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ARTF tail feathers - what glue do you use

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Megawatt28/05/2019 12:43:34
22 forum posts

Most ARTF instructions say you should use epoxy to fix the tailplane and fin to the fuselage - having removed the film to allow a wood to wood joint. I can't help but think it would be far easier and less messy to use PVA or aliphatic glue instead as we are constantly told that these glues produce a joint stronger than the surrounding wood. However I am very mindful of the tragic fatal accident some years ago where (I believe) a tailplane came adrift of a model and it was noted in the report that the wrong adhesive had been used. Now if I were ever to be in that horrible position I would at least like to think that the same report would say that the model was constructed in accordance with the manufacturers instructions. Does anyone know why they specify Epoxy (gap filling?) and what glue do you use?

Jon - Laser Engines28/05/2019 13:02:19
5510 forum posts
268 photos

It depends on the fit and the way it all goes together. A good cyano bond will be very strong but requires a very tight fit on the parts.

The last one i did was an acrowot xl and i used epoxy as it was a sloppy fit. I put masking tape on the edges of the joint, then used a syringe full of epoxy to make sure i got it into the gap. Some gentle wiggling and prodding got the glue well into the joint so its nice a strong now.

cymaz28/05/2019 13:12:27
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9253 forum posts
1195 photos

30 min epoxy and masking tape on the edges. Also meths will clean off epoxy from the covering nicely.

When glueing the tailplane I sit with it continuously checking it for square and level. You have only one chance to get it right !

Bob Cotsford28/05/2019 14:25:21
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8577 forum posts
477 photos

On several models I've cut out a section of the rudder post using a razor saw so that I could slide the tailplane in from the rear rather than the side, then replaced the missing section. That way I could get a good coat of epoxy on all the surfaces to be joined and not all over the tail. IIRC I did both the Acrowot and WotsWot XLs that way. As Cymaz sais, masking tape to limit the spread of glue and a spirit clean-up.

On smaller models I've wicked CA in and not had a tail fall off - yet!. It does need a good fit though.

Re that accident - wasn't that the one where the covering film hadn't been removed before gluing the rudder in place?

Megawatt28/05/2019 17:30:11
22 forum posts
Re that accident - wasn't that the one where the covering film hadn't been removed before gluing the rudder in place?

Cant find the report right now but I believe you are right - there were other factors too from memory.

paul coleman 128/05/2019 17:38:46
103 forum posts

Im with cymaz,all day long,on his reply.

Bob Cotsford28/05/2019 18:33:08
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8577 forum posts
477 photos
Posted by paul coleman 1 on 28/05/2019 17:38:46:

Im with cymaz,all day long,on his reply.

you using 24 hour epoxy Paul?laugh

paul coleman 128/05/2019 19:28:29
103 forum posts

actually yes bob,,i have read that it can take 24 hours to cure.

cymaz28/05/2019 19:40:57
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9253 forum posts
1195 photos

Look what I found

Ron Gray28/05/2019 20:36:38
2166 forum posts
940 photos

Having previously used epoxy on several ARTF I have now changed to Super Aliphatic where there is a good fit. But I've also experimented with Gorilla glue where the fit wasn't that good and that was / is fine. The only issues I have with cyano is that it isn't waterproof (shouldn't be an issue!) and its not fuel (petrol) proof.

Piers Bowlan29/05/2019 08:31:06
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2141 forum posts
53 photos

With ARTFs I think the problem can be how a strip of covering film can be removed from the tailplane for a good wood-to-wood joint. The edge of a covering iron turned up high, or a soldering iron to melt the covering have been suggested. A new No11 blade in your swan morton can still lightly score the wood beneath the covering, even when used with care. The slightest score across the tailplane can be a stress riser for a future failure. Instructions don't seem to point this out. What do others do?

I have always used 30min epoxy for gluing wooden tailplanes but cyano on foam seems reliable.

Dwain Dibley.29/05/2019 08:46:23
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1504 forum posts
1487 photos

I have always used a blade to remove covering from tailplane/parts to be glued.

I have used epoxy, C.A., and Aliphatic to glue on tailplanes. Most recently aliphatic on the 120, as I didn't want to ruin the Chrome covering. sometimes C.A. can run and spoil things, and epoxy is just messy.

A tip with epoxy...........Once applied, if you heat it with a heat gun it will run and wick into joints, but will then go off quicker.

D.D.

Doc Marten29/05/2019 08:58:12
580 forum posts
7 photos

If I were building from a kit, I'd be using Gorilla wood glue (the white stuff) why should it be different for a ARTF?

Epoxy is heavy in comparison and is overkill for strength, if I need a gap filler then I'd use the standard Gorilla glue (brown stuff).

Cuban829/05/2019 09:47:03
2956 forum posts
1 photos

I use 30 minute epoxy, you get a chance to adjust your work before the glue sets fully and with a quick wipe with meths, the joint cleans up nicely. Weight is minimal considering the little amount used and is really not an issue with anything other than a small model.

On the problem of cutting away covering on ARTFs without damaging the wood below, I've made a reasonable job by lightly scoring the cut line in the covering with a new and very sharp blade then carefully lifting the start of the scoreline and cut the covering against the blade as you go along over the scoreline again. If you can tape a flexible steel rule in position to cut against, that'll help. Needs care without rushing - horses for courses, naturally, but I couldn't imagine burning through the covering with a soldering iron (perhaps with a wire end?) would end up in anything other than tears!

Martin Harris29/05/2019 10:51:06
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9333 forum posts
249 photos

I don't believe the glue type was the critical factor in the unfortunate accident (it wasn't an ARTF IIRC):

Mike Goldby, developments officer for the BMFA, told the inquest: "After the accident the radio equipment was found to be not working. The joints of the plane were very weak because the glue used to stick parts together had been put on after the parts were painted."

A friend was once asked to investigate a complaint to the BMFA of tailplane failure on an ARTF and found a very obvious score mark where the failure had occurred. I do wonder, given the fibrous nature of balsa, whether a very light score would affect the strength significantly - but it's best to avoid any damage of course. I have tended towards the lift and cut method as well but many ARTFs (and my own builds) come with a clear gluing area provided during covering. When I tried the soldering iron method, it did seem to mark the wood underneath so I reverted to my previous method.

Doc Marten29/05/2019 10:55:10
580 forum posts
7 photos

Weight in the tail may be minimal using epoxy but when you apply that minimal weight over an average sized fuselage with the CofG at 1/3rd, that force needs something like 22 times in the nose to balance it. Any weight saving in the tail is wise.

Edited By Doc Marten on 29/05/2019 11:03:35

Paul Marsh29/05/2019 11:16:07
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4025 forum posts
1217 photos

I use epoxy, but warm it up so that it seeps everywhere. Cyano is too brittle and one knock it cracks. Aliphatic is ok, but not the best I think, unless there is lots of contact area.

Martin Harris29/05/2019 12:36:10
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9333 forum posts
249 photos
Posted by Doc Marten on 29/05/2019 10:55:10:

Weight in the tail may be minimal using epoxy but when you apply that minimal weight over an average sized fuselage with the CofG at 1/3rd, that force needs something like 22 times in the nose to balance it. Any weight saving in the tail is wise.

Edited By Doc Marten on 29/05/2019 11:03:35

While I'd agree that excess weight added to the tail is normally best avoided, I'm struggling to recall any models with a 22:1 ratio between the C of G position and tail/nose! It's normally something in the range between 3:1 and 4:1

Edited By Martin Harris on 29/05/2019 12:37:00

Doc Marten29/05/2019 13:00:46
580 forum posts
7 photos

Unless I've worked it out wrong, which is likely as I haven't done Moments of a force since school:

Fuselage length= 32"

CofG= 10" (1/3rd)

Weight added to tail= 0.5g (to keep the maths simple)

Weight needed in nose to balance= 11g

11= 22 x the 0.5g added to the tail.

Even so, more lead in the nose by a quadrupled factor of what was added to the tail is still best avoided

Edited By Doc Marten on 29/05/2019 13:04:28

Martin Harris29/05/2019 14:04:33
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9333 forum posts
249 photos

I think you need to specify the moment arm of the nose weight...say it's positioned 8" forward of the C of G then to balance 0.5g x 22" (not that the glue's centre of mass would be at the extreme) would require (w=11/8) 1.375g of lead.or a ratio of 2.75:1

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