NA-73 Mustang I, best options in 1/72nd

[72modeler]

3 hours ago, Jure Miljevic said:

Hello

I must correct myself. 17,5 inches is 1,458 ft. and not 1,416 ft. Slip of finger while calculating probably. So, P-51D and Mustang I airfoil wing positions I had been referring to are one third of an inch apart. Even so P-51D airfoil is thicker for more than twice this length than Mustang I airfoil, far too steep an increase on such a short distance. So I stick to my guns in I claim P-51D has thicker airfoil than Mustang I. All data I worked with are in primary documents linked to in my previous post and, if in doubt, anyone can calculate it by himself or herself. Also, these documents contain plenty of very useful drawings and other information.

Justin, in a book I read some time ago (and I still cannot provide a quote because I cannot find it) the reason given for modified airfoil was higher weight of a D model. Slightly thicker wing provided more lift, however drag also increased. More room inside the wings eliminated the need for tilted machine guns more as a byproduct (though a very welcome one) and higher weight and more drag resulted in slightly lower maximum speed. Cheers

Jure

Jure,

 

In the P-51 SIG website there was considerable discussion on comparing the thickness of the P-51B versus the P-51D wing; the original poster wanted to know if the D wing was thicker due to the six guns being mounted straight up and not canted as they were in the B/C variants. The article quoted an aerodynamicist named Dave Lednicer, who used NAA factory data to compare the wings. I am no expert and certainly no authority, so I am going to paraphrase from the topic discussion and list this summary below, and each reader can draw his/her own conclusions. Please understand that I'm just a model builder, not a designer or engineer, and having examined the articles you posted, my head is spinning- however, if I understood what I read, both reports were based on wooden wing models; I believe Lednicer's findings were based on NAA factory data. Bottom line being regardless of which figures are actually the most accurate, I would think the difference in thickness would be invisible in a scale model from 1/72 to 1/24. The discussion was extensive, as was the data, but being a member of the SIG, I do not want to violate the rules regarding displaying information without permission- I trust all of you  will understand.

 

From the topic discussion: The P-51 thru through the P-51K had the same airfoil, same T/C, same space height-wise for internal mounting of guns from .30cal through 20mm. The first significant change was the root chord for the D/K, and later for the H. The essential change was in the LE assembly from wing station 61 to the fuselage interface, leading to a washout difference out to WS61, then the wings were identical out to the wingtip. Only the XP51F and its derivatives out to the P-51H had a different airfoil- from NACA/NAA 34-100 to the NACA 66 series. (I have no idea what that last statement means, but I'm guessing it referred to the wing airfoil used.)

 

I am certainly not as gifted a model builder as you seem to be, from all that I have seen and read, and I am in no position to dispute what you have submitted, but I am attempting to reconcile what I have read and what you have proposed. I am very sorry for drifting so far off of the original topic- as I think I mentioned in past discussion on the poster's original query, we are still waiting for a really accurate Allison-powered Mustang in 1/72 scale.

 

I would be happy to relay specific questions regarding the wings to the resident authorities on the P-51 SIG if that would be helpful. Bow- let's get on to much more important things....what WAS the color used on those beautiful blue-nosed 352nd FG Mustangs? (Yes, I know I am one sick puppy!)

Mike

[Bedders]

3 hours ago, 72modeler said:

let's get on to much more important things....what WAS the color used on those beautiful blue-nosed 352nd FG Mustangs? (Yes, I know I am one sick puppy!)

Almost as important as "what colour is Olive Drab?"

J

[Kari Lumppio]

my mistake in the heat of a moment.

 

352nd FG Mustangs. At least two different blues used? My recollection.

 

 

Edited February 2, 2018 by Kari Lumppio
Answered wrong question.

[gingerbob]

Kari, that is an entirely different question.

[Jure Miljevic]

Hello

Justin, I believe it was Dana Bell who decades ago suggested Humbrol 108 is a close match to OD. I compared this paint to remains of original paint on bits and pieces of shot down WWII USAAF aircraft and I tend to agree with him.

Mike, yes, thickness of an airfoil is irrelevant for us model builders. However, debate here has strayed from OT to differences between airfoil of P-51D and earlier models quite a few times so I thought posting those two documents would do no additional harm. By the way, Leading dimensions table in RAE document refers to a full scale aircraft and not to a 1/6 scale wooden model. Amount of data on airfoil in Master dimensions document is immense and the document could probably be used to create shop drawings. I guess nobody in your SIG has found it yet as it certainly is worth studying and provides answers to many other questions apart from airfoil thickness.

Here is my penny's worth on original query. I have Italeri kit in my stash and while it could probably be sculptured into something presentable is it worth the effort? Probably not, so let us hope somebody in model building industry will take pity on us and provided new, accurate, rich in detail and reasonably priced kit of Allison Mustang in 1/72 scale soon. Am I asking for too much? Cheers

Jure

[Jackson Duvalier]

On September 24, 2017 at 11:05 PM, 72modeler said:

 

On September 24, 2017 at 2:37 PM, Graham Boak said:

On these early Mustangs the kink should also droop, i.e. go downwards as well are forward, something missing in most if not all of the kits I've seen.  The kink also begins at a different place on the wing - from memory the D kink is larger and so begins slightly further outboard, but I can't confirm that at the moment.  To correct it would be a matter of reducing it in size and bending it downwards, along a line that is the continuation of the outer leading edge.  There is a picture around taken from behind and slightly above the aircraft: it appears to have a simple straight leading edge all the way to the root because the drooped part cannot be seen from the angle from which the photo was taken.

Graham is correct on the 'droop' of the leading edge of the kink; IIRC, the only 1/72 kit to get this feature correct for an Allison-engined Mustang or P-51B/C is the old Monogram P-51B.

Mike

 

There's also the High Planes P-51A if the leading edge droop is a critical consideration. Most folks consider HPM kits to be a bit hairy, though. I've got most of the early Mustang kits out there, and almost all have some incredibly frustrating cock-up that makes extra work, or renders the entire beastie visibly unprototypical. Only Frog, HPM, and Academy have the Allison Mustang fuselage at the correct-ish depth (i.e., about a scale 3" shallower than a Merlin Mustang). The also-rans (Italeri and the various Czech offerings, most recently Brengun, who should've known better) may offer some appropriate detail parts in addition to an inappropriate fuselage.

 

In my humble opinion, the Academy P-51 is the most user-friendly starting point for an early Mustang; moderate modelling skills should see you through the necessary mods for a Mk. I. I found the easiest and least expensive way to lay hands on the Academy kit was to order from Korea; I ordered two and now wish I'd bought four. Be prepared to deal with Academy's trademark pointless, obvious, utterly frustrating, never-should-have-made-it-to-the-mold-cutting-stage absurdity (they include one as a sort of lagniappe on every kit), in this case the heavily scalloped "fabric" control surface "detail" on the rudder and elevator that will add a few hours to an otherwise straightforward and well-fitting build. Next time round I might just use the empennage from an Academy P-51B/C kit, except those are earmarked for my P-51D-5 models.... Why, Academy, why?   Or I guess you might cannibalise rudder and elevators from some other Mustang kit? 

 

ETA: I'm presently un-XXXXing an Academy P-51 tail, I'd share pix if I could get my computer to share image files. Basic strategy is to fill the ridiculous scallops and reinstate rib tapes with 0.4mm Aizu tape.

Edited February 2, 2018 by Jackson Duvalier
Added some info re. a current project

[Jackson Duvalier]

12 hours ago, 72modeler said:

let's get on to much more important things....what WAS the color used on those beautiful blue-nosed 352nd FG Mustangs?

 

7 hours ago, Kari Lumppio said:

352nd FG Mustangs. At least two different blues used? My recollection.

I have it on good authority the 352nd FG used Tamiya X-4 or XF-8, depending on the airframe. 

[72modeler]

2 hours ago, Jackson Duvalier said:

 

I have it on good authority the 352nd FG used Tamiya X-4 or XF-8, depending on the airframe. 

Good grief- I was just kidding in  my post! Do NOT want to let those worms out of their can- again! There was a lot of discussion on that very topic a while back, and my head is still spinning from trying to digest everything submitted. Thanks for your info, though, Jackson!

Mike

[Bedders]

I came across a Special Hobby 'Red Stars'-boxing Allison Mustang at my local model shop today, and having read this and other threads from start to finish, I'm relieved that I left it on the shelf. I think Academy might be the best starting point. If the wing of that is no good, the KP B-model wing is nice and might fit, though clearly some rescribing will be necessary. As for the drooped LERX, some semblance of it can be achieved with some judicious filing.

 

Justin

 

[John Thompson]

3 hours ago, Bedders said:

 I think Academy might be the best starting point. If the wing of that is no good, the KP B-model wing is nice and might fit, though clearly some rescribing will be necessary. As for the drooped LERX, some semblance of it can be achieved with some judicious filing.

 

Justin

 

 

The wing of the Academy Allison P-51 is not "no good", it matches in plan view the best drawings available - see below. What it lacks is the leading edge root extension droop; the same "judicious filing" which would rescue the KP wing will also work with the Academy wing.

 

On 9/25/2017 at 2:07 PM, John Thompson said:

 

So much information is being presented, quoted, requoted, and disputed here that I think confusion is setting in. I see nothing in this thread which says the Academy P-51 (kit #12401) has a P-51D wing. Direct comparison shows that the wing matches exactly the Allison P-51 drawings prepared by Jumpei Temma, and that's pretty damn good, in my book. FYI:

http://www.geocities.jp/yoyuso/p51a/p51a-1.html

 

 

John

[Graham Boak]

Judicious filing of the upper surface is not enough - you have to take the extension into the jaws of a pair of pliers and bend it down.  I'm not sure whether the underside of the extension is flat (as opposed to curving up into a normal aerofoil shape) but it certainly needs bending too.  There's at least one photo taken of a Mustang from the rear 3/4 somewhat above, and the entire extension cannot be seen.

[Jure Miljevic]

Hello

There is are several drawings of P-51B's leading edge droop, including one on page 8 (although for Station 0), in the first document I posted the link to on previous page. The second document from the same post also has a Mustang I wing root drawing (thou somewhat crude one) on page 67. Also, in his latest post John Thompson again provided the link to Jumpei Temma's impressive drawings of Allison Mustangs. They are certainly worth a very close examination. Cheers

Jure

[Jackson Duvalier]

I remember building a 1/72 Monogram P-51B as a kid, the re-issue from 1988 or '89.  A few bits of it yet survive in the spares bin, but not the all-important upper and lower wings.

 

At a recent club meeting, I scored one with a 1979 date, still in the wrap.  Just a little younger than me and still utterly virginal.

 

Feels a bit odd to cut it open, like an archaeologist opening a tomb...  but the interest of science and all that.  Feels like I ought to film this momentous event!  My ongoing and exhaustive survey of the Mustang in TOTS means I was gonna do it sooner or later, and since we're hashing out the LERX issue, out comes the knife.  (I put on some ELO for that period feel.)  Here we go....

 

Wrap's off.  Felt oddly satisfying.  Up with the lid... Hm.  Two clear sprues!  Thank you, Monogram packer from 1979!  Cracked decals, but that's to be expected.

 

At first glance from overhead, the LERX droop doesn't appear much different from the KP wing I have handy here at the bench.  A closer look shows a bit of droop when viewed from the front, but an even closer close look makes me think the plastic might just be warped after sitting in a box for 39 years.  Fitting the upper and lower wings, I'm not seeing anything different droopwise than any other 1/72 Mustang.  Except for raised panel lines.

 

While I'm at it, let's compare fuselage molding profiles.  When the KP fuselage is aligned at the leading edge, the top contour aligns quite well with the well-regarded Monogram interpretation, but the KP radiator bulge is deeper by about 1.5 mm-- I could probably live with that as I'm (slightly) less concerned with the undersides of my models.  When the Monogram and KP fuselage halves are aligned as well as possible along the lower contours, the much maligned wonky nose and fin of the KP moldings seem to appear.  

 

I doubt this has cleared anything up really, but I feel a bit better about foisting off a completed KP P-51B upon an unsuspecting public whose fondest wish is merely to witness an accurate early Merlin Mustang in 1/72. 

 

Still awaiting the Holy Grail.

Edited February 8, 2018 by Jackson Duvalier
Droopwise-- is that even a word?