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

[JayW]

While fiddling around with the two fuselage pieces last night, I lost grip on the tail section and it nearly fell to the floor.  i caught it in time, but still a couple of things popped loose.  Repair was easy, so I got away with it.

 

It occurs to me once again that a large build like this carries with it the risk of ruin.  The thought of the forward fuselage, with that big heavy engine in it and the precariously attached canopy,  falling and bouncing off the floor just horrifies me.  There would be breakage that I just couldn't fix.  I guess this is true of smaller scales too - but I would submit 1/72 scale doesn't have this issue!  And 1/1 scale really does - hence the factory fixtures and stuff that are necessary when building the real thing.  I need to build a holder for the fuselage I believe, put it there, and just leave it the h_ll alone unless I really must work with it.   

[JayW]

Yes I have visited that website before.  Thanks!

[CATCplSlade]

On 7/16/2018 at 9:37 AM, JayW said:

 I need to build a holder for the fuselage I believe, put it there, and just leave it the h_ll alone unless I really must work with it.   

 

Um, yeah you do. The odds are stacking against you emerging unscathed the longer you wait.

[Gazzas]

Amazing result with the LG, Jay!

[JayW]

More than a month ago I posted about progress on the tail wheel and tire:

 

 

And then the lathe motor gave up the ghost.  Now finally I have in my possession a new lathe motor with a healthy armature and windings, and it didn't take long to finish up the tail wheel tire machined part:

 

  

 

It sits next to the TW tire for the 1/18 P-51, which was not machined.  This is just to show size difference - P-47's had larger tires for a larger aircraft.

 

Here it is painted and next to one of the main gear tires:

 

 

 

The wheel is made of several concentric tubes (copper, alum, and plastic), with some tiny inserts for lugs, and then nuts and bolt heads:

 

 

 

I continue to wonder about showing pictures in such excruciating detail.....better to step back a bit!  Anyway you can see some weathering, the bulged flat, and a little red strip for maintaining balance alignment when the tube was changed.

 

Final installed it looks like this:

 

 

That turned out to my satisfaction.  Note the axle cap (a very small brass lathe turning).  The strut can swivel in its mounting hole so i can orient the tail wheel however I want.  Note also the h/stab and elevators are finished up and installed.  That work was very straight forward and doesn't require any description, so I won't.

 

Now this picture shows the outlet vent for the supercharger exhaust:

 

 

The toy part was woefully inadequate.  I had great challenges getting this to look OK - using bent up thin gauge plastic.  You will see more of this when the forward fuselage is joined with the aft fuselage sometime this century.

 

And just like that, the fuselage is essentially done!   So now, it is on to the wings:

 

  

 

The wing project will be enormous - just no better way to describe.  Although it's a nice looking wing with a good shape, it lacks soooo much.  I believe i am going to start with modification of the flaps and flap supports - a very large sub-project itself.  I think you will find it very interesting.  See y'all next post!

Edited August 4, 2018 by JayW

[Shawn M]

man, Jay this is excellent.

Keep at it!

[JayW]

OK this is the beginning of a whole lot of posts about the wing work, over time.  I really want to do the flaps work first, but I think the fixed trailing edge ribs I will add will be too fragile to stand up to all the demolition work I must do.  I came to this conclusion after already completing a set of flap support ribs.  But first things first:

 

Here is a shot of the interior of the wing:

 

 

 

Like so many airplane models, the wheel well walls are coincident with the skin cutout, when in reality the walls are always composed of spars and end ribs.  So, the walls you see there are going to disappear, and new structure will take its place.  Lots of dremmeling to come!

 

That is not all the heavy lifting I'll need to do.  For example, the machine guns on the toy need to be replaced, as well as the leading edge panel they protrude from:

 

 

I can do better than that.  Sooo, I swallowed hard and took that stuff off:

 

 

Oh man - I sure hope I can do better, because I am now committed.  Not sure when this work will proceed; I am just now thinking hard how to sequence the wing work.

 

OK the flaps:  Here is part of the installation drawing for the flap linkage - P-47 (drawing 99C22116):

 

 

Unlike the P-51 which deploys its flaps on simple hinges (with hinge line near the lower wing surface), and unlike the P-38 which deploys its flaps with tracks and rollers, the P-47 has a 6-bar linkage as shown above.  This linkage shows up in three places per flap, except the actuation portion of the linkage which has two places per flap.  The actuation is offset from the links you see on the left by 4 inches, as can be seen in the plan view on the right.   

 

What this linkage does is to not only rotate the flap (40 degrees) but also translate it aft 6 or 7 inches.  I have attempted to show this in a crude layout:

 

 

It's pretty darned ingenious.  Now my task is to show this mechanism and the flap in its deployed position.  I cannot just copy and scale the drawing, because there are too many inaccuracies in the toy's flap shape and fixed trailing edge cove shape.  But I can come close.  So I started with a pair of fixed TE ribs:

 

   

 

 

Local carving of the wing was necessary, and there is much more to go.  The parts are fragile, and I must now somehow protect them from harm as I tear away at the wheel well and other areas.   You will see the work interspersed with wheel well and LG support work.  This is nerve racking, because considerable destruction must be accomplished, and I live in fear of ruining this huge effort.  Stay with me!  

 

Edited August 12, 2018 by JayW

[A-10LOADER]

Brilliant work !!

 

Steve

[JayW]

Hi folks - I have an update.  The past few weeks I have been doing some very exacting work in the wheel well, creating the landing gear support structure, and assuring myself that the result will be a good stout gear strut that is correctly oriented (the right rake and the right splay).  First, the upper strut had to be finished, with the actuator arm and the down stop arm.  A real P-47 main landing gear strut looks like this:

 

  

 

Mine looks like this:

 

 

The features were made with simple plastic or aluminum tube, filing, trimming, and throwing away and starting over when it didn't work the first time.  The clevis lug on the rotation shaft is where the hydraulic retract actuator rod attaches, and the other arm with the round slanted lug on its end is the down stop feature.  It took some trial and error to get these additions to work right, and I had no drawings to help me.  You Aircorp Library folks know that landing gear, since they are made by a specialized manufacturer rather than the airframe manufacturer,  typically have no drawings available to us.

 

A couple more shots:

 

 

 

The P-47 main gear strut is mounted in a heavy structural box, like this:

 

 

 

BTW - these are pics from the Dottie Mae restoration.  This box then is inserted into the wing from the bottom and bolted to spars and ribs.

 

Here is my version:

 

 

Those of course are the four individual heavy fittings, made from plastic sheet and strip.  The layouts were hard, the building easy.  Here is the box with those fittings comprising the four sides:

 

 

What finicky parts!!  I was slow as a turtle with them, being oh so careful not to screw anything up.  Drawings were available for the parts, which is good.  But the thick plastic gauge of the model's wings really made things difficult requiring major modifications relative to a simple scaled part. 

 

Inserted (from the top) into the wing, it looks like this:

 

  

 

You see the front spar (bottom), the aux spar (top), the station 104 rib (left) and the station 86 rib (right).  You also see support struts on the spars, and importantly a plastic rod that penetrates the aux spar and aft plate, to engage a hole in the down stop arm.  This, my friends, controls the down position of the gear, and it took lots of patience to get it right.  But it's right.  Some more shots:

 

 

 

 

The end result is a properly oriented main landing gear - yahoo!!!:

 

 

If I take the down lock pin out, this gear actually swings into the hole, almost.  Some clashes happen on the way because of errors I have made in scaling, and because of the thick plastic gauge issue.  That would be nice so as to make painting easier, but no big deal.  

 

Now, to get the left hand wing to the same place as the right hand wing.  That's gonna take some time.  Must be very careful to duplicate everything exactly, so that I get the same orientation for the left hand gear.  Is modeling supposed to be stressful?  I think not.  Then, plenty more wheel well stuff to do, and my next post will show that progress. 

 

Take care. 

 

Edited August 29, 2018 by JayW

[A-10LOADER]

Amazing stuff Jay, WOW !!

 

Steve

[Trak-Tor]

Wow! All thumbs up!

And thanks for the detailed report!

 

Juraj

[Thunda]

Absolutely breathtaking work- Bravo!

[JayW]

I forgot to show y'all some stuff.  First, one cannot totally redo a wheel well without removing the original one.  In this case, it's pretty scary.  The original well is the wing depth control for the entire inboard half of the wing.  Without it, the wing skins are pretty flexy.  So I had to take depth measurements in many places prior to removing, and using the data for the new spars and ribs.  Here is a before/after comparison (RH wing modified, LH wing waiting for same):

 

 

Lotsa action dremmeling all that stuff outa  there!  See that little step on the inboard end of the unmodified part?  That step interferes with the canted inboard rib I plan on including.  So it had to go too, at least a good bit of it.  You can see on the modified part it has been partly machined away.  I did this with the end mill (the Unimat mini-lathe converted to end mill), and a large diameter flat cutter.  Worked superb!  

 

And just prior to all this wheel well work, I had done some more on the trailing edge flap support ribs, along with a segment of spar 3:

 

 

This was a mistake to do that work - they are fragile parts and the wheel well work can get strenuous, so they are subject to being damaged.  So far they have survived; I will re-sequence this on the other wing.  One of these days you will see much more trailing edge work.  It's in the queue right after the wheel well, I think.

 

OK, it's off to the LH wing.

Edited August 30, 2018 by JayW

[Jim Barry]

Great work,  Jay. 

[TwoHands]

Looking great JayW! In the past I have made for lack of a better word a "roll cage" of plastic strip to protect delicate parts from an accidental brush with your hand or tool but not a trip to the floor. Maybe just some bent .040 strips glued into "angle iron" and glued root to tip inboard the root parts would cover those rib ends and still let you work on them from behind? Just throwing out the idea and hoping it's somewhat clear what I mean. LOL . Enjoying your work! J