. If not why not?
>
> Very good question!
I've been considering a wrap to refinish my fiberglass top. Does anyone have experience with this option?
Thanks,
Craig
JS[_5_]
July 17th 18, 07:42 PM
On Tuesday, July 17, 2018 at 11:00:30 AM UTC-7, wrote:
> On Tuesday, July 17, 2018 at 11:45:05 AM UTC+1, Ken Payne wrote:
> > At 09:38 17 July 2018, krasw wrote:
> > >I haven't ever seen metal top Cobra that requires painting. I have never
> > >seen glass top that doesn't.
> > >
> >
> > Do Cobra offer a paint finish on their fiberglass tops. If not why not?
>
> Very good question!
Similar questions to "Do they offer LED lighting?" or "Do they offer felt instead of foam-backed carpet?"
Like a new sailplane, it seems there is always something the buyer needs to work on.
Believe they're all being delivered with "beer friendly" fenders (mud guards) now, so one less option to consider.
Interior lighting is nice.
After installing one of each, the IMI drawer seemed better than the Cobra.
Tom, if you're getting an ASH31 (or for anyone considering JS1C or perhaps other multi-span polyhedral wing) have a look at the wider "DoSi" trailer as an option. Things are awfully tight in the standard width trailers, a recipe for trailer rash. At least either trailer will be shorter than the ASH26 (or Duo) trailers.
But uncertain that the newer wide metal top trailers still have a seam along the top. The 2000-vintage ones do. Alfred's sheet metal brake is huge, but has limits.
Jim
On Tuesday, July 17, 2018 at 11:42:54 AM UTC-7, JS wrote:
> On Tuesday, July 17, 2018 at 11:00:30 AM UTC-7, wrote:
> > On Tuesday, July 17, 2018 at 11:45:05 AM UTC+1, Ken Payne wrote:
> > > At 09:38 17 July 2018, krasw wrote:
> > > >I haven't ever seen metal top Cobra that requires painting. I have never
> > > >seen glass top that doesn't.
> > > >
> > >
> > > Do Cobra offer a paint finish on their fiberglass tops. If not why not?
> >
> > Very good question!
>
> Similar questions to "Do they offer LED lighting?" or "Do they offer felt instead of foam-backed carpet?"
> Like a new sailplane, it seems there is always something the buyer needs to work on.
> Believe they're all being delivered with "beer friendly" fenders (mud guards) now, so one less option to consider.
> Interior lighting is nice.
> After installing one of each, the IMI drawer seemed better than the Cobra..
>
> Tom, if you're getting an ASH31 (or for anyone considering JS1C or perhaps other multi-span polyhedral wing) have a look at the wider "DoSi" trailer as an option. Things are awfully tight in the standard width trailers, a recipe for trailer rash. At least either trailer will be shorter than the ASH26 (or Duo) trailers.
> But uncertain that the newer wide metal top trailers still have a seam along the top. The 2000-vintage ones do. Alfred's sheet metal brake is huge, but has limits.
> Jim
Jim,
I just looked at the Cobra trailer options, and could not find anything about a wider "DoSi." I will ask Rex about this tomorrow.
Thanks,
Tom
Michael Opitz
July 18th 18, 03:41 AM
>Jim,
>I just looked at the Cobra trailer options, and could not find anything
>abo=
>ut a wider "DoSi." I will ask Rex about this tomorrow.
>Thanks,
>Tom
>
"Dosi" is German slang or a shortcut word for Doppelsitzer
(two-seater), so a trailer that was initially conceived to house a
two seater.
RO
JS[_5_]
July 18th 18, 04:21 AM
I asked Alfred about the wide "DoSi" trailer option for single seaters at Reno, he said nobody asks as it does cost a little more. Perhaps fixing trailer rash does too.
Rex could show you a 31 in a standard trailer, I'm sure. You're essentially squeezing 21m in a 15m trailer.
Believe the wide one for the ASH31 or JS1C would be the same size externally as the trailer for a Karat, if you know someone with one.
Jim
On Tuesday, July 17, 2018 at 6:31:06 PM UTC-7, 2G wrote:
> On Tuesday, July 17, 2018 at 11:42:54 AM UTC-7, JS wrote:
> > On Tuesday, July 17, 2018 at 11:00:30 AM UTC-7, wrote:
> > > On Tuesday, July 17, 2018 at 11:45:05 AM UTC+1, Ken Payne wrote:
> > > > At 09:38 17 July 2018, krasw wrote:
> > > > >I haven't ever seen metal top Cobra that requires painting. I have never
> > > > >seen glass top that doesn't.
> > > > >
> > > >
> > > > Do Cobra offer a paint finish on their fiberglass tops. If not why not?
> > >
> > > Very good question!
> >
> > Similar questions to "Do they offer LED lighting?" or "Do they offer felt instead of foam-backed carpet?"
> > Like a new sailplane, it seems there is always something the buyer needs to work on.
> > Believe they're all being delivered with "beer friendly" fenders (mud guards) now, so one less option to consider.
> > Interior lighting is nice.
> > After installing one of each, the IMI drawer seemed better than the Cobra.
> >
> > Tom, if you're getting an ASH31 (or for anyone considering JS1C or perhaps other multi-span polyhedral wing) have a look at the wider "DoSi" trailer as an option. Things are awfully tight in the standard width trailers, a recipe for trailer rash. At least either trailer will be shorter than the ASH26 (or Duo) trailers.
> > But uncertain that the newer wide metal top trailers still have a seam along the top. The 2000-vintage ones do. Alfred's sheet metal brake is huge, but has limits.
> > Jim
>
> Jim,
> I just looked at the Cobra trailer options, and could not find anything about a wider "DoSi." I will ask Rex about this tomorrow.
> Thanks,
> Tom
Gavin Short[_2_]
July 18th 18, 07:34 AM
At 18:27 17 July 2018, Craig Funston wrote:
>On Tuesday, July 17, 2018 at 11:00:30 AM UTC-7, wrote:
>> On Tuesday, July 17, 2018 at 11:45:05 AM UTC+1, Ken Payne wrote:
>> > At 09:38 17 July 2018, krasw wrote:
>> > >I haven't ever seen metal top Cobra that requires painting. I have
>never
>> > >seen glass top that doesn't.
>> > >
>> >
>> > Do Cobra offer a paint finish on their fiberglass tops. If not why
not?
>>
>> Very good question!
>
>I've been considering a wrap to refinish my fiberglass top. Does anyone
>have experience with this option?
>
>Thanks,
>Craig
>
Craig,
I have an Aero-works 'Rikki' trailer. There weren't many made. The top is
aluminium and is 'wrapped'. The prine options, in terms of ascending cost,
were roller paint, film wrapped, and spray booth painted. I went with the
wrap option as it seemed easy to care for and any damage could be repaired
by me by simply cutting out the damaged wrap and replacing that section. I
took delivery of the trailer in summer 2014 and the wrap is holding up well
(the trailer winters in the club hangar).
f.i the aluminium roof is not insulated but has a solar vent and
ventilation exhaust grilles at the back of the trailer (hidden by the
trailer number plate). No condensation problems ever encountered (as yes
it does rain in the Eifel national park in Germany).
Gavin
Std Cirrus, G-SCNN, #173
SFV Südeifel, Utscheid, Germany
I owned a JS1c 18/21 in a standard 15m type Cobra trailer and it was just OK for width except that I had to be careful to lower the top exactly centrally otherwise the flaperon horns at the rear of the trailer could get caught (never did). The problem for me was the lack of adequate storage space at the front of the trailer. A better option would be the same width but 40cm longer part no 031/030 trailer which also has a slightly taller top. I have helped to put a JS1 in one of those different and it makes more of a difference than it sounds. I am going to get that size for an 18m-only glider just for the extra storage.
I have also seen a JS1 in the Cobra "DoSi" Duo type trailer and it certainly was extremely roomy but it looked like overkill to me.
Craig Funston[_3_]
July 18th 18, 03:45 PM
On Tuesday, July 17, 2018 at 11:45:04 PM UTC-7, Gavin Short wrote:
> At 18:27 17 July 2018, Craig Funston wrote:
> >On Tuesday, July 17, 2018 at 11:00:30 AM UTC-7, wrote:
> >> On Tuesday, July 17, 2018 at 11:45:05 AM UTC+1, Ken Payne wrote:
> >> > At 09:38 17 July 2018, krasw wrote:
> >> > >I haven't ever seen metal top Cobra that requires painting. I have
> >never
> >> > >seen glass top that doesn't.
> >> > >
> >> >
> >> > Do Cobra offer a paint finish on their fiberglass tops. If not why
> not?
> >>
> >> Very good question!
> >
> >I've been considering a wrap to refinish my fiberglass top. Does anyone
> >have experience with this option?
> >
> >Thanks,
> >Craig
> >
>
> Craig,
>
> I have an Aero-works 'Rikki' trailer. There weren't many made. The top is
> aluminium and is 'wrapped'. The prine options, in terms of ascending cost,
> were roller paint, film wrapped, and spray booth painted. I went with the
> wrap option as it seemed easy to care for and any damage could be repaired
> by me by simply cutting out the damaged wrap and replacing that section. I
> took delivery of the trailer in summer 2014 and the wrap is holding up well
> (the trailer winters in the club hangar).
>
> f.i the aluminium roof is not insulated but has a solar vent and
> ventilation exhaust grilles at the back of the trailer (hidden by the
> trailer number plate). No condensation problems ever encountered (as yes
> it does rain in the Eifel national park in Germany).
>
> Gavin
> Std Cirrus, G-SCNN, #173
> SFV Südeifel, Utscheid, Germany
Hi Gavin,
Thanks for the feedback. I haven't priced the wrap out yet, but it does appear to be an attractive option.
Best regards,
Craig Funston
Andrzej Kobus
July 19th 18, 02:12 AM
On Monday, July 16, 2018 at 4:44:25 PM UTC-4, wrote:
> On Thursday, July 12, 2018 at 12:13:33 PM UTC-4, 2G wrote:
> > I am interested in the pros and cons of aluminum vs fiberglass top for Cobra trailers.
> >
> > Tom
>
> My experience, having owned both, is that the current production glass to Cobra trailers keep the glider cooler and drier than metal top trailers.
> Neatly done repairs are much easier in glass. I am experienced in both.
> When the finish deteriorates, my opinion is that it is easier to refinish the glass trailer. This involves surface sanding to get a clean, slightly roughened surface, followed by a couple light coats of spray filler to clean up surface defects, orbital sand with 220 grit, and then spray with acrylic urethane.
> The metal trailer, if the paint is bad, requires stripping to bare metal, etch, conversion coat, epoxy prime, then paint with AU.
> FWIW most of the damage to either is meaningfully reduced by simply getting them out of the weather. This also keeps the glider cooler which slows aging.
> In my view the dominant consideration is how well the trailer protects the glider that costs somewhere between 8 and 20 times what the trailer does.
> UH
I am 100% with UH on all points. Get a fiberglass top you will not regret. An auto-body shop can paint a fiberglass trailer top for you for $2k, probably less than the insulation cost for an aluminum top.
On Wednesday, July 18, 2018 at 6:12:30 PM UTC-7, Andrzej Kobus wrote:
> On Monday, July 16, 2018 at 4:44:25 PM UTC-4, wrote:
> > On Thursday, July 12, 2018 at 12:13:33 PM UTC-4, 2G wrote:
> > > I am interested in the pros and cons of aluminum vs fiberglass top for Cobra trailers.
> > >
> > > Tom
> >
> > My experience, having owned both, is that the current production glass to Cobra trailers keep the glider cooler and drier than metal top trailers.
> > Neatly done repairs are much easier in glass. I am experienced in both.
> > When the finish deteriorates, my opinion is that it is easier to refinish the glass trailer. This involves surface sanding to get a clean, slightly roughened surface, followed by a couple light coats of spray filler to clean up surface defects, orbital sand with 220 grit, and then spray with acrylic urethane.
> > The metal trailer, if the paint is bad, requires stripping to bare metal, etch, conversion coat, epoxy prime, then paint with AU.
> > FWIW most of the damage to either is meaningfully reduced by simply getting them out of the weather. This also keeps the glider cooler which slows aging.
> > In my view the dominant consideration is how well the trailer protects the glider that costs somewhere between 8 and 20 times what the trailer does.
> > UH
>
> I am 100% with UH on all points. Get a fiberglass top you will not regret.. An auto-body shop can paint a fiberglass trailer top for you for $2k, probably less than the insulation cost for an aluminum top.
The insulation costs about $1,200 at current exchange rates.
Tom
How does one go about having insulation installed inside an aluminum trailer?
Are there specific spray-on materials that are commonly applied that auto repair/painting shops would know how to work with? Are there some specific materials one should avoid? Seems like the material needs to be fairly abrasion resistant. Is the outgassing of some materials potentially damaging to a glider?
All the glued on carpet in my trailer is falling off for the second time and I do not look forward to redoing it all when a spray insulation may do double duty as padding for the glider bits and pieces.
vBulletin® v3.6.4, Copyright ©2000-2025, Jelsoft Enterprises Ltd.