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Airfix 1:24 Grumman Hellcat


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The P&W 2800 double wasp 10W is a little model all in itself and I think I spent more time researching this than most other models in their entirety.

So to business. I'm sure most know that the crankcase of the engine is far to large in diameter to allow the various push rod rings and cylinder blocks to pass over it so lots of flexi file work needed as almost 1mm needs to come off across the diameter. I baulked at paying £9 for a resin one cast from a reduced master, after all this is what modelling's all about.

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While Airfix seem to have reduced the ejector pin marks, they've made up for it in seam lines so quite a bit of scraping and sanding needed.

Once that's done, the cylinders need painting. The bottom halves I did in steel and the top halves in aluminium. I've used Vallejo Metal Colors as I think they're excellent. Quick drying, no mess and no smell and lovely coverage. The push rods were painted gloss black with aluminium ends.

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The crankcase colour was a first attempt at a mix but it had far too much blue in it. I read it should be Grumman grey but since the engine is made by Pratt & Whitney, not Grumman, I couldn't see that being the case and went for the engine grey specified. I finally settled on a mix of 4:3:1 of Mr Color Aqueous RLM 75 Dark Grey: Tamiya Flat White: Tamiya Blue. It seemed to be not too far away from some of the reference material.

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You can also see on this photo that I've removed the basic plastic links provided on the parts and replaced them, as they were originally, with rubber hose. The jubilee clips are thin strips of tinfoil. The oil flange is flat black suitably chipped and oil stained.

 

Once everything fits onto the crankcase properly, it's time for the ignition wiring. I used 0.6mm braided cord from Hiroboy along with 1:24 sparkplugs in metal. I was a bit mean to spend a small fortune on scale nuts for the ends of the sparkplugs so I used 1mm evergreen hexagonal rod, drilled and painted silver then sliced into thin slivers and slipped over the end of the sparkplug before the ignition wire was attached.

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The intake pipes are gunmetal then brushed with copper and duraluminium till I was happy with the effect.

The exhaust pipes go on very easily as long as you mark them up when they come off the sprues, otherwise it's a happy half hour mixing and matching. (me? never :rolleyes:)

Paintwise, I followed a plan of painting them Tamiya red/brown then airbrushing with a very dilute solution of black/red brown as well as metallics and a light grey around the pipe ends.

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The heavy wear and chipping on the supercharger intakes is seen on many reference photos and was achieved by spraying first with a coat of duraluminium followed by chipping solution then a top coat of zinc chromate green. It's then a simple task to remove the green layer to the desired effect.

Oil effects (which don't show too well on the photos) are sprayed on as a mix of black/redbrown mixed with Alclad Aqua Gloss varnish and diluted with IPA.

The oil tank cap is yellow and my eyes were given a great workout by deciding to put the "US 19 Gal" writing on there in individual wet decals :BANGHEAD2:

Some pics of the engine ready to mount are below, I'll be needing to add a fair bit of non supplied pipework when the time comes but next it's onward and upward to the cockpit.

Thanks for looking.

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Fantastic detail on the engine, I really like the different metals appearing very realistic. The braided wiring adds to the appearance. Please continue your WIP, I'm really interested how the big cat turns out.

Cheers Rob

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Hi all, thanks for the kind comments. I've just reviewed my first post and realised my initial paragraph wasn't included so here it is:

"This is my build of an Airfix 1:24 Grumman Hellcat built through the dreaded lockdown(s). It was finished in around May of this year but I've only gotten around to posting it here now. I'll post in installments so hopefully no one will get too bored reading it all in one chunk then I'll post the RFI pictures at the end. Currently I'm on with a 1:32 HK Lancaster Dambuster which I WILL post here realtime in a few days"

 

Engine finished it was time for the cockpit. It all goes together very well, a little too well at times as some of the tolerances are very tight. I've used the full cockpit upgrade from Airscale to spruce it up a bit. 

So, the build of the cockpit itself was quite straightforward, HGW Seatbelts and I like to drill a little hole in the seat side and pass a small pinhead through to act as a fixing point.

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The whole cockpit assembly went into the port half of the fuselage as sweet as a nut, then came the other side! The radio equipment in the fuselage is a nightmare as it's too broad for the fuselage so has to be trimmed. The metal framework holding the tanks etc is incredibly tight to fit in. Too tight in fact. After about 30 tries, taking a bit off each time, I did something I hate to do. None of it is visible and so because I feared I was going to damage something intrinsic it I kept on fitting and unfitting, I took out the frames and, while still very tight, I finally managed to get a fit and a glue to give me a finished fuselage. 

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Some general pics below. Thanks for looking

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Engine done, cockpit done, fuselage together and filled and sanded. Wings!

The wing build is straightforward and some of the fits are VERY tight!. I'm building port wing retracted and starboard wing down, just to be awkward.

The gun bays are where you can really go to town if you want. I'm doing the port bays open.

Airfix's gun barrels had to go in favour of Model Masters turned ones. They're not cheap but they make a difference. Satin black base coat then highlights with Vallejo Metal Color

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Lots of gunpowder residue and pigment in the bay itself. The ammo shutes are silver and the bullets painted brass with a copper head. Ammo boxes the same and chipped to show wear etc.

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I then added a bit of detail not supplied, namely, the electrical gun firing electrics and wire

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Top of the wing next and this is where I wonder why I build aircraft exclusively:BANGHEAD2:. Trying to get clamps to sit where you want them on an aerodynamic surface tests the patience somewhat.

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But it goes on very well and then we can go with getting the open gun bay flap doors sorted and weathered. Brownings were dirty, greasy beasts so I've tried to show that on the doors and interior.

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HVAR rockets next! 

A bit of filling to do and the ever fiddly bit of painting a thin line round a cone but, with the kit decals on and a little red decal on the support arm from my spares tray to make it look right, I'm quite happy. I've still got to add the ignition wires round the back, maybe tomorrow.

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I've had a bit of a tidy up day really. Tried to get a bit of variation on the fabric control surfaces but you can't do much with GSB :BANGHEAD2:

So I tried a trick that the WWI boys use of painting in a lighter colour than the base colour then sticking thin 1mm strips of masking tape over the ribs then spraying with the base colour. It just gives a hint of something lighter over the ribs and you can then play around with mist coats to get it right. It shows up better in actuality than the photo but the effect is VERY subtle, maybe too subtle to be worthwhile.

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Also, although it's the wrong side in the picture, I took out the horrid little plastic push rod for the trim tab and drilled and inserted a wire one instead

 

Next the firewall. Not finished yet but done in Zinc Chromate Yellow and weathered with Mig Jiminez engine grime and fresh engine oil

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If you're leaving the panels off the lip either side is too deep so I've filled it with thin rod.

Lastly ,lastly today, some engine grime on the engine and fresh engine oil around the oil filler area and a thin film on various surfaces. Propeller gets finished tomorrow and I'll check the quality of the Glossy Sea Blue paint job.

 

Thanks for taking the time to take a peek.

 

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Right so today it's on to the thorny subject of the oil system. As chuck540z3 says on his hellcat build, there's a complete dearth of pictures of the rear of the engine. Chuck posted this image and asked "where is that gizmo at the bottom where all the oil lines go?"

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It's the oil cooler but all the oil cooler assembly sits behind the firewall so presumably all the oil pipes from the oil tank and the engine which are in front of the firewall have  to get through there somehow.

This is a blow up of the oil cooler assembly. I guessed from the bit of cut off text in the diagram above that it was a Harrison oil cooler assembly

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The "gizmo" Chuck refers to is part of the cooler assembly and is actually a thermostatic valve for the hot oil. If the oil is cool enough already as it enters the cooler the valve stays open and it bypasses the cooler ant heads straight back to the oil tank.

If it's too hot, the valve closes and the oil is forced through the cooler to cool down before heading to the oil tank.

Here's the gizmo exploded

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Again, since this is bolted to the oil cooler, it must lie behind the firewall. And all the pipes have to make their way through but there's no pictures of it!!!:BANGHEAD2: :blowup:

I trawled the internet, youtube and anything else as well as trying to reconcile different drawings of the oil system such as this one

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Then this morning I found a video on Youtube of the restoration of an f/6/f-3 /BuNo 25910 and blessed be here were stills of the whole firewall assembly!!

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It now becomes crystal clear that the oil pipes attach to the fittings to the right of the front of the oil cooler then attach to the "gizmo" or thermostatic valve behind it.

In other words, all I have to do is fashion the fittings and fasten my oil lines to them. The oil cooler assembly is invisible behind the firewall so I've nothing to scratch build or invent except for the little fittings which are holes and styrene rod, PHEW!!!!:yahoo:

So, tomorrow I can get on with that. In between tearing my non existent hair out I also managed to get the prop about done today as well....Happy

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So now the oil system quandry is sorted, I can get of with tarting up the firewall a bit. Bit of murk and dirt to start. Zinc chromate yellow base then some Tamiya clear orange heavily diluted with IPA about 9 :1 and sprayed to represent a bit of heat damage. Engine grime next again heavily diluted and lastly fresh engine oil a thin sheen covering most parts. Hopefully looks better already.

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I also realised the interior section below the firewall also needs to be Zinc Chromate Yellow so that was sorted as well.

Next up are the wires for the control surfaces and the pipework going out from the firewall to the wings. One pair are to deliver fresh air to the cockpit, not sure on the other pair.

Anyway, I have a pathological hatred of kit plastic pipework and wiring.

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My original thought was  to separate the horrid plastic pipes from the control surface wires underneath and use the control wires while making new pipes. But the wires looked messy and then when I got this image of the firewall I realised the lot had to go

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So I fashioned new wires and spacers from sheet styrene and 0.6mm aluminium wire. Sprayed black, hopefully they look better than the kit plastic. The pipe work was easy. The thinner pipe from 1.2mm aluminium wire and the thicker from 2mm both sheathed with shrink tubing and dunked in boiling water for a few seconds then shaped and fitted. This picture also gave me the colour of the little black box on the upper right and the fact that there's an electrical wire dropping out of it. In fact, this pic gives loads of wiring and pipework I hadn't seen which, with some other photos should mean i can get most of the important wires pipes and other gubbins needed and which Airfix don't include. I won't put it all in though, just enough to give it a busy feel. So, this is the firewall to date. As ever, thanks for looking

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Here are some better pics (although I'm no photographer) of the brilliant cockpit enhancements from Peter at Airscale. I'll be fitting the windshield tomorrow so wnted some pics for posterity while it's still relatively open 

I've just got a commission for a 1:32 Lanc and I'm hoping the Border model will be out before I buy one, although I'm not holding my breath on that one. If it is, I'll be banging on his door hoping he's producing one for that. Otherwise HK Models it is. Anyway, here's the pics:

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Also today, I painted the tailfin. I'm doing the White 32 version from The Randolph as there are loads of wartime shots of it. My main problem is that the Virgo in me keeps trying to make me paint the lines geometrically perfect but, when you look at the contemporary photos it's clear these were rushed clumsy paint jobs done on board. Look at some of the numbers in these shots. I struggled to let myself be that slipshod so I deliberately left the white with a tiny bit of blue showing through to try and show the workmanlike job that was done on board. Still think my lines are too straight though....I might mess 'em up a bit later. But the thought of reproducing those wonky numbers......:rofl:

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Well wonky numbers time came and went...not without issue.

I normally like to paint markings and insignia wherever possible, it just looks more realistic. But this time I thought "Shiny plane for once, shiny decals, might just work" so I decided to give it a try.

My first big mistake, I put all the tiny "oil filler her, water filler there, don't step here" kind of decals on first. BIG mistake. They looked great then came the first star and bar for the port wing. 

Into water and this, thanks Airfix, was the result

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You'd have thought I'd bought a 25 year old kit off of eBay with decals to match. Seriously??

So, that sort of took the choice away from me, I was painting the damn things.

Problem number 1: I hadn't sprayed white first then masked before the GSB topcoat so now I had to spray white then mask then spray GSB again :BANGHEAD2:

Problem number 2: remember those little decals I'd confidently put on first? Some were now perilously close to the paint job

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careful masking there then and a mental note of aftermarket decals at all times.

 

The Number 32 decals were going to have to be used as There was no way I could mask around all the little instruction ones near the cockpit successfully. Load of clear carrier film around the number 2 and I had to separate them to get the "wonkiness" They split too but as I didn't have to get them exactly square, it was workable.

Lots of micro sol and a judicious fine brush tipped with white and it looks ok.

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Tried the engine and the fit is ok.

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Now for the oil, fuel and water lines and some of the electrical and control wires (not all) and we're not far off done I reckon.

Let's get moving with this engine. I realised quite early that, if I wanted some flexibility but also hold (sound like my wife talking about hairspray) I needed to line my lines with something. I'm using 1mm inside diameter heat shrink electrical tubing for the oil and larger fuel lines. The trade off is that if  i use a 1mm wire inside it to give a nice tight look to the lines then it's going to be harder to shape after the engine is glued in. A finer wire will be more pliable but won't look as good. 

I went with the 1mm wire and decided to soft fit the engine then shape the lines, fir the engine then then hard wire in the lines, already pre shaped for ease. 

All main oil lines were fitted plus the fuel lines to the carburettor and some assorted control lines and thinner pipes. For the thinner pipes I used coloured florists wire in varying diameters. The fittings are 2mm OD aluminium pipe cut to size. Good because you can leave a "tail" on each end of the fit point and you have a tangible palce for the glue to set.

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The firewall was ready to receive it:

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so all that was needed was to bring them together.

 

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I needed the whole plane to be vertical till the engine gluing had time to set solid so my straps and case from my portable photo background photo shooting thingy came in handy. Only having one wing doesn't half make it lopsided from a centre of gravity point of view.

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All in and set, I added the fuel lines last of all, along with control lines and assorted. It's impractical to add all the lines and also, a bit of a guess I feel. I'm not an aeronautical engineer and, while there's a wealth of stuff on pipework etc out there, a lot of it is from restored aircraft and it's difficult to know sometimes what's original and what's there from a modern standpoint as necessary for H&S etc. 

 

The engine is in and plumbed, I'm getting a new camera in the next couple of days so holding off on new photos till I can have a go with that.....should be fun:BANGHEAD2:

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