Before it became a popular XBox game, Crimson Skies was originally a PC game conceived and produced by FASA Interactive.
FASA was a Chicago-based game company headed by a fine fellow named Jordan Weisman, that created and produced role-playing and PC software games. I was brought in as a conceptual artist on this, as well as some later projects that would ultimately be produced for XBox and Playstation.

Crimson Skies was one of the first projects on which I worked. The developers there were putting together an 'Aircraft Manual' for the PC game, which would contain the basic rules of game play, but also technical descriptions and illustrations of all the different models of planes used in the game. Given the game's premise, scenario, and time period, these planes defied conventional design for a more 'steroid injected' look. These were aggressive dog-fighters.
I was given the copy pages describing each plane, then I was given free reign in designing them.
They would need orthographic views of each plane drawn for one page, and a 3/4 view action shot of the same plane for the other.

The view drawings were done using fine felt-tip pen, and the dramatic action shots were rendered using gray-toned Pantone markers.
With some minor back-and-forth feedback, all 26 planes took about 4 weeks to design and render for delivery.

Here are 12 of the 26 planes found in the published manual;