1/18 Scale P-51B 3D Print Build

[Thunnus]

Wow, Jay... that nose assembly looks so convincing!  The weathering is spot on. I'm glad I was able to provide an assist via the masks and decals.  I can print and send the larger masks when you need them!

[JayW]

Happy Holidays modelers.  As I stated in my last progress report, I needed to do more surfacing, and so I have.  Missing were the surfaces around the radiator and oil cooler outlet areas.  Recall I already did the inlet and made a part - this:

 

 

 

It's been gathering dust.

 

Just aft of it will be surfaces as defined by these additions to my surfaces Rhino model:

 

 

Those new surfaces, like the surfaces already there, are defined by tables of point data from vintage North American Aviation "ordinate" drawings.  I put those points in my Rhino model and create curves from them, and then create surface patches and/or lofted surfaces from those curves.  Sometimes it is easy, other times it is very difficult.

 

The hard part here was the transition from the contours at the aft end of the outlet to the fuselage proper - this:

 

 

Another exercise in frustration, exasperation, and determination.  But it is done and is behaving well, meaning it can be used to make a solid model and then a part.  

 

A couple more pictures:

 

 

 

Part of making surfaces in this area is surfacing the insides at least those that will be seen.  In that last shot, imagine the radiator in there at the front end of the opening, and a hinged door covering most of the opening depending on how closed or open the door is.  Mustang fans know this:

 

  

 

I am getting to the point where my fuselage surfacing is complete back to station 248 (the manufacturing splice where the aft fuselage and tail attach to the mid fuselage).  This model will also have a manufacturing splice there.  That means I can commence with more part design and 3D printing.  Namely - the windshield area, fuselage around the cockpit, and the radiator and oil cooler area.  Lurking in the shadows though are the wing-to-fuselage fillet fairing surfaces which I would like to avoid for now, but might have to address sooner rather than later.... 

 

Stay tuned - it's gonna be fun I guarantee.     

Edited December 4, 2023 by JayW

[BiggTim]

On 11/8/2023 at 6:39 AM, checksix said:

Awhile ago I had a canopy SLA printed at Shapeways using something called "Accura 60". After sanding out the layer lines and dipping in Future, the canopy was crystal clear. Here's some info:

 

https://www.shapeways.com/materials/sla-accura-60

 

Not sure if this will help you, but thought you might be interested.

 

 

 

--Derek

 

 

Interesting little tidbit - I wanted to try this "Accura 60" resin for myself, so I contacted a sales rep to find out where I could buy some. It retails for 2635 USD per 10 kg jug, and that's the smallest quantity available! So, if you're unhappy about Shapeways ridiculous prices for items using this resin, at least now you know part of the reason why. Needless to say, I did not buy any. 

 

Tim

[JayW]

I decided that the next set of parts to be made would be the windshield and surround.  A few weeks ago I 3D printed the windshield glass parts (four in all):

 

 

 

I have hopes that this will surpass what can be done with vac-forming.  We shall see....   One of the side glass parts has what looks like a long crack (it isn't though), so I redid that one but it isn't fully prepared yet.  The most problematic of them all are the two side glass parts.  The top part turned out pretty good (you might recall I had made a gray test part a few months ago).  And note the front glass is thicker (to denote bullet proof).  None are perfect (the front glass comes closest), but if they fit within the framing (see below), like they are supposed to, they ought to look good.  Especially when I get around to adding the exterior frame strips that will hide the joints. 

 

So I have been spending lots of time Rhino modelling details.  Here is what I have so far:

 

 

 

Almost all you see there will be 3D printed.  The cowl will be one part, the window framing will be one part, the shroud will be one part, the instrument panel frame will be one part, with the IP itself separate.  The hand holds and the defrost nozzles will be separate parts.  That is the plan anyway.  Next post you should see how the 3D printing worked.  And maybe some assembly. 

 

The assembly you see above is designed to slip onto the upper longerons - these (the green parts):

 

 

I have truncated the longerons at Station 200 which is the aft end of the fuselage tank.  That is where I plan to end the forward fuselage section.  The longerons will barely fit in the build space of my printer, but they fit.  Yay! 

 

In order to make the forward fuselage section, I am going to have to create a fixture designed to assure proper location of all four longerons (two upper and two lower) at least.  Once they are firmly positioned, then assembly of this section can commence.   The windshield cowl assembly (described here), skin panels, Malcolm hood parts, cockpit parts, and importantly the fittings that attach the wing to the fuselage.  Those fittings will be closely tooled up to assure a good wing-to-fuselage interface.  Tons of parts.  That's the plan anyway.  Ambitious as hell - and not a sure thing at all at this point. 

 

Stay tuned!  I hope to post something before Christmas.  

Edited December 12, 2023 by JayW

[JayW]

Happy New Year LSP'ers! 

 

The next adventure for this 1/18 scale P-51B is shaping up to be the cockpit and windshield surround.  This is going to involve some "major tooling" where the upper and lower longerons will be exactly located in a jig, and then the windshield surround stuff and side panels can be assembled.  In the coming posts you will see that jig and that assembly work materialize.

 

Meanwhile alot of hours in Rhino happened over the past couple weeks, allowing me to print up a fresh batch of 3D-printed parts:

 

  

 

It was not without adventure.  The first effort was a partial fail, I think due to the lower temperature of my office where my printer resides (was in the low 60's I think).  It is after all winter now in the northern hemisphere.  A couple of the large parts detached from the build plate early in the process unbeknownst to me, and I got a surprise when the printing was finished.  So I got the office heated up to about 70 deg F, and retried with successful results.  You see above the windshield surround paneling, the windshield frame, and the coaming, or shroud, that sits atop the instrument panel frame.  Some are duplicated.  Also little tiny parts that are the handholes and defroster nozzles that will attach to the top of the shroud.  One day.

 

Freed from their bonds: 

 

 

A couple of the clear parts I  made a while back too.  The new parts are fragile in the extreme, and/or very small such that an errant sigh or cough will blow them into elisium forever gone.  Already I have lost a couple and will be re-printing on the next batch.  Once assembled the assembly will be more stout.  But they cannot be assembled until the longeron jig is complete, with longerons fixed securely in the jig.  They (the upper longerons and firewall plate) will serve as assembly jigs of their own, and lock down the shape of these flimsy parts and allow an exact assembly.  Like so:

 

 

Stay tuned for that; it will be very tricky.

 

Here, a sneak preview of the front and top glass parts dry-fitted onto the windshield frame.  So far so good...

 

 

Alot of potential with these parts as long as my fumbly fingers can keep me from ruining it all.  The parts printed very well, and everything pretty much fits as intended.   I'm excited.

 

Part of me wants to do the clear parts over again.  They could use more polishing, although the Imgur huge thumbnails are pretty cruel and unforgiving.  And part of me doesn't want to - it's excruciating work getting clear 3D print parts to be useable.  I am not real happy with the Nova3D "High Transparency"  resin I am currently using.  And I don't know a better alternative that is affordable.  Guess I'll do some more digging.

 

The coming year in modeling in my home is going to be quite a ride, I anticipate.  Stay with me!

 

 

 

 

Edited January 2 by JayW

[Shoggz]

I’m with you all the way Jay!

[Antonio Argudo]

this is wonderful Jay,  Happy new Mustang!

[geedubelyer]

Neat work Jay.

Roughly how large are these glazing components?

It strikes me that there are no complex or particularly large parts so far?

Could you use acetate sheet? 

I've had success with sheets out of food wrapping. 

A 3D printed mold should be relatively simple to produce for the curved upper portion of the windshield. Plunge molding that shape ought not be too challenging? 

 

Looking forward to more soon. 

 

Happy New Year

[JayW]

17 hours ago, geedubelyer said:

Neat work Jay.

Roughly how large are these glazing components?

It strikes me that there are no complex or particularly large parts so far?

Could you use acetate sheet? 

I've had success with sheets out of food wrapping. 

A 3D printed mold should be relatively simple to produce for the curved upper portion of the windshield. Plunge molding that shape ought not be too challenging? 

 

Happy New Year Guy!  I get the strong impression from several of my dedicated followers on this build that you are not that happy with the 3D-printed transparencies.  And that perhaps I have fallen in love with the idea and cannot see the problems.  And I appreciate this sort of feedback - that improves our modeling.  Part of me thinks you would be right.  But part of me does not, at least not yet.  

 

Here are the reasons currently that I want to stay the course with 3D printed transparencies:

 

1.  I am rather committed.  The windshield frame, the cowl, and the shroud are specifically designed for the transparencies to be a certain shape and a certain thickness.  To change to a plunge mold or some such vacuum molded process would degrade dimensional accuracy - especially thickness -  and force me to abandon the frame concept and basically incorporate the frame into the transparency like we see most of the time with all other models.  I can do that but I am not ready to go that far.

2.  In order to have flush external frame strips (they are indeed flush on the real aircraft), "rabetted" edges of the windows are necessary:

 

    

 

I took great pains to incorporate those edges into my transparencies:

 

 

 

Were I to go with molded parts, I could never get that kind of edge, and would either have to settle with edge strips proud of contour, or just incorporate the edge strips into a one-piece mold.  

3.  I have seen 3D printed transparencies on the web that are just beautiful.  They appear to be just as clear as any other method to make transparent parts.  Even though they have been built up layer by layer.  So it can be done. 

 

I am not really happy with my transparencies either.  But I do not want to give up on the idea yet.  I have just ordered another brand of clear resin that I hope behaves better than my current Nova3D stuff.  We shall see if that improves the parts.  Fingers crossed.  And, I could still go to Shapeways - it's just money.  Who can argue against this (thanks to "checksix" post a few weeks ago):

 

That is a 3D printed canopy made from "accura 360" resin, produced by Shapeways. 

 

I think everyone here, if I had much better transparencies, would rather I do it this way with separate frame and individual panes.  That is what I am after.  

Edited January 3 by JayW

[Oldbaldguy]

I don’t know for certain because I was not there, but I suspect that windscreens and canopies from the WW2 era were less clear and flawless than we’d like to think because the material was not space-age polycarbonate stuff.  It was much the same as what has been used for decades in general aviation - clear but relatively soft and easily scratched and prone to fog a bit around the edges.  While I have no doubt the crew chiefs did their best to keep canopies and windscreens buffed out and clean, there was a war on and these guys had an awful lot to do.  Could be that the best you can get from clear resin, once polished out and installed, will be more realistic than some of your other options.  It’s at least worth the attempt.

 

On a completely different note, after watching your progress on this totally 3D effort, I wonder how long it will be before someone 3D prints and assembles a scale model exactly the same way as the 1:1 was built and with all the same parts.  It’s bound to happen at some point.

[daHeld]

Happy new year to you, too, Jay.
Your 3D-printed windshield looks marvellous.
 

Fingers crossed that your new clear resin will give you better results.

All the best
Andy

[JayW]

I have much to show.  Progress seems slow, but actually it is not.  

 

In order to continue with fuselage construction including a good cockpit, and in order to assure this model P-51 is going to look straight, with wings accurately attached, I know I must create a major assembly fixture for the forward fuselage (forward means between the firewall and the tail section).  My forward fuselage will be in two pieces - one from the firewall back to station 200 (this is where the fuselage tank ends), and one from station 200 to the beginning of the tail section at station 248.  The main reason for this is the size limitations of my 3D printer.  The short aft portion (sta 200 - 248) will not need an assembly fixture; I will 3D print practically the whole thing, like I did the engine cowl.  

 

Actual P-51 fuselages were manufactured in much the same way, or any fuselage for that matter.  Here is a photo of some major assembly tooling for the Lope's Hope forward fuselage at AirCorps Aviation:

 

 

Peter Castle gave me a whole lot of pictures including this - thanks Airscale!  Note there is a heavy frame and plate for the firewall interface, and way in the back a similar frame and plate for the station 248 interface.  Also note the longerons and some of the fuselage frames are in place.  And there are posts coming up from the floor to support the lower longerons.  My fixture must have the same stuff.

 

The upper and lower longerons are the major structural elements of the fuselage. plain and simple.  Everything starts there.  That will also be the case on my 1/18 model.  So first thing for me to do was to design, in Rhino, the longerons.  In real life they are H-section heavy extrusions, machined to be lighter the further aft you go.  And they have tension fittings on either end.  I would attempt to duplicate all that where the longerons are visible.  Many many things attach to the longerons, so it was a long drawn out project with much research into the configuration - fuselage frame locators, simulated cockpit floor brackets, all manner of other location tabs or flanges for other stuff (like the engine control quadrant, the flap actuator torque tube mounts, landing gear uplock fittings, windshield frame tabs.....) - endless it seemed.  And I probably missed some stuff.  But here are completed longeron details in Rhino:

 

 

3D printed:

 

 

 

See that little nested white block on the top longeron?  I fractured that one and repaired it with CA'd plastic.      The real forward fuselage longerons are longer - they go from the firewall to the manufacturing splice at station 248.  Mine will end at station 200 as I already mentioned.  As they are, they barely fit into my 3D printer.  Glad mine is as large as it is; many are smaller. 

 

In order to produce those longerons, I had to model many of the parts that interface with them, so the locator features could be included.  Here are some of those parts in Rhino:

 

 

 

Took quite a while.  You have already seen the windshield parts.  I will remind everybody that before any of this modeling could be done, I first had to generate exterior surfaces using ordinate data from the original drawings - something I have been toiling at for months now.  That's where it all starts.

 

Now for that major assembly fixture.  It must have the following features:

 

1.  A firewall plate with four longeron locators (two upper, two lower).

2.  A station 200 frame plate also with four longeron locators.

3.  A center platform that controls the four points where the wing attaches to the longerons. 

4.  Two intermediate supports/locators for the longerons (they are long and flexy and need those additional supports).

5.  A flat floor plate to assure no warping or bending, with attach holes.  The attach holes for the firewall plate and the station 200 plate must be slotted to allow fore/aft movement such that fuselage side assemblies can be extracted and re-inserted into the fixture during build-up.

6.  A centerline slot in the floor and matching flanges on the tools to assure good alignment.

 

And it must be very dimensionally accurate if I expect the model to fit together - for the already completed engine cowl to properly attach, the aft fuselage to attach, the wing to attach, and the radiator intake/exhaust area to attach (you have seen some of these parts as well).  I cannot rely on pre-molded parts like in an actual kit to fit everything together, and felt I could not make equivalent parts.  So I will build up this part of the fuselage like they did the actual airframe.  And hoping I get great accuracy with 3D printed fixture parts.

 

Here is the forward fuselage major assembly fixture in Rhino:

 

     

 

It consists of two end plates and frames, two center support bases, two intermediate detachable support plates, and a stiff mounting floor. 

 

The canted firewall plate and frame (note the four longeron locator posts and skin panel flanges): 

 

 

The station 200 plate and frame (also note the longeron points and flanges for skin panels):

 

 

And 3D printed.....

 

Half the fixture parts fresh out of the resin vat still dripping resin:

 

 

Cleaned, cured, painted.  Note the flanges on the undersides that will fit into a full-length slot on the floor: 

 

 

The center pieces mounted to the floor (no end plates yet):

 

 

The floor is made of .08 thick plastic sheet, and will itself mount onto long .25 x .75 inch evergreen plastic bars (due in the mail any day now).  That should give me a robust flat floor that doesn't flex.  Right now it's a bit flexy.  As noted in the picture, this fixture has locating posts for the wing, located with great accuracy.  Critically important.  There are holes in the lower longerons that match up to those pins.  

 

All the fixture parts in their glory, bolted onto the yet-to-be completed floor:

 

 

And viola - with the longerons!!

 

 

All appears to be in order, and I believe I have the accuracy I need to build up a proper forward fuselage.  Now I can begin fabricating individual frames and other elements and attaching to the longerons using the integral designed-in locating features.  Next post you should see some of that.

 

And a sneak preview of how this jig will work for me:

 

 

A very pumped modeler here.  Hoping I can make my dreams come true with this approach.  Some of you may suspect this is a bit overkill.  I think not.  This assembly method is going to allow me to do alot of very cool things.  You will see.  Stay tuned, and keep warm all you folks in the Northern hemisphere!

 

 

 

 

 

 

Edited January 16 by JayW

[chuck540z3]

Very cool Jay.  You 3D modelers are in a whole new world that most of us will never experience.  No matter, I'd rather watch you!

 

Cheers,

Chuck

[TAG]

Next level modeling, so cool to see, Jay

 

Can't wait for the next installment!

 

- T

[Troy Molitor]

Some really great efforts going on here Jay.  Love the support and Longeron Installation.