The development of a parametric method of measuring fin fatigue loads based on flight measurements on a lightning MK T5

Abstract

The Report discusses briefly the philosophy of parametric methods of load measurement in which load is not measured directly, but is deduced from a statistical correlation with an appropriate combination of aircraft motion variables and control surface angles. It describes a full-scale flight experiment on a Lightning Mk T5 aimed at developing a parametric method for the measurement of fin fatigue loads under operational conditions. An empirical relationship is established between the fin root bending moment, as determined from a multi-strain gauge installation, and a combination of parameters. The parameters from which the combination is selected include translational and rotational accelerations, rates of rotation, rudder angle and angle of sideslip. The study covers the measurement of fin loads under a wide range of loading conditions.