Hinge Material

[Paul Gleeson]

What material is used to make the hinge lines on DLG wings?

Peel ply? Kevlar cloth? Use epoxy or CA?

Thanks, Paul

[satinet]

Is the basis of your question repairing a dlg or making a DLG?

When they are made it is probably peel ply laid in to the wing skin, but if you want to repair thing hinge you can't replicate this as it's done at the construction phase. In the case of repairs you need to use a flexible product like geocel fish tank sealant. 

[Paul Gleeson]

Tried that, but is it too flexible. The split is right by the aileron horn.

[Lloyd_d]

Peel ply or 36g/m2 Kevlar is used. I personally use Kevlar. I cut it on the bias and pull the fabric so the fibres pull tightly together across the hinge line.

As you have broken the hinge in the highest load area you may have no option but to look at getting a new wing. If you try to cut into the skin material and add a hinge and it isn't exactly in the same plane as the current one it will not allow the aileron to move properly.

The joys of live hinges..

[satinet]

How big is the split?

Some models that I've seen have the whole surface hinged with silicone.  I've got a 3m hollow moulded glider where the flaps are hinged with silicone from the manufacturer. I've hinged whole control surfaces with fish tank sealant before. 

You could do sealant and tape. 

[Paul Gleeson]

The split is about 100mm

So a fully rigid hinge might be a issue. Stiff tape might be an option

[satinet]

It's not a big split. Geocel should be fine. What happened when you tried it?

[cirrusRC]

Both my aileron hinges failed on my NXT.  Both held on full length with diamond tape.   Same with rudder and elevator too .   Doesn't hold me back.

Just make sure you get surface clean before applying tape.

[isoaritfirst]

Short aileron horns put more strain on hinges. Consider if they could be lengthened. 

[MikeDLG]

For DLG hinge line repairs, I usually use diamond tape on the bottom and black electrical tape on the top, down into the hinge gap.  Works very well for me. 

[Paul Gleeson]

Ah... the black tape is a great idea. Thanks Mike

[BigT]

How about if the whole of the elevator gets broken off? This is whats happened to this old kit I am updating so its like a build situation with the elevator and stab as two parts. Options are limited due to the thickness of the surfaces which is under 3mm.  Blenderm, diamond, electrical tape is too floppy to hold the spring  in place.  Mylar strip glued to one side is one option but the glue choice is limited as the material is an epoxy coated foam. Option 2 build a new horizontal stab from balsa or buy a new or used stab from another model?

 

[f3fman]

9 hours ago, BigT said:

How about if the whole of the elevator gets broken off? This is whats happened to this old kit I am updating so its like a build situation with the elevator and stab as two parts. Options are limited due to the thickness of the surfaces which is under 3mm.  Blenderm, diamond, electrical tape is too floppy to hold the spring  in place.  Mylar strip glued to one side is one option but the glue choice is limited as the material is an epoxy coated foam. Option 2 build a new horizontal stab from balsa or buy a new or used stab from another model?

 

If you mean that a tape hinge  is giving you a floppy hinge line then can you do what I call "piano hingeing" where you do maybe 3 sections of alternately double sided tape that ends up going from top surface to bottom surface then bottom to top, then you do the normal top tape hinge and normal bottom hinge over the top of the double sided tape.

It's a bit like doing the old fashioned sewn hinges

[BigT]

I did think of that method and sewing a hing. What happened was that the elevator joint just cracked off due to age. (10 plus year old unstarted kit). The elevator could not be used as it was just too flimsy. So I have made a new elevator from balsa which is actually the same weight as the foam one even after a light glassing.  As I need a hinge that will allow a spring I have decided to go with an old school method. Two strips of solartex sewn glue side to glue side, backing removed and then heated onto the the top side of the stab and elevator. The elevator then folded over 180 deg and the underside then the lower strip heated onto the underside of the stab and elevator.  This should be well strong enough. I have used this on big 7KG plus gassers. The advantage is that if the hinge becomes loose it’s dead easy to either replace or reheat. 

[BigT]

BTW I am actually loving getting back into the workshop and modding and modernising this model. When this was first produced 3 d printers where like fiction, getting 2 kg pull from a sub micro Servo was impossible, sprung control surfaces  had not been invented, FrSky Taranis was not invented.