The ability to track time varying frequency and damping parameters using on-line versions of seven time domain system identification algorithms; Least Squares, Double Least Squares, Correlation Fit, Instrumental Variables, Instrumental Matrix with Delayed Observations, Extended Least Squares and Maximum Likelihood, is examined. Comparisons are made on results obtained from data generated from various simulated time varying systems, corrupted with both input and measurement noise, as a preliminary step before advancing onto real data. Only the Maximum Likelihood and Double Least Squares methods gave acceptable results on the most difficult data sets that were considered. The choice of an exponential weighting factor is crucial to the performance of the on-line methods when applied to data from time varying systems. The effect of assigning various values of the weighting factor is demonstrated. Further work is required to determine the optimum schemes for defining this parameter.

Experiments at transonic speeds have been performed on several boat-tailed afterbodies and sting combinations with a view to assessing sting corrections to the measured afterbody drag at transonic speeds. Measurements made included afterbody total drag and base pressure in the Mach number range of 0.6-1.0 and Reynolds number range of 8-9.5 x 106. Correlations of base pressure and boat-tail pressure drag for the sting diameter and flare effects have been proposed using dimensional arguments. The correlations provide quick and reliable estimates for corrections that can be applied to the measured zero-lift drag of axisymmetric bodies with either contoured or conical boat-tailing.

A general dynamic model of the hang glider is applied to the analysis of response to control. The transfer functions of the glider to the longitudinal and lateral controls are formulated and some significant results, in terms of frequency response are presented and discussed. The relevant effects of the unsteady aerodynamics on the dynamics of the system are shown and the characteristics of poor lateral control are confirmed as observed in flight.