[Dan_San_Abbott]

Langdon:
my reference to the rudder was if the engine exhaust produced "soot" that would adhere the the fuselage and darken the vermillion to a dark red approaching maroon, then the white on the rudder would have been darken to a mid grey. It was not, How did the "soot" get on the upper surface of the top wing? it can't. Finally after a rotary engine airplane shuts down, it is not covered with exhaust soot, it is covered with castor oil or in the case of the Germans, it covered with Voltol. You clean uo the bottom and sides of the of the fuselage and inner part of the lower wings and stabilizer and the exhaust residue is gone. You won't find it on the upper wing cross fields. The vermillion was darken with carbon black, and poorly mixed, with some particle in suspension sitting on the surface like lumps of coal when viewed with a microscope.
Blue skies,
Dan-San