Warbird Information Exchange

Folks,
I am rebuilding the horizontal for a P-51D. I have found something I need help in identifying.

It appears that in the past the lower skins were removed, the interior painted with zinc chromate and new skins were installed.

But the funny thing is they didn't zinc the new skins.

The question is what does this writing mean? The writing is in continuos bands spaced about 10" apart. The top line is 12p/3, below is 1,00 mm which is about .040 inch (Thickness of material) followed by 8 and then 10/46 which would be the date of production of the metal.
Also why would an American product have foreign mfd metal skins installed? Was this done in Sweden or by the Swiss? The horizontal probably was built with no paint protection on internal components and the operator wanted to protect the insides but then to not zinc the skins is a strange situation.
The upper skin still in place has remnants of the US 24ST Alclad writing. I don't believe it was ever removed.
As I further tear this apart I'll let you know if any other mysteries are uncovered.
Rich

Not a direct answer to your questions, but the "decimal comma" as opposed to a decimal point, should direct the research towards Europe as you have already begun to state, where that nomenclature is used (it is also used in some Latin American nations, but I would risk saying that in the case of this Mustang, no Latin American-connected restoration took place).


Saludos


Tulio

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Will the previous owner has pics of this double cabin sample

GOOD MORNING, WELCOME TO THE UNITED STATES OF AMERICA
Press "1" for English.
Press "2" to disconnect until you have learned to speak English.

Sooooo, how am I going to know to press 1 or 2, if I do not speak English????

I think you're right about the European nature of the repair. In my past career I ran into a lot of similar metric designations while working on equipment of European origin.

Have you found any corrosion in there yet?

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Hey Rich,

I found the same thing one time! I am pretty sure it was a Horizontal Stab and I think it was on Daddy's Girl. I'll check to see if I've still got some pix. I was thinking Latin American repair as well. Not sure. What about CAC??


Mike Vadeboncoeur

CAC would be Imperial measures, when built, I'd have thought. Aus went metric between 1971 and 1988, so it could be after that, but you don't see the , rather than . here for a decimal; that's continental.

If I get the chance, I'll ask my local CAC Mustang magicians for any comment.

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Does the airplane have WW2 combat history in Europe ? My immediate thought was maybe a "in the field repair" say in France after June 1944.

Just my 2 euros worth ....

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It's been a long time since I have worked with metals, but it apears the markings are, type markings, which sometimes show up on the top or bottom sheet of a pack. The marks usually show the strength and quality of the sheet

Steve

I am familiar with US sheet metal markings. WWII type markings would be 24ST .040 Alclad. The modern equivalent would be marked 2024-T3 .040 Alclad. Different alloys have different numbers in both systems as well as designations for the temper of the metal. The Alclad refers to a process where a few thousands of pure Alum is rolled onto each side of the base alloy (Strength of the metal is based on the alloy and it's temper as pure alum isn't very strong and can't be heat treated) to improve the corrosion resistance. Alloying Alum improves its strength but decreases its ability to resist corrosion. These markings are inked onto the metal sheets or shapes if we are talking about angles, rounds or Ts.
This is the 1st I have seen markings of this type. The date of 10/46 really puts this as early after the war. If the marks show a European source I don't think the Germans had rebuilt there industry by that point. Since the Swiss and Sweden operated P-51s at this point and had the high end of maintenance practices I surmised that a possibility would be that they Zinced bare areas internally to make them last longer.
There is the possibility that sheets of this batch of Alum sat around and ended up being used who knows where and who knows when.
The aircraft served in the Dominican Republic. The airframe had been rebuilt a number of times so I can't say if any of the parts are native to the original or to any other airframe.
My original question still stands as far as what the markings on the metal mean.
Rich

I need to rule out Switzerland since 'we' scrapped the surviving P-51 fleet during the years 1958 - 1960 and only little remained to find the way to today's warbird industry. A few wings from a shooting range turned up in the U.S. during the 90's - the Swiss AF did not sell any surplused P-51's to other countries at all.

If you say that this aircraft has a FAD (Dominican) history, it most probably is of ex-Swedish origin, where this skin most probably comes from.

Cordially
Martin

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My source of a Tierney Metals catalog shows nothing that corresponds to this code 12p/3 when looking at an Intl cross reference chart for alloys.
A google search only shows 1 good hit for a surplus sale of metal in lots.
I don't read the lingo but 12p/3 is listed as is 12/2, 12/3 and 12p/2. All have the prefix of ML. It also lists some things that appear to be alloying materials that match up with 2024. Anyone know what GLODCAT or PLATERAT (Plate or plating?) mean?
www.fmv.se/upload/Bilder%20och%20dokume ... sheets.pdf
This is the Mil Surplus sale- was this sale in Sweden?
Rich

We found the same markings when rebuilt the horizontal and vertical fin to our Seversky P-35 which is actually a Swedish EP-106

Other lower skin is now off and bears the same markings. This is the lower R/H and the pics show the lower L/H side. The removed skins show good size areas of light to moderate surface corrosion. Not to bad considering the age and being left bare.
Rich

Upper skin is now removed.

I have also gotten the lower center skin off as well.

Rich

Was there anything in particular wrong with this part or did you guys just want to do an inspection?

Come on Brandon- You know my inspections, they normally go further in depth than this.
The Horizontal leading edge has several impacts from exhaust stack chunks of which a couple left cracks which were filled in with bondo. There were a couple scratches on the top and bottom wing skin which exceeded 1/3 the thickness of the .040 skin at points, creased the skin and were over a foot long. These were also filled in with bondo. The scratches are pretty much in line with the span and appear to be caused by dragging the horizontal out of a pile of parts or dragging an adjacent part out of the pile. Also the entire surface was sanded with a DA, has spots of corrosion on the external skin and has surface scuz in the trailing edge area.
Much of the rest of this P-51 showed signs of corrosion, Third World maint. and even being pieced together from different A/C. The main fuselage was 2 different A/C spliced aft of the pilot. The fus fuel tank shelf had a splice going side to side.
Based on our past history that the A/C was "Restored in the late 80s" at 1st I figured that all we would need to do is replace the fuselage. Now we are getting new spars and skin on the wings. New Engine mount. 1 rebuilt aileron. Every time I stripped the paint or looked really close at something I got a surprise. Now we want to look close as the 1st step as too many times we assumed that since the rebuild was done recently that part would be ok and it really wasn't.
Rich