How to unplug sticky wings?

[oipigface]

Some of you may remember the day about 7 years ago when I lost my new purple and green Extreme in the forest at the back of Mickey's West. It was by some degrees the strongest wind I had ever tried to fly in, and the plane wasn't heavy enough, nor its pilot experienced enough to avoid it blowing back over the trees, where it wound up almost half a mile away in the middle of a dense Forestry Commission plantation. I know now where it landed because it was found last weekend, by a local resident out on his motorbike trying out a new track that the Forestry Commission cut recently. Not only a biker, but a bit of a flyer himself, he contacted the right people and I went to pick it up yesterday. Thanks to him, Andrzej and Clive.

You wouldn't expect after that amount of time that there would be much left of it, but the wings and the fuselage seem at first sight to be in quite good nick. The boom is broken, and there's a tear in the starboard wing LE, but the structure seems fine. I haven't checked the servos yet, and the tailplanes are a different matter. I suspect that they would be OK to fly again, but the skin has sagged around the substructure, so the section is very far from accurate.

The main problem I'm confronted with at the moment is that I can't get the wings off! Has anyone any idea how I might tackle this? The port wing root has had copious amounts of WD40 squirted on it, and has moved about 1mm. I don't want to try forcing them off with a screwdriver because at the moment both wing roots are undamaged, and I'd like to keep them that way. I don't know if heating would help or make matters worse, and it runs the risk of damaging the skins as well. The best I can think of is to put some kind of expanding device (like a printer's quern) between the root and the fus and see if it will ease it off. I don't know of any such device that would fit into a 1mm gap. A wedge system may do the trick as well. It is also possible that just leaving it to dry out will do the trick.

Any ideas?

[SilentPilot]

I’ve had luck separating tail halves that had seized by freezing them. The idea was to try contract the joiner so they would slide off. 

It seemed to work!

When it comes to removing wings obviously freezing isn’t an option unless you work at a place with walk in freezers (I do btw!). I’ve used butter knives or pallet knives to slide in the gap and try work it apart. Even when deliberately using blunt knives care has to be taken not to damage the surfaces. 

 

Tony

[satinet]

Cutting the wires near the wing servos might be a good idea. I assume the green connectors will be rusted together and cause this problem. 

Plastic wedge if needed?

[Phil.Taylor]

Big congratulations on getting the plane back !

Getting the wings off - I suggest wide thin wedges - maybe an inch or two wide ply - a couple of them. Also - if you can get it in - thin ply either side of the wedge so the wedge isn't acting directly on the wing.

Thinking about what might be stuck - its probably the steel incidence pins that are corroded into the holes in the fus & causing the sticking - maybe more WD40 where those pins are?

(maybe as a last resort surgery on the fus to get at those pins? - fus is easier to rebuild than the wing root !)

Good luck !

Phil.

[satinet]

54 minutes ago, Phil.Taylor said:

Big congratulations on getting the plane back !

Getting the wings off - I suggest wide thin wedges - maybe an inch or two wide ply - a couple of them. Also - if you can get it in - thin ply either side of the wedge so the wedge isn't acting directly on the wing.

Thinking about what might be stuck - its probably the steel incidence pins that are corroded into the holes in the fus & causing the sticking - maybe more WD40 where those pins are?

(maybe as a last resort surgery on the fus to get at those pins? - fus is easier to rebuild than the wing root !)

Good luck !

Phil.

Could be the pins but they were stainless as i recall. Might be a job to get the wings off if it is. Least it won't be metal on metal though. 

[George Young]

Hmm..

I am wondering about improvising a small slide-hammer from a length of rod with a hook on one end and a stop on the other with a drilled metal weight sliding on the rod. Then apply gaffer or glass-fibre tape to top and bottom of a wing extending past the wingtip and form a loop beyond the wingtip. Hook the improvised slide hammer onto the loop, hold onto the fuselage and use the sliding weight against the stop to try to free the wing. Too brutal? Probably! There may be issues taking the tape off again and not removing paint!

Just a thought .

[oipigface]

On ‎10‎/‎11‎/‎2018 at 19:04, pete beadle said:

If the wings move AT ALL you've done it,

If you are right then I've done it!

After several hours building an apparatus from old greenhouse shelving, some scrap plywood, four 2x2x2 wood blocks, more than 60 screws and two screw clamps, the gap between the wing and the fus is about 0.5mm  greater than it was!

The greenhouse shelving is about 1/2mm thick, so two thicknesses just fit into the gap that we were able to create just by pulling manually. The rest of the bits are put together in such a way that force is applied by the shelving at right angles to the wing root, pushing the fus away from the wing root and the pulling the wing away from the fus. (I'll post some photos if I ever get a design that works successfully.)

I stopped when the plywood started to twist and make ominous cracking noises, so I've added some reinforcement, and will try again tomorrow when the glue should be dry.

As far as I can tell I've not damaged anything yet.

What's curious about it is the first 1mm was quite easy to achieve. Usually one would expect any movement to be a good sign, but this one just seems to get tighter as it's pulled out, almost as if the joiner is fatter at its ends.

 

 

[Phil.Taylor]

Well it is progress !

Anyone got an endoscope or similar inspection device to look down inside the fus by the wing roots?

Phil.

[oipigface]

1 hour ago, Phil.Taylor said:

Well it is progress !

Anyone got an endoscope or similar inspection device to look down inside the fus by the wing roots?

Phil.

I've got an endoscope, but I'm not sure what you think I could see in the fus that would cast light on what is going on in the joiner boxes.

[Phil.Taylor]

2 hours ago, oipigface said:

I've got an endoscope, but I'm not sure what you think I could see in the fus that would cast light on what is going on in the joiner boxes.

I don't think the main joiner boxes are the problem - I still think it's the incidence pins - corroded/expanded at the inner fus end so they won't come out. 

Phil.

[Kyri]

What about getting enough gap between fuz and wing (you might have that already) to get a dremel disc to grind through the pins. Then the remains can be drilled out. Or even tapped into the wing and fuz to maintain the integrity of the holes in which you can put new pins.

[oipigface]

Actually Pete, It's hard to tell how much of the force is being transmitted to the wing. The metal that goes down in between wing and fuselage is being deformed, and so are the 'planks'. I've devised a system of steel runners to try to stop this tendency, but I'm not going to be able to try it until Monday at the earliest - I'm going flying three days in a row at the weekend!

I can see the incidence pins and they have clearly moved. Whether the movement was in the wing or the fus, I can't tell. I have also been able now to cut the MX plug in two with a hacksaw blade, so that's not a problem. WD40? I've put a gallon of the stuff on it, but it is almost impossible to direct it. If it is the joiner that's jammed, then it's hard to know how it would penetrate, even if it were being squirted in the right direction.  

[isoaritfirst]

Radical plan.

slice through the bottom of the fuselage with a dremel grinding wheel then insert hacksaw blade and saw through the centre of the joiner. 

This should leave you with a small amount of joiner still protruding from the wing root. 

Ckamp that in a solid vice and tap the wing root with some type of drift. 

Ypu will of course need to be able to get a new wing joiner. 

Fus repair is simple of course. 

[oipigface]

Thanks, Mike. I hadn't thought of that. Let's hope that a less destructive method works soon. George's 'hammer' is still a possibility, although if I understand it correctly, it too will need something thin down the joint that is strong enough to withstand the forces without bending. I've been thinking of buying a couple of steel rules. They would certainly be less prone to giving way than my recycled greenhouse staging.

[isoaritfirst]

I don’t see why you think it so drastic Pete. 

Fuselage would be a very simple and quick fix. Possibly simply cramming the cut slot with wetted out carbon tows and a quick rub down before applying a glass cloth patch. 10 minutes plus finishing. 

And if the wing is then able to be knocked off the joiner or worst case the joiner chiselled out leaving a non stressed wing. Job is quick and easy. 

All depends on availability of a new joiner. 

Lots of jobs are better cut back to clean then reworked, rather than fiddling for ever trying not to bite the bullet. 

[isoaritfirst]

Further though once the wing was off if the joiner still fails to move ypu could insert heated up ballast pieces to sweat the joiner a little 

further thought ballast tube may be in the way. So possibly better to acccess through  the top. 

[rwhitt]

I had a joiner stick on a summers day, all the force I could give it wouldn't shift, the other half shouted freezer block from the cool box!....indeed literally seconds and it was loose and off!

I would try the same to see if it would work, if not dry it out for quite a while and then try again

Three days flying on the trot....very nice

[satinet]

I like hitting things with a big hammer

[satinet]

Hows big is the gap, if you can get a piece of wood in either side you could create a kind of reverse press with threaded bar.

 

Although the big questions is how did it go in the car?

[George Young]

7 hours ago, oipigface said:

Thanks, Mike. I hadn't thought of that. Let's hope that a less destructive method works soon. George's 'hammer' is still a possibility, although if I understand it correctly, it too will need something thin down the joint that is strong enough to withstand the forces without bending. I've been thinking of buying a couple of steel rules. They would certainly be less prone to giving way than my recycled greenhouse staging.

John. 

Re. my “slide hammer” suggestion. I am thinking that it would be better to put some lengths of gaffer/glass fibre tape on the opposite wing as well (top and bottom) extending past that tip too and end in another loop. This end could be attached to something immovable. That way the pulling impact force would be through the wing/joiner and not the fuselage. I am still not convinced it is the answer but could be worth a try.