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Mitsubishi A5M4 "Claude" [1:32 Special Hobby] - RFI


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1 minute ago, Alex said:

Ah, the voice of experience!  That is indeed an elegant and (now that you’ve said it) obvious solution.  Fortunately the *next* Japanese plane in the queue is also a fixed-gear type, so I’ll have a chance to try that out...


I think you're solution is probably more foolproof to be honest, but in circumstances where it's not as convenient to mask the wheels as this one, it's certainly a trick worth knowing about. One thing you have to watch for, though, is the wheels drifting while you're spraying, and then getting overspray on more than half of the wheel, making it difficult to hide inside the spat.



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I've managed to clean up the wing seams and re-scribe the panel lines that wrap around the leading edge.  Also made a metal pitot tube to replace the lump of plastic that came with the kit.



I'll make sure the pitot tube is straight when I actually glue it in...


Most of the mis-alignment between the upper side of the wing and the wing root that's molded into the fuselage can be fixed by carefully wedging the wing to spread the top and bottom apart by a bit less than a mm.  This is the same approach that I took on the Ki-27 kit (originally suggested by dennismcc).



I also hollowed out the exhaust stubs.  Not sure I'll use them, though.  I may just replace them with brass tubing.  We'll see how it goes when I get to the engine/cowl modification part.  That's likely the very last bit, though, since both can be installed after the rest of the model is completely finished.


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Springing the wing with that little wedge pretty much eliminated the mismatch on the starboard side.



Port side is still off



The panel line wash shows (kind of) the scribed line that demarcates what needs to be removed.



Fairly quick work with a round file and some sanding sticks


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  • 2 weeks later...

OK, back in the saddle after a bit of a digression into civil air stuff...


One of the last steps on prepping the wing subassembly is letting in the wingtip running lights.  These are provided as clear parts in the kit, but you have to saw out the relevant part of the wingtip to make room for them.  Of course, the molded-in line denoting the place to cut was placed differently on the top and bottom wing sections...


I had cut these off the clear sprue early on and painted then with clear red and clear blue (the IJN did green starboard lights by putting a yellow bulb under blue glass).  At the time I did not notice that they were not identical, but in fact had a subtle handedness to them.  I had a 50:50 chance of getting the right color on the right one just by chance, but of course...   After removing the paint from them with thinner I repainted them in the correct color and installed them using PVA glue.



The surface looks a bit grotty because I've already painted over the "glass" part with masking fluid.


The next major operation to tackle was the cowl.  As I noted earlier, it was my hope to modify it to allow the cooling flaps to be flared, as is often seen on these aircraft when they are sitting around the airfield, for instance:



The kit provided the cowl with the flaps molded closed (in very thick plastic, like the whole kit).   My goal was to do a subtle flare, enough to be noticeable without opening them so much as to invite peering in the see that there are no engine bearers or other details behind the engine.  I decided to try and do this with the kit plastic, rather than committing (gulp) to cutting the cowl apart and making them out of sheet metal.  After gluing the cowl pieces up and cleaning up the seam, I re-scribed the lines demarcating the flaps from each other and the forward part of the cowl, making them quite a bit deeper than they started.  (Sorry for lack of in-progress photos - I was on a roll)  I then carefully ground down the backs of the flaps to make them thinner, then razor-sawed the lines dividing the individual flaps from each other.  Then, having the ends of those sawn slots as a guide, I used a ball-head grinding tool on my little motor tool to carefully grind away *almost* all of the material from the inside of the cowl in back of the line where the flaps were to hinge (and finally remembered to take a picture):


That photo shows (obviously) the effect after I set the thing flaps-down in boiling water to soften it and then gently bent the flaps outward.  Here it is from the other side:



Not too bad for an hour's effort.  remaking them from scratch definitely would have taken longer.  After some clean-up sanding, I went ahead and sprayed it with black Mr Surfacer, expecting to find a bunch more flaws to correct.



But it looked surprisingly OK, so I went ahead and shot it with Mr Color C-125 "Cowling Color" (a very dark blue-black).



Of course, doing this with the flaps meant eliminating the means that Special Hobby engineered to attach the cowl to the fuselage, so now I have to figure out how I'm going to manage that.  Fortunately, it *should* be pretty straightforward (famous last words).  Unlike some SH kits, the attachment of the engine to the fuselage is robust and positive on this kit.  So I just need to build a jig that will allow me to hold the engine centered and in plane with the cowl while I glue some scrap plastic brackets from the backs/tops of the cylinders to the inside of the cowl, then just glue the engine on and let the cowl float around it.  I have a pretty clear idea how to do this.  I'm also starting to think about fudging up some engine bearers, which I should stop thinking about, because this model is almost done!  


The next major construction step (and really the last such major step) is to join up the wings to the fuselage and sort out the seams.  Then I need to do a bit more work on the undersides of the tailplanes, and it's off to the paint shop!  Barring that, there's the windscreen to polish, Future, mask, and paint.  The gunsight.  And attaching a few fiddly bits like the bombs and drop tank, which I've already built and painted.  Really pretty close now. 

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Did the wing-to-fuselage glue-up.  I had to introduce just a bit of tension by strapping a piece of tape between the wingtips across the top of the plane, so I left it to set up fully for 24 hours before removing the tape.  The goal was to get the upper surfaces to match as tightly as possible, leaving any mismatch in the parts to come out on the bottom of the model.


This strategy paid off on the starboard side especially:



Which just needed some light trim/sand to remove plastic that squeezed out from the glue line - no filler at all.


The port side needed a bit of CA to fill it.  I've almost stopped using anything else as a filler - the combination of bonding strength and ability to sand it smooth makes CA glue unmatched, in my mind, for most "putty" scenarios.



Given what the initial dry fit looked like, I'm pretty happy that this was the *worse* of the two sides.


Of course, that left the underside to deal with, which had significant gaps/steps at both front and back.  I have finally gotten past the impulse to "sneak up" on these things with fine-grit sanding.  It takes a long time and often results in smooth but stepped surfaces.  Instead I've reverted to my woodworking basics and learned to start with a "stock removal" tool - in this case a (very) small rasp.


The gap at bottom is filled with CA - but the stuff is clear so it is sometimes hard to see.  You can see at top the state of the forward part, with CA glue applied and hardened, but no smoothing yet.  As I've learned by reading on LSP, it's critical to attack this CA fill process quickly - I add glue, catalyze it immediately with "zip kicker", and file/sand away.  It is solid but not fully hard for 30-60 minutes and much easier to work in that state than it is the next day, for example.


While the stuff is still semi-hardened, it's a pretty quick job to go from rasp through various sanding sticks to a pretty smooth surface (through 1000-grit in this shot):


You can see at the bottom of the photo that the starboard trailing edge of the wing/root join still needs a touch more fill, which I subsequently added.


This is the front end smoothed out and with destroyed surface detail restored.



I think I need to still do a bit more smoothing on the fronts of the wings to fully level out the join.  But it's close.  Once I'm happy with it I'll wet sand the whole thing with 3200, 4000, and then 6000 grit to get a uniform surface tooth, clean the living heck out of it, and see what a coat of Mr Color Gloss Black looks like.


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16 hours ago, Alain Gadbois said:

Great work. The care you have taken in assembly is really showing!




9 minutes ago, Kagemusha said:

Terrific work, really paid off. 


Thanks guys!  I'm pleased with how it's coming together so far.  I still need to make some final decisions about which aircraft I'm committing to doing and how weathered it's going to be.  But I've got a week at least to ponder that - whatever it is starts with a good all-over aluminum finish.

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Started on my strategy to mount the cowl onto the engine.  First step was to drill the prop and the engine for 1/16" brass rod.  This will enable a much more solid mount of prop to engine when it's all finally assembled.


Yes, I could have filled the sink marks on the back of the prop, but it will be pressed right up against the cowl opening so only the plug wires will be able to see them...


I then made this simple jig.  The brass rod centers the engine, and the recessed area around it allows the nose of the engine to sit down in to achieve the right depth relative to the cowl, which slides down around the styrene disc.  The marker line is just a visual aid to make sure that "up" is set the same way on engine and cowl.



Cowl goes on like this



Then the engine drops in



With the two pieces held securely in the proper relation to each other, I can glue some connections between the backs of the cylinders and the sides of the cowl.  But first I need to decide how I'm going to represent the support struts that run from the front of the engine housing to the inside front of the cowl (these will be much too thin to be my structural solution, unfortunately, they're just for accuracy's sake.

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31 minutes ago, LSP_Kevin said:

Nice work, Alex! For greater control over CA as a filler, you could try mixing it with talcum powder (I believe some folks use baking soda).



Yes, I’ve been meaning to give that a try for more surface-applied uses.  For gap filling I like that the liquid CA wicks in (I use medium-thickness and apply it with a piece of 0.3 mm wire).

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Nice work Alex, the cowl flaps look ever so much better and the rough stuff looks like it is turning out well, like you I use CA for just about everything and it's really satisfying when that shiny black/dark grey line of CA appears when you have finished sanding it back.





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Before joining the engine to the cowl I had to make the little braces that extend from the crankcase cover to the front inside of the cowl.  I discovered by trial and error that a #79 drill bit would make a hole just big enough to accept three pieces of 34-gauge stainless wire.  When is everything just going to be metric?







Installed into the cowl.



I will probably apply a little bit of clear flat paint mixed with a touch of light gray to those wires to tone down the shine.


Onward to painting!


Here's the underside of the wing-to-fuselage join fully cleaned up.



And the whole airframe sanded through 6000-grit



I've developed a bit more of a system to try and get that all-important glossy black undercoat that is the foundation for a good metallic finish.  From this fully-sanded state, I 1. wipe the model down with water (on a lint-free Kimwipe, which is the only thing I'll clean the model with from this point on),

2. let it fully dry,

3. vigorously scrub it with a clean soft-bristle toothbrush to get all of the sanding dust out of the panel line and rivet detail,

4. wipe it down with 70% isopropyl alcohol and let that dry


I also have found that I'm better off doing the paint job in sections, masking off the other parts so I don't get drifting/drying paint sticking to areas that I don't want it on.  So for this one I'll start by painting just the wings (top and bottom) from the main stiffening rib outward.




Another thing I am experimenting with is fighting static buildup, which can attract dust to the wet paint surface.  In addition to running a small dust precipitator 24/7 in the room I paint in, I have made this little ground wire to attach the model directly to the airbrush.



The static buildup occurs because the aerosol paint flow strips electrons off of the airbrush and transports them to the model.  This direct metal wire connection should allow them to flow back to the airbrush much more efficiently then the path through my body (a comparatively good insulator).


Focusing on a small area allows even someone with my limited airbrush skills to get a uniform wet coat of paint down (in this case Mr Color C-2 - my go-to Gloss Black).



The paint still looks a bit orange-peely when wet, but it levels nicely.  This is partially dry; it will be even smoother when fully hardened off:



I'll let this dry for a full day so I'm 100% confident in masking over the black paint to isolate the next region for painting.  I'll probably do two more separate sections, or possibly even three, to complete the black.  Then do the Alclad in a similar fashion.  It takes time, but I haven't been able to get a decent result when I try to paint an entire 1/32 model airframe in a single shot with an NMF.  Whereas this piecemeal approach worked really well on my P-51 for the last GB.

Edited by Alex
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