Sacrificial layer for gear-up protection.

Lets say you are deploying a retractible gear glider in a club with members who some might suspect of landing the thing gear-up someday. (Of course, you private owners never land gear-up...) Is there a way to minimize the damage when the inevitable day arrives?

Maybe. One of my favorite materials is UHMW-PE - a plastic with many superlative characteristics including astonishing abrasion resistance and a very low coefficient of friction. A 9mm thick strip, 150mm wide might very well withstand a gear-up landing of an 850 kg glider. It's also very light, cheap and a shade of white closely matching gel-coat.

Until recently, there was no way to glue this stuff to anything even itself but new epoxy adhesives have appeared on the market that advertize the ability to stick it to almost anything including fiber reinforced composite epoxy structures like glider belly's and wing tips.

So, obviouisly, some testing is in order before slapping a strip of UHMW-PE on the belly of your glider. A test rig on a pick-up's reciever hitch could slam a patch of it down on a concrete runway to simulate a gear-up. Anybody interested?

Bill,

Could you provide the brand name of the particular epoxy that will stick to this stuff? I would like to install a couple strips to the down-turned wing tip skids on my LS-3. The design of the tips makes it difficult to use mechanical fasteners.

Thanks,

Ron C.

On Friday, May 15, 2015 at 2:59:26 PM UTC-4, Bill D wrote:
Lets say you are deploying a retractible gear glider in a club with members who some might suspect of landing the thing gear-up someday.

I've seen this eventuality addressed on an L-23 by putting a ziptie around the gear lowering handle.

On Friday, May 15, 2015 at 1:31:32 PM UTC-6, wrote:
Bill,

Could you provide the brand name of the particular epoxy that will stick to this stuff? I would like to install a couple strips to the down-turned wing tip skids on my LS-3. The design of the tips makes it difficult to use mechanical fasteners.

Thanks,

Ron C.

Here's one - there are dozen more.
http://reltekllc.com/adhesivesforuhmw.aspx

Just Google "uhmw-pe epoxy adnesive"

On Friday, May 15, 2015 at 3:36:48 PM UTC-4, son_of_flubber wrote:
On Friday, May 15, 2015 at 2:59:26 PM UTC-4, Bill D wrote:
Lets say you are deploying a retractible gear glider in a club with members who some might suspect of landing the thing gear-up someday.

I've seen this eventuality addressed on an L-23 by putting a ziptie around the gear lowering handle.

all of the club retracts I've flown have had the handle disabled, either with a ziptie or with safety wire

On Friday, May 15, 2015 at 2:59:26 PM UTC-4, Bill D wrote:
Lets say you are deploying a retractible gear glider in a club with members who some might suspect of landing the thing gear-up someday. (Of course, you private owners never land gear-up...) Is there a way to minimize the damage when the inevitable day arrives?

Maybe. One of my favorite materials is UHMW-PE - a plastic with many superlative characteristics including astonishing abrasion resistance and a very low coefficient of friction. A 9mm thick strip, 150mm wide might very well withstand a gear-up landing of an 850 kg glider. It's also very light, cheap and a shade of white closely matching gel-coat.

Until recently, there was no way to glue this stuff to anything even itself but new epoxy adhesives have appeared on the market that advertize the ability to stick it to almost anything including fiber reinforced composite epoxy structures like glider belly's and wing tips.

So, obviouisly, some testing is in order before slapping a strip of UHMW-PE on the belly of your glider. A test rig on a pick-up's reciever hitch could slam a patch of it down on a concrete runway to simulate a gear-up. Anybody interested?

While a "sacrificial layer" seems good, best method I've seen is to have the offender help with doing the repairs.
Granted, it means some glider downtime, but "word of mouth" goes miles as a reminder.
Since I tend to do "final finish & polish", I have a vested interest in what happens to ships.
;-)

[yes, UHMW-PE is a great material, even "good" adhesives are short term in my eyes.]

On Friday, May 15, 2015 at 3:29:47 PM UTC-6, Bob Pasker wrote:
On Friday, May 15, 2015 at 3:36:48 PM UTC-4, son_of_flubber wrote:
On Friday, May 15, 2015 at 2:59:26 PM UTC-4, Bill D wrote:
Lets say you are deploying a retractible gear glider in a club with members who some might suspect of landing the thing gear-up someday.

I've seen this eventuality addressed on an L-23 by putting a ziptie around the gear lowering handle.

all of the club retracts I've flown have had the handle disabled, either with a ziptie or with safety wire

I don't think that's going to work with a Discus

On Friday, May 15, 2015 at 2:29:47 PM UTC-7, Bob Pasker wrote:
On Friday, May 15, 2015 at 3:36:48 PM UTC-4, son_of_flubber wrote:
On Friday, May 15, 2015 at 2:59:26 PM UTC-4, Bill D wrote:
Lets say you are deploying a retractible gear glider in a club with members who some might suspect of landing the thing gear-up someday.

I've seen this eventuality addressed on an L-23 by putting a ziptie around the gear lowering handle.

all of the club retracts I've flown have had the handle disabled, either with a ziptie or with safety wire

Disabling an aircraft control sounds not only insane but likely also illegal.

Mike

On Friday, May 15, 2015 at 3:54:17 PM UTC-6, Charlie M. (UH & 002 owner/pilot) wrote:
On Friday, May 15, 2015 at 2:59:26 PM UTC-4, Bill D wrote:
Lets say you are deploying a retractible gear glider in a club with members who some might suspect of landing the thing gear-up someday. (Of course, you private owners never land gear-up...) Is there a way to minimize the damage when the inevitable day arrives?

Maybe. One of my favorite materials is UHMW-PE - a plastic with many superlative characteristics including astonishing abrasion resistance and a very low coefficient of friction. A 9mm thick strip, 150mm wide might very well withstand a gear-up landing of an 850 kg glider. It's also very light, cheap and a shade of white closely matching gel-coat.

Until recently, there was no way to glue this stuff to anything even itself but new epoxy adhesives have appeared on the market that advertize the ability to stick it to almost anything including fiber reinforced composite epoxy structures like glider belly's and wing tips.

So, obviouisly, some testing is in order before slapping a strip of UHMW-PE on the belly of your glider. A test rig on a pick-up's reciever hitch could slam a patch of it down on a concrete runway to simulate a gear-up. Anybody interested?

While a "sacrificial layer" seems good, best method I've seen is to have the offender help with doing the repairs.
Granted, it means some glider downtime, but "word of mouth" goes miles as a reminder.
Since I tend to do "final finish & polish", I have a vested interest in what happens to ships.
;-)

[yes, UHMW-PE is a great material, even "good" adhesives are short term in my eyes.]

Much better to just put the glider back on its wheel and go fly. Usually the offender is sufficiently embarassed.

Are you saying the UHMW-PE adhesives don't really last?

Not the best idea for a Club LS4 going cross country.
BillT