glider trailer top opening styles

Does anyone have any opinions about the relative benefits of an "alligator"
style opening trailer vs a full opening top?
the Luebke plans trailer I am building will be 31 feet long and 53 inches wide with a 17.5 inch tall lower sides. the top would be 37 inches taller in the front half and taper down in the back half. Steel square tubing frame with aluminum skin. if I build the front half fixed and open only the back 16 feet, I could dramatically reduce the weight of the opening portion, with a small penalty of limited access.
The problem of the top weather seal is more difficult, but not impossible.
Also the ability to control the opening top "shake" while on the road is much easier.
I think the full opening top might easily get to 300 lbs, while the partial top could be as low as 120 lbs.
Last year I saw a online article of a Lak with a partial opening top and it seemed to be a good solution.

Thanks,
Scott

On Monday, August 11, 2014 2:46:26 PM UTC-4, shkdriver wrote:
Does anyone have any opinions about the relative benefits of an

"alligator"

style opening trailer vs a full opening top?

the Luebke plans trailer I am building will be 31 feet long and 53

inches wide with a 17.5 inch tall lower sides. the top would be 37

inches taller in the front half and taper down in the back half. Steel

square tubing frame with aluminum skin. if I build the front half fixed

and open only the back 16 feet, I could dramatically reduce the weight

of the opening portion, with a small penalty of limited access.

The problem of the top weather seal is more difficult, but not

impossible.

Also the ability to control the opening top "shake" while on the road is

much easier.

I think the full opening top might easily get to 300 lbs, while the

partial top could be as low as 120 lbs.

Last year I saw a online article of a Lak with a partial opening top and

it seemed to be a good solution.



Thanks,

Scott


Getting a good sealing of the center joint is a meaningful complication.
It also means that the roots get close to the top of the trailer as the wings go forward which is a problem the full clam shell type does not have. They are easier on the back of the tip carrying person,
UH






--

shkdriver

On 8/11/2014 6:58 PM, wrote:
On Monday, August 11, 2014 2:46:26 PM UTC-4, shkdriver wrote:
Does anyone have any opinions about the relative benefits of an
"alligator" style opening trailer vs a full opening top?

The Luebke plans trailer I am building will be 31 feet long and 53
inches wide with a 17.5 inch tall lower sides. the top would be 37
inches taller in the front half and taper down in the back half. Steel
square tubing frame with aluminum skin. if I build the front half fixed
and open only the back 16 feet, I could dramatically reduce the weight
of the opening portion, with a small penalty of limited access.

The problem of the top weather seal is more difficult, but not
impossible.

Also the ability to control the opening top "shake" while on the road is
much easier.

I think the full opening top might easily get to 300 lbs, while the
partial top could be as low as 120 lbs.

Last year I saw a online article of a Lak with a partial opening top and
it seemed to be a good solution.


Thanks,

Scott


Getting a good sealing of the center joint is a meaningful complication.
It also means that the roots get close to the top of the trailer as the wings go forward which is a problem the full clam shell type does not have. They are easier on the back of the tip carrying person,
UH


"What UH said," wrt the center joint seal. That noted, nearly 3 decades-worth
of ownership/use of a George Applebay designed/fabricated "alligator style"
trailer never bothered me leak-wise. The Applebay joint did/does allow a small
amount of (western U.S.) dust to enter along with a minor/slow drip leak
top-dead-center. Perhaps a perfectionist's problem...

And "True," for the smaller root clearance, but gravity is your friend.
Clearance is clearance; never an issue for the aft-end-tapered Applebay trailer.

FWIW, the Applebay "jaw" - aluminum-covered square-steel framework - was
designed to be spring counterbalanced. It definitely helped, but wasn't an
operation-killer when the original cables needed replacement...at least not
for a reasonably functional lower back. Maybe 50-60 pounds at the lift gate? YMMV.

Bob W.

The Cobra design WORKS.
Better access to the whole trailer when the top is up.
Easier to get inside to clean.

On 2014-08-11, shkdriver wrote:

Does anyone have any opinions about the relative benefits of an
"alligator" style opening trailer vs a full opening top?

Please forgive my reopening an old topic, and for that matter, my
general ignorance on the topic for that matter.

When I was last involved in the sport 25 years ago, most of the trailers
at our club were simple long tubes with a big door at the back, and
maybe a small hatch at the front. (Was "Minden Trailer" a brand in those
days?) As a sometimes helper during rig and de-rig, it did not seem
to add much (or any? my memory is hazy) difficulty to the operation.

Yes, you have to bend over to enter the trailer, but I'm not sure how
often you would have to do that. Why is it worth the extra expense, weight
and complexity (especially in a homebuilt) for a top-opening trailer?

On Wednesday, November 19, 2014 2:45:06 PM UTC-7, Rob Brown wrote:
On 2014-08-11, shkdriver wrote:

Does anyone have any opinions about the relative benefits of an
"alligator" style opening trailer vs a full opening top?

Please forgive my reopening an old topic, and for that matter, my
general ignorance on the topic for that matter.

When I was last involved in the sport 25 years ago, most of the trailers
at our club were simple long tubes with a big door at the back, and
maybe a small hatch at the front. (Was "Minden Trailer" a brand in those
days?) As a sometimes helper during rig and de-rig, it did not seem
to add much (or any? my memory is hazy) difficulty to the operation.

Yes, you have to bend over to enter the trailer, but I'm not sure how
often you would have to do that. Why is it worth the extra expense, weight
and complexity (especially in a homebuilt) for a top-opening trailer?

To the extent there was a problem with tube trailers, it's that they were too small in cross section. If the builder had added as much as 12 inches to the width and height, it would have been noticeably easier to get gliders in and out of them. Then too, no one ever worked out a really good rear door design.

Tubes are inherently stronger and lighter than cam-shell types and probably cheaper to build. Any additional aerodynamic drag incurred with a wider tube probably costs less in fuel than the extra weight of a cam-shell.

The Pfeiffer tube trailer that my Mosquito came in had an excellent back
door design. The door was hinged on the right side and, when swung open
had brackets for rigging tools, grease, rear jack crank, etc. There was
a ramp hinged at the middle and bottom which folded up before closing
the door. When swung up, the ramp secured the wingtips with padded
cuffs. I thought it was a great design, much better than the home built
trailers, but you did have to bend over to get inside.

Dan Marotta

On 11/19/2014 3:19 PM, Bill D wrote:
On Wednesday, November 19, 2014 2:45:06 PM UTC-7, Rob Brown wrote:
On 2014-08-11, shkdriver wrote:
Does anyone have any opinions about the relative benefits of an
"alligator" style opening trailer vs a full opening top?
Please forgive my reopening an old topic, and for that matter, my
general ignorance on the topic for that matter.

When I was last involved in the sport 25 years ago, most of the trailers
at our club were simple long tubes with a big door at the back, and
maybe a small hatch at the front. (Was "Minden Trailer" a brand in those
days?) As a sometimes helper during rig and de-rig, it did not seem
to add much (or any? my memory is hazy) difficulty to the operation.

Yes, you have to bend over to enter the trailer, but I'm not sure how
often you would have to do that. Why is it worth the extra expense, weight
and complexity (especially in a homebuilt) for a top-opening trailer?
To the extent there was a problem with tube trailers, it's that they were too small in cross section. If the builder had added as much as 12 inches to the width and height, it would have been noticeably easier to get gliders in and out of them. Then too, no one ever worked out a really good rear door design.

Tubes are inherently stronger and lighter than cam-shell types and probably cheaper to build. Any additional aerodynamic drag incurred with a wider tube probably costs less in fuel than the extra weight of a cam-shell.

On Wednesday, November 19, 2014 7:41:04 PM UTC-5, Dan Marotta wrote:
The Pfeiffer tube trailer that my
Mosquito came in had an excellent back door design.* The door was
hinged on the right side and, when swung open had brackets for
rigging tools, grease, rear jack crank, etc.* There was a ramp
hinged at the middle and bottom which folded up before closing the
door.* When swung up, the ramp secured the wingtips with padded
cuffs.* I thought it was a great design, much better than the home
built trailers, but you did have to bend over to get inside.

Dan Marotta
On 11/19/2014 3:19 PM, Bill D wrote:

Also very good for tripping and shin banging if you are not used to it.

On Wednesday, November 19, 2014 6:57:37 PM UTC-7, wrote:
On Wednesday, November 19, 2014 7:41:04 PM UTC-5, Dan Marotta wrote:
The Pfeiffer tube trailer that my
Mosquito came in had an excellent back door design.* The door was
hinged on the right side and, when swung open had brackets for
rigging tools, grease, rear jack crank, etc.* There was a ramp
hinged at the middle and bottom which folded up before closing the
door.* When swung up, the ramp secured the wingtips with padded
cuffs.* I thought it was a great design, much better than the home
built trailers, but you did have to bend over to get inside.

Dan Marotta
On 11/19/2014 3:19 PM, Bill D wrote:

Also very good for tripping and shin banging if you are not used to it.
UH



I got a brief look at a small Asian crossover SUV in a shopping center parking lot (too brief to get the brand) whose rear hatch used two arms extending forward ending at hinges on the roof. The hatch neatly lifted up over the roof and completely out of the way. It was obvious the weather seals worked better than traditional hatches where the seals get squeezed at the a hinge. I couldn't help thinking of glider trailers.

Applied to a tube trailer, the door and "doghouse" would lift up and clear of the fin and rudder leaving the opening at the back of the trailer completely clean.

On Wednesday, November 19, 2014 8:57:37 PM UTC-5, wrote:
On Wednesday, November 19, 2014 7:41:04 PM UTC-5, Dan Marotta wrote:
The Pfeiffer tube trailer that my
Mosquito came in had an excellent back door design.* The door was
hinged on the right side and, when swung open had brackets for
rigging tools, grease, rear jack crank, etc.* There was a ramp
hinged at the middle and bottom which folded up before closing the
door.* When swung up, the ramp secured the wingtips with padded
cuffs.* I thought it was a great design, much better than the home
built trailers, but you did have to bend over to get inside.

Dan Marotta
On 11/19/2014 3:19 PM, Bill D wrote:

Also very good for tripping and shin banging if you are not used to it.
UH



One of the biggest problems I've noticed is that the wing spars have to come out past the end of the tube trailer before you can lift them. That involves some combination of ramps, free-floating dollies, or back breaking lifting. The only time I've actually hurt my back assembling/disassembling a glider was helping a friend to stabilize an LS3 wing that was about to tip over.

In a Cobra/Komet, the dolly is captive in the trailer and the root of the spar is easily accessible to lift and start swinging the wing around. I'm sure a good design could be built for the tube trailer, but I haven't seen one yet.

NOTE: I have seen the Shirenewton (I think) trailers where the wings go in tip-first, but that means a lot more maneuvering to get the spar to the fuselage.

So, the bottom line: Clamshell trailers seem to require the least awkward lifting, fewest steps, and provide the most stable platform for assembly/disassembly IMO.

P3