Hi Kevin,
Welcome to the Forum! You will probably find a number of threads on similar topics if you do an archive search. Let me first quote Alex Imrie's "The Fokker Triplane" on the subject:
"The choice of red stemmed from the use of reddish-brown as a camouflage colour on the wings and tails in late 1916 and early 1917, but extending this colour to the varnished plywood fuselages of Albatros fighters at tht time showed that, far from being a good camouflage colour on this component, it actually made the aircraft more easily visible at long ranges. This property was turned to good effect in the adoption of markings to enable individual pilots to be identified...The use of red was fostered by Jagdstaffel Boelcke, the unit in which Richthofen had served until he was given command of Jagdstaffel 11 on 14 January 1917, and this caused him to develop a more obvious red as his own colour..." Alex is referring to the fact that Albatros D.I D.II's, and D.III's featured reddish-brown camouflage as one of the colors on their wings, and he says that some D.Is' and D.II's had lighter reddish-brown stained plywood fuselages, which could certainly give an impression of a red aircraft in the air.
There is circumstantial evidence that Richthofen may have used red on an Albatros D.II or D.III before he left
Jasta Boelcke (but probably not the well-known D.II with the white 'stripe' around the nose which has been discussed on this forum) or at least flew a machine that was perceived as red.Certainly his machine had reddish-brown camouflage on the wings, as did the others in the Jasta. During Richthofen's 5th victory on 16 October 1916, when BE12's of No. 19 Sqn were attacked by Richthofen and others of Jasta 2, 2/Lt Baker identified what he later said was a "red doped aircraft (Nieuport type) and two 'Rolands'. This is probably a confused reference to Albatros D.II's, though the 'Nieuport type' was occasionally used to refer to the sesquiplane Albatros D.III, but this was not in service yet. However, this is circumstantial at best and will remain controversial.
What is certain is that by his 18th victory on 24 January, when he was now commanding Jasta 11, Richthofen was flying a red-painted Albatros D.III. His combat report states that the captured English crew was interrogated: "According to the English crew, my red painted plane is not unknown to them, as when being asked who had brought them down, they answered: 'Le petit rouge." This may indicate that he had been flying the D.III in this colour for awhile. When writing to Floyd Gibbons in 1926, one of the crew, Lt J E MacLennan wrote, "...a burst of machine gun fire from behind notified the attack. I looked around and perceived a red enemy machine diving away..."
By mid to late April 1917, many of the other Albatros D.IIIs in Jasta 11 had had their fuselages painted largely red (with trim in some other identifying color) so that Richthofen's machine would not be so singularly conspicuous.
Hope that helps.
Greg VanWyngarden