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

[JayW]

5 hours ago, Ralph-D said:

Do you know or have the document "Mustang Modeller & Enthusiast". I have it and send PM if you would like to have it.

 

I am not familiar with that publication.  Do you think it helpful?  

[JayW]

On 9/1/2023 at 6:42 AM, Maxim61 said:

I had similar problems printing my 1/24 LEM

 

Maxim - I just googled 1/24th LEM.  Holy Moley man!  That's AWESOME!  Is that yours?  All I can tell is that some guy from down unda did it. 

[JayW]

Last post I stated that I have surfacing to do.  So that is what I have been doing.  It turns out that I am not the only one to digitally create surfaces for vintage aircraft.  Another fellow I was made aware of has painstakingly done this for several aircraft, where he had access to point data.  I would use what he has done, and he offers it to the public, only it was done on a CAD program different from mine.  So I will keep soldiering on.

 

What I have so far:

 

 

 

The windshield - boy the windshield. 

 

 

 

 

 

It was as hard as the smiley face, which I did not expect.  The P-51B windshield surface has three components - a flat forward portion, a single curvature side portion (and its opposite), and a top compound curved portion.  The flat portion was easy of course:

 

 

  Only one side was modeled; the other side is just a mirror opposite.

 

The side glass, not easy at all.  First, I used a fairly simple technique of lofting from edge curves, where I scaled the windshield assembly drawing (see above) for the lower curve and projected it onto the basic fuselage surface, used the station 113 loft (remember I have point data for that) for the aft edge.  I don't even remember how I came up with the top edge.  The forward edge coincides with the flat plate front glass.  Four edges, and viola: 

 

 

 

 

But I really didn't know how accurate it would be.  So I studied the engineering drawing for the laminated glass detail:

 

 

 

What you see there is a ton of point data for a periphery, and a cross section that gives a single-curvature part.  Back then, compound curved plexiglass was just being introduced, and manufacturers did single curvature wherever they could.  There is precious little information on that drawing defining how to place it in space where it is supposed to be.  Just enough for a supplier to make the part.  So, to check how good or bad my side glass contour is, I digitized that point data into a surface:

 

 

 

And then did the best I could to put it on the surface i created at the start of this process:

 

 

The yellow is the digitized drawing of the side glass.  The turquoise blue is my simplified 4-edge surface.  You can see they do not perfectly match.  BUT - the mismatches are small.  And at 1/18 scale, very small indeed.  So for reasons I will not further bore you with, I chose to go with the original blue surface.  This exercise was but a check, and a successful one.

 

Then it was on to the compound curved top glass.  What a PITA that was, but I got something I think is pretty accurate:

 

   

 

 

So now, I think I need to start in on the feared and dreaded wing-to-fuselage fillet fairings.  Nothing there at the moment:

 

 

But in order to do that, I need to finish the fuselage side panels, and the radiator scoop behind the wing.  That radiator scoop might be the toughest challenge yet. 

 

I also have a tub of resin left over from my prop spinner efforts.  Rather than take the trouble to pour it back into a bottle, I might make a couple more parts.  Parts that do not need my unfinished surfaces.  Hmmmm....

 

Stay tuned!        

 

 

 

Edited September 15, 2023 by JayW

[Gazzas]

Truly amazing and innovative work.  I don't think i would have the patience.  And then to think about rivets...ugh.

[LSP_Kevin]

Fascinating stuff, Jay! What is "lofting"?

 

Kev

[JayW]

39 minutes ago, LSP_Kevin said:

What is "lofting"?

 

Kevin - lofting is generating lines and surfaces for a boat or an aircraft.  Word has it that at boat building houses way back when, when hulls were being designed, the lines were drawn up in "lofts" above the factory floor.  From there, often tooling or molds were generated from the loft lines, for building parts.  Back in the -70's "master plaster's" were made for producing skin panels or form tooling and such.  These master plasters were made out of lots of metal plates trimmed to loft lines, placed in the proper relation to one another, and filled in with clay or plaster to make a surface.  Hence the term, and it stuck.  Even today when an aircraft surface is digitally defined, the surface is called the "loft".  At least it was where I worked.   

Edited September 16, 2023 by JayW

[Maybach_man]

I have a copy of the Erection and maintenance manual and the merlin engine overhaul manual

[JayW]

On 9/18/2023 at 10:28 AM, Maybach_man said:

I have a copy of the Erection and maintenance manual and the merlin engine overhaul manual

 

Thanks.  Aircorps Library has the E&M manual, so that works for me.  I will not be putting an engine in this thing, although it's tempting.  In what form is that Merlin OH manual?  I'd be interested in that.

[JayW]

Last I posted, I think I had declared victory on the digital surface of the top glass of the windshield:

 

  

 

Well no.  When attempting to make a solid from the surface, in order to 3D print a test part, I ran into all sorts of issues.  Did you know that contoured 3-sided surfaces (note the piece is basically three triangle shaped surfaces connected by two blend radii) do not want to be offset to make a part with some thickness?  The corners fold over themselves.  Well I will not get into how I eventually got there, but it took a couple of days of banging my head against the wall, and re-watching a couple episodes of "Primary Surfacing" on YouTube. 

 

Here is a test part made from standard grey resin, shown with "Huge Thumbnails" from Imgur for your detailed inspection:

 

     

 

 

OK.  The main reason I printed off a test part was to see if the contour looked good.  And it looks GREAT.  Mission accomplished.  It is .02 inch thick, which is what I want.  I intend to try to print this part from clear resin, which is, based on some experience with a test canopy for the P-51D in 1/18 some of you may recall, going to be much more challenging.  You can see where some of the supports were by the acne scars they left on the inside.  So I will obviously have to rearrange my support config when I do the clear part some time in the future.  If I fail, I am going to have to get somebody to vac form one.  Not in my skill set...

 

Well since I still had a big pool of liquid resin sitting in the tub on my printer, I decided to make some more parts - parts which do not require a still incomplete surface.  How about main landing gear?  Peter Castle aka Airscale made most of his undercarriage for Lope's Hope from 3D print parts.  At least the wheels/tires/brakes.  He recently sent me a huge data dump from his work on Lope's Hope, and included are some Rhino models.  And included in that are models of his wheels and tires and brake housings.  So what you are going to see here, are versions of what he sent me.  Thanks a million Peter.  Here, hot off the curing station:

  

 

Now these are also test parts.  Note one of the brake housings has a broken flange.  Not enough care taken snipping off supports.  And the outer wheel has a pretty serious blemish by the axle cap.  That is Peter's part almost without modification.  Magnificent.  The brake housing and the inner wheel are my own, but using Peter's parts as a start.  I will make a couple of minor changes to the support arrangement, and make some "production" parts pretty soon.  But these test parts were mostly to check and see how round they are and if they will fit inside the tire.  Based on my misadventures with the prop spinner, I didn't have a ton of confidence.  

 

A few shots of the parts in more detail:

 

 

 

 

 

Note the interior stiffening ribs inside the inner wheel half.  I wondered if they would print OK - They did and I am excited about that.

 

Tires you say?  I want my tires to have diamond tread patterns, and to have bulged flats, and hopefully "Good Year" on the sides.   Like this:

 

 

Yessir.  So I am doing my own from the ground up.  First though, I wanted to make another test part to see if my support arrangement is good, and if the tire and wheels fit together (meaning no out-of-round).  Here is the tire test part, with a very pesky bulged flat:

 

  

 

What do you think?  When I did the Corsair, there were pages of discussion on how the flat should be.  This flat is quite subtle; I am tempted to redo it with more bulge and/or more flat.  But it is sooo tedious to model it in Rhino, I am more likely to just leave it.  Accepting comments.   I might tone down that ridge a bit, but it is needed for the tread pattern to run out onto.  Next time you see a tire it will have the diamond tread pattern on it.  BTW - I have seen umpteen pics of wartime aircraft including Mustangs, where the LH tire is not the same as the RH tire.   Should I do that?  I could....

 

So did the parts fit together?  Yes they did!

 

  

 

 

 

My test parts were largely a success, and I learned a couple of things.  Next post you should see some tread pattern, and maybe the Good Year lettering and winged foot emblem on the sides.  Never done that before.  And, I hope to show progress on the surfacing of the radiator intake scoop under the wing.  And, depending on which way the wind blows, I might try modeling the Malcolm hood.   I have enough fuselage modeled where I could do that now: 

 

 

Or maybe the LG lower strut.  I can barely contain myself.  This is one exciting project at least for me it is.  Until next time, take care and enjoy the beginning of Fall (or Spring for those of you on the bottom of the world). 

 

 

Edited September 22, 2023 by JayW

[LSP_Kevin]

Nice work, Jay! To my eye (and tastes), that tyre flat is perfect. Don't touch it.

 

Kev

[MikeMaben]

Yep, I agree with Kev, looks great so far...

 

 

[geedubelyer]

2 hours ago, JayW said:

Last I posted, I think I had declared victory on the digital surface of the top glass of the windshield:

 

     

 

 

 If I fail, I am going to have to get somebody to vac form one.  Not in my skill set...

 

 

Hi Jay. Glad you achieved the correct shape. Nice job. 

Alot of what you have accomplished on your modelling journey wasn't your skillset before you tried it. Look at you now!

If all else fails you have a perfectly good mold to create your own windshield top piece. Once polished smooth it should be easy to "smash mold" the component.

Place the resin master on a short pedestal, cut a square of clear acetate (I use stuff from food packaging or food trays), warm it over a candle and once it softens pull it down over the master. The shape of the part is not complex and with practice I forsee you creating a piece in no time.

 

Quote

2 hours ago, JayW said:

This flat is quite subtle; I am tempted to redo it with more bulge and/or more flat.

 

 

Can you not simply sand the bottom a little to give you that look?

 

I'm enjoying your journey of discovery, keep at it. 

[JayW]

Before I finalize my tire details, I would like to open up the floor to a bit of tire size discussion.  I am getting deja vu, as I have done this before, but I didn't document it well.  The P-51 uses a 27 inch diameter tire.  That much is clear.  But what is not so clear is the width of the tire.  I have some reason to believe the width is 9.25 inches, and that is currently the value I have used for the test print part.  But on Miss Velma I used 9.5 inch as the width. 

 

Inputs?    

[TAG]

17 hours ago, JayW said:

BTW - I have seen umpteen pics of wartime aircraft including Mustangs, where the LH tire is not the same as the RH tire.   Should I do that?  I could....

 

My vote is a resounding YEA

[JayW]

These landing gear digital models fought me every step of the way, for one reason or another.  One significant reason is the relative inexperience of the user, but I get better every day.  Look:

 

 

 

 

On 9/22/2023 at 4:34 PM, TAG said:

On 9/21/2023 at 10:32 PM, JayW said:

BTW - I have seen umpteen pics of wartime aircraft including Mustangs, where the LH tire is not the same as the RH tire.   Should I do that?  I could....

 

My vote is a resounding YEA

 

Thomaz - your wish is my command.  I really like how the block tread tire came out.  It was much easier to model than the diamond tread.

 

Gonna print these up over the next few days, along with the final versions of the wheels and brake housings, assemble them, and post on it.  Stay tuned!  And BTW - anyone with constructive criticism, let me know now before I print these parts off.

Edited September 28, 2023 by JayW