Estimation of Stability and Control Derivatives for a Piper Cub J-3 Remotely Piloted Vehicle

Abstract

The aerodynamic stability and control derivatives for a scaled Piper Cub J-3 remotely piloted aircraft are estimated here, principally using the Engineering Sciences Data Unit (ESDU) data items. These modern semi-empirical methods rely on the use of the aircraft's geometry and location of centre of mass to estimate the stability derivatives. The methods are a mixture of aerodynamic and aircraft stability theory with supportive experimental data. This paper describes a workflow for deriving a complete set of standard longitudinal and lateral/directional derivatives for the aircraft configuration. Work-arounds are given for issues dealing with extrapolation of data beyond empirical results and modeling equivalent straight-tapered planforms from highly elliptical wings. Static stability and dy namic derivatives are estimated and presented. The work is compared to the results from the semi-empirical method DATCOM and the vortex lattice method AVL and shows over-all agreement. Details on the construction of an average flight dynamics model are then discussed using a least squares optimising routine to generate a weighted average model.