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Sabrejet

Wingnut Wings 1/32 Bristol F.2b Sunbeam Arab - FINISHED (at last)!!

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Posted (edited)

First off I should explain that my model-making pace is (at best) pretty slug-like and so please don't imagine I will be declaring success on this one anytime soon. I also can't guarantee that it will get finished, but here goes.

 

Having looked at WNW kits for some time I thought I would give one a go, but wanting to do a training machine from my local airfield (Yatesbury) I had two choices: a fairly drab colour scheme for a Falcon-engined F.2b; or a more interesting one but with the added issue that it would have to be a Sunbeam Arab-engined version. Having done a great deal of research into this one airfield's use in WW1, I should point out that the only Falcon-engined F.2b unit to operate from Yatesbury was 59 Training Sqn, late in 1917 (59 TS departed for Beaulieu in October of that year); the station didn't get any other F.2b's until resident units converted to the unloved Arab Fighter in late 1918. 

 

And since WNW only does the Falcon version I am left with one alternative: to scratch-build the engine/fwd fuselage, plus a few other training-only tweaks.

 

So as a starter (using the Roden box art as the clearest graphic), here's the visual difference between the two versions:

 

01 (2)

 

The Arab, being a V8 engine configuration (versus the Falcon's V12) is a great deal shorter, and I was fortunate to photograph the relevant drawings at The National Archive a while back, giving me some good measurements, which I converted to 1/32. The lengths below are for full-size:

 

01a

 

Another view, which gives me a nice idea of component placement, v-angle etc (I also used the Roden 1/48 engine as a 3D guide).

 

01b (2)

 

And finally I am going to do a Yatesbury-based Arab F.2b from 37 Training Depot Station, circa December 1918, which looked like this:

 

01c

 

I've done a colour rendition to show how it should look (it's not the machine shown above):

 

01d

 

So don't hold your collective breaths, but more soon I hope!

 

Edited by Sabrejet

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Hmmm sounds very interesting, although I would imagine it won't be an easy task that you have set yourself. I will be keeping an eye on this one with interest :thumbsup:

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Kudos for even attempting this one! Watching with interest and good luck.

 

Gary

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I had never even heard of an Arab powered version. That's quite a challenge you've set yourself, so I'll be following along on this one.....

 

Ian

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Posted (edited)

Well progress (so far) seems OK. I've built the F.2b fuselage as per WNW with no real deviations, except for leaving out the ammunition drums in the observer's cockpit: I haven't seen any photos of Yatesbury BF's with the MG fitted. I have also sanded off all the raised detail on the firewall, ready for attaching some bulkheads/formers there. Observer's cockpit surround will be taped in place until later (I have a loose wire in the cockpit which I need to re-attach)

 

03

 

I also have made up a simple mould for the engine cowlings, which on the real aircraft just consisted of upper and lower halves. Since there are no compound curves on the Arab cowlings, it was simple to make fwd and aft bulkheads, fill the gap with milliput and then sand a straight line between the two. It's still quite a complex shape underneath though.

 

Having done that, I've shaped a couple of test mouldings (just heated over the gas ring and draped over the mould I made), with top cowling at left and bottom at right. I'm happy with the results, so with a few tweaks, endless resources of plastic card and burnt fingers I think I'm good to go!

 

05 (2)

 

Edited by Sabrejet

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Posted (edited)

Quick update: managed to get some time off today and did a bit of trimming the top cowling, using the above heat-moulded example (I gather this type of moulding is nowadays called 'crash moulding'). The bottom part of the 'hole' will be removed and the bottom edge trimmed to match the joint line of the bottom cowling, so I'm just going to use this 'to be trimmed' part as a guide to where the engine's cylinder block will sit.

 

06

 

Another comparison between the Roden (1/48) cowlings, just to show how much shorter the Arab engine installation (lower) is compared to the Falcon III (upper). The red outline shows where the radiator goes, so the difference in length is even greater (the Arab rad is enclosed fully by the cowlings).

 

04a

 

Edited by Sabrejet

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Now this is very interesting, not only because I love Biffs, but also becuase I'm not far from Yatesbury. I occasionally pick up a trailer from a little industrial site about 300 yards from the original 1916 hangers.

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Oddball: If you're going to Hangar 45 then you are on the site of the first hangars constructed there (45 was WW2-era but next door is the old collapsed ARS hangar from 1916). The hangars further west are from 1917-era. It's a very interesting place!

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Posted (edited)

Been going great guns with this and managed to get a basic engine bay structure completed, which will allow the cowlings to be firmly attached, and give a good attachment point for other bits such as the reduction gear case/propeller, engine bits etc. I'm not aiming to construct the full engine, but there are enough holes in the cowlings for me to know that I'll have to give the impression of a full engine once everything's in place. Thus I have added a brass gun tube so that this part has depth; and also made a box for the engine gear case to sit in - hopefully that item will fill the 'box' enough to make it look the real deal. All those engine bits will need to be made of course.

 

I have also inserted some brass pegs in the aft end of the whole assembly, to make it easier to locate on the kit firewall, and also to add strength. The cut-out in the bottom of the main fore-aft part is to just show where the engine's sump plug will go: since there is an access hole in the lower cowling at that point, it's important to know where to put the corresponding opening etc.:

 

04

 

I placed the new engine bay assembly on the kit firewall (the brass pegs have enough of a friction fit for it to stay in place without any adhesive - I'll glue it in place once I'm sure it all looks OK and once I think I haven't forgotten anything!). As a quick check, I put the top cowling on too. I think it's looking reasonably OK so far...

 

07

 

Edited by Sabrejet

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You're a brave man to chop up a WNW kit!

 

That said, it's looking very nice so far 👍

 

Trevor

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Indeed this seems to be coming on a lot faster than you led us to believe it would. Looking very good :thumbsup:

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Posted (edited)
2 hours ago, Beardie said:

Indeed this seems to be coming on a lot faster than you led us to believe it would. Looking very good :thumbsup:

 

I managed to get a couple of days off (off work + off shopping duties etc); plus the weather here has been changeable, so not feeling so guilty about not being out and about so much. I've surprised myself a bit. I also have to be in the mood for model making, so I am making hay while I can...

 

And I should mention that I had already put together a lot of the cockpit bits, waiting to decide if I was going to do the Arab conversion or just build it out of the box.

Edited by Sabrejet

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A Bristol, and a conversion to boot! Count me in!

 

The Brisfit is a little early for me, although as I complete more of my WW2 era Bristols i will eventually get to WW1. 

 

Looking very good so far!

 

Matt

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13 hours ago, Sabrejet said:

Oddball: If you're going to Hangar 45 then you are on the site of the first hangars constructed there (45 was WW2-era but next door is the old collapsed ARS hangar from 1916). The hangars further west are from 1917-era. It's a very interesting place!

 

That's the one yeah! It is indeed, lots of history all around. I've been up there at night quite a few times and looking across at the old buildings at the west camp, very atmospheric.

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Posted (edited)

Bit more done. The top cowling isn't too 'busy', and varies from aircraft to aircraft in terms of the size of the aperture for the cylinder heads (and ditto for the bottom cowl). But common to all are two prominent holes in the top of the cowling, roughly in the area of the carburettor flanges/inlet manifold joint (placed there to assist in carb adjustment?), and also the prominent oval hole for the MG blast tube gas exhaust (WNW part A41). I have marked and drilled the former (1), then drilled and filed the latter (2). Also, the Arab F.2b cowlings totally encase the radiator, in contrast to the Falcon installation which has the radiator in front of the cowlings. Therefore hole (3) will be for the radiator filler neck, and I'll get on to holes (4) next. 

 

09f

 

OK to those holes numbered (4) above. On the real aircraft they are covered on the port/LH side by an exhaust duct, which is placed parallel to the panel edge aft of it. On the Starboard/RH side, it's an inlet duct, and placed at an angle to the panel edge aft of it. I assume these paired ducts function as a means of getting airflow through the aft cowling area to vent gases etc. 

 

09b

 

09a

 

Strangely, Roden's 1/48 cowling (left below) has these rendered incorrectly as  vents, running parallel to the panel edge, but the box art (see above) is correct. Anyway, I made a simple resin male mould and heat-formed a couple of ducts, which were dressed with plastic card to represent attachment flanges. This assembly will need a few swipes of a sanding stick to tidy it all up, but I'm happy with the result.

 

09c

 

Edited by Sabrejet

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Posted (edited)

Moving along a bit, I've trimmed the panel a bit and done a few fit checks on the WNW fuselage.

 

09d

 

I've also decided to use the crankcase of the WNW Falcon engine, but only so that I can mount bits to it and also have a representation of the sump. The engine obviously needs to be shortened, and since I had made the initial fore-aft former part of the engine frame a solid piece, I have had to thin the halves of the engine commensurately to get the correct width when sandwiching the plasticard former between the two engine halves. Does that even make sense? Hopefully so. I have also reshaped the kit oil tank at placed it on the firewall (as per Arab), since it will be visible through the two aft/upper panel vents. Again, it sandwiches the fore-aft former. Nothing like making things difficult eh?

 

09e

 

So with that in place, I used the National Archive Arab drawings to correctly place the tops of the crankcase at the correct angle and location so that the 'vee' is right. To check that it will all look OK, I made up some oversize mockup cylinder blocks, which will also allow me to see how much I need to pare off etc. These mockup blocks are just tacked in place with a dab of liquid cement and will be discarded as soon as I can get my head round the key faces/locations etc.

 

10

 

Looking OK so far with the top cowling in place: I still need to remove the bottom half of the top cowling, but for now it lets me see that the holes in it (those for the cylinder heads) are in the right place and the correct size.

 

11 (2)

 

 

Edited by Sabrejet

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Some very impressive scratch building going on here :thumbsup: Well beyond my scratch building abilities.

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Very kind of you to say so Beardie: it's proving to be an enjoyable build so far - which for me is the main thing. 

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Posted (edited)

Made a start on the engine, starting with the rocker covers: these will be fully visible on the model and so need to look OK. I started with two blocks of laminated plastic card, to the right dimensions and then cut the correct angle for the sloped top face of the rocker cover with a razor saw:

 

12 (2)

 

Next I sanded them both to shape, filed the access recesses for the rocker cover bolts and filed a notch in one end of each (two rockers because it's a V8 engine) to accept a punched plastic card disc which represents the camshaft drive housing.

 

14

 

Next I need to make a flange to go around the base of each rocker cover and rather than spend a long time measuring, I used the bolt recesses in the rocker covers to show where the bolt flanges will go, transferred these in pencil onto a piece of thin plastic card and then just traced round the rest of the rocker cover to show how big the flange needed to be. It was then just a process of filing and cutting round the outline, and after a bit of adjustment, here's the finished flange (note that I was a bit over-zealous with the razor saw on this one and had to fill a piece of the top face):

 

14 (2)

 

With that done, it's just a case of gluing it all together:

 

15

 

Finally, I made some bolt heads from stretched sprue, cut them into short lengths, and whilst holding my breath a lot, superglued them in place. A wash of liquid cement helped to soften the edges a bit.

 

16 (3)

 

They still need a bit of fettling but generally look the part.

Edited by Sabrejet

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Sabrejet, I wasn't expecting this subject from yourself, I thought it would some Sabre after your recent postings!

Very impressive in what you're doing...keep it up.

 

Stuart

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It's a fair point: this one is a bit of therapy. I've made a large number of Sabre/Fury models over the years and though I'm not fully 'done' with them, I do like something a bit different. 

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Posted (edited)

Minor diversion onto the propeller. I'm not quite satisfied with the WNW prop flange/boss, which (very unusually for WNW) seems a bit indistinct around its edges on both propellers (2 and 4-blade) in the kit. The Arab also rotated in the opposite direction to the Falcon, so at some point I need to address a new/modified propeller anyway, so I thought I would attempt making a new propeller hub/boss/flange (what is that bit called?). It will also make it easier to paint the propeller when the time comes. I dare say there is an aftermarket set to sort this all out but I couldn't find one.

 

So first of all I made a simple female mould using Milliput:

 

21

 

Then, happy that I had captured the detail I sanded off the hub detail.

 

22

 

Next head-scratcher was to work out how to mould the 'male' bit I need. I had thought about molten plastic (which I think would have been OK with the Milliput mould), but the easy route was to try Milliput as a first effort for the moulded part too. I put a pea-sized ball of the 'wet' Milliput onto a flat piece of metal, then pushed my home-made mould into it as far as it would go (I also slightly wet the mould before I did this). Luckily when I removed the mould, the 'wet' Milliput stayed stuck to the metal surface and not the mould!

 

It was then a case of waiting a day for the Milliput to harden and then gently easing the cured part off the metal surface by applying a gentle sideways shear force and cleaning it up (still needs a bit more clean-up but this was a test piece to see if it would work). WNW's hole recesses were a perfect fit for a 0.7mm drill, so clean-up was pretty simple.

 

23

 

Finally a quick check to see how it looks:

 

24

 

I think the holes need opening out a bit to maybe 0.8mm, and a bit more clean-up needs to be done but overall I'm happy with the results. I'd recommend using this method of simple moulding for all sorts of modelling jobs: it's the first time I've done anything so delicate, but in the past I've used it to replicate missing kit parts and all sorts of duplicated scratch-built items.

Edited by Sabrejet

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Great bravery and ingenuity showing in this build. Top descriptions and pics, too.

 

I'm back here in the stands punching the air.... you go, lad.

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