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Heavy Mod - 1/18 21st Century Toys P-47D Razorback


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Yay!  It took about 6 weeks, but the landing gear bays are done - at least as done as I can make them prior to gluing the wing halves together:




I have some more details (all of the RH wing):


This shows a partial rib up against the aft shear web, and the long station 64 rib.  The larger diameter tube on the aft wall is a fuel tank drain line - it penetrates the lower wing skin and the end is painted red.  The left wing doesn't have this detail.  You also see hydraulic lines for the side-of-body landing gear door actuator, a brake line, and some wiring.  




Here you see the forward (rarely seen) region of the inboard gear bay, with partial ribs (stations 40 and 52).  This is where the gear door actuator will reside later on - you can see where the two hoses will connect.  




This shot looks outboard down the gear bay.  Every rib is unique looking.  Note on the station 64 rib the gear upstop fitting: 




And where do all these hydraulic lines come from?  The aft end of the inboard canted rib, mostly:






And a shot with the gear strut temp installed, showing how the gear actuator attaches:




And closer:




I will be providing a bolt that joins the actuator rod to the gear clevis - oh yes!  But later.  Much later.


Meanwhile, it is off working other parts of the wing that must be done prior to gluing the halves together.  Probably machine gun supports and leading edge holes, and that leading edge air duct hole on the RH wing.  Both very challenging.  Stay tuned!

Edited by JayW
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Help!  A while back, when I first began the wing work, I had a knee-jerk reaction and cut away the machine gun ports.  Before:








No real thought to it - I just dremmeled it away like a madman.  Now - it is time to do the gun ports and supports.  Why did I do that?  Well, the biggest reason was that P-47 machine gun penetration holes do not simply follow the center plane of the wing as you see in the first picture.  Instead they are on a plane that is roughly level to the ground as you can see in the end view below:




Most P-47 models get this about right, but 21CT did not, alas.  Well that's the biggest reason, and reason enough on its own.


But here's the thing.  I now have to restore that highly curved leading edge surface.  The panel must fit very nicely in the cut-out, and it must have dead-on located 1/8 inch holes for the gun barrels.   Actually, unless someone has a better idea, there will be two panels (each .01 thick) that will nest together, the outer panel with squarish larger holes and the inner panel with close fit 1/8 inch holes.  Has to do providing the ability to boresight the guns.  BTW - 1/8 inch tube comes pretty close to scaling properly for the very distinctive natural metal gun barrel sleeves you see on P-47's.  Here is what I mean about the LE panels:




You can see each penetration has an oversized squarish hole on the outer surface, with a trapped sliding panel underneath that has the close fit holes for the barrel sleeve. 


To properly model this, I have four challenges:


1.  Form curvature of panels fairly close to contour.  .01 inch plastic has alot of spring-back.  How do I overcome it without overforming or creasing or otherwise adversely deforming the sheet?  And, the panels must be formed prior to drilling the holes; otherwise the regions near the holes will not form the same.  Also, the panel upper and lower edge will want to flatten out.

2.  The panel periphery must closely match the cutout, or it's going to look lousy.  I would like to somehow get the panel to a tight fit, and then sand the edges back to provide a decent gap around the periphery (like .015 inch or so).   

3.  The panel must mount on something.  My plan (so far) is to create fairly thick (.04 inch or so) ribs on the inboard and outboard edges of the cutout, offset inside contour .02 inch to account for the thickness of the nested panels.  And then create straight section pieces for top and bottom using maybe .04 by .04 strip, also offset .02 inch inside contour.   This in effect will provide a shelf around the periphery which backs up the panel edges, controls the contour exactly, and gives a gluing surface.  Making those rib parts is very difficult - the .02 offset from contour is hard to control.  

4.  I must drill four 1/8 inch holes in 0.01 inch plastic and keep the hole locations exact.   Drill bits that large want to tear the material instead of drill it, even if you "sneak up on it" using progressively large drill bits.  And the "squarish" holes are .156 inch dia initially before filing square, harder still.


There are sooo many problems with this approach.  I wish I could just get a big chunk of plastic block, or clay, or some material that is easily carved/sanded/dremmeled/filed.  But I have no confidence I would duplicate the contour accurately enough.  I have a few little tricks up my sleeve, but are they enough....


Anyone have some radical ideas?  I fear I am going to make a bit of a mess out of it.  Oh, BTW - I heard once that putting sheet plastic in hot water helps it to maintain a curved shape.  Anyone have any experience with that?



Edited by JayW
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Have you considered annealed thin brass or aluminum sheet. It will retain shape and will drill without ripping.

Make a form out of a hard wood then layout the pattern, cut , drill it then bend over form.



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That's interesting how the spent shell casings and link chutes are interconnected between the guns, I never really thought about how that was done before. 

Re: The task at hand, I'd agree with Barry about using sheet brass or aluminum. 

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Hi Jay


Those are double take pictures of the gear bay - I thought they were reference shots of the real one! absolutely convincing - brilliant :)


One thing for your gun panel problem - if it were me, I might try using the kit wing as a template - if it is thick enough plastic it won't deform in the process I am about to describe...


get a bit of thin sheet stock and tape it to the wing surface with electrical insulating tape - it's quite a rubbery strong & flexible tape that should hold the thin sheet fairly well to the wing contour across the one bend along the leading edge that it is being made to accept


Then get some cotton gloves and hold the wing where the taped part is over the steam head of a boiling kettle for a moment - keep taking it out of the heat and pressing down on the tape & part & reinforcing the shape you want it to take


Then pop it in the freezer for a few minutes


viola - the taped sheet will have adopted it's new profile and can be worked - I use this process a lot where I can't plunge mould a part - the only thing is I am not sure how close all your hard work in the gear bay is to the heat so one for you to call as to whether there is any danger?


I am sure you will solve it - if you have any resin you could make a quick copy of the shape in  a plasticine mould to derisk your parts maybe


looking forward to seeing how you get to the answer


all the best


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All right you guys - I will sand off the "made in china" lettering!  For the sake of realism, which is what we try to do.  Geez.....  :)


Barry and others suggested using metallic sheet for the gun panels.  I thought about that too, and yes I will try that if I can find the right stuff.


How about this from Peter (aka airscale):


"Those are double take pictures of the gear bay - I thought they were reference shots of the real one! absolutely convincing - brilliant"  


Reference shots of the real one?  Oh a great complement from the guy who is doing Lopes Hope in 1/18, who's cockpit cannot be distinguished from the real thing!   Thank you - that is what modelers want to hear.  I cannot wait to see what you do with your own gear bay.  So Peter suggests staying with the plastic material for the gun panels, and using heat and then cold to form them.  And this is kind of in line with what I was thinking originally.


 Also Shawn suggests using a reamer for holes.  


Thanks all for good suggestions.  I am formulating a plan:  I am first going to form the plastic sheet, probably like Peter suggests, but using a wing leading edge section further outboard of the guns to keep the steam away from the gear bay.  The contour will not be that different from the desired.  I will hope the curvature is well set in, and will return after I flatten the sheets between thick flat plastic sheet, making a sandwich.  I will align the thin sheets as much as possible to assure the contour is oriented to the gun barrel holes.  Then I will make use of my mini-end mill, and drill the holes precisely located relative to one another.  The thick outer layers will prevent tearing of the thin inner layers (Have done this before with the instrument panel).   When I remove the thin panels (now with good holes), from the sandwich, I will rough cut the peripheries, then hope the curvature returns at least mostly.  If not I can heat/cool them a second time I suppose.  Then I glue the two .01 panels together to make one .02 panel.  Then comes the exacting work of final trimming the panel edges to match the cutout.    I think a template will not be exact enough - I will have to just trim a bit here, fit, trim a bit there, fit, trim some more here, fit, etc, etc.  And then if that all becomes a big fail,  I will try alum panels and hope for the best.   Man - I feel like this sub-project is a must-succeed; otherwise all this effort is for not.


Stay tuned.  Hopefully I can get this part done before we re-floor half of our house, including the man-cave where my modelling happens.  That will force a temporary halt to the P-47 effort. 



Edited by JayW
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