Maximum control moments are limited by hang glider geometry which is dependent on the length of the pilot‘s arm. Pitch and roll control of the hang glider is an aerodynamic phenomenon and results from the pilot adjusting his position relative to the wing in order to generate out of trim aerodynamic control moments about the centre of gravity. The unique control properties of the hang glider are described in some detail. The depth of mathematical modelling employed enables the differences to be explained satisfactorily. In particular, the dynamic stability properties are very similar to those of a conventional aeroplane, but the predicted lateral directional stability margins are significantly larger. Solution of the equations of motion is illustrated and the flight dynamics of the typical hang glider are described. The mathematical aerodynamic model is then used to estimate the hang glider stability and control derivatives over the speed envelope for substitution into the linearised equations of motion. The performance of the model is shown to compare satisfactorily with measured hang glider wing data obtained in earlier full scale experiments. In particular, the modelling attempts to quantify camber and twist dependencies. The development of a comprehensive semi-empirical mathematical model of the flexible wing aerodynamics is described. The mathematical development shows that control is effected not by pilot weight shift, but by centre of gravity shift and that lateral-directional control by this means is weak, and is accompanied by significant instantaneous adverse response. By making appropriate assumptions the linearised small perturbation equations are derived for the purposes of stability and control analysis. The development of the non-linear equations of motion for the hang glider from first principles is described, including the complex geometry of control by pilot ‘weight shift’.

Collapsible hang glider