Special Hobby 1:72 Curtiss Hawk H-75

[dr_gn]

This follows on from this thread from a few months ago: http://www.britmodeller.com/forums/index.php?/topic/234928858-curtiss-hawk-p-36-or-h-75-in-172-scale/

So in a fit of enthusiasm I've started my 1:72 Special Hobby Curtiss Hawk H-75.

http://en.wikipedia.org/wiki/Curtiss_P-36_Hawk

I figured that since the wife grudgingly allowed me to start the Spitfire, she wouldn't notice a second model being built simultaneously. This is on the basis that most women know nothing about model building and are absolutely hopeless at aircraft recognition. If this turns out not to be the case, this will be a very short thread.

Anyway, I've been after one since getting to have a poke around and sit in TFC's example at Duxford last year:

http://fighter-collection.com/cft/hawk-75-2/

Special Hobby are a Czech manufacturer of limited run kits. Couldn't find one at Telford, but at Huddersfield one appeared, so I snapped it up:

Being limited run (the moulds aren't as robust as in a mass produced kit) the parts require a bit more work than those of Tamiya or Hasegawa. For example, the tailplanes don't have any locating spigots, and there is more flash. Surface detail however (the thing that really matters IMO) is excellent.

As you can see from the photo, it's a multi-media kit, with injection moulded airframe, photo-etch fine details, resin cockpit/wheels etc. and a vac-form canopy. Some of the parts (cowling & wheels for example) have two options to suit different engines fitted to the various marks of the aircraft. Basically you get pretty much everything you need to build a nice model. Price for all this? Just £9 !

So after about 1/2 hour of cleaning up with a blade and sanding sticks, I've taped the main structure together. Of course there are no locating pins. I must say it is much, much better than I expected for a kit of this type:

You can see the totally plain tailplane stubs: I'm planning on through-drilling and putting some thin brass rod through there to locate in corresponding holes I'll drill in the tailplanes.

The one thing that I'm a bit apprehensive about is the vac formed rear canopy glazing, and how it will fit. I think I'll do that next just to get it out of the way.

BTW does anyone know of a suitable resin engine for this aircraft? The kit one is OK, but will require a bit of detailing to bring up to scratch.

[warhawk]

Good luck with your project.

Always nice to see someone tackle a short-run kit.

[perdu]

Watching here too dr_gn

Wouldnt miss it

b

[dr_gn]

Watching here too dr_gn

Wouldnt miss it

b

You might get deja vu...

[dr_gn]

Spent this evenings alloted time to cutting and shaping the vac-formed glazing (which is a bh of a job). Still, it gives a more realistic effect than injection moulded plastic at this scale. Not sure about the windscreen profile - I think it should be less bulbous, but it might look ok when trimmed. There are two sets of all the glazed parts in the kit, just in case:

And I started to fettle the resin cockpit. Here are the parts with some of my own refernce pictures of the aircraft. That was a great day at Duxford!

[sean]

Great start dr, if this turns out half as good as your Spitfire w.i.p, it will be well worth watching.

Sean

[perdu]

I love the shape of the Curtiss fighters, there's a real symmetry to the wing and tail shapes that reminds me of when as a kid I would draw fighter planes. They either came out Spitfire shaped or that rounded taper of the Curtiss wing silhouette.

And how good can it be to have you doing that lovely beefy radial, you took some great photos G

settled in and watching avidly

b

[dr_gn]

Ta Perdu!

So the engine is a bit of a blob. I like modelling engines, and since I can't find a resin replacement (didn't try too hard TBH, plus I like messing about with bits of wire) I thought I'd try to improve it:

First off, the reduction gearbox casing on the front of the engine was a bit lop sided. I drilled out the centre hole on the pillar drill to get everything square, then stopped with the drill still in. This way the plastic cooled around the drill and made it into a nice spigot for...mounting in my trusty ML7 for a bit of turning action:

This improved things a lot. Next up was to cut the moulded-in pushrod tubes off and make some new ones out of brass wire. Then I made a circular ignition wire conduit out of brass tube joined with some st.st. wire and cyano:

The pushrod tubes obviously need trimming and squaring off at the ends, and the ignition leads (lead wire) routing properly, but it will look OK:

I'll also add a pitch control unit to the top of the casing, and a few more wires.

[dr_gn]

Great start dr, if this turns out half as good as your Spitfire w.i.p, it will be well worth watching.

Sean

Thanks Sean. I'm begining to wonder why I started two kits at once now. It seemed like such a good idea at the time.

[perdu]

I just knowed you would want to do that

I have every faith that you will make a blooming good job of it too

as you are

b

Edited May 15, 2013 by perdu

[dr_gn]

I just knowed you would want to do that

I have every faith that you will make a blooming good job of it too

as you are

b

Yeah, any excuse

Anyway, early start tomorrow - going to Howden Dam to watch the Lancaster flypast (weather permitting).

[dr_gn]

Finished the engine tonight. I've scratch built the propeller pitch control unit and the thing on top of the gearbox casing (not sure what it is). Also added some pipework and wiring with lead wire. The brass pushrod tubes look ok too. I had some spare Luftwaffe data plates, so I used one here - adds a bit of interest:

Interesting instructions on fitting the propeller: just an arrow pointing vaguely in the direction of the nose. There was no spigot to locate the propeller hub onto. Then again there was no hole in the hub anyway. My pin drill set has seen some action this evening. Turns freely enough now - it must be all that midnight oil.

It's never going to be a match for an aftermarket resin engine, but it's better than what I started with:

[woody37]

I disagree with you, it's certainly as good as any resin I've used, Stunning work so far

[Sgt.Squarehead]

Blimey, you've tarted that lump up a treat.....Splendid work!

[sean]

Fantastic work on the engine, wish I had the patience to do that. Look forward to seeing more,

Sean

[perdu]

lovely job on that engine doc

bodes

yes it bodes, it bodes well for the rest of the Hawk

n i c e

bill

[dr_gn]

So after completing the Spitfire, and yet still fumbling about with files and scalpels, the missus finally realised something was afoot, and I had to admit I'd in fact been building two models simultaneously. Now the cast has been removed, I've re-started this one.

Tonight's job was pinning the u/c legs and tailplanes. This is a short run kit, and as such there is little in the way of moulded location features. I decided to use brass rod to reinforce these parts, but the problem was how to align everything. I settled on this method which has worked quite well:

1, Drill the tailplane stubs:

2, Glue the tailplane on with dots of cyano:

3, Back-drill the tailplanes using the fuselage stub holes as a jig:

4, Snap the tailplane off, clean up the faces and cyano brass rod into the sockets:

Finished, ready for final assembly and filling:

The u/c legs and wheel wells were drilled 'freehand':

Now to continue doing battle with the vac-formed windscreen which is an absolute bh to profile.

Edited July 10, 2013 by dr_gn

[Duncan B]

I've got this kit in the stash but it has never made it close to being started so I'll watch this with interest and maybe it'll creep up the list.

Duncan B

[dr_gn]

Bit of work on the cockpit - the resin sides are in place, control column fitted, the photo etch rudder pedals and various levers fitted, and everything painted in base colour. Also painted the p/e instrument panel black.

[dr_gn]

Cockpit bits weathered a bit, the resin isn't that good, fairly porous, so it's difficult to get a finish thats not grainy. Seat is currently in brake fluid - looked a bit too rough. Even considering using a spare Spitfire seat and separate harness.

[gruffy]

So after completing the Spitfire, and yet still fumbling about with files and scalpels, the missus finally realised something was afoot, and I had to admit I'd in fact been building two models simultaneously. Now the cast has been removed, I've re-started this one.

Tonight's job was pinning the u/c legs and tailplanes. This is a short run kit, and as such there is little in the way of moulded location features. I decided to use brass rod to reinforce these parts, but the problem was how to align everything. I settled on this method which has worked quite well:

1, Drill the tailplane stubs:

2, Glue the tailplane on with dots of cyano:

3, Back-drill the tailplanes using the fuselage stub holes as a jig:

4, Snap the tailplane off, clean up the faces and cyano brass rod into the sockets:

Finished, ready for final assembly and filling:

The u/c legs and wheel wells were drilled 'freehand':

Now to continue doing battle with the vac-formed windscreen which is an absolute bh to profile.

Thats a very good tip for tail planes with short run kits!

[dr_gn]

Glad it's of use Gruffy!

Got the wings and tailplane on tonight, and a first attempt at the photo-etch engine gills. I'll have to do those again, they don't fit too well after a guide coat of primer. Still, it looks far more Curtiss Hawk shaped now:

[dr_gn]

So the original cowling didn't fit, and despite trying to mod the original, there was no way it was ever going to fit both the engine and the fuselage.

I thought why not try Rapid Prototyping a replacement. I started by scribing and filing a step in the fuselage over which the new cowl would fit:

Then, found some 3-views online:

Surprising how bulged the cowl is in plan. Anyway, after scaling and measuring I drew a new cowl on proE Wildfire. Quite a simple job, only about 1/2 hour of work:

Then 'grew' it on an RP machine. Ours uses the fused deposition moulding method, and extrudes hot ABS plastic in layers:

The first one was slightly too thin, and cracked easily so I added 0.25mm onto the wall thickness on the CAD model, and tried again. This time it was OK, so I covered it in thin cyano to make it more durable, and sanded it back smooth:

The resolution of the RP machine isn't good enough for surface features, so these were scribed by hand and a drill bit:

And here it is slotted onto the fuselage:

No, it's not perfect, but it will at least allow me to hopefully finish the model, plus I've learned a hell of a lot about the process. Once higher resolution RP machine become cheaply available the filling and rescribing will not be needed and the above would be the work of a couple of hours.

Edited September 7, 2013 by dr_gn

[Sgt.Squarehead]

Great save.....Technology FTW!

[stevehnz]

Impressive & quite exciting, maybe the way forward for this industry.

Steve.