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Short Gurnard - 1/72 scratchbuilt FINISHED


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There, I think that ought to hold

the fuselage together while the cement dries...

 

20200710_210019

 

The vacform top of the upper wing was scraped using a cabinet scraper and sanded with a sanding block, then cemented to a piece of 40 thou plastic card to form the lower surface. After it had thoroughly cured more sanding followed until I got to a reasonable wing shape. The main rib positions were transferred from my plan onto the plastic and very carefully drawn over with my Edding paint pen using a strip of plastic card as a flexible straightedge:

 

20200710_210045

 

I was pleasantly surprised to draw all the lines without the pen dumping at least one puddle of paint on the wing! A couple more applications should give a decent rib effect to work with, then I can add the leading edge riblets.

 

This work resulted in an extra rib being drawn on the right-hand wingtip, which led to the discovery the starboard upper wing is slightly longer than the port. This can just be seen against the cutting mat grid above. After checking against the plan (okay, enlarged 3-view) I think that the trailing edge cutout is ever so slightly off centre.  Correcting it will mean that the span will be a couple of millimetres too short compared with the 3-view, but it isn't something I'll lose sleep over.

 

Jon

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The tape is off and the fuselage halves seem to have bonded well. I cut a slot on the upper port nose and glued a piece of plastic tube into it, then sanded it flush to form a gun trough. It needs a lot of fettling, but after one dose of filler and subsequent sanding it looks like this:

 

20200711_211236

 

I intend to make two male half moulds for the main float, then vacform it in the same manner as the fuselage. I started by making an identical pair of profiles from 40 thou plastic card (useful stuff, that), using the aircraft profile very handily included in the Aeroplane Monthly article as my reference. I then used dividers to mark out where the keel meets the upper part of the float at defined points along the length of the float.

 

The AM 3-view did not include a plan view of the amphibian, so I sketched out an 'imagineered' plan that looked about right and again marked out those dimensions using a pair of dividers.

 

Using those measurements I cut some plastic card formers and cemented them into place on each float profile. Once they have set I'll start on shaping their curves. They'll eventually have a strengthening plastic framework and be filled with P38 to make the moulds:

 

20200711_210924

 

So, this is where I've got to, with a plank made from pieces of 40 thou and 60 thou plastic card laminated together with plenty of liquid poly to make solid lower wings. If you sit quietly and watch carefully, you might get lucky and see a Gurnard:

 

20200711_211218

 

Jon

Edited by Jonners
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Jon

 

Looking good.!

 

Do you have Harry Woodman's book on scratching aircraft? I assume you do, but if not there's some very good advice/guidance on doing wings. The book is I think in the public domain and published on the internet.Can't recall where at moment, but I have a copy if you want. Just PM me.

 

Matt

 

 

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30 minutes ago, Mattlow said:

Do you have Harry Woodman's book on scratching aircraft? 

Hi Matt,

I have it printed from an internet PDF download, thanks. I considered following his method of skinning a wooden core but decided that the curved wingtips would be awkward to create and blend in nicely, plus I wanted to try vacforming a wing as I haven't done that before. The laminated plank for the lower wing is partly to avoid the faff of creating a vacform mould, but if it doesn't work well then I'll just do the same as I did for the upper wing. I like experimenting!

 

Thanks for the suggestion and the offer though - it's appreciated.

 

Jon

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I’ve made thick wings by both methods. On my Junkers JI with a wood core the tip was just closed off with milliput and sanded to shape. 
49712839828_cfd8851df6_c.jpg

 

For my Horsa and Caproni I molded the wings. Tbh pretty much six of one half a dozen of the other.

50058427303_d4b195ba5e_c.jpg

 

Edited by Marklo
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Well folks, although I haven't been able to devote much time to modelling recently I have made a bit of progress on the Gurnard. Unfortunately I'm at the stage where I seem to have to put in a lot of effort - which generally consists of filling and sanding! - without actually seeing any major progress, but I know that I'm getting there.

 

Firstly the upper wing had a couple of slots cut in its upper surface with a razor saw, then each wing was bent at this cut and reglued with a 5 thou strip in the cuts to form the appropriate dihedral outboard of the centre section:

 

20200716_123520

 

Plenty of work still to do there, including cutting ailerons and adding quite a lot of surface detailing.

 

The lower wing was shaped from laminated plastic card using a cabinet scraper and a variety of abrasives. it also had dihedral added in an identical manner to the upper wing and a first set of rib tape lines added with my Edding paint pen. The lower fuselage was marked out, cut and fettled, and the wing was cemented in place:

 

20200716_103529

 

Again, there's a lot of work still to do there, especially filling and smoothing around the underside joint. 

 

The main float is a pain, but I'm persevering. I've added 2 or 3 applications of P38 but more are needed to define the shape that I need to make vacforming male masters. The two halves have been tacked together with CA to assist in getting halves that actually match!

 

20200716_103456

 

I considered modifying or combining floats from my spares box (top: Novo/Frog Blackburn Shark, middle: Matchbox Fairey Seafox) but the shapes really don't lend themselves to it, especially aft of the step. I'll persevere with the moulds for now.

 

By temporarily bodging the parts together with Blu-tac the overall configuration can be seen:

 

20200716_123753

 

Back to the filling and sanding!

 

Jon

Edited by Jonners
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Superglue makes excellent grain filler for balsa, and it uses up your old stock so you don't find out it's gone off when you start rigging :)

 

Regards,

Adrian

On 10/07/2020 at 17:12, Jonners said:

a bit clunky and lacking in artistic finesse

I'm sure they said that about the shadowy bits of Rembrandt's paintings too.

 

Regards,

Adrian

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After a bit more fettling (okay, actually mucho filling and sanding) I got to a float shape that I thought would do the trick. It was split into its two separate halves, like this:

 

20200719_212407

 

I then connected my homemade vacforming box up to the Dyson and taped the holes to match the bespoke frame that I had cut from thin plywood. Each float half was vacformed individually:

 

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This is the result, which I obviously have yet to cut out but which I'm pretty confident will give me something I can work with:

 

20200719_212312

 

Thanks for looking; now that I've made the major parts, hopefully I can start to make more interesting progress!

 

Jon

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  • 4 weeks later...

Blimey, has it really been a month since I last reported / made any progress on the Gurnard? Tempus fugit, and all that. I've been busy with work and other projects, including removing and replacing a fireplace, hearth and surround and also restoring this:

20200808_145709

....which has kept me from committing modelling recently.

 

Anyway, the home-vacform central float came out okay but all of the edges, especially the chines between the upper and lower surfaces, were too rounded. These had thin strips of plastic card glued to them which, once sanded, resulted in a much sharper corners. A full-width slot was cut at the step with a razor saw into which a rectangle of card was cemented and, once dry, sanded back to give another set of sharp edges. Plenty of filling and sanding followed. Apologies for not having pics to illustrate this, but the result looks like this (underside view):

 

20200816_133634

 

The clunky-looking undercarriage was mounted to small fairings on either side of the float in line with the step. Small pieces of sprue, sanded to an oval section, were glued to each side along with plastic card strakes and filler used to blend them in (still a bit of a WiP). A 0.8mm hole was carefully drilled in each side and a short piece of brass rod inserted right the way through to confirm that the holes aligned. This will form the basic axle for both undercarriage legs in due course:

 

20200816_131925

 

Two 5 thou discs have been speculatively added to represent float inspection covers, and mooring cleats will be added much later in the build, but I haven't yet found a clear pic of the float's upper surface so I won't go overboard with invented detail here.

 

I'd been musing for ages over how best to portray the slightly recessed engine exhaust stubs. The forward fuselage seemed to have a single long slot through which the individual oval exhausts vented. After a couple of false starts I cut a dozen short sections of thin brass tube and gently crimped them into oval shapes with the flat section of a pair of narrow-nose pliers. The scale exhaust slot measures about 12mm, so I drew six 2mm marks on a couple of pieces of 10 thou card and superglued six of the brass pieces go each, with the 'outside' oval ends in line (ish...):

 

20200815_205100

 

A piece of 5 thou card was superglued to the top of the brass to create 'sandwiches' which were then trimmed to 12mm wide and carefully wedged and cemented into the nose slots:

 

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Once the cement had dried the protruding card was sanded flush giving a fairly satisfactory result:

 

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The louvres were made by scraping a piece of card at 45° with a Stanley knife to give a serrated effect, which was then cut into small strips and carefully pushed into slots cut into the sides of the nose. Once in position they were cemented from the inside to suggest rearward-venting louvres. I still have to pluck up the courage to attempt ho scribe the nose panel lines, but the obvious fuselage joint 'strips' have been replicated with paint. This will probably have to be redone, as the fuselage longerons showed clearly under the fabric of the original aircraft and I'll have to decide how to replicate this.

 

Hopefully there'll be more progress to report soon, before another month flies by!

Jon

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Coming on very nicely Jon. The float looks really good with the fillets added at the edges. I did the same on my Donnet-Leveque, a very simple but very effective cure for vacformed corners!

And I do like those exhausts!

 

Ian

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This evening's little job has been to create the pillar radiator between the float and the fuselage.

 

The basic shape was made by cutting two 13mm half-tubes from a missile from the spares box (an AGM-78 Standard, to be precise, from an Italeri F-4G that I built as a teenager!) and adding 10mm long plastic card 'sidewalls' between them. The front half-tube was drilled and cut to create a rectangular opening, then a sandwich of card pieces was made to represent the radiator matrix:

 

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The radiator part was fettled until it fitted nicely into the pillar piece:

 

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The inner radiator part was then cut to length and cemented in place. The whole piece will soon be mounted on the float like this:

 

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...and the fuselage will eventually sit on top like this:

 

20200816_211548

 

Isn't Blu-Tac useful stuff?

 

Jon

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On 8/17/2020 at 6:59 AM, ColinChipmunkfan said:

Amazingly skilled modelling Jonners, I am following this with a sense of awe. 

 

23 hours ago, Ex-FAAWAFU said:

This is fabulous!

 

23 hours ago, SafetyDad said:

Wonderful stuff! Ingenious, creative and clever.

Whoa! Steady on there! I’m just stumbling my way along - and far more slowly than I had intended. Too much to do, too little time...  Seriously, though, thanks for the generous and encouraging comments.

 

12 hours ago, bigbadbadge said:

Great work particularly like the exhausts and radiator, fantastic problem solving.

Cheers Chris, but I’m only repeating what I’ve seen others do here on BM!

 

1 hour ago, Courageous said:

I'm particularly taking notes on how to make your central float

To be honest, Stu, it was a faff. The shape is a bit of a guesstimate, for a start, and vacformed floats will always need their edges to be sharpened up. The biggest difficulty is with the P38 filler: as it cures it must shrink very slightly as tends to bend the shape inward very slightly - a bit like those cellophane fish party trick thingies that you put on the palm of your hand - if only plastic card is used as the main backing piece. Building a really rigid skeleton helps, as I did with the fuselage, but I could have done more with the float halves. The second benefit of this skeleton is that, without it, the filler tends to separate from each plastic profile piece when the whole thing flexes, so you end up with a series of separate segments all joined on to the backing piece. Glueing them together works, but adds extra faff. Next time I might try a one-piece filler / Milliput / basswod mould part with concave ‘female’ shapes to check the shape of each section. Hope that makes sense,

 

51 minutes ago, woody37 said:

Nothing more therapeutic than seeing bits of plastic turn into an aeroplane :)

Nothing that can be described here, anyway...

 

Jon

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  • 2 weeks later...

Another update, primarily to prove (if only to myself...) that I am actually making some progress on this build!

 

Photos of the original Gurnards show that the rear curved fuselage 'turtledeck' upper surface continued over the tailplanes right to the tip of the tail. I wanted to incorporate a single-piece horizontal tail to ensure strength, so decided to replicate this turtledeck section with filler.

 

The tailplane piece was cut from plastic card then scraped and sanded to profile.  The elevators were then separated and reattached slightly drooped. A quick bit of work with the razor saw and craft knife allowed me to fit the horizontal tail:

 

20200824_213227

 

At this point I realised that I should have added the rib tape lines before glueing the tailplanes in place. Oh well - I'll have to do it the fiddly way later.

 

The longerons showed very clearly through the fabric on the rear fuselage of the original Gurnards, so I replicated this by drawing lines with my trusty Edding paint pen. The effect isn't quite accurate, but I'm happy with it under a coat of primer:

 

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As you can see, the float has been cemented to the fuselage. It took about 3 attempts to get it to look right as the homemade vacform shapes aren't perfectly symmetrical, but it's now the best that it's going to be. Small side radiators were added to the pillar using scribed plastic card and filler was added to start building up the top fuselage fairing over the tailplanes. I also removed the circular 'inspection covers' from the floats, simply because I thought that they looked a bit rubbish:

 

20200827_104019

 

Then, having exhausted all attempts at prevarication, I finally had to face up to my nemesis.

 

Scribing! Arghh...

 

Actually, I gave myself a stiff talking-to and told myself to get a grip, on the basis that if I could create a curvaceous biplane from flat plastic card then I should be able to scribe a panel line. Feeling suitably admonished, I ordered a Tamiya scriber and a roll of Dymotape so that, for the first time, I would have the proper tools for the job:

 

20200827_151018

 

The nose of the Kestrel-engined Gurnard had some obvious panel lines. While it would in theory have been easier to scribe these before the fuselage halves were joined, the amount of filling and sanding that was required would have pretty much eradicated them. Getting correctly-positioned straight lines on the curvy nose was tricky, and some filling and correction will be required following this first attempt, but I'll get there:

 

20200827_154746

 

Of course, the main issue with getting the nose panels properly scribed will be that I'll then have to work out how to make all those struts!

 

Jon

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2 hours ago, Courageous said:

I'd attempt it before putting the float on.

Yup, that would have been the sensible thing to do, Stuart. Instead, though, impatience won the day (will I never learn?) so I pressed on with assembly while I waited for the scriber to be delivered. Why make things easy?

Jon

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