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

[JayW]

Well - I read something that said the block tread tires were made by Uniroyal.    Can anyone verify that?   

[JayW]

Well the last couple of weeks I have, instead of doing surfacing like I should be doing, indulged myself in the world of 3D printing parts where there is very little guesswork (well - a little here and there) - just digitally defining the parts per drawing data, and turning that into resin parts.  You know of course this is main landing gear parts.  I made some test parts; now comes the real thing.

 

First, recall that I was doubting Good Year made the block tread tire.  I think I am right, and it matters because I have put manufacturers lettering on the tire sidewalls for the first time ever for me.  Before and after:

 

  

 

 

Uniroyal.  May be right; may be wrong.  But I found some discussion on the web where someone was sure Uniroyal provided block tread aircraft tires at that time.  The style of the lettering is a guess, from a web search.  And I also put the tire size on there just for kicks.  Also I had asked about tire width - 9.25 inch or 9.50 inch.  No definitive response, so I went with 9.5 inch, or in 1/18 scale .527 inch wide. 

 

So with some other tweaks here and there from whatever learning I received from the test parts, I printed off a set of production parts:

 

 

Two kinds of tires, two outer wheel halves, two inner wheel halves, two lower struts, two brake housings, and four tow rings (a couple of spares).  They came out really nice, except the brake housings where the brake line fittings are too small and fragile.  So I will redo the brake housings.

 

Cleaned up and assembled:

 

   

 

 

 

 

 

 

And the lower strut, with a 3/16 inch diameter aluminum tube, and the tow ring dry-fitted:

 

 

 

Again - I have to credit Peter Castle with the outer wheel half at least.  It is just excellent, and he gave me the Rhino model. 

 

There was a time when I worried that 3D printed parts were too fragile to be asked to support the weight of a large model.  No more.  Some will recall that I ran a bench test on a 1/18 scale F4U lower strut for my multi-year F4U project, where I put up to five pounds of weight on it, and it held.  This P-51 MLG lower strut is going to be fine; don't you worry.

 

As you can guess, this P-51 is going to have mismatched tires, like we see so often in wartime pictures. 

 

Alright enough with the MLG for a while!  I need to get back on task.  Next post is going to be all about surfacing around the radiator intake, maybe more too.  Hope you are enjoying this half as much as I am....   

Edited October 2, 2023 by JayW

[Shoggz]

I'm enjoying it immensely Jay!

 

Your work bench looks very similar to mine.

 

Just wish my modelling skills matched yours too.

[BiggTim]

7 minutes ago, Shoggz said:

I'm enjoying it immensely Jay!

 

Your work bench looks very similar to mine.

 

Just wish my modelling skills matched yours too.

Me too! Very inspiring!

[geedubelyer]

Loving this. 

What a treat to watch.

 

 

[scvrobeson]

Those wheels look fantastic! Beautiful design and printing

 

 

 

Matt 

[Citadelgrad]

Wow Jay, your skills with 3d printing are really amazing. I am just starting to look into it, and am working through some Fusion 360 tutorials.  I know just enough to confirm that it is a very complex subject.  Your wheels and tires look incredible.   

[LSP_Kevin]

Fantastic stuff, Jay!

 

Kev

[JayW]

Well, it's not all fun.  Preparing for part making means I have to have a surface, and I am laboring away at it.  Some parts are easy; some are hard.  Here is a hard part:

 

 

Got alot done but alot remains. 

 

The Meredith effect radiator intake duct.  For those unfamiliar, the "Meredith effect" radiator inlet is an inlet design that at least partially offsets the aerodynamic drag produced by an inlet with a thrust introduced by expanded hot air exhausting out the back of the inlet.  Not a net gain, as some think (that is physically impossible without added energy like fuel burning).  But a minimization of induced drag.  Anyway - that inlet leading edge was a big PITA.  But it's pretty:

 

    

 

Like the other parts of the fuselage, this part was created using point ordinate data from vintage drawings, along with much gnashing of teeth and cussing.  

 

Here it is displayed alongside the other big PITA inlet - the carb air smiley face inlet (one of the very first things I did for this project):

 

 

I am pleased to get those two little buggers out of the way.  Now for more surfacing aft of that inlet and the external cowl that goes over it.  The only thing that might stop me is if I get impatient and digitally defining the Malcolm Hood becomes too intriguing to resist.

 

Stay tuned!

Edited October 6, 2023 by JayW

[Gazzas]

Inspirational work, Jay!

[JayW]

Surfacing work continues.  Nothing is coming easy, but that's OK.  I am tackling what I believe to be the most complex surfaces first.  What I have so far on the radiator scoop: 

 

 

I'm excited about that.  A test part is coming soon.  Stay tuned.

 

Meanwhile, the Malcolm hood was talking at me, loudly.  So I spent a few days on it.  This too fought me every step of the way.  But in the end, I got a hood that I think is pretty close.  A good bit of guesswork, because as you may have surmised - there is no dimensional data available.  Just pictures.  Here:

 

 

 

 

 

The hard parts were - well just about everything.  But the stiffening beads on the fore and aft edges fought me.  The transition from a circular (or elliptical) fishbowl shape to the straight bottom rails was a challenge as well. 

 

For those really interested in my Malcolm hood development, feel free to go back to the hoard of pictures TAG gave us, and compare.  Tell me what you think - good and bad.  BTW - I will do a test part for the hood, probably grey resin first, and then I will gird my loins and try a clear one.  Really - I will be surprised if I get a good clear part.  More likely, I will have to make a mold so that it can be vac-formed. 

 

More surfacing.....    

[Antonio Argudo]

loving your updates in the big Mustang,  view of the Malcolm hood , cheers

 

[SwissFighters]

10 hours ago, JayW said:

Surfacing work continues.  Nothing is coming easy, but that's OK.  I am tackling what I believe to be the most complex surfaces first.  What I have so far on the radiator scoop: 

 

 

I'm excited about that.  A test part is coming soon.  Stay tuned.

 

Meanwhile, the Malcolm hood was talking at me, loudly.  So I spent a few days on it.  This too fought me every step of the way.  But in the end, I got a hood that I think is pretty close.  A good bit of guesswork, because as you may have surmised - there is no dimensional data available.  Just pictures.  Here:

 

 

 

 

 

The hard parts were - well just about everything.  But the stiffening beads on the fore and aft edges fought me.  The transition from a circular (or elliptical) fishbowl shape to the straight bottom rails was a challenge as well. 

 

For those really interested in my Malcolm hood development, feel free to go back to the hoard of pictures TAG gave us, and compare.  Tell me what you think - good and bad.  BTW - I will do a test part for the hood, probably grey resin first, and then I will gird my loins and try a clear one.  Really - I will be surprised if I get a good clear part.  More likely, I will have to make a mold so that it can be vac-formed. 

 

More surfacing.....    

 

More fantastic work Jay! I'm really enjoying following and am a bit jealous of your developing skills in 3D imaging and printing. Wish I could do (and afford) the same! Looking at the following image, though, I wonder if the lines I highlighted can represent fair curves? Their path doesn't make sense to me but I might be misinterpreting what they represent. Can you enlighten me? TIA. Tony

 

this 

[JayW]

7 hours ago, SwissFighters said:

Looking at the following image, though, I wonder if the lines I highlighted can represent fair curves? Their path doesn't make sense to me but I might be misinterpreting what they represent. Can you enlighten me? TIA. Tony

 

this 

 

Yeah - Perhaps you can see that there are three zones of surfacing - the leading edge, the middle (where you have highlighted the two curves), and the aft end where the transition to the wing lower surface takes place.  Also the middle and aft zones are split by a water line (WL -39 actually).  Incidentally, the surfaces were generated on the LH side, and then mirror images were created (easy to do in Rhino) along the airplane center plane (BL 0).   In complex areas, I have found that you have to tackle it one bite at a time, and then combine. 

 

Anyway - the middle zone has some wacky looking contour lines, as a result of where I placed control points on the several cross-section curves I used to generate the surface.  It appears then that the contour is wavy, yet it is not (I think it is not - I have submitted it to some pretty good curvature analysis, but I will make a test part just to make certain).  I could have been more careful in where I placed control points, but it would not have resulted in anything really different.  Without getting into the weeds (and boy can you get into the weeds in primary surfacing techniques), complex surfaces can be generated by connecting a series of cross-sections where each cross-section is created by a curve or joined curves (I did this for all three of the zones above), or by creating an array of 4-sided patches where each edge is a curve generated in the same fashion as for cross-sections, and then the patches are "stitched" together carefully, using special commands which control tangency and assure patch edges are "water-tight".  I have used the latter technique for the fuselage, which is why it looks like a square-pattern sweater in my pictures.

 

BTW - what I am doing here is not particularly expensive.  I had a one-time expense purchasing Rhino (several hundred $), and then it's free forever, unlike some other programs which have an annual renewal fee.  My 3D printer was $300 and change, with a bit more for the cleaning/curing station.  And the resin is around $25 per 1000 gram bottle.  Bottles last a while too.  Oh, and I do subscribe to Aircorps Library which has an annual fee, but it is very reasonable. 

 

Thanks for your interest Tony!       

Edited October 11, 2023 by JayW

[Maybach_man]

On 9/19/2023 at 10:45 PM, JayW said:

 

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.

Sorry for the delay... its currently on a cd