1/18 P51C Mustang "Lopes Hope the 3rd"

[JayW]

From 102-00001:

 

 

A couple of many very important dimensions which can be referenced on this drawing.  Note the exhaust stack slot is not exactly horizontal - it droops 1.75 deg down.  On my 21st Century Toys Mustang, they actually drooped it up!!!  Comical.  That's why I had to start over on the engine cowls.  I think most model manufacturers who do the Mustang just have the slots horizontal.  That's cool.  But that 11 deg landing gear angle is a must do.  Otherwise it just won't look right.

[airscale]

afternoon folks

 

Thanks for the tips Jay - useful to have the angles needed - I just did the stubs with a Mk 1 eyeball against the plans, but when the time comes for the gear I will make some templates

 

I am loving this free time as I have had a chance to get stuck in on areas of the airframe that need some heavy lifting...

 

..as I move around it, one area that is immediately obvious as a problem is the fin - check this out...

 

 

..reminds me of a MR1 Nimrod with some sort of radar pod  as it is so thick and fat - but rather than witter on about how this is not what I expect for my money in this day and age from a kit manufacturer (this base moulding from HpH from their museum range is not cheap..) it just needs fixing..

 

I actually made two tails - the first did not have a dorsal fin as in the only pic of Lopes Hope I have, you can't see the tail, and the other shots I have of A/C from the same unit don't have them - but then Kagemusha put me onto this image where there is most definately a dorsal fin (as there is on the restored -10NT)..

 

 

..so I started tail number 2 by using a nice side on shot to derive the dorsal shape (I can't find any drawings of it) and made up a scale template... I also included a tiny bit of the fuselage top so I can see exactly where the kink from dorsal to fuselage is..

 

 

..this was then printed and transferred to a brass sheet to act as a keel - 0.15 brass is ideal as it can be taken down to a very fine trailing edge without deforming...

 

 

..rib positions were marked and plans used to derive the rib profiles - there is a big keel at the bottom to let into the fuselage...

 

 

..I used cotton to set out the fuselage datum line on the model and arranged it so it was completely level, then after cutting off the old tail and making a slit the length of the new one it was carefully let into the fuselage and the angles checked for accuracy...

 

 

..first fill of P40 filler starts to bulk out the shape...

 

 

..while that was drying I started on the rudder..again, the first step was to interpret nad scale plans to derive templates to work from - here the outline and all the internal features are mapped..

 

 

..same process.. transfer to brass to be cut out with a slitting disc in my dremel..

 

 

..all the internal structure was also marked out so after cutting out I can just follow the lines..

 

 

..features were then built out with plastic stock and coffee stirrer sticks - I find the solartex covering bonds well to these..

 

..the trim tab has been cut so as to be able to be broken out after finishing the structure so it is in keeping with the profile of it's surroundings..

 

..you probably can't see them, but at four positions card templates with black outlines were added to show the profile all this needed to be sanded down to to get the correct shape..

 

 

..then a coarse sanding thing in my dremel allows me to virtually carve away the waste - it is very effective and not really dusty as with the heat it sort of acts like a scraper rather then a sander..

 

 

..the basic rudder is complete, a bit more finessing and it will be ready to cover..

 

 

..and here is where I am at..

 

 

..got more than a week off to go, so expect to have the empennage done by then..

 

TTFN

Peter

 

 

Edited December 30, 2018 by airscale

[Trak-Tor]

Wow!

I'm loving your free time as well!

 

Juraj

[MikeMaben]

On 12/29/2018 at 7:12 AM, JayW said:

From 102-00001:

 

 

A couple of many very important dimensions which can be referenced on this drawing.  Note the exhaust stack slot is not exactly horizontal - it droops 1.75 deg down.  On my 21st Century Toys Mustang, they actually drooped it up!!!  Comical.  That's why I had to start over on the engine cowls.  I think most model manufacturers who do the Mustang just have the slots horizontal.  That's cool.  But that 11 deg landing gear angle is a must do.  Otherwise it just won't look right.

 

Hi Jay , it looks like this drawing is a reference to the stations and angles only.

Nothing else is meant to reference anything dimension or contour wise.

I would ignore the exhaust opening as well as everything else on the drawing.

 

[JayW]

Well Mike - it is indeed a reference drawing, and I agree it does not drive any manufacturing information.  Also it looks suspiciously like a poorly redrawn Allison -powered early version.  However the dimensions are in agreement with all the various production drawings where the geometry is truly defined.  I verified this a few years ago when I did the Miss Velma 1/18 project, at least as far as the D-model is concerned.   Plus, this drawing has undergone alot of revisions, and it has been used as the basis for general arrangement drawings for later models (like the D/K) - where you see the exact same callouts.  I highly doubt NAA would have let erroneous info remain through the revision process, if it were erroneous to start with.

 

Edited December 31, 2018 by JayW

[JayW]

Peter - some major heavy lifting on the empennage.  And much needed!  Well done.

[MikeMaben]

Sure the info on the drawing is correct, I was just refering to your concern

about the exhaust being off. I don't see any info re that specifically. It 'appears'

to line up with the centerline, but the drawing being so crude, I don't think it's

meant to.  But then again I could be wrong 

 

 

[airscale]

hello again

 

Rudder is now complete...

 

..first step is to cover it in solartex which is what RC folks use for their flying models - it has a nice scale fabric effect - this is my seventh try to get a nice clean straight bond - it is heat activated with an iron which causes the adhesive to bond and the material to shrink - pretty tricky on a part this small (by comparison..)...

 

 

 

..there is also a metal fairing at the bottom of the rudder which I assume protects it from crap thrown up from the tailwheel - I pressed the part into plasticine to make a female mould and then cast a buck in resin to vacform the piece over..

 

here I am marking it for cutting, with the part taped to the buck..

 

 

..and the covered rudder - started marking out all the rib positions for the rib tape...

 

 

..you can see on a real P51 the rib tapes go over what look like small circular depressions (rather than a Spit which has raised bumps where the knots are) - look along the line of the top rib tape and you can see the effect we need to get..

 

 

..to get the effect, I used a rivet awl to punch small holes in tamiya tape and laid these down first along the rib lines..

 

 

..then for the rib tape itself, I use plumbers aluminium tape - this was made to scale width from the plans and the 'pinked' edges (fine zigzag cutting to avoid fraying) I ran a rivet wheel along the line and tried to cut through the punched holes to make the pinking..

 

these were then laid out according to the NA covering diagram..

 

 

..all done - hopefully you can see the dimples along the rib tapes - this was the effect I was after..

 

also made up a trim tab from the part broken out of the main rudder & skinned it in litho...  the rivets on it are perpendicular to the leading edge, not in line with the ribs as you would expect..

 

 

 

..also added the trim tab hinges to match the cut-outs in the tab...

 

 

..to finish off I added the trim tab control horn & arm, and at the top leading edge the balance weight - this was actually quite complex as it it shaped in many directions to match both the aerofoil and the tapering tip of the rudder post..

 

 

 

..coat of primer to settle the details & textures..

 

 

..the rib tapes look good to me so job done..

 

 

back with something else soon

 

TTFN

Peter

 

[Shoggz]

Altogether amazing.

[Iain]

Beautiful work and use of materials (yet again!) Peter...

 

Really love the way you look at new materials and solutions - always an inspiration.

 

Iain

[TorbenD]

Say what!

 

As ever Peter, verrrrry noice. Steaming on....

 

Torben

[Durangokid]

When you start working on a piece, take the tail for instance, it doesn't look all that great and I think there's no way that will work. Then you magically transform it into something that looks exactly like the real deal. Incredible talent, either that or you have invented a shrinking machine! Haha

[JayW]

That rudder is marvelous.  Love this build! 

 

As for the cowling slots -   

 

This is part of drawing 102-31001 Cover Installation - Fuselage Complete.  It is a component installation of the top drawing for B/C models - 104-00002.  

 

 

The actual call-out for a 1 deg 45 min droop angle for the center of thrust is not on this drawing, however the drawing shows clear as a bell the drooped orientation of the forward fuselage cowlings, and that includes the exhaust stack cutout.  That call-out is somewhere; I just cannot find it at the moment.  I suspect the Allison-equipped Mustang was different.  It is important when modelling Lope's Hope to get the cowl panel lines and cutout in agreement with this; otherwise it won't look right.  Face it - with the level of quality this build is currently at, this is a detail not to be ignored or messed up.  

 

Wish I could find the definitive callout for this geometry.  However this is from Charlie Neely's excellent 1/16 drawings of the D/K-models (he has an equivalent set for the B/C).

 

 

While I recognise these drawings are ref only, nobody alive has done more research into the accurate configuration of the various P-51 models as Charlie.  Note that the power plant has a coordinate system all its own where Cowl Station 0.00 is on Fuselage Station 41.60, at the fuselage reference line (FRL).  And it is tilted down 1 deg 45 minutes (or 1.75 deg) relative to the FRL, and that defines the thrust centerline which is how the engine drive shaft is oriented, and the prop, the spinner, the exhaust stacks, etc, etc.  The FRL is what we can all assume to be "horizontal".  Peruse through dozens of forward fuselage drawings, or power plant drawings, and you will see this same tilted orientation every time.  Don't ignore it.

 

Am going to get off my high horse now, lest I wear out my welcome!   Will be following your every step.  I  love Mustangs especially the B-model.

 

Here, a cool painting of a B-model in action:

 

 

Don't know the artist, but American pilot is Robert Volkman, 361st FG (Yellow nosers).  The painting depicts a real life duel where the opponents made repeated head-on passes at one another at an altitude where bailing out was not an option.   Both survived and returned to base, after shooting one another up some.  Man.....these guys had some big ones.

[Kagemusha]

Amazing work Peter, I was having a google about something Mustang-related and came across a line drawing of a B/C with dorsal fillet here from this website, hope it helps regards panel line and rivet detail. 

 

Arthur Bentley has a set.

[Hacker]

Eventually you will be scribing the gun and ammo bay doors. A question that has plague my mind is the size between the B and the D. Upon visual inspection the bays and the doors seem to be the same size between the two which my luck isn't so. Any clarification on this and is there measurements to go by?

 

Hacker