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Short Gurnard - 1/72 scratchbuilt


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Darn it! I've given in to the urge again. Another silver pre-war unsuccessful British prototype is in the 1/72 scratchbuilt planning stage...

 

The Short Gurnard was constructed in response to Air Ministry Specification 22/26 which called for an aircraft that could fulfil the fleet spotter/reconnaissance role but also be capable of intercepting enemy bombers as well as be operated as either a floatplane or from an aircraft carrier's deck. It also had to be strong enough to withstand catapult launches. The Air Ministry advised the company that its new duralumin monocoque structure would not be acceptable as it was considered that the necessarily small access hatches inherent with this construction method (to maintain strength) would hinder servicing at sea. Designs were submitted by four manufacturers: the Fairey Fleetwing, the Blackburn Nautilus, the Hawker Naval Hart (which won the competition and entered service as the Osprey) and the Short Gurnard. The Gurnard, by the way, is a small fish that could only be described as attractive by the most ardent zoologist.

 

The Air Ministry issued Short with a contract to build two prototypes. The first, known as the Gurnard I with the serial N228, was to be equipped with the Bristol Jupiter radial but was actually the second Gurnard to fly. Although built initially as a floatplane, it was converted to landplane configuration prior to its first flight. It is seen here in its wheeled configuration with a Townend ring fitted around the engine, which was later removed:

 

Short Gurnard 1

 

The second aircraft (but the first to fly) was the Gurnard II N229 fitted with the Rolls Royce Kestrel inline engine. It was fitted with twin floats and made its first flight from the River Medway at Rochester on 16 April 1929. This was hardly an auspicious event: serious aileron overbalancing caused the aircraft to bank 45 degrees left and right three times immediately after takeoff, causing the pilot to lose his grip on the control column and only prevent disaster by gripping it between his knees.The aircraft was safely landed and returned to the factory for modification. It was then converted to landplane configuration for service testing, as shown here:

 

Short Gurnard 2

 

Neither aircraft was particularly impressive in landplane form, and test reports were especially critical of many aspects of the Kestrel-engined Gurnard II's handling.  In fact, the Aircraft and Armaments Experimental Establishment (A&AEE) report on N229 concluded that it was "unsuited to its purpose in its present condition"  and summarised by stating that "the Gurnard needs a complete redesign". Testing of the Jupiter-engined N228 gave somewhat better results. After some redesign work to address the worst problem areas, the A&AEE asssessed the Gurnard I as being suitable as a deck landing aircraft but "rather too large and clumsy" for a two-seat fighter.

 

N228 was eventually fitted with twin floats for testing at the Marine Aircraft Experimental Establishment (MAEE) at Felixtowe, but no great success seems to have followed. The Kestrel-engined N229, however, returned to the factory where in 1931 it was fitted with the Short patented amphibian undercarriage.  This somewhat ungainly structure comprised a single central float with small outriggers, a central pillar radiator, mainwheels that could be wound up and down by a cockpit handwheel and a profusion of additional supporting struts. Oddly, the water rudder doubled as a tailskid for land operations:

 

Short Gurnard amphibian

 

In the late 1990s the magazine 'Aeroplane Monthly' ran a series of excellent articles entitled 'Limited Editions', each of which covered a different obscure interwar British aircraft design. The subject of the article in the February 1998 issue was the Short Gurnard. I had acquired a copy some years ago, extracted the article for possible future reference and pretty much forgotten about it until I found it recently. I've been looking for a suitable subject for a new scratchbuild that will set me a new series of challenges and had made a mental shortlist but, as I read the article, I decided that the radial-engined Gurnard I should be added to that shortlist.  As I read on and saw photos of the Gurnard II amphibian I was intrigued, and the final small photo in the article sealed the deal - the amphibian taxying across grass on its extended wheels and using its water rudder as a tailskid, with its scaffolding-like struts and towering above its groundcrew running alongside. It just looked so bizarre that I immediately knew I had found my next subject.

 

This will be quite a challenge, as I will have to create my own male moulds and vacform parts for the fuselage and, almost certainly, the central float. The wings, radiator and wing floats might also be best made by vacforming but, as I've only tried making vacform parts once before in a very limited way, there could be some trial and error involved.

 

My primary reference will be the Aeroplane Monthly article and my plans have been created from the very neat three-view (with variant profiles) that appear in the article, enlarged to 1/72 scale. I have also printed a set of drawing at 98% of 1/72 from which to make the male moulds to take into account the thickness of the plastic card (it's approximate, but you won't find me counting rivets!):

 

20200627_172412

 

I apologise in advance for the probable slowness of progress; this will be as much a challenge to myself to see if I can do it as an attempt to create an unusual model. I have an Airfix Swordfish 'in progress' on the workbench at the moment, but creating a WiP thread will give me a focus for sticking with it. Who knows: I might even be able to make a radial Gurnard I at the same time...

 

Jon

Edited by Jonners
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Very interesting subject. I’d definitely be looking at vac forming the fuselage. I’d also be inclined to vac the wings, or look for a similar plane like a swordfish as a donor kit.


I do scratchbuild quite a bit but generally things with thin wings using the Harry Woodman method.

 

i did get fairly good results on my Horsa which has thick wings, even getting reasonable rib detail. And I have high hopes for my caproni ( but the wings were plunge molded.

 

 

will be following with interest.

Edited by Marklo
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Posted (edited)

Well, in for a penny etc. The poor Swordfish kit hasn't been touched today, as my limited modelling time has been spent making a start on the Gurnard. 

 

I began by copying the 98% three-view onto 135gsm heavy paper, then cutting it to produce templates of the fuselage and float side elevations and fuselage and upper wing plan views. I then used the fuselage templates to mark two shapes onto 40 thou plastic card with an ultrafine permanent pen, then cut these shapes out with a sharp blade. These will be the basis of the left and right vacform fuselage halves. I then did the same for the nose former shapes and added these frames to the fuselage pieces. More plastic card was added to make more fuselage frames, which were then cut to approximate shape:

 

20200628_201018

 

I still have plenty of plastic card pieces to add to these 'skeletons' to maximise strength and rigidity, then I intend to sand them to shape by eye before using P38 car body putty to build up and shape the male moulds. 

 

I'll probably also create a nose section mould for the radial version. Who knows, I might even be masochistic enough to build it...

 

It all looks terribly Heath-Robinson at this stage, mainly because it is, but it keeps me quiet.

 

Jon

Edited by Jonners
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Hi Jon!


Oh my, another scrachbuild of a type I've never heared of. This just shows that my knowledge about British interwar types is non-existant :lol: Are you going to print the decals yourself or cobble them together from generic sheets?

 

Following with interest, oh yeah!

 

Cheers

Markus

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19 minutes ago, Shorty84 said:

Are you going to print the decals yourself or cobble them together from generic sheets?

Hi Markus,

When I eventually get to that stage I will mostly "cobble them together" (I have a good selection, helped significantly by the recent generosity of a fellow BM'er) but might have to print the fuselage and rudder serials myself. Thankfully the markings were pretty basic - roundels and codes, plus rudder stripes.

Jon

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Messy, smelly and very slow...but also strangely satisfying. This is where I've got go after 2 or 3 applications of P38 epoxy car body filler:

 

20200629_193854

 

I learned from vacforming the fuselage for my Avro Avocet that, if you only put in vertical plastic card fuselage formers, the fuselage halves will be too weak and the P38 filler will easily separate from the formers. Hopefully the stronger plastic 'skeletons'will prevent that from happening here. The halves do want to curl slightly, though, as the filler cures, so they were clamped together to reduce this as soon as the filler had hardened sufficiently.

 

I think another couple of applications should do it, then my family can stop asking what the smell is.

 

Jon

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Nice subject.

 

The in-line engined float version looks 'right' to me. A bit 'beefy' but purposeful...

 

Will follow with interest.

 

Matt

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That looks really good so far. I’d like to try P38 for my next molding project but if it’s particularly smelly I might get lynched for trying :)  Actually l’m not sure what’s that going to be, I have a pretty full que but not many new scratchbuilds planned, hmmmm

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Now that I think of it, I’m planning on an Osprey, a DH5a, and an Avro Spyder, which won’t need molding but I’m also thinking of a sparrow hawk and a Nightjar which will.

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After plenty of filling, sanding, filling, sanding etc, the fuselage shapes eventually reached the stage where I was fairly happy with them. A coat of primer then highlighted the inevitable flaws, so the routine changed to fill-sand-prime for a couple of cycles until I ended up with these, being examined by my 'in-progress' Swordfish:

 

20200702_202121

 

I then dug out my homemade vacform box, inspired by (and shamelessly copied from) that made by @AdrianMF for his Empire scratchbuild. Mine is a bit smaller at about A5 size but, as the Gurnard fuselages only need a 14cm x 8cm piece of card, I taped off half of the holes for extra 'oomph'. The card was stapled to a simple frame and the box was connected to my Dyson:

 

20200702_210206

 

The card was heated under the electric oven grill on a medium setting until it started to sag, then with some nifty footwork it was laid over the fuselage moulds and the Dyson was switched on. What happens next is quick but extremely satisfying:

 

20200702_210133

 

The first attempt worked very nicely so, to make sure that it wasn't a fluke and to give myself a spare fuselage (and fewer excuses for not building a landplane variant too...) I tried it again. This was the result:

 

20200702_210112

 

Two identical pairs of fuselage halves that have come out better than I had expected.

 

So, here I am ready for a bit of vacform building, starting with a pair of completely undetailed fuselages and nothing else! I've done an initial rough cut on one of the fuselages, but I'll be at work for the next few days so the full cutting-out process will have to wait:

 

20200702_210049

 

This may sound daft, but I'm finding this to be far more satisfying than building the superb Airfix Swordfish. What's happened to me?

 

Jon

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Okay, I couldn't resist cutting out just one of the pieces - just to see what it looked like, you understand. It still needs some tidying with the wet 'n dry, but I'm feeling quite pleased with myself.

 

20200702_214247

 

Right, that's definitely it for tonight. I can hear my conscience calling:

"Put the knife down and step away from the workbench."

At least, I hope it's just my conscience...

 

Jon

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Smooth results on those vacforms Jon. :thumbsup2: You're  dead right about the satisfying nature of the task - I giggle very time!

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Nice!

 

Passing on some tribal BM knowledge...

  • It doesn't look like you need any more suction because those halves look great, but if you did, running packing tape around the edges and joins of the box is a simple way to get more air tightness.
  • I raised my halves up from the vac bed by two or three mm. This allows the plastic to stick right down to the bottom of the master, and indeed run slightly under it, avoiding a flare out at the bottom edge.

If you've come from vac forming transparent plastic it's a real breath of fresh air doing "regular" plastic - much easier than the clear stuff.

 

4 hours ago, Jonners said:

This may sound daft, but I'm finding this to be far more satisfying than building the superb Airfix Swordfish.

I have very some very nice shake and bake kits like the latest Airfix Swordfish in the stash. I'm always reaching past them for some old dog of a kit...

 

Looking forward to a Gurnard or two! It's an strange looking fish, glad to see the aeroplane carries on the tradition!

 

Regards,

Adrian

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Great there Jon, looking great so far.

I agree with @AdrianMF about lifting your master slightly, you negate any flare, works great when I do canopies. I'd keep those 'masters' in a safe place as I might cheekily ask for a set, so I can do 'floater' Gurnard.

 

Stuart

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Posted (edited)
10 hours ago, Jonners said:

Put the knife down and step away from the workbench."

No that’s just the voices in your head. Your conscience is saying let’s just see how those halves look together :) 

 

Great progress on the Gurnard. Makes me start thinking of my next molding project, might be a new front end for my Sea Bee hmm.

Edited by Marklo
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Loving your vacuum form rig.  Following with interest.

 

Dennis

 

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7 hours ago, AdrianMF said:

I raised my halves up from the vac bed by two or three mm.

 

1 hour ago, Courageous said:

I agree with @AdrianMF about lifting your master slightly,

 

The halves were shaped on a 40 thou / 1mm backing piece to allow for the curve which could then be trimmed away, but I agree that another millimetre would be better. Thanks for the advice - appreciated.

7 hours ago, AdrianMF said:

running packing tape around the edges and joins of the box is a simple way to get more air tightness.

I made sure that the edges were well glued to create a seal as well as screwed, Adrian, but taping the joints can do no harm. Cheers for the top tip.

 

1 hour ago, Courageous said:

I'd keep those 'masters' in a safe place as I might cheekily ask for a set, so I can do 'floater' Gurnard.

No probs there, Stu; I’ll happily pass on a set of mouldings. Let me see how the fuselage pieces look once they’re trimmed, and how I get on with the wings. I’d prefer not to give you rubbish!

 

Jon

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Veeeery interesting, to miss-quote a rather well-known German soldier peering through a bush. (Older folks may remember him!)

 

Another one who'd never heard of this somewhat unlovely machine, although if you cover the tail, the Kestrel-engined one doesn't look unlike the Hawkers....

Great start so far, I'll be following along!

 

Ian

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I've been away from the workbench for a few days, then focussing on some other non-modelling projects, but I'm back at it now.

 

After cutting out one of the pairs of fuselage halves, which I though I'd vacformed successfully, I discovered that they were in fact too narrow:

 

20200708_194101

 

That's the nose, which should be circular to match the propeller hub.

 

I considered adding plastic card shims to widen the front fuselage but also noticed that the cockpit was incorrectly shaped, being too deeply curved. Rather than commit to bodging extra bits if plastic into the vacformed pieces I bit the bullet and modified the masters. The cockpit opening had extra P38 filler added and then sanded, and I put a row of 60 thou / 1.5mm card strips around each base to deepen the vacform 'draw'. 

 

After commandeering the kitchen oven grill I manage to produce a decent pair of fuselage halves (and another 3 that were rubbish... ), so I've decided to stick to building just one Gurnard variant for now.

 

I also managed to produce an upper wing top half, as I'd made a mould from balsa. This had been hardened with 3 or 4 coats of liquid poly, then the grain was filled in and smoothed with a couple of layers of Humbrol filler. I'm sure that there's an easier way to do it, but it seemed to work:

 

20200708_195726

 

It still needs plenty of scraping and sanding before I even think about surface detail.

 

I discovered that the June 1998 issue of 'Aeroplane Monthly' contained photos of both Gurnard airframes in varying stages of undress, so I bought a copy online for reference. Internal detail isn't easy to see, so I've used a bit of 'imagineering', but the interior is well on its way to completion:

 

20200708_194554

 

That's kept me out of trouble. The Airfix Swordfish at the back of the workbench must be wondering what it's done wrong...

 

Jon

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Progress is progress and your Swordfish can sit there for a while, I've heard that some models can sit there for years>

 

Stuart

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After making use of a perfectly-timed idea from @Martian for incorporating an instrument panel, the fuselage is nearly ready for closing up:

 

20200710_170121

 

Purists will see the interior as a bit clunky and lacking in artistic finesse, and they'd be perfectly correct. On the other hand it suits my scratchbuilt purposes, will be largely out of sight once the model is completed and I ain't no purist!

 

The scratchbuilt pilot's seat needs a harness and my imagination suggests that the shelf-thingy in the gunner's cockpit (inferred from the Aeroplane Monthly images) ought to have a cushion of sorts, then the fuselage halves can be joined. 

 

Jon

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On 7/8/2020 at 8:07 PM, Jonners said:

I'd made a mould from balsa. This had been hardened with 3 or 4 coats of liquid poly, then the grain was filled in and smoothed with a couple of layers of Humbrol filler. I'm sure that there's an easier way to do it, but it seemed to work:

Yes, use bass wood. It’s a bit dearer than balsa but it carves really well and has a fine enough grain it doesn’t need filling

Edited by Marklo
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23 minutes ago, Marklo said:

Yes, use bass wood

Cheers Mark, I'll pick some up when I can. The only reason I used balsa is because I didn't have any basswood!

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