August 02, 2005

Computers Between Driver and Vehicle

In this GameSpot review of the Falcon 4.0: Allied Force computer game, they mentioned a fascinating quirk about the F-16 jet fighter:
A great example is the F-16's tendency to enter a "deep stall" when a ham-fisted pilot pushes the plane well beyond its flight envelope. The F-16 was the first fly-by-wire plane ever manufactured in great quantities, and it relies on constant computer assistance to overcome the inherent aerodynamic instability that gives it such a tremendous edge in terms of maneuverability. Even in straight and level flight, with no input from the pilot whatsoever, the control surfaces of the aircraft make constant, tiny motions to keep the plane flying in a straight line (with everything controlled by the computer).
 
Because the computer is always looking over the pilot's shoulder during maneuvers it makes the F-16 incredibly forgiving to fly. But the downside to this is that it's easy for beginners to get into a situation where their speed is so low that the plane becomes uncontrollable. It doesn't simply stall like most other planes would, quickly dropping their noses and picking up enough speed to give the control surfaces some bite. Instead it enters a "deep stall" where the plane falls like a leaf and the nose gradually pitches up and down as the computer vainly tries to find some angle that will end the stall. This happens in real F-16s, and the only way to get out of it is to manually override the computer, push the stick back and forth in time with the natural motions of the nose, and gradually rock your way out of the stall.
Fighter jets are not the only place where we put technology between the driver and the vehicle. Automatic transmissions started the process decades ago. Anti-lock brakes and stability control systems extend the process today. In some high end cars with extensive stability control systems, the programmers can have as much effect on the "feel" of a car as the people who tune the mechanics of the suspension.
Posted by georgegmacdonald at August 2, 2005 09:16 PM