Control Loading and Sound Simulation

resistance to its movement. This resistance is ‘‘felt’’ by the pilot on the stick, if it is a reversible system. Thus, the pilot gets the feel of the forces acting on the control surfaces when these are moved. This should be simulated in the flight simulator to enhance its fidelity. This aspect is achieved by the control loading system (CLS), which produces the feel forces on the simulator flying controls [1]. To achieve the correct control feel, it would be necessary to utilize a good math model of the system. This math model can be formulated from the aircraft manufacturer’s control data. The information on wiring diagrams, mechanical gearing, graphical representation of forces, and control surface deflection would be used. The models are derived from the analysis of these data with associated features. The numerical values of position limits, inertias, control surface gearings, and autopilot drive rates are included in the model. In most cases, the second-order models are used to represent both the ends of the control arms. Aircraft surface actuator is modeled using a first-order TF. The pilot’s applied force is obtained from the load cell data and the autopilot drive is synthesized in the host computer. The minimum interaction rate required for the computer is 500 KHz so that the simulated feel is properly integrated with the pilot’s senses.

If required, sound simulation should be incorporated in the flight simulator. The current trend is the use of DSP and a totally digital sound system can be integrated with the other systems. Often the actual sound recording is done from the aircraft (engine/propulsion systems) and the sound is synthesized using filtering algorithms and DSP.