Scale Soaring UK

B Sharp wrote: ↑01 Jun 2021, 15:25
'.....................There will be no further posts for a little while as I am heading off to rediscover the very north of my country'

Brian.

Brian, I think I can put your mind at rest there and save you quite a journey - it's still there (nice to see John's Oly getting a new lease of life - seen a few campaigns has that one).

Thanks Robbie, I'm going to do my best to do it justice. I just hope that I don't scare the pants off John in the process.
Brian.

When I returned from my vacation in the far north I was delighted to find that a large roll of Diacov1000 had been delivered.
As I had never used this material before, and there were no application instructions, I decided to try a couple of test pieces. I found it was better to use a higher heat setting than usual, around 140deg. I started on the left tailplane section and found the Diacov went onto the bare timber very well and was exceptionally pliant around the compound curves at the wing tips. I have now completely covered all the tailplane components and shrunk tight the open sections. I still have to fix the trim tabs back onto the rear of each tailplane half but I am very happy with the end results so far.
I will be leaving them unpainted until the rest of the wings are repaired and covered as I want to see if any bubbles appear in the covering and whether it all stays taught.
Brian.

The left wing is now completely stripped of paint and the underlying layer of tissue and is now a bare wood surface.

I started the repairs with a skin insert over the existing aileron servo hatch. I was pleased with the result and it will only require a minimum of filler to provide a smooth surface for covering.

I have been contemplating the best method to re-skin the long cut-out in the leading edge sheeting. The difficulty is matching up the existing 1/64 ply edges with a new 1/64 ply patch. Sitting with a glass of Scottish Falling Down juice the other evening I came up with a “cunning plan” (thanks Baldrick). The rear edge of the patch would be supported with balsa inserts located between the ribs and under the edge of the existing wing skin. The 1/64 patch would have plywood tongues at the front edge to slot under the existing front skinning. I made up a test piece of 1/64 patch material and fitted it into place where it was a very accurate fit – problem solved.

So today I will set about cutting out the remaining patches.

Brian.

As the aileron servos are to be mounted out in the wing close to the aileron itself I decided to reinforce the upper wing skins inside the servo hatches. I don’t want the 1/64 ply wing skin buckling when the servo arm moves. I lined the ply skins inside each servo bay with two layers of fibreglass mat wetted out with polyester resin. This will now give a firm surface for the servo mounting blocks.

The underside leading edge hole has now been closed with a long 1/64 ply patch. I have used aliphatic resin spread on the ribs, balsa supports and the plywood tabs on the patch to glue everything in place. The location tabs seem to be successfully holding the front edge of the patch in line with the existing wing skin while the rear is pinned to the balsa supports.

This means that all of the holes in the underside of the wing (apart from the servo hatches) have been successfully repaired.

Brian.

After the glue had set I gave the big long patch a sanding back and then filled any irregularities with Ronseal wood filler. After the filler had hardened I sanded it back until I had the profile I wanted over this area. I have to say that I am very pleased with the final finish and I suspect that when the wing is covered and painted the scars will be hardly noticeable. The wings will have a wibbly wobbly surface, but that’s how very old wings look in real life.
I still have the servo bays to finish off and that work will be completed when the new servos arrive. I don’t intend to cover the wing as yet as I want the left wing up to a similar point before applying the ‘tex’.
In the meantime I still have to sort out a new hinging solution for the ailerons and cut new aileron horns from 2mm epoxyboard.
Brian.

I am now working on the left hand wing and I am nearly finished the paint and tissue stripping process. If anyone ever tells you that restoration work is glamorous you have my permission to put them right. I am up to my elbows in gunk and my workshop stinks to high heaven. (please see the attached image.

However, in-between applying paint stripper and scraping sessions, I have manufactured four identical aileron horns from 2mm epoxy-board. I find this a pleasant and soothing process except that you must wear a good mask while sawing and filing epoxy-board as the dust will do your lungs no good at all.

Brian

I have now cleaned up the left wing, removing all the paint and the underlying tissue before giving it a light sanding. This wing is rather more patched than the right wing, especially on the underside at the root. I have also discovered that the 1/64 ply sheeting has detached from the ribs in a couple of locations leaving the skin buckled and loose. After some thought I can see three options available to me .
1. Ignore it and hope that the wing is not substantially weakened.
2. Re-attach the sheeting in some way – I’m not sure how as yet.
3. Remove all the sheeting and various patches and re-skin the whole of the inner portion of the wing underside.

I would not be happy with ignoring the problem as I would always be a bit nervous when flying the model.
Stripping back and replacing all the sheeting is a major job, plus I want to keep as much of the original model as possible.
As to re-attaching the skin to the ribs? Any suggestions would be appreciated.

One other problem is that the airbrakes (when fully closed) protrude from the wings top and bottom by about 3/32 inch. No amount of opening and shutting them gets them flush with the wing surface.

While I have been pondering these issues I turned my attention to ‘Fred the pilot’.
I want to reuse Fred when the model is complete as he is part of the character of the model. Unfortunately he is suffering from old age and the material of his head has started to degrade in places and leaving gaping holes. I decided major reconstructive surgery was in order. I donned my scrubs and facemask and started to reconstruct his jaw and forehead. Once I am happy that he has healed he will get a little touch-up with a paint brush.

Brian.

Help comes from the most unexpected places sometimes. My little wifey saw my dejected face and asked what the problem was. I showed her the wing and her reaction was – Easy, remove all the affected area and put a new piece in. She obviously had a higher opinion of my capabilities than I did!
So I set to and removed all of the skinning from the wing root and I have cut a single piece of 1/64 ply to cover the resultant massive hole.

It’s amazing what you learn when you expose and area like this. I was surprised to find that several bays were as black as a coal cellar. On further inspection I discovered that there must have been a carbon rod joiner at one time which had been subsequently cut away and replaced with a similarly sized steel bar.

Brian.

Hi Brian, John is more than happy to see his model getting another lease of life in your hands. He recalled 1 flight going vertically out of sight in a strong thermal. After doing several hundred loops and flying with air brakes out, he landed the Oly and found it had gained a few degrees more dihedral! It maybe well worth while checking it before boxing the wing root in again.... Paul