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oipigface

How to unplug sticky wings?

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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?

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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

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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?

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pete beadle

Hi OPF

WoW! after all this time it's still salvageable.......result!

The usual problem with planes that have been lost in forests/brambles/long grass and weeds etc is that, by being heated and cooled every day it's outdoors, moisture has got in to everything, especially all the bits that have been exposed to the elements for any length of time

In the good old days it was rust that did the damage but, these days it's surfaces exposed to water ingress that the plane has been protected against all its life

First thing to do is get some padded oven gloves, then put everything in a warm and stable environment to dry out, airing cupboard, boiler room, anywhere warm and DRY and well ventilated.

Have you got wing bags? When the airframe is 100% dry put the wings back in the bags and don't work on them anywhere there is the slightest bit cold or damp

First job is to get the wings off their wing joiners. Never handle any surface without the protection of the oven gloves and DON'T try any thing metal  to attempt  prising  anything apart with. Get a friend to hold the fuselage while you try sharp tugs on the wing panels. If that doesn't work at all take the plane back into the airing cupboard/boiler room again, preferably twice. If the wings move AT ALL you've done it, its just persistence then, if not, do whatever someone else suggests OK?

Good luck

Regards

Pete

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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.

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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. 

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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 😱.

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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.

 

 

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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.

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pete beadle

Hi OPF

Yes, what you've done so far is to break the grip of the dust  and nastiness that is acting as an adhesive between the joiner and the walls of the joiner box

I know it's thinking a long way ahead but, when you do get the joiner out (tomorrow?) I would sand a millimetre or so off the faces of the joiner, then re-instate the shininess of the joiner's surfaces with a little spray-on furniture polish.......it's what I do to any model where I can feel resistance to removing the joiner......it doesn't affect that lovely pop you hear when the  joiner come out of the joiner box, but it does prevent this sort of thing happening again

Best of luck

Regards

Pete

BARCS1702

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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.

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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.

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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.

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pete beadle

Hi all

Personally I have never seen any type of corrosion in any incidence pins, the ones that are steel, or the ones that aren't, are usually chromed, plus the pins are usually simply a friction fit in the fuselage and wing mouldings, so even if they were jammed they should only be jammed on one side

I also think the power exerted by OPG's planks levering the wing/fuselage apart would seem more than enough to separate pins not glued in place

Moulded carbon joiners are inert so there's no reason for them to expand, or contract, so, hopefully that shouldn't actually be happening......the only other thing that I would suggest you try, is not try to pull the wings and fuselage apart smoothly, but to somehow to apply the force in a jerking manner

Something I haven't suggested yet is WD40, might that help do you think?

Once again, the very best of luck in your endeavours chaps:yes:

Regards

Pete

BARCS1702

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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.  

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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. 

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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.

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pete beadle

Good Lord Mike!

If that is truly a plan warranting consideration I think I'd be putting it so far down the line it would come after "Give up and leave it!"

For example, just one of the ideas not floated yet would be to approach one of the moulded model manufacturers and ask them for suggestions, or perhaps a UK manufacturer making precision moulded one-off parts......they have engineers that are specialists in solving problems like this, and have high-tech tools and things like X-ray scanners and ultrasonic checking equipment used in the manufacture for Formula One cars or prototype aircraft for example.....anybody know one?

No, breaking something to make the repair easier is, to me, a bit like that saying "the operation was successful but the patient died" I hope OPF is still a long way from  acting on a suggestion like that.........I mean, let's be objective, the easiest answer is just to buy another one innit! Come on, who's up for the challenge!

Any development engineers or makers of one-off and prototype parts with access to specialist checking equipment out there that just happen to be model flyers?

Regards

Pete

BARCS1702

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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. 

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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. 

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