TABLE OF CONTENTS Although Eq. (12.19) provides a model characterizing both the transient and quasi-steady stall characteristics in terms of four parameters, namely a 1, ?*, ? 1, and ? 2, as common to any exercise, estimation of these parameters requires appropriate flight maneuvers containing adequate information necessary to estimate each parameter separately. Determination of both the time constants ? 1 and ? 2 requires highly dynamic stall maneuvers.
In many cases, however, a simplified approach accounting for quasi-steady stall characteristics is adequate and recommended. For example, in the case of real-time flight simulators, the primary goal is usually to train pilots for correct recovery procedures from quasi-steady stall conditions. Elimination of an additional state equation also leads to minor reduction in overall computational burden.31 Furthermore, flight data with dynamic stall is more difficult and risky to gather, whereas quasi-steady stalls can be performed more readily. Flight data with quasi-steady stall would enable estimation of the hysteresis time constant ? 2 only. Accordingly, in the following investigation we neglect the transient effects by setting ? 1 to zero, which eliminates the need for differential equation and simplifies Eq. (12.19) to:
The three parameters a 1 (airfoil static stall characteristics), ? 2 (time constant), and ?* (break point) are completely adequate to model the stall hysteresis.
Thus, the total lift given by Eq. (12.16), which is repeated here, and considering simplified expressions for the purpose of demonstration, the...
