Size of US insignia?

[AlexM]

Hi there,

 

having received my Silhouette Portrait 2 cutter yesterday, I can now make paint masks for my projects. For the Marauder, I have a question about the size of the US insignias, which I hope the experts out there can easiyl answer. I am aware that the bars and the circle are in a certain proportion to each other. However, in my reference book, two sizes are given for the markings.If the insignia size is for example described as 44in/40in like on the picture below, how large is the insignia then? Do the two sizes refer to the diameter of the outer blue circle respectively the inner white star?

 

 

Cheers

Alex

[D Bellis]

You'll have to do some math, but this is how they were laid out:

 

HTH,

D

[AlexM]

Allright, thanks. Once the radius is given, the rest is just a matter of math. Maybe I don't get it but I still wonder how to interprete the size indications in the picture (44in/40in). Is the radius in the picture 44in or 40 in? Or do the numbers refer to something else?. If the 40in stand for the star-radius, the radius of the outer circle should be 45in (9/8th of 40in)

 

 

Edited February 1, 2020 by AlexM

[AlexM]

On the fuselage diagram in the book, the size of the insignia is described as 33in/30in

[D Bellis]

The size given as 44" or 40" refers to the outside diameter of the blue circle. 

 

To determine the star's radius (marked "RAD" on that drawing), you must divide the outside diameter by 2, then subtract 1/8th of that number. That will give you the "RAD" number by which all of the sizes are determined.

 

HTH,

D

[Juggernut]

The size difference we’re taking about is 1/8-inch.  That’s 1/16-inch on either side of the circle (or added to the radius if you prefer).  If you can’t find confirmation any place, i wouldn’t worry too much about it.  In the end, it will not be that noticeable to anyone but you...and you have a 50/50 chance of being correct.

[D Bellis]

It appears that Jennings is correct.

 

Here is the diagram cropped from the P-51D factory blueprint referring to the size being based upon the star: 

 

HTH,

D

[D Bellis]

Without knowing the context of what his reference is calling "44in/40in", it is impossible to know what they mean by that. It could be that they are calling out 44" for the overall diameter of the blue field on the Star & Bars insignia and 40" for the earlier blue circle/star insignia. Who knows...

 

D

[AlexM]

Thanks all. The diagram is from this book, which also contains own information about the size of the earlier type1 and 2 insignias.

 

I have just drawn the insignia in the 3d-software, and placed it over the wing. I wasn't aware until now that the bars aren't totally in the middle but slightly higher to be in line with the horricontal lines of the white star. Learned something new

It seems that the numbers mentioned in the book don't describe the radius, but rather the diameter, as otherwise the insignias would be way to big (including the bars about 14cm wide in 1/32...).

For comparison, I made a "44in" and "40in" version refering to the diameter of the white star (or propably more correctly said: 22in and 20in refering to the radius). When looking at photos of the real aircraft, I somehow find the bigger version more appropriate:

 

[sluggo]

On 2/1/2020 at 1:05 PM, D Bellis said:

 

This is obviously a production compromise to simplify the painting process at this particular factory.

The drawing calls for a 2 inch constant border around the insignia.

The proper border widths (using the ratio from spec) for 30 and 35 inch insignia would be 1.875 and 2.1875 respectively. So, on the 30 inch you are looking at a 1/8 inch deviation from spec and on a 35 inch 3/16ths. You could easily get away with this deviation because it would go unnoticed without measurement, probably even at scale. That said, it does not make the above formula correct. I'd also venture to guess it is where the 40/44 interpretation come from.

 

I will add that I never noticed how many decals were "off" until I started laying properly dimensioned drawings over scanned decals. Now that I'm looking at the above drawing and thinking about it from a production standpoint, I would not doubt if this was common practice in other facilities as well. That said, I'm still hardcore "If it ain't true to spec, it ain't right".

 

 

5 hours ago, Jennings Heilig said:

 

That’s because the B-26 used a 40” diameter star, which means the bigger one is correct, which is what I’ve been saying all along.  Every *single* official reference I’ve ever seen has referred to the diameter of the circle, not the radius.  A 15” insignia is 15” in diameter.  Otherwise somebody would have put a 30” insignia on the side of a camouflaged F-4C.

 

Along with the above, I agree with everything else Jennings has posted in this thread. The "diameter" always refers ti the inner diameter or circle the star fits into if you will, and is always a multiple of 5. The radius (of the inner circle) is simply used to calculate the other elements of the insignia.

 

I think confusion about the ratio (particularly the bar placement) is rooted in the fact that a star is asymmetrical. You can see what I mean in the images below.

 

Below we have a star in a 4 inch diameter (2 in radius) circle. The circle has a height and width of 4 inches, making symmetric. The star on the other hand is 3.808 in wide by 3.6216 high, making it asymmetric. The star and the circle below are "eyeball" centered. The blue cross-hairs represent the circle's center.

Below you can see the star's true center compared to the circle's center.

And here is what you get when you align centers. This is why the bars align relative to the star instead of the circle.

Here is a finished 4 inch insignia produced using the ratio spec. The highlighted area being the 4 inch diameter, 2 inch radius starting point.

 

 

 

Full dimension: 8.308" wide by 4.5" inch high. Why the oddball width? Because the star has an oddball width. I'm guilty of eyeballing the star's size, it probably should have came in around 3.8"

Edited February 2, 2020 by sluggo