P-51B "Cripes a' Mighty" 3D Printed in 1/18 Scale

[JayW]

Hello folks.  I would like to present to you my 2-year long project "Cripes a' Mighty" P-51B-10NA Mustang, flown by Major George Preddy of the 352nd FG ("Blue-Nosers").  Scale is 1/18 - she is a big girl for sure.  She is about 99% 3D printed using an Elegoo Saturn 2 printer.  All components were designed in Rhino 7, using original NAA engineering drawings obtained from Aircorps Library.  The build thread can be found here:

 

 

Here she is:

 

 

Before I present more pictures, let me offer some comments on the build. 

 

First, the reason I picked this subject (a P-51B) was mostly two-fold.  One, I really wanted to do a Malcolm hooded, natural metal finished -B model.  And two, the P-51 is just about completely defined by micro-filmed engineering drawings available from Aircorps Library.  That, along with learning Rhino 7, and purchasing a good 3D printer, allowed me to produce a model with near perfect dimensional accuracy.  That applies not only to the fuselage, wing, and tail, but also every detail I chose to include.  Hardly any guesswork.  Hardly any errors.  As for the selection of "Cripes A' Mighty" - well that was mostly from a sort of vote by many of those who were following the build, and my concurrence.  There were other great subjects to choose from; Cripes won out.  And the nose art was do-able - important.

 

This was my first effort at building a model totally by 3D printing, with absolutely nothing to start from.  And what a learning process it was.  3D print resin is amazing stuff, but it is fragile.  I cannot count how many times I broke a part and either had to repair it or print a new one.  But when done properly, what results is detail that often cannot be obtained from plastic, or even scratch building.  As a result Cripes is the most realistic model I have ever built.  I would also add she might be the most fragile model I have ever built.  Not the basic model - it is super-stout.  But little things like wing tips, gear doors, mirror, etc.  And, this is my second effort at aluminum skinning using .005 inch thick aluminum sheet.  Not easy to do, and it can be very tedious, but this process can result in a very real-looking natural metal finish.  I learned this technique from Peter Castle - we know him as Airscale.  He has been doing it for years.

 

This project was a mix of elation and pride - why we build models - and panic/anger/fear/frustration.  Cripes was no easy build.  And big mistakes were made (all were ultimately fixed).  How about mislocating the flare gun hole one full bay and royally screwing up the left-hand cockpit sidewall.   Or putting the three colored ID lights on the wrong wing.  Or screwing up the main landing gear rake angle by a couple of degrees.  Or a huge one - tipping it over late in the build and breaking off the centerline gear doors and the left hand landing gear strut.  OMG that was awful.  There were painting disasters, disbond issues, fractured parts too numerous to count.  But there were also moments of huge victory and feelings of accomplishment.

 

I think perhaps the most interesting and successful element of this build was the use of a 3D printed highly accurate fuselage assembly jig, designed by myself.  Here is a picture of it:

 

 

 

The bulkheads in front and back slide in slotted holes to allow the longerons to be loaded.  Below you see it with some fuselage parts loaded (four longerons, and all the frames):

 

 

I show this because this jig provided the foundation for the entire build - an accurate forward fuselage with cockpit, and accurate attach points for the wing, engine cowling, and aft fuselage.  Everything was square, with no twist.  Had to have that before adding anything else.

 

Another interesting element of this build was my decision to use 3D printed transparencies.  As opposed to vacuform, although that was cussed and discussed at length.  If you look closely you will see rabbetted edges on the transparencies for framework to fit onto, which probably could not be done with vacuform.  Ultimately the canopy and aft quarter window parts were provided by Shapeways at high prices, after I just flat failed on those parts.  The windshield parts were adequately printed by myself.   The concern of course was clarity.  Most of the followers of the build were very skeptical of 3D printed clear resin to deliver.  I will let you judge for yourselves.  BTW, an amazing amount of sanding and buffing was required just to get the clarity you see.

 

The area where I had to do some serious guesswork was the Malcolm hood and the cockpit modifications for same - there are no drawings or other specs.  Dozens of pictures both period and from restos helped immensely.  During that time of the build, I learned a whole lot about the Malcolm hood modification, and how involved it actually was.  Some of you may not be aware that the Malcolm hood was a field modification entirely.  A -B or -C (or even an -A) model would go into the field hangar, and several days and hundreds of man-hours later, it emerged with a big fishbowl sliding hood replacing the greenhouse style canopy found on production aircraft.  The mod was a big deal - major surgery for the cockpit.  From what I read, pilots universally loved it, as seeing was life (along with speed and fire power).  Visibility with the Malcolm hood was superb compared to the stock greenhouse canopy.  At any rate, the hood was driven by a crank handle and chain drive.  I am not aware of any modeler other than myself attempting to model the various cockpit modifications for the hood.  Look for that in the pictures.

 

This model is heavy - about 2.5 pounds or so.  So the landing gear struts needed help, especially the tail gear.  This was the first time I re-inforced landing gear struts with metallic rod (brass or music wire steel).  Here is a picture of the tail gear strut and an internal bent-up stiffening rod formed on a 3D printed forming block of my own design:

 

  

 

The main gear struts were re-inforced similarly with thicker rod.  The re-inforcements have worked to perfection.  

 

To my horror, after the main gear were installed onto the airplane, I discovered the rake angle was off by a noticeable couple of degrees.  That after being so careful to design it right.  I still don't know for sure what happened.  So I created a fixture where pressure could be applied over days to the gear struts via simple plastic shims with ever-increasing thicknesses, to gradually force the struts back to a correct rake angle:

 

 

See the white shims?  I show this because the multi-day exercise was some of the most stressful days of the build - hoping to get some permanent deformation on very stout gear support parts without breaking something important.  Believe it or not - it worked!  The hope of course is that it stays that way.

 

Lastly some details to look for in the pictures:

 

- Mismatched tire treads (you see alot of that in period pictures)

- 3D printed unshrouded exhaust stacks

- 3D printed chains nested in between flanges of the upper longerons, which drive the Malcolm hood

-  3D printed clear transparencies with rabbetted edges

-  External rails and rollers for the Malcolm hood

-  Spitfire-style exteral rear view mirror

-  Malcolm hood that can actually be slid fore/aft (if very careful)

-  Movable tail surfaces

-  3D printed head rest pad and seat back pad (thanks Antonio Argudo for that!!)

-  The crazy shaped early-style bomb racks

 

Here we go:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I guess that is enough.  I would like to thank first of all the 40 or so followers of my build thread.  All were very patient and supportive during the 2-year effort.  And special thanks to Airscale for giving me the extensive decal set for his 1/18 P-51C Lopes Hope, hundreds of pictures, and a few helpful Rhino files.  Oh, and the 1/18 scale seat belt hardware.  Also Antonio Argudo for designing some really great models for me - the head rest, seat back cushion, and tail gear bay canvas cover.  Also Thunnus who provided me with nose art decals and stencils, and stencils for other things like squadron buzz letters, tail serial numbers, national insignias, and kill markings.  Also TAG and Antonio for priceless period pictures of anything and everything P-51B.  And lastly Aircorp Library - OMG.  Their collection of engineering drawings and other documents is absolutely priceless. 

 

I hope you like Cripes a' Mighty.  She is not perfect, and she appears rode hard and put up wet.  But it is the best I can muster!  Thank you.    

 

 

 

  

  

Edited January 21 by JayW

[titan]

Absolutely stellar build.  Amazed at build quality, finish, and attention to detail in the design.

 

Well done seems inadequate.   

 

[thierry laurent]

One word says it all: MASTERPIECE!

[chuck540z3]

Truly awesome model Jay that will never be replicated.  It looks so real, which is the best compliment I can think of.  Congratulations and I look forward to your next scratch built masterpiece!

 

Cheers,

Chuck

[BiggTim]

The best compliment I can think of that Peter Castle (Airscale) would probably be proud! 

[Oldbaldguy]

The best you can muster is well beyond good enough.  The bar continues to creep higher and higher and you are the one pushing it.

[Antonio Argudo]

it is a happy/sad feeling right now to see come to an end such project of this magnitude, a big scale Mustang from scratch is a  huge challenge therefore your  accomplishment deserves to feel so proud of yourself Jay, you have a achieve a Masterpiece! you solve numerous bumps  and challenges along the way wonderfully, we learnt from you a lot!  I really enjoyed the cockpit build and wheel bays, so accurate and realistic! can only thank you for sharing this awesome journey! love Preddy's B Mustang scheme too, guess I will make one for my self when the eduard kit is released one day, keep the awesome work, good luck  the next project and we will following, cheers

 

Antonio

[Johnny Cloud]

Your masterpiece...  so far.

A truly inspiring build, thank you.

[Landrotten Highlander]

my flab has been gasted while the gob was being smacked...

[SwissFighters]

Thanks Jay,
Your build has been a great source of interest, information and entertainment. I have really enjoyed seeing it develop and how you have found ways to engineer the results.
Looking forward to seeing whatever it is you do next.
Tony

[TankBuster]

Amazing build and it was a joy to follow along, well done. Cheers Bob.

[Rocat]

Absolutely stunning work. Bravo!

[Troy Molitor]

A wonderful two year journey to follow Jay.  Excited to find out what your next project might be.  A superb and beautiful P-51B to see come to fruition. Well done.   

[MikeMaben]

                        A beautiful thing.

 

[jcweston351]

I think you've used the incorrect rivet on... Damn this has been a great journey to watch & the finished article was well worth all of the effort.  Love your work!