S 102B Korpen Photo build

[COLIN SHIPTON-KNIGHT]

Dear All,

This is going to be a bit of an experiment for me, as I have never done this before.

I am going to attempt to make a record of my build of an interesting aircraft, a version of the Gulfstream IV in Swedish service and called the Korpen. It is an electronic reconnaissance aircraft.

It is also a vacform model....



The kit as it came out of the box, the only thing NOT in the kit is any decals, so you either have to be lucky finding the sheet with them on, as I was being next to a very helpful chap on the table next to me at Telford. Or go looking in your decal stash.



Well that's the first two photos, will continue to post as I go.

[Deleted]

Ayup Colin, nice to see you got the hang of putting photos on here.

[COLIN SHIPTON-KNIGHT]

Next instalment....

Having got all the sheets out of the box,







You discover that the model is a lot bigger than you think, and the way they have done this is by cutting the fuselage into not only port and starboard, but fore and aft. The same applies to the wings, with a join on the lower surface at 1/3 wingspan. These joints could prove difficult to make them look convincing, particularly as the aircraft is in a very pale grey scheme. The only good thing is the upper wing surfaces are complete from root to tip.

I am dreading doing the highly polished leading edges.......



There is a small bag of injection moulded parts for the undercarriage, winglets and various aerials.



Usual start with a vacform model for me, drawing around all the parts with a permanent pen.



Two reasons, firstly it gives a good line to cut, or more correctly 'score' along prior to 'breaking the part out', but it also leaves a small black line on the part that aids sanding later.



Scoring/cutting around the parts.



Prior to gently breaking the parts out with my fingernails.





End up with the part separate from the vacform sheet.



Lots of parts to cut out, time consuming but care has to be taken.

Next step will be some sanding, not the most exciting of stuff, and not all that easy to catch on a photo.......

[Ianshaw]

Hi Colin,

You know that idea you gave me of filling the rear side of vacform parts with resin so they are more substantial and easy to sand. Well I tried it with another TBM-3W Avenger Vacform from Falcon. Hit a snag though the Halfords resin I used gets very hot as it goes off and sadly it blistered the plastic on the outside !

Just thought I'd give you a heads up in case you planned to try it on this build

regards

Ian

[popeye]

Colin:
May the force be with you !

Colin & Ian:

Instead of using some heavy epoxy filler for this purpose try:

DARWI extra light white modelling paste.
manufacturer Bodson-Nelis, Belgium.

paste can be modelled with water and hardens without baking to a compact light body. Not much tensile strength after hardening but useful for stiffening with almost no weight.

I use it also for supporting clear vacu canopies while filing, sanding and decaling.

Doesn't react with plastic but can be extracted after hardening and fixed in the plastic parts again with white glue.

Rolf

[popeye]

I am dreading doing the highly polished leading edges.......




Have you ever tried "Bare Metal Foil" ?

or mask and apply "Aluminum" by airbrush at the end.

Rolf

[COLIN SHIPTON-KNIGHT]

Ian,

Whoops, I completely forgot to mention that.........

My fault. I am aware of it and I tend to cool the part under a running tap as it 'cures'........ Completely forgot to mention it....... Forgive me.

Sounds like Rolf's suggestion is worth having a look at.

Any idea where we can find this wonderful stuff in England Rolf?

I do intend to use some form of filler in the Korpen build, particularly the fuselage.

How well does it sand?

Colin

[COLIN SHIPTON-KNIGHT]

Couple of photos of the material Rolf mentions.....

[popeye]

DARWI:

Suppose you best have a look at one of the shops that sell all kind of material for handicrafts.

As far as I know it is mainly used for filler for bodies / heads of dolls and for scenic modelling.

The paste is sold in blocks, you have to add some water and knead it until it can be modelled or inserted.
Surface can be evened with finger or spatula and some more water.

After complete drying it is quite stable and fibrous, can be sawn, cut with scalpel and sanded - but surface will then be porous.

Good luck,

Rolf

[COLIN SHIPTON-KNIGHT]

Got all the parts cut out, fiddly with the smaller ones.

Gets to sanding them, I use an old bread board with a sheet of wet and dry glued flat to it.

First I have a look for the remnants of the Black line I drew around the shapes before cutting, this gives me a guide as to how far to go when sanding...



Then gentle circular sanding on the board, constantly checking until the black line disappears.



Some parts prove difficult to hold, so I attach a bit of tape to give a handle.



Noticed fuselage had a bit of a curve in it, so started gluing straighteners and stiffeners in side.



Now having a look at both photos and the clear canopy supplied. I have decided to go with painting windows, all the fuselage ones seem to have black curtains or blinds inside, and you seem to be able to see precious little in the cockpit. That plus my lack of bravery to chop the whole cockpit out, and it was a swift decision to start moving towards joining the halves.

First fore and aft..

Bit of filing.



Then they fit,



Port side better than starboard as there seems to be a slight curve in the outer profile of that side.



Once one side was together, started adding small flanges to aid gluing them together, and make the whole thin a bit more 'robust' for when it comes to sanding it all. Plus adding some weight..

[COLIN SHIPTON-KNIGHT]

Fuselage together, with a few points of discrepancy between them. It almost looks as if the original moulds were made either with a vacform or two different models, as the shape and lines, do vary between the four parts. Port and starboard, fore and aft..



And just to give some indication of its size. Compare against the Nimrod I am doing....



Starting to 'stiffen' the lower wings,



Then comes the fin, again 'stiffening' it and adding a long stub to line up with both upper joint and lower.



Then glue it down.

[popeye]

impressive progress !

Isn't that 1/72nd scale ?

keep reporting - most interesting, might help motivate "almost vacu builds" like Mach2 Valiant.....

Rolf

[Julien]

Looking good colin, makes me want to think about my 1.72 737 Wedgetail.

Julien

[COLIN SHIPTON-KNIGHT]

Julien,

You know you want to do it, but be of stout heart.....

The saga continues, having sanded down the wing edges,




Something I am always wary of, as the last thing I want is one wing 'thicker' than the other. That's why I tend to stiffen the wings with strips of plastic.

With this model, I decided to glue the lower wing assembly onto the fuselage first, with small flanges glued onto the lower fuselage to ensure that the wings will be perpendicular to the fuselage.



With the lower wings on, I could then trim the upper surfaces to try and ensure they fit the rather 'public' joint onto the fuselage. Glued them with loads of superglue, all held in place with tape to try and ensure they 'sit' at the right angle, the Gulfstream having a very flat bottomed wing with distinctive anhedral on inner upper surface.



When dry, a quick bit of sanding and then a quick coat of primer to give me a better idea of how things are going. Staring at white plastic drives me crazy, funny how a bit of primer shows all the faults..



Starting to look like lots of 'wet and dry' action coming up......

Bit disappointed at some bits of the model, some mismatches in panel lines, well they are all going to be filled. Dimples and sink holes in the wings.

Ah well, kind of getting used to sanding.... what with this and the PR 9.

Colin

[Julien]

Is the PR9 a putty monster then?

Julien