Your going to have to trust me on this. The a/c speeds are for a/c at 15000. The Brits did extensive testing of their own and captured a/c before and after the war. There used to be a marvelous monthly publication called Aircraft in Profile. For each WW1 a/c they did, they gave the specs for the tests when they knew them. The relative speeds of the a/c are against each other at the altitude of 15000 ft. since that was the most common, other than 1000m.

The a/c in the game are the most popular and the oddities, such as the D-XII that I could find that kind of information on.

Another consideration was finding interesting color schemes for the a/c in the game. Every a/c in the game is a bit of art of a real a/c. Rich told me he really enjoyed doing them, but he felt he spent to much time on researching the ones he put in.

If you want to know how to determine the hits, here's how it was done,

Wings- 1 box for every 10 square feet of wing
Fuselage-1 box for every foot of length
Tail. small-4 boxes (Dr-I, Nieuport)
large-6 boxes (Albatros, etc.)
Engine- Rotary-6
Inline-8
Fuel. 12 1/2 boxes per half hour of endurance. This is the limiting factor in dogfights and is a design feature intended to limit the number of turns. It rather handily creates an unknown number of turns in the game, forces you to use more than one speed, and plan a bit. And all without much complication.