FlyghtyMac

Flyghty is a rare 2D flight sim involving pre 1950 propeller planes with both civilian and military challenges.

You can design your own airplane -- wings, body, engine, colors etc.
Modifications affect flight and ground dynamics: thrust, lift, drag, weight and inertia. Civilian options include takeoffs, landings, loops, stalls, dives, wind, fog and various Equipment failures.