Cool ship, nice book set, I ordered mine immediately. Thanks Bob.
Jim, typical and legal registration on civil US airplanes up until 1960 or so are small numbers on the tail and big numbers on the top right and bottom left. Once vintage airplanes were starting to become a movement in the country, the law was changed to allow 30 year old airplanes to use the old positioning instead of 12 inch profile numbers. The rules were later changed to allow any airplane 2 inch profile numbers.
Racing planes turned left usually so the racing number was positioned on the bottom of the right wing but not always. In the post war Bendix some years a 6 foot number on the bottom oriented top at leading edge was required so observers could allegedly site the numbers as they progressed past certain city checkpoints. During the 70's Mojave hosted right turning races so some airplanes reversed their number positions from one race to the other. When I raced at Reno I only had 36 inch numbers on the sides of the airplane and none on the wings. I've also helped people change their number colors, fonts and positioning during the event because the contest committee required it owing to timing and scoring not being able to read it.
Photos are the best source and luckily our rules consider both for documentation.
Chris...