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JayW

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

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Note I edited my last post (concave versus convex).  Now, it's update time.

 

I am steadily if slowly checking off the list of many items to be done for the wings.  I live in fear of gluing them together only find I had to do something prior to.  Recall that -30 variants have a newly located landing light.  So here is the new landing light:
 

zuP0AhLl.jpg

 

The step drill worked to perfection, giving me a perfect .5 inch diameter hole in which to put a lathe-machined acrylic piece done so to depict the hollow look of the light.  The "bulb" is a piece of .06 round plastic.  I wish I could have better smoothed out the machining marks....  Now all I have to do is putty in one of those access doors, which I will do after the wing halves are joined. 

 

Next up were the ID lights, which were done similarly with the step drill.  Nothing spectacular here, but here they are:

 

 a7oJFvkl.jpg

 

I just drilled out the existing (pitiful) circular indentations, put in .005 inch thick cover rings, some clear plastic "glass", and filled in with some clear epoxy.  Clear red, green, amber paint, and there you go.  Must mask really well once I paint.

 

Now the tip lights - some of you were waiting to see how I do this.  My first plan worked well enough, so no need for the toothbrush!  First, I turned to the trusty lathe and turned a large diameter thin piece like this:

 

  5O8wmAil.jpg

 

Yeah, my machined tires are similar!  This part was just as big a PITA as the tires though; I don't want to do it again.  How is this like a tip light?  You cut out pieces:

 

fvCQZUvl.jpg

 

x06XBGLl.jpg

 

My surgical saw (that's what I call it) cuts through acrylic nicely.  The secret to this method turned out to be one, creating a good representative cross section on the lathe.  Alot of contour study was involved in order to do that.  And two, making the right cuts on the lathe-turned 2-inch diameter piece.  You will see two chunks cut out in the picture above.  One is too small, the other more like it.   I will cut the part for the other wing, and then I must wait until after the wing halves are joined to finish it all up.  Challenges remain but I feel pretty good about it.

 

Meanwhile, I began the aileron work (when will I do the flaps?????).  The flaps will be last.  So I must have aileron supports in the outboard fixed trailing edge (FTE) that match up well with aileron attach points.  At the same time the ailerons must be made somewhat more realistic even though they will not be movable.  What I started with is no good:

 

iJ4pjsYl.jpg

 

oNUV7xOl.jpg

 

Those two pics show before and after.  I sanded away the leading edge to give it an aero cross section.  It is more true to form, but these ailerons are much thicker than the real thing.  That's just the way it is.  Note I cut off the stupid tabs that attached the original part to the wing.

 

While I was at it, I corrected the trim tab on the RH aileron.  While the LH aileron has a controllable trim tab on P-47's, the RH aileron does not.  However it does have a fixed tab on its inboard end.  I had to correct this on the RH aileron:

 

HL7NRNMl.jpg

 

2T79XQkl.jpg

 

The RH aileron is basically finished:

 

9WJv2Oul.jpg

 

Yes!!  That is an aileron drive arm!  Part of it is actually seen with the aileron attached to the wing, so I wanted it there.  

 

Lastly - here are the aileron supports for the RH wing:

 

3YxjpMgl.jpg?1

 

Just well-supported .04 thick horns that will fit into the slots on the aileron LE.  This will be a vast improvement over what was there.  I guarantee it.  

 

Now, to get the LH aileron and wing outbd TE into shape.  More later.  Can't wait for the flaps and flap linkage.  That's gonna be fun!  

 

 

 

 

 

 

Edited by JayW

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Hi folks - hope your Thanksgiving was terrific.  Mine was. 

 

Last August, I got started on the flap support ribs, and then thought better of it and delayed any progress.  I left it like this:

 

rdF4Qmxl.jpg

 

Now after four months of all the other wing stuff,  alot of which was heavy lifting where you don't want fragile stuff exposed to damage, it is time to return to the flap supports and linkage.  I have really been looking forward to it.  

 

What you see above are two flap support locations - the outboard and the mid.  So I set out to make an inboard support, which is so far inboard it practically falls off the wing:

 

 bxgzgTHl.jpg

 

I know, it looks awful.  But it's going to be fine later.  It actually sits underneath the wing-to-fuselage fillet fairing, and in real life occupies the inboard end of "spar 3".  I had to create a spar 3 segment for it, and it was messy.

 

In parallel with the trailing edge rib work, I started on the flap linkage.  I have determined that the linkage needs to be installed prior to gluing together the wing halves. 

 

Recall the flap linkage looks like this:

 

 Vnrfyxml.jpg

 

 

That view on the left is a little confusing because it shows the 3-piece support linkage and the 2-piece drive linkage as if they are in the same plane, when really they are several inches apart.  That can be seen in the plan view on the right.

 

The forward link (89C22305) looks like this:

 

quc7hXRl.jpg

 

My forward link looks like this:

 

7vyGDF7l.jpg

 

The resemblance is fleeting at best, but the link is nearly buried inside the wing with flaps out (and of course completely buried with flaps stowed).  Anyway that's all six.

 

The aft link (89C22306) looks like this:

 

3MVZmINl.jpg

 

My aft link looks like this:

 

BGGfVeNl.jpg

 

The resemblance is much better, and this link is fully visible with flaps out.  Here is the assembly line for the aft links:

 

EcXUpzml.jpg

 

Basically two side plates, a center web, and a lug, all made from simple plastic stock.

 

And lastly the third translating link - I will call it the boomerang link - (89C22307) looks like this:

 

HPdOfHbl.jpg

 

Mine looks like this:

 

4UsRwW6l.jpg

 

This one, of the three, is the biggest pain because of the stiffening flanges, which are small slivers of plastic strip, trimmed to shape.  I have a good bit of micro-surgery to get all six, as you can see.

 

Assembled together they look like this:

 

 npxf0SNl.jpg

 

And attached between rib pairs on the wing:

 

r10XxEAl.jpg

 

The geometry of these links differs some from true scaled parts - I had to do this to deal with the inaccuracies of the toy wing.   Anyway, pretty rough looking right now, but I promise it's going to look awesome once I am finished with it.

 

BTW, here are some flap support linkages on Dottie Mae:

 

  4ICoqHsl.jpg

 

Next post I hope to be done with all six flap supports, including support rib pairs, support linkage, and the drive linkage in two places per flap.  Til then!

 

Edited by JayW

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"Complicated shape."  says Mark (dodgem37).

 

yeah - I thought about reproducing it, but it would have been a big PITA for a link that is largely unseen.  Note also the severely slanted clevis slot - the shot of the stowed linkage shows clearly why that clearance is needed. 

 

So linkage mechanisms are right in my wheel house - that is what I did before I retired.  Thinking on it a little (why it is the way it is in real life), this link is mostly a two-force member meaning that it is intended to only take tension or compression inline loads.  There is no significant in-line bending (like the boomerang link sees).  MOF, the primary load is tension - as the flap provides lift, the forward link reacts it with a tension load.  The only compression load it sees is from the dead weight of the flap, times some inertia factor - a much smaller load than the load resulting from flap airloads.  That said - its cross-section (a cross or "+", as opposed to an "I" or an "H") is ill suited for compression loads.  It would buckle under a significant compression load.  The aft link (which does see a significant compression load) has a nice stable "H" section for that purpose.   But the forward link has a nice efficient section for tension load.

 

But that's not all.  To be a true 2-force member, the end joints must be spherical bearings.  But they are not.  They are "journal" joints meaning they can take side load (sphericals cannot).  Why?  Well something has to hold the flap in position spanwise.  If all the joints were sphericals, it would wiggle to and fro in a spanwise direction!  To do that at least one attach joint must be a journal, on both the forward and the aft link.  Side loads however will be small.  Airloads go fore and aft with almost no side component.  The only side load of any significance at all would be getting bumped or pushed by something on the ground (these are typically called "abuse" loads, and are a factor of the weight of the flap - 6x or something like that).   Even with the factor the load is small in comparison with the air load.

 

 

Edited by JayW

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The RH wing flap linkage is done, and it wasn't easy.  Here:

 

fy6RNGhl.jpg

 

Some things to note - You see three supports, each with a pair of fixed ribs, and a linkage in between the ribs, just like the real thing.  Most exposed are the "boomerang" links, sticking out inviting damage.  That is also just like the real thing.  So far no damage, but I live in fear of breaking one, and/or what it attaches to.  Repair would probably be very involved.  Each linkage is movable to a certain degree.  That way I can better attach the flap when it comes time, and get it to the flaps-down position I want.  You also see an unpainted torque tube between the inboard and mid supports, just like the real thing.  Look closely and you will see the actuation arms on either end of the torque tube, directly adjacent to the main supports.  The ends of these two actuation arms attach to fittings growing out the nose of the flap.  At this point the arms can rotate, independent of each other (NOT like the real thing), again to better attach the flap in the correct position.  The torque tube is actually two halves, with a crude torque tube support at the tube's mid span.  This allows me to get that independent rotation.  Once the flap is positioned later on, I will drop in some liquid glue on all the linkage joints to firmly fix the flap in its flaps-down position.  

 

With both wing halves, the supports look like this:

 

  CvFFJfxl.jpg

 

Hopefully, this scale aircraft will have robustly mounted flaps in the down position, when it is all said and done - during my lifetime hopefully!

 

That is all I have for now.  The LH wing flap supports are almost done.  Then some wing panel painting (some but not all of it).  At that point, I will have ticked off all the items required prior to final landing gear installation, and wing half join.   That is a milestone I have been waiting for, for a very long time.  Then - after joining the tail to the fuselage, and temp installing the wings to the fuselage, I get to put "weight on wheels" for the first time!!!  Oh yes.  It's only a week or two away (hard to predict, with all the holiday activities).  You will see it soon. 

Edited by JayW

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Last on the long list of things to do before joining wing upper and lower halves (and not least) was to permanently install the main landing gear and associated stuff (like shrink link, strut door, strut door links, gear actuator rod, etc).  This was not hard at all, as I had dry fit these parts numerous times.  Pictures of the RH wing (LH is a little behind):

 

abMf2UOl.jpg

 

This shot shows the previously missing bolt which joins the gear retract actuator to the gear itself (just had to show that):

 

4rx9MLMl.jpg

 

The black flex hose which is part of the brake line run is now properly connected too.  Cannot tell you how good it feels for all these separate projects to come together like this.  And check this out - it's new:

 

eyvqUjxl.jpg

 

That little flap you see there where the strut door meets with the wing lower skin panel is the shrink link flap.  The shrink link, with gear down, would clash with the strut door unless modified.  So it has a slot in it, as does the wing skin itself.  And that little spring-loaded piano-hinged door is there.  But all you P-47 experts know this already! 

 

The long term milestone I have been working toward for months now is "weight on wheels".  What does this beast look like with her shoes on?  To do that, the main gear had to be permanently installed (check!), and the aft fuselage (with tail gear) had to be joined to the main fuselage (check!):

 

  NNZIFaKl.jpg

 

I have some work to do on that join - later.

 

Over a year ago, this picture inspired me to add to my scratch-built engine so that I could display it with canopy off.  Love that picture: 

 

 

QIl0jGQl.jpg

 

Well here is my version of it:

 

aeHD4qMl.jpg

 

Good Lord this is a big model.  Here are some shots of the landing gear:

 

xsSqIrml.jpg

 

D0IPD67l.jpg

 

The wheel/tire is just slid on the axle, without the axle cap.  I will wait until the wings are finished before I permanently attach them.

 

Here are a couple more shots of the beast on its gear:

 

qAxqp04l.jpg

 

9HkjxPgl.jpg

 

This shot is an attempt to show the 3-degree splay of the gear struts, which gives P-47 main gear a bit of a "bow-legged", or over-extended, appearance.  

 

OkZpUH1l.jpg

 

By and large I can declare victory on the landing gear.  The two main gear are absolutely symmetrical - got lucky, but worked very hard to try to attain that.  The gear doors and links are fitting up well, the shrink link is well integrated.  And the gear orientation looks realistic to my eye.  I am going to relook at the tail gear and decide if it should extend down a bit more - to me it looks like it has too much weight on it.  Maybe - maybe not.

 

Well I am going to have to make a bigger shelf!  But for now, the next tasks are to actually glue the wings together, paint (including the US insignia stencil by Maketar), finish up and install the ailerons, and then the flaps.  So far I still have all six flap linkages, but they are in constant peril, until I get those flaps installed.

 

Take care all of you, and Happy Holidays!  

 

Edited by JayW

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Oh man Jay!

 

You certainly don't like taking the easy option do you? I've got to say you certainly have a knack for replicating complex mechanisms..... a theme which seems to come up in each of your builds!!!

 

Exceptional work my friend..... Keep at it!

 

Craig

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'So far I still have all six flap linkages, but they are in constant peril, until I get those flaps installed.'

Fold and tape an index card over them.

 

Great update.

 

Sincerely,

Mark

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"Fold and tape an index card over them."

 

Thanks Mark - I am going to take you up on that, soon as I get the wing halves joined.  That's easier than a plastic "roll cage".

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