Primary Flight Controls

Force Feedback

The fact that flight controls don't always influence the aircraft's flight the same way or have the same feel to them during all phases of flight can have a big impact on the design of a simulator. When it comes to a commercial sim used for training, clearly you want the controls to faithfully mimic the changes in effectiveness and feel of actual controls due to different flight conditions. In a training sim you want the student pilot to learn the meanings of all those subtle cues the controls can present.

Controlling the feel of the flight controls in a simulator is called control loading. It's done with computer controlled hydraulic and/or electric actuators. Wittenstein Solutions, Inc.  is a company that manufactures such systems for professional training simulators. (If you're interesting in investigating force as a feedback element in simulations, you might also search using the term "haptic", a scientific term for having fun with computers.) Control loading in recreational simulators is often done simply with springs. When the computer manages control loading, it is referred to as force feedback.

The amount of force that potentially can be transmitted through the yoke during a real flight can overpower a pilot (at least in non-fly-by-wire aircraft). This is rare and generally the result of some sort of failure, but it is just these disastrous situations that serious training simulators address. Commercial control loading systems that faithfully reproduce the forces generated throughout all flight conditions are likely to be a bit too much of a handful (not to mention wallet-full) for the recreational market.

What you can get on the recreational market is a very tame force feedback flight control. These devices have small electric motors that supply limited forces to the player based on computer input. Springs are still used to provide a centering force. The electric motors can add various shakes, wiggles and thumps to the spring force. This allows the simulation of missiles being launched, or of the control buffeting that immediately precedes a stall. (Or in the case of a heavy with damped control linkages, the "stick shaker" that the stall warning system uses to alert the pilot of an impending stall.)

Although somewhat dated (first published in 1986), the book Flight Simulation edited by J. M. Rolfe and K. J. Staples has a short section on control loading.