Repairing Acrowot Wing Pins, help!

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[uhf]

Hi,

Firstly, my experience in model building it limited to gluing together my first Ready 2, aside from that I know nothing, the Acrowot came pre-built

Its had a number of good flights but I suspect that from taxi'ing on heavy ground the wing pins have been persuaded loose.

Currently I can push both of them almost all the way into the wing so its definately not flyable, a few times I have managed to get them to stay put with a drop of cyno but this is far from a perfect and long term solution.

So, i'm after advice on how to fix them, does it involve stripping the centre part of the wing down, re-gluing and reassembling?  the wing appears to be covered in fibreglass strips.  I have no idea how the wings are consructed internally so a bit of knowledge in advance will safe me sripping things I dont need to.

Thanks in advance

Dave

[Chippie]

Re-securing the wing dowels(pins) is best done with epoxy....Cyano is definitely a no-no...The wing is made from foam and the cyano will melt it!

[BridlingtonFlyer]

Personnally I'd pull the pins out they are only glued into the foam core.  I'd then try to scrape the foam so you have a nice clean hollow.  Then use an expanding glue such as gorrilla glue to stick some balsa blocks in the cavity.  Let it go off then re-drill holes into the blocks and hopefully into some more foam if you can drill deep enough.  Then fit some new longer wing dowels.

Hope this helps

[uhf]

 , this might explain why they are looser this week :(

Do i need to strip the wing to secure them properly or is there a cunning technique required to squeeze the epoxy between the dowel and the wing itself?  i feel that i need to get it in the hoel rather than around it (oh er).

[uhf]

btw, i like the sound of clearing it out and making it stronger with balsa blocks, not one for this weekend tho, i'm going to fly my ready and fixup the acrowot mid week, thanks

[alan c]

This needs investigation,   i suspect that the cyno you have used has erroded the foam round the dowels,  only cure could be surgery, that being to cut out the bad foam, and fit a balsa block,  i suspect you are not up to this, so i would seek help in your club,   

[uhf]

advice and caution understood, thanks.

I've pulled the pins and they were indeed clean from foam up to about half an inch inside from the edge of the wing, further than that they were covered in foam.

The idea with the blocks sounds like a plan, but I might take it one step further, the dowels are about 3" long of which the last half an inch pertrudes to go into the holes model, I think i'll construct a 2.5" long block to fill the void, recess the dowell in it, leaving half an inch of dowel sticking out of the leading edge.  Epoxy around the block should give it a lot more strength and surface area to bind to the foam.  sound like a plan?

[Michael_Rolls]

advice and caution understood, thanks.

I've pulled the pins and they were indeed clean from foam up to about half an inch inside from the edge of the wing, further than that they were covered in foam.

The idea with the blocks sounds like a plan, but I might take it one step further, the dowels are about 3" long of which the last half an inch pertrudes to go into the holes model, I think i'll construct a 2.5" long block to fill the void, recess the dowell in it, leaving half an inch of dowel sticking out of the leading edge.  Epoxy around the block should give it a lot more strength and surface area to bind to the foam.  sound like a plan?

Yes, but it would be easier to ensure that they line up correctly by gluing in the block without them, offering the wing up to the bulkhead and use that as a jig to ensure that the dowels go in absolutely the right place.
HTH
Mike

[Neil Ivanovich]

UHF,

I would amplify one of my colleagues comments about Gorilla Glue. It is rock solid, and, a side benefit is that its foaming action will fill any small gaps. (its also very easy to clean off, let it dry and chip it away very easily)

just make sure you wear gloves. I get a rash when I get it on my skin...to make things worse, I once went for a tinkle and....well...work it out yourself 

[Patmac]

UHF,

I would amplify one of my colleagues comments about Gorilla Glue. It is rock solid, and, a side benefit is that its foaming action will fill any small gaps. (its also very easy to clean off, let it dry and chip it away very easily)

just make sure you wear gloves. I get a rash when I get it on my skin...to make things worse, I once went for a tinkle and....well...work it out yourself 

Is Gorilla glue polystyrene foam friendly ?

Pat.

[Neil Ivanovich]

Is Gorilla glue polystyrene foam friendly ?

Pat.

Give it 24 hrs to set and I'll tell you !!!

[GASPIN]

One method which works well, is to let in a peice of ply 1/32 or 1/16 about 1 1/2" back from the leading edge where the foam is undisturbed, just cut a slit chordwise with a Stanley knife right through both skins of the wing about 3" long. Glue up the ply with eoxy and push through the slot until it just protrudes on each side. Sand off flush when dry. Gently drll out the ply using the holes through the leading edge as a template, glue up the dowels with epoxy and push through the foam and throuh the holes in the ply.
If required place some balsa reinforcing behind the leading edge to stabilise this end of the dowels, but if the leading edge is in reasonable condition its not really required.
Gaspin 

[Geoff_Sleath]

Is Gorilla glue polystyrene foam friendly ?

Pat.

I don't know about Gorilla Glue, but Falcon Foam (which I think is the same, or similar) is excellent on foam.

Geoff

[Pup Cam]

I don't know about Gorilla Glue, but Falcon Foam (which I think is the same, or similar) is excellent on foam.

Geoff

And Wudcare

Alan B

[The Doc]

I had to perform the gut away and add balsa trick on one of my acrowots.  I just attacked it with a hacksaw to remove the decayed foam then built up the "block" with 1/4 hard basla sheet secured with aliphatic wood glue.  I then sanded back to the shape of the wing and recovered.  To find the position of the dowels I covered the dowel plate on the fuselage with paper and cut out where the holes were.  I also taped come paper to the front of the wing.  Then I painted around the holes with a liberal coat of paint and then offered up the wing.  The impression of the hole is then transferred to the paper on the wing and you know ecactly where to drill for your dowels.

On the other hand that all takes time, time which could be used to build something like this...

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