Turbulence and Gust Models

The aircraft flies in an atmosphere where its responses are affected by atmos­pheric disturbances (Appendix A) and these create additional forces on the aircraft. These disturbances are (1) gust, (2) turbulence, (3) wind shear, and (4) cross wind. The turbulence is a random phenomenon (Example 6.3). The other effects are represented by suitable deterministic models, which are usually obtained from experimental data.

6.2.12 Sensor Modeling

Sensors are used to derive the measurements of the aircraft’s positions, angular rates, accelerations, and other information of importance for monitoring the flight performance as well as for the use of sensed variables in the computation of control laws. Rate and acceleration sensors can be modeled as first-order lag. The vanes used for deriving the measurement of flow angles can be modeled as second-order TF. Flow angles can also be determined from the pressure probes that measure local and impact pressures. The computation of the flow angles from these data involves a computational delay. A first-order lag model can be used for the flow angle simulation.