Polecat Rebuild

This was the Ron Broughton Polecat that I got from Phil.

This was the Polecat after I lost the plot after flying on Meio earlier on in the year. 

So now the rebuild begins and I have  stripped the covering from the wing and underneath is laminate film, what some would call, "new stuff". 

So the lam has to come off and then I have to get those creases out as much as possible using the boiling water method. Then using light weight filler to fill in what's left before I recover with glass fibre. 

I need to get some advice because I haven't covered anything before with glass although I do know the technique. But what I want to know is, after rubbing down to a smooth finish, will I be able to cover with iron on film or does it have to be painted? Or even better, is it possible to add colour to the Poly C water based polyurethane, which is what I shall be using instead of epoxy resin. 

If you know the answer to any of these questions, please let me know. 

I shall update this build as I go on but it certainly won't be a quick job, well, I'm

a busy boy you know. 

Catch you next time. 

Steve

** So I've been thinking about this since I wrote this post and as the lam is quite good with no bubbles and fixed securely to the foam, I think I'm just going to stick with the lam and not glass the wing. So I will remove the lam from the wing tip so I can remove and fill the creases, and recover the tips with lam before covering in iron on film.

The fuselage is a different matter. As it has split in two across the wing seat, I think I will glass it to give it additional strength in this area, as it now, it will always be a weak spot.

Thursday 5th November

So I have decided not to glass the wing and to just tidy up the wing as it stands.

So last night I used a heat gun on the laminated foam and most of the smaller creases came out and the larger ones weren't quite so pronounced. So I began filling in all the creases with light weight filler and sanded back.

I don't think I'm going to begin covering the wing until I have completed the repairs on the fuselage and then perform a dry fit.

Friday 6th November

Last night I finished off sanding down the filler on the wing and that is now ready for covering.

So I made a start on the fuselage by using the heat gun on it to loosen the iron on film and the laminate film underneath so that I could strip it back to the bare foam.

Once the covering was off, I used the heat gun on the bare foam around the nose which was a bit creased and dented, and the heat brought it back to a better shape.

I laid out the bits and put them together in a dry fit before mixing up some 30 minute epoxy and began gluing it back together.

By the end of the evening I was left with only one last piece to glue back, a piece about 70mm long which fits above the wing, so I've left that for another evening. However, before packing up completely, I drizzled some Gorilla Glue into some of the gaps where I had to rejoin pieces and small holes in the foam, to use as a filler.

So the next job is to rub it down and fill where necessary before I apply the glass cloth.

So the final piece was epoxied back into place and once the glue was dry I rubbed it down with medium glass paper. There wasn't a great deal of foam to foam contact area so this was going to be a weak area, so I added a piece of glass cloth over the top just to strengthen it up a little.

I then set about sanding over the entire fuselage before spreading light weight filler, or "spackle" as our American friends would call it, over its entire length, just to fill in the foam void holes and create a smooth surface for the laminate film to adhere to.

So now this is done and I'm ready to laminate. However, I thought I had some laminate film in my materials box but there wasn't enough, so I ended up having to order some more. Hopefully this will arrive by Friday so I can get on with it over the weekend.

Thursday 12th November

So at the beginning of this thread I had plans to glass the entire fuselage, but then the more I thought about it, the more I had doubts about this.

This is an EPP model which doesn't fly slowly, (think M60 racer), and it doesn't land slowly either, so it's likely to have some fairly hefty landings. I thought it best to retain the bouncibility of the EPP, so I changed my mind and went with a laminate film covering. So that was last nights job, covering the fuselage with 75 micron film.

It's a job I do enjoy doing and I seem to be getting better at it as this is the third model I've covered in lam. I've managed to get a nice smooth finish with few wrinkles or air bubbles. The most fiddly bit is always the pointy bit at the front, and it's just a case of making lots of little snips with scissors, folding over and sticking down, but it does take a bit of practice to make a half decent job of this bit.

Of course the better job you make of this at this stage gives you better results when you go to cover with your choice of iron on film later.

So now with the fuselage completely covered, I did a test fit of the wing and that was fine, so this evening I'm going to cover the fuselage in shrink film whilst watching Children In Need and enjoy a well deserved beer.

Monday 16th November

Friday evening was spent covering the fuselage with iron on film. I used the Hobby King stuff which I have used before and not had any issues with. I believe some users have said that the colour fades but I haven't been using it long enough yet for this to happen, so we shall see if this is true. But it is an awful lot cheaper than other brands and is supplied in 5 metre rolls.

The weather at home was awful on Saturday so I stayed in during the afternoon and covered the elevons with laminate film, which really stiffened them up, then began to cover the wing with the HK film. I did get one side done and I hope to continue this evening.

I can see a problem looming which I am going to have to find a solution for. I'm planning on using glass fibre cross weave tape to hinge the elevons, and I want to tape those on before I cover the wing. The wing slides through the slot in the fuselage, but it can only do this with the elevons removed.

I guess this means that I will have to apply the film to the top of the wing, but not stick it down fully until I have slotted it through the wing, attach the elevons, then iron down the film on the trailing edge. I think!

Here is a photo of the fuselage, an some wine :o)

Tuesday 17th November

So last night I continued work covering the wing. There isn't really a great deal to say about this as I didn't encounter any problems.

I was pleased with the finish though, when I consider how badly creased the foam was in places, particularly at the tips, it has turned out well.

The next jobs are to cover and attach the elevons to the wing, connect the elevons to the servo arms, glue the wing in place and fit the battery, receiver and switch. Hopefully I should be able to get this done before this Sunday and then just pray that the weather plays ball so I can chuck it off a big hill.

Thursday 19th November

So the project has been coming along nicely!

Tuesday evening I glued the wing into the fuselage and left it 24 hours to set properly.

Last night I attached the elevons to the wing and covered them.

I decided to try using laminate film as my hinging material and cut four pieces of 75 micron film, approximately 3" long x 1" wide for each wing, and used part of the mylar hinge method to attach these. So I stuck two pins, evenly spaced, through the centre of each tab of lam and ironed this onto the elevon, the pins butting up to the beveled edge of the elevon. I then mated up the elevon to the wing and temporarily secured it with masking tape, with the pins now also touching the trailing edge of the wing, thereby creating a small, even gap between the wing and the elevon, and then with full downward deflection of the elevon, I ironed the lam film to the top of the wing.

Next I had to do the underside of the wing, and for this I used the almost tissue thick 42 micron laminate film. This was cut into strips the length of each wing and about 1½" wide. The elevon was then raised and bent over until its top surface was touching the top surface of the wing and I ironed on the lam to the beveled elevon edge and the wing trailing edge at the same time and the excess was ironed onto the underside of the wing and the elevon. Once this was done, another similar strip of lam was cut and ironed onto the top of the wing and elevon. This seems to have made a hinge which is strong, clear, will not degrade or become brittle ....... hopefully.

I have to say that I was impressed with this method of hinging, and if after a few months of flying it is still secure and showing no signs of any issues, then I'll use this on all my future foamie model projects.

It also got me thinking about the way I build foam wing type models, and I think my next model, (that Santa is going to bring me), will follow the following build procedure.

• sand the foam to make it as smooth as possible
• spackle the entire fuselage and wing with light weight filler to fill in the voids
• sand back again to create a smooth surface
• cover with 75 micron laminate film
• cover with my choice of iron on film
• cover again with 42 micron laminate film which will increase strength and protect the iron on film covering but without adding too much extra weight.

This should create a really strong and rigid model.

I then covered the elevons with the iron on film to finish the evenings work.

All I have left to do now is to create a little more space in the battery and receiver compartments to accept those items as currently there isn't enough space for those and the corresponding wires. I have to fit new elevon control horns and connect them to the servo arms, and add some orientation bands of iron on film to the underside of the wings, then Bobs your uncle, it's finished.

I can't wait to chuck it off a hill this weekend now.

Saturday 21st November

Flipping eck it was cold standing in the snow on the VR98 slope at the Bwlch. And I was the only one brave or foolish enough to go flying today.

It was 0°c and the first snow of the season when I chucked the newly rebuilt Polecat off the slope. It immediately dived, bounced off the snow then headed off into the blue sky. A few clicks of up elevator and two clicks of left aileron and she was flying like a good un. 

Landing is usually tricky on the VR98 with the road being only a few metres behind you, and it took me three attempts to get her down as she was moving very quickly, but get her down safely I did and I look forward to giving her another flight tomorrow. 

The VR98

Safely down.