ARTF's - covering materials

[Terry Mason]

I have had two incidents with wing covering materials coming off or loosening in flight - one model total right off, the other survived. The first was a Blackhorse Diablo. On a low mid speed pass the stbd wing covering ahead of the main spar came off. The wing is not balsa sheeted so it 'opened up the wing ' on one side - result was a violent roll/yaw and straight into the ground. As it did so the strip of covering material fluttered to the ground ! Needless to say the damage was extensive. The model had only flown about ten flights.
The second was a World models Zen90. Normally I consider World Models ARTF's to be of a very high standard. A decorative strip covering one wing from the leading edge to about on quarter chord lifted over 90% of it's length - only remaining attached at the root and the tip of the wing. As it lifted it caused a yaw and a very strange noise. The wing of this model is sheeted. The effect was worrying but a hasty landing was executed successfully.
This model had less than 10 flts. Neither model had been kept in hot or damp conditions. Regularly checks on any model are of course a must but may I suggest you pay particular attention to the covering - perhaps see if it lifts if you delicately try sliding a knife under the edge of the material to see if it is loose - it was not at all easy to spot on the Zen.
Has anybody else had this experience ? If so, what model ?

[winchweight]

'Fraid not. My only experience of ARTF covering was trying to remove the covering of a VNH Mustang. Nightmare! It is self adhesive and horrible to remove. Incredibly sticky and ripped as soon as you looked at it. i'm staggered it came off yours in flight.

Oh.... sorry to hear about the Diablo

[flytilbroke]

I have had this experience of peeling covering, not lost a model tho`, and from observing other fliers we are not alone. The Blackhorse sticky covering is not a good experience when repair is required. I had a Travelair which did a lot of flying though mostly after being repaired and recovered with Solarfilm. The big problem was getting the Blachorse glue off of the woodwork. (can we get a swearword smiley?)

[Antony Wright]

I must admit as I look at my Arising Star the covering is becoming more wrinkled the more it flies. Ive run the iron over a few spots already.

[Terry Mason]

For Shaun - yes that covering is a pain ! It is fairly thick, very sticky and I think if I remember correctly it is not shrinkable with a hot iron. On my two models the material is different - it was conventional covering that can be reattached with a hot iron and also shrunk. Maybe the extra sticky type does have some advantages !!

[Chris Dickens]

DONT TRUST THE COVERING ON ANY ARTF
I do a fair number of reviews of ARTFs and I alway go over the entire model with an iron sealing all the joints, sticking down the trim, and tightening it all up before I start the construction, then I check the joints again and reseal before I fly. even so I have lost the occasional piece of trim but never enough to loose a model.

The better kits do tell you to do this but some of the cheaper one do not.

With all film covered models (even ones you have covered yourself) make checking all the covering joints part of your post flying session checks and reseal any bad joints before the next session.

[Diamond Geezer]

Hi Chris
Hear what your saying but have had trouble trying to reseal joints due to fuel under the film,as I'm pretty new to thissome of my planes are second hand,and could do with resealing,and what about that solar film how do you get it off?

[flytilbroke]

Some artf model brands tend to use a sticky type film which is not very good when trying to re-stick. It also leaves it`s adhesive on the wood when it is removed, causing the problem of replacement by conventional heatshrink not sticking. Dont leave the edges raised and soaking up oil, clean them inside and out, with raw Meth then apply solarlac under raised edge, allow some time to dry then use heat iron to seal. The sealed edges can be "painted" with Solarlac to help prevent lifting

The sticky back stuff can be patched with care, using lowest possible heat on conventional shrink film, low heat as the sticky stuff melts rather than shrink.

With proper heat shrink covered models do the same, the main difference is that it can be recovered or patched much easier.

If the wood is oiled at the edges of the covering a big overlap patch can be applied with some success.

With heat shrink remove by heating the contact surface and peeling gently, only doing a small area at a time.

[Chris Dickens]

I agree with most of what flytibroke has said, but as usual everybody has their own techniques. for oily joints that have lifted I clean them up and degease them with acetone or cellelouse thinners then apply Prymol (solarfilms etch primer) then iron back down, if it doesnt stick then I will give it a coat of solarlac and iron down again.

To remove film I use the reverse of putting it on - iron over a small section of a joint until it is hot and the glue is soft then using a knife blade lift the edge. Once you have a lifted edge iron a small area away from the joint and lift the film from the surface. The idea is that you must get the glue layer soft enough to release it from the surface below if you do not then when you lift the film it will, usually, leave the glue and colour layers still attached to the model. any glue still on the surface after removing the film can be removed with celelouse thinners.

[Diamond Geezer]

chris
thanks for the reply but cellulose thinners i don't think so, tell you why,thought i would use cellulose thinners on my built up hi boy wing,as i said being a newbie, thought this would be a good idea ,like yourself, but it seeped through the veneer and melted the foam inside, disaster, took me ages to repair it.

[Chris Dickens]

True, if you brush thinners on to a veneered foam wing then there is a good chance it will seep through the venerer and attack the foam, but I just use a rag with some thinners on it to wipe the glue from the surface, assuming that you are not doing it outside on a cold day it will evaporate before it penetrates the veneer. I did melt a wing 30 years ago on my first attempt just like you did but since I learnt the correct technique I have had absolutly no problems.

[Lee Sheppard]

Yes i had it with a Great Planes Venus 40 with the covering on the left wing this was on the first flight. I went all over the model with a iron. I did got the model down ok. The covering on all Great Planes model is MonoKote and i would not say it is the best in my books. I used Balsaloc in the end to keep it there. And i have had no more problems with the model.

[arthur bishop]

yes Anthony,my Arising Star also wrinkles whenever it feels like it, I must admit I am really disappointed with it and I havent even flown the thing yet,still I suppose it was a monday morning manufactured kit.