Old models/old glue?

[Paul Jefferies]

Hi Folks,

I am trying to get back into model flying after a twenty six year layoff. I used to fly aerobatics (or tried to!), my last Nats was in 1987. It is nice to see that there is still an interest in the old designs and that some of the "old faces" are still around......... and still building beautiful models Terry!

I still have the model I flew in 1987 but I have not flown it mainly because I am a bit nervous about the strength of the glue after all these years! It was built using both cyano and PVA. So I am prompted to ask....... Has anybody flow an aerobatic model of this age? It needs a little TLC but if I did refurbish it, could I expect it to hang together when I start pulling G?

Paul Jefferies

["L"Plate]

I have flown trainers that are that old and pulled some "G" with them. The PVA glue appears to stand the test of time, the CA of that time though is less predictable as is the epoxy.

If it is film covered it might be worth removing it and using some fresh CA and check it out before recovering. I have found the old film after being stored for some time and exposed to sun light tends to separate from the glue/colour fairly easily especially along the edges and the outer clear film gets a bit brittle.

[ken anderson.]

hello Paul-I'm flying a model made in 1991...cyno/pva and 5 min epoxy......it's in better nick than I am.....

ken Anderson ne...1 ........ 1991 dept.

[Shaunie]

Funny you should mention it...

I'm flying an early funfly plane, a Dare-U, which I built around 1991. Re-engined it with a TT 46 Pro (according to the instructions far too much engine) about 2 years ago. It has +/- 45deg control throws, was built with cyano and the wings are still on it! If its been kept in reasonable conditions I wouldn't worry too much.

Shaunie.

[Mark Agate]

Fun 3: wings built in 1980 from foam core and obeche veneer, using Copydex glue. Fuselage was rebuilt in about 1984 from balsa/PVA, and this is the one it's still flying with. It had about 20 years sat in a loft getting extremes of temperature, but is now flown quite regularly & aerobatted fairly violently (flick rolls etc).

[Bob Cotsford]

I don't know when my 70s design Marabu was built but it's still hanging together despite my best efforts, as is my Veron 1 1/2 Strutter built in 1980, and when I routinely splat my mid-80s Acrowot it's the wood that breaks, not the joints.

[Paul Jefferies]

Thanks chaps for these replies. It was a good model so I will try to refurbish it. I have another project on the bench at the moment...... I will let you know how it goes "in the fullness of time".

["L"Plate]

What model is it? Is it open frame structure or foam wing? Post a picture Paul.

[Paul Jefferies]

It was (still is!) an own design with balsa skinned foam wings and a balsa and ply fus. OPS .60 rear exhaust + pipe.

It was called "Symphony No.3" but I don't have any pics. I will dig it out and iron it (Solarfilm has gone a bit wrinkly!) and post a pic in the not too distant future.

["L"Plate]

Well with that structure it should be fine to fly as soon as you de-wrinkle the covering. Sounds realy interesting, I always love own designs as they often depart from standards or fashion of the time and help to test ideas (good or bad), always an oppertunity to learn.

[Paul Jefferies]

This is she..... freshly ironed! It is suffering a bit of "Hanger rash" (or perhaps I should call it loft rash) and I have found some delamination between the fuselage sides and ply doublers which I think should be repairable but apart from that and the fact that the engine needs de-gumming I think it could fly again. I think the thing to do will be to take it over an open piece of land where there is nothing to hit and do a few flick rolls and if it survives that then I think we can assume that the glue is still ok. From other parts of this forum I see that the cutoff date for "Classic" models is 1986........ This flew in the 1987 season but was designed and built during the winter of 1986/7. Does that qualify?

["L"Plate]

Very nice classic 80's. Like the cockpit and cowl.

If you can drill into the ply doubler fron the inside then use slow CA and clamp it you might get around the delamination. I would think it would hold together Okay, it tends to be engine firewalls that suffer the most with fuel soaking; if you did a good job on that when you first built it (and looking at the photo you did a good job on the rest) than that should be fine. Good luck with the air test.

I am sure you wouldn't do this (other might), but I have been told of others who have not changed RX switches on test such as this and had problems with the old black wire even some chap who thought the batteries would still be good, shame two old models lost from the accounts I was given.

[Terence Moore]

What a very nice lookinh model, look forward to hearinng how it flies in the new season. Are you intending to update the radio gear?

Terry M

[Steve Dunning]

Hi Paul

The idea behind the '86 cut-off was to try and make sure that only '60 size models were used. As Algy say's, a classic looking model. Come and join the fun in 2014, I'm sure you'll remember a lot of the fliers from that era.

Seasonal wishes to all

Steve D

[Paul Jefferies]

Many thanks for your comments and suggestions all. I had more or less accepted that this model would never fly again but you have at least prompted me to have a closer look at it and yes, I will have a go at refurbishing it.

I have invested in a 2.4Ghz outfit so yes, I will upgrade the radio though the old servos (JR 4002) were fairly good in their day and still seem OK. I will have a good look at the switch harness and yes, probably replace that too. I think one of the most difficult things to refurbish is likely to be the Rom-air retracts...... All the plastic plumbing has gone crisp and some has even snapped off! 'don't yet know about seals etc.

As I said in an earlier post, I have another project on the bench at the moment but 2014 promises to be an interesting year........ Happy New Year one and all!

[Edited at Poster's request]

Edited By Biggles' Elder Brother - Moderator on 27/12/2013 18:48:45

["L"Plate]

Hi Paul,

I would definitely replace the switch, they are so cheap compared to a model, as for the retracts new air pipe shouldn't be too much of a problem, as you say the seals might be past their best in the retract units. I have some spring air retracts that are of the same sort of age and they are still working but with my new builds I now use electric retracts, they appear more reliable and fit in the same space as the old air retracts and only need servo leads running to them.

Come on you have to get it back in the air, a model actually for the classic period. I wish my Merlin was in a condition that allowed refurbishment but it is past that.

[Peter Android]

Your Model looks very nice , in a cool - classical way . be a shame not to fettle it and fly , even I can see that colour . just.

I keep reading mention of electric retracts : would appreciate any info please from those in the know ? or are they mentioned elsewhere in the Forum ?

Cheers.

["L"Plate]

Hi Peter,

There are a few companys that produce electric retracts, they are easy to retro fit in the main using simular mounting methods but rather than air just need to be conected to the RX by a "Y" lead, they are slower than spring air retracts in operation (but you don't have the problems with air seals like you can get with air systems, either having the retracts come down in flight or not working leaving you to do a belly landing). All the electric retracts I have tried have worked well, even the cheap ones from Hobby K.

[Peter Android]

Thanks for reply ,

I have only ever used the wire type - linkages - retract servo setup , which often drove me to distraction , but , I ain't the best builder in the world and better geometry may have improved matters ......

Come to think of it, I still have a set of new ripmax type mech's somewhere , and a few unused retract servo's I think.

I don't like the sheer weight of mechanicals either . No experience of using spring / air type ( in models)

Yorkshire instinct ( Scotsman with generosity removed ) thinks use what I have , but the leccies do sound appealing .

Thanks again for info.

[Paul Jefferies]

This thread seemed to come to an end at the end of last year but since it appears to have re-surfaced, an update may be in order.......

I did eventually renovate the model, mostly with judicious use of cyano, a heat gun and a sealing iron. I dismantled and degummed the engine, re-plumbed the tank and fitted electric retracts which slotted neatly into the recesses made originally for the old Rom-Airs. Even the screw holes were in the right place! The disadvantage of the electric retracts is that they require a second battery and a second switch which proved a little awkward to locate without affecting the CG. However you don't need a dedicated servo so whilst they do work out heavier, not significantly so. Yes, I did replace the original switch even though the old one still seemed OK.

I heeded the advice not to use the old MK glass props, even though I still have a couple of unused ones. I used an original OPS 12x7 wooden prop and the original Burley tuned pipe and I am pleased to say that the engine absolutely sang........ It was music to the ears though I did later have a couple of engine cuts when recovering from long downward verticals which I can only assume were caused by the clunk weight coming out of the fuel, but it never had that problem "back in the day".

I haven't flown it a lot, maybe 15 or 20 flights as it is elderly and I want to keep it in one piece for "Classic" events. However it flies just as straight as ever it did and the airframe has hung together through all normal manoeuvres. The only "age-related" problem was in (I think) the second flight when there was a stange rumbling sound so I landed immediately and found that despite having been carefully reheated and sealed, the black Solarfilm ouboard panel had started peeling off one of the wing tips. I removed the rest of it and replaced it with new Solarfilm and also did the other side as a precaution and there have been no further problems.

So thanks to all for your advice and encouragement, it was a worthwhile exercise with a happy outcome!

Paul

[Peter Android]

Well intentioned restorations are never normally dull , and make very interesting reading . thank - you.

Q."Literature is strewn with the wreckage of those who have minded beyond reason the opinion of others."
- Virginia Woolf