Ken,
He said trim tab colors and wing stripe colors differentiated squadrons.
He went further on to state that one had white trim tabs and white stripes on the wing, another had a black trim tab with black stripes on the wing. He said his squadron, the 302nd had a yellow trim tab with yellow stripes on the wing.
Yet every P-51 Tuskegee rendition that I've seen has yellow wing stripes - hence me saying "Hmmm...."
Ah, I see now your reason. I knew about the squadron sub-markings so that's why I failed to understand. I think the reason you see the predominance of yellow sub-marks is from the desire to pay respects to Archer himself. But, also a lot of it is just plain ole poor research.
The prime purpose was the same as for the color marks on the bombers, to assist fighters and bombers making correct rendezvous. One can imagine the gross confusion if two fighter units rendezvoused with the same bomber unit -- it would leave another unit unescorted. Of course, as the "stay with the bombers" order was eliminated under orders of Jimmy Doolittle, who favored the highly successful, "find them and kill them" order, the need for the markings went away and after that became a simple case of unit pride. The squadron sub-marks could be smaller since they just assisted in squadrons reforming and most of the time fighters separated stayed that way and they just flew home in two-ship or even single ship units. In a P-51, such a situation wasn't as dangerous because they could fly higher and faster than anything except the Me-262's and to a certain extent the Dora-9, though the Dora-9 was really more of an even match, which means interception is doubtful.
The more interesting background on why the Tuskegee Airmen became so beloved by the bombers crews is a direct result of the racism of the era, but in a very interesting manner. You see, General Davis knew what his men were up against, and knew their detractors would leap on bomber losses to use against them. So, for these airmen, preventing the loss of bombers was vastly more important to them than racking up fighter kills even though destroying the Luftwaffe by all means available ended up saving the bombers.
Now, if you are in the bombers, you want to see those fighters, and no one can disagree with that!
So, the fact that the Tuskegee Airmen never left the bombers was absolutely loved by the bomber crews, who regarded them as something truly special, and likely never understood the complex array of racial prejudices that were the root of why they never left! General Davis was certainly tactically wise enough to know his men could have inflicted more harm to the Luftwaffe by adopting the same loose protection rules the other fighter units eagerly adopted, and sometimes abused frankly. But, they were up against a most unfair situation and made the best calculation they could.
Ken