What is the significance of the yellow stripes on the wings of WW 2 fighters in particular the P-51? I have seen them on planes from many different units.
Let's get back to the original question about "yellow stripes on the wings of WW 2 fighters, in particular the P-51". I am assuming the question is about the leading edge stripes that appeared on the wing leading edges.
I will not list the references for this information, but please understand, I have material in my library that provides the following information.
The yellow leading edges stripes were applied early in the war (WW 2) initially on the British fighters to help identify the British aircraft over Britain during the Battle of Britain so that ground gunners would not shoot down their own aircraft. As the air war progressed after D-Day, allied fighter aircraft carried yellow leading edge stripes to again help allied gunners (on the ground and in the air) identify friendly aircraft. In the case of the P-51 in its escort role with the bombers, the yellow leading edges stripes also helped the gunners on our B-17's and B-24's identify the P-51's from the German fighters, particularly in the matter where the profile of the P-51 is similar to the Messerschmidt Bf-109. Some German fighter aircraft had yellow noses, but those were not so easily confused with the yellow leading edge stripes of the allied aircraft. Later in the war (August 44), the yellow leading edge paint on RAF P-51's was removed to improve airflow over the wing.
Ty was correct in his initial response on this thread, including the comment that the Japanese used the same yellow leading edge so that their friendly gunners would not shoot them (in the air or on the ground). I do not think there were any US Naval aircraft after the beginning of WW 2 that had any yellow leading edge stripes.
Yellow was used in a number of other ways to denote various unit markings on US WW 2 aircraft of all types.
Now, for some of the other comments made in this thread, the black and white stripes were added to allied aircraft in the European theater during and after D-Day and are often referred to as "invasion stripes". These were added as chord-wide bands around the wing and bands around the rear fuselage. These stripes were to be added on June 5, 1944 but were delayed for one day. After the end of 1944, most of these stripes had been removed.
I am not sure what the comment above was regarding "yellow stripes for training aircraft". Prior to the war, British training aircraft were painted yellow. After 1938, these aircraft retained their yellow undersurfaces but were camouflaged in the usual colors on the upper surfaces and half-way down their fuselage sides. British experimental aircraft had yellow undersides and normally carried upper surface camouflage colors. British aircraft that towed targets had wide yellow and black diagonal stripes across the entire bottom of the aircraft and sometimes around the entire aircraft.
Now, everyone is probably as confused as ever. There are books written about this stuff.
Keith