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Pete's Cavallino Rampante Italian Aerobatic Team Sabre

Colourful Italian Ice Cream Sabre

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John H. Rood04/01/2020 17:31:12
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263 forum posts
385 photos

Fuselage_Shell.jpg

Peter, once again I shall crawl on my belly down the alabaster tiles of my aeromodelling HALL OF SHAME... another unfinished project... this one here is a bogey in 1/10th scale ... I pollute your thread here because this MiG-15 has her nice portly fuselage constructed via the LOST FOAM process.

I designed her in another lifetime, never finished her, and/but/however now I feel I just might need to raise the stakes for all these F-86 Sabres on zee rise...

Peter Garsden05/01/2020 09:42:49
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Interesting John. Fibreglass has been around for a long time. Not many people attempt it but I think it is quicker and easier than planking. A round fuselage lends itself well.

Peter Garsden16/01/2020 16:21:56
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Well, with the wing finished attention had to be paid to the fuselage. I had cut out my side and top and bottom cardboard templates ready for cutting out the blue foam block with my hot wire cutter.

When I came to assemble it I realised that I did not have enough foam so tried to cobble together sheets from bits - which was a bloody mess if I am honest, so I invested in some new pieces of under floor radiator sheet of the right size - not easy to get now - I found it on Amazon and this is the URL if you need any - **LINK** - there seemed to be a lot of small sheets used for dolls houses but nothing thick or big enough.

Anyway I glued it together and Keith and I cut the block to size last night.

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You can see that I marked the position of the formers so I can match up my templates with the sides at the appropriate point to ensure I get the correct shape to the fuselage. I have both outside and inside profiles which are working well - thanks to Gordon for putting them on the special top view plan he did for me.

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These are the tools I use - a Japanese type fine toothed pull saw made by Irwin - great for cutting foam and a coarse permagrit file.

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I was able to draw the shape at F1 on the front of the fuselage to give me a good start.

This will of course form the template for the lost foam mould which will be wrapped with parcel tape then fibreglass before dissolving it out of the middle with acetone.

dirk tinck17/01/2020 00:22:08
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458 forum posts
723 photos

Nice going Pete !

Are you making two halves here ?

I would like to try this someday!! I'm following !cool

Peter Garsden17/01/2020 12:26:18
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1678 forum posts
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Posted by dirk tinck on 17/01/2020 00:22:08:

Nice going Pete !

Are you making two halves here ?

I would like to try this someday!! I'm following !cool

No, I'm not making 2 halves. I have done a full run through of the procedure on my Tornado blog as that is also fibreglass. I am using your fellow Belgian chap's process, can't remember his name now of lost foam (Paul Janssen I think), so the steps are:-

  1. Do a cardboard template for top and side view.
  2. Pin it to a block of blue foam or the equivalent - has to be firm so it can be sanded.
  3. Cut out top and side views with a hot wire (you need a mate to help with this).
  4. Carve out the shape from the block. This fuselage is bigger than what I have attempted before and it was taking ages manually, so I have used my Bosch Shoe Sander which is working well. I am using side templates as you can see.
  5. Wrap the block in brown parcel tape - I use an iron to flatten it and help it adhere at about 100 degrees C to avoid melting.
  6. Cover the parcel tape with wax
  7. Apply spray contact adhesive to hold the first layer of 150 gram fibreglass and soak with epoxy resin - I use laminating. It is quicker to use polyester but I find it dries too fast. I also put in some reinforcing strips of carbon and kevlar in stressed areas.
  8. Let it dry then apply a second coat of 150 gram. I have used peel ply to cover the fibreglass but it is a bit difficult to get it to adhere. It does soak up any excess resin well.
  9. Final layer of 80 gram
  10. Paint on a layers of microballoons and epoxy then sand down for a smooth finish.
  11. Cut a hole under the wing and pour in acetate. You can pull out the goo with the parcel tape. I usually make holes in the foam to pour the acetone into. This is the worst bit.
Peter Garsden17/01/2020 21:14:06
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1678 forum posts
1259 photos

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The formers helped a lot as did the shoe horn sander. I used both rough and flne pads

Chris Barlow19/01/2020 03:18:18
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1897 forum posts
1303 photos

That's a fine looking sculpture there Pete. It's a shame to melt it down into goo!

How do you deal with the blue foam sanding dust? I have only used it in small amounts and the dust is horrible! Sticks to everything through static and clogs the vacuum filters up very quickly!

Peter Garsden19/01/2020 15:29:22
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1678 forum posts
1259 photos

The Dust - that is the thing according to "Dark Materials" that children don't have which adults do and is responsible for all evil deeds, but I digress. Yes it gets everywhere but I am using a shoe horn sander which has a dust collection bin. That helps a lot. As for vacuuming up we have a Kirby which vacuums up small children it is so powerful.

Well I have finalised my shape which fits the templates and finished it off with some foam sanding sheets to follow the curves. Also started to apply some parcel tape with the film iron set at 125 degrees C which seems fine.

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Peter Garsden19/01/2020 19:22:50
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1678 forum posts
1259 photos

Well I have cut out and attached with the contact adhesive (foam friendly) 3M 77 which I have used before but is running low, all the pieces of the first layer of fibreglass ie 150 gram per square metre together with some reinforcement from a 2 inch carbon bandage, some 150 gram kevlar for the nose (signal friendly), and some carbon tape down to the tail.

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Not the bbq skewer type arrangement to support the fuselage, which are pieces of wood and lengths of thick wire with a point ground into it. They clamp to the bench at one end and screw to the end of the bench at the other.

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The fibreglass will overlap at the end then be cut off.

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I use the templates to cut out the cloth

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This is ready for dousing with resin. I have overlaid but not pictured the reinforcement carbon and kevlar.

Edited By Peter Garsden on 19/01/2020 19:23:47

Steve McLaren19/01/2020 21:10:31
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232 forum posts
246 photos

Very interesting Pete. Do you put all the fibreglass layers on now in this dry state? And do you vacuum bag the whole thing when you add the resin?

dirk tinck19/01/2020 22:37:25
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458 forum posts
723 photos

Hi Pete,

I guess you have a whole lot of sanding ahead of you on the fuse...surprise

I would have skipped the parcell tape and laminated the glass direct to the foam like when glassing parts.The acetate does his job with or whitout tape.

Or am i seeing this completely wrong ?thinking

Peter Garsden20/01/2020 16:05:39
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1678 forum posts
1259 photos

Thanks for the questions guys

  1. I have doused layer 1 with resin. I have let it dry and will then apply layer 2. I did a shroud of peel ply draped over the top and pinned down each side to keep the fibreglass sheet flat, which sort of worked. The problem is that you can get bubbles. The peel ply does however soak up the excess resin, and keep the weight down.
  2. I don't put all the layers on at once because the resin wouldn't soak through 3 layers of cloth properly. I don't bag it No, thought it might not be a bad idea to do so. Dirk can no doubt advise.
  3. As to dispensing with the parcel tape, this was recommended by Paul Janssen the pioneer of lost foam for PSS. His site has been taken over by Maarten Werner. The method is described on his site here - **LINK** I think as he was using polyester resin which would had attacked, I think, the foam, whereas I am using epoxy resin which doesn't react. I do find, however, that the tape helps you pull the goo out in one go at the end. It also leaves a smooth inside surface, which admittedly is not what you want. So the jury is out and Dirk is the professional expert on the subject? What say you sir?
  4. I use Copydex to glue the sheets of Blue Foam together but it is difficult to get now and expensive. What is the best glue for this chaps?
  5. I use 3M77 to attach the cloth to the parcel tap but that is also expensive, any suggested alternative?
dirk tinck20/01/2020 20:09:31
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458 forum posts
723 photos

Hi Peter,to glue foam parts i use the cement that's used to glue the fairings between ceiling and walls. It's quick drying and sands like foam. Very cheap too !

dirk tinck20/01/2020 20:37:39
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458 forum posts
723 photos

Yes, the resin will stick to the foam without tape but will not attack it. And the inner surface won't be shiny but is not nessecary, is it? It will be less sanding for sure! I would have to try to know the difference. .

dirk tinck20/01/2020 22:55:21
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458 forum posts
723 photos

I would 'nt use the glue spray Pete : It will give you a hard time to get the wrinkels out of the glass !!

Oohh man i would love to come and help you !...face 7

Peter Garsden29/01/2020 18:30:37
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1678 forum posts
1259 photos

Thanks for all the great tips Dirk. Yes, shame you aren't in England but that is the disadvantage of being in slope free Belgium.

Anyway, all the cloth is now on, and I have done a top layer of epoxy/microballoons. And yes there were wrinkles - next time maybe follow the Tinck method. Must look back on this as and when.

This is before the acetone went in - what an almighty mess. This time I used thick smooth resin friendly gloves but the goo stuck to the gloves - any tips Dirk? Went everywhere....

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And without foam

 

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Edited By Peter Garsden on 29/01/2020 20:40:35

dirk tinck29/01/2020 23:09:01
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458 forum posts
723 photos

Hi Pete !

I use the ''trow away'' gloves wich i renew about 5 times a night!

There's no way arround the mess Pete ....If you can't stand the heat , stay out of the kitchen !!

Atleast you have a fuselage now !

Peter Garsden04/02/2020 16:41:12
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1678 forum posts
1259 photos

The only problem with a fibreglass fuselage is that you have to make the formers fit afterwards from the inside which is a difficult fitting job.

I decided to use the same cradle (F15) for the taiplane bellcrank, F9 and F10. Getting them to fit was a labour of love. Try as you may you can't accurately replicate the shape of the fuselage. Anyway it is done now and everything glued in position. I used epoxy mixed with fibreglass powder to strengthen the joint. The fin seems to fit so it is a case of leave to dry.

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Fortunately the cradle seems to be more of less square ready for the pivot.

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F10 from the rear

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After fiddling around a lot I decided to cut a hole in the bottom of the fuselage at the rear in order to gain access to position F9. You can see that I had to join the formers together before I glued them in once I had sized each half to fit each side. I also added some 1/64" ply reinforcement across the join.

Peter Garsden11/02/2020 20:46:26
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1678 forum posts
1259 photos

Well finally I have formed the outside fairings for the tailplanes, and the bellcrank, wires and tubes.

I was wary of which order I put the bellcrank on the tube, and bent the wire. I have a strong vice, unlike some and was able to anchor the wire in the vice to bend it to the right angle using the very handy template. The secret is not to put the brass tube in the vice as it will squash and be unusable.

I found that the bellcrank will slide over the bend in the wires even after both sides are bent. This was welcome because I should have slid the spacers (made of circuit board) over the tube before bending the 2nd wire.

I decided not to use a brass tube for the rear pivot hole which I am sure will be fine. I think there would be enough space if you are careful with the pillar drill to form the hole for the tube

Before gluing in the brass tube, I made a slot in the balsa fairing then filled it afterwards with balsa. I also coated the wire with Vaseline to stop it sticking to the tube and make sure it stayed free.

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Peter Garsden11/02/2020 20:51:22
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1678 forum posts
1259 photos

I have also formed the fin and tailplanes using my handy sanding disc which saves so much time. I also used it to form the farings which are not a perfect fit to the fuselage but are the same height as each other. I had to put filling pieces in to fill the gaps underneath and at the end.

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I'm going to cut out the rudder later when everything is fitted. We will need to fit in some filler pieces around the fin for the concave fairings either side. I will probably cover it with the film prior to gluing as well.

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