The Aerodynamics and Stability Analysis of a Vertical Tailless Aircraft with Rotary Horizontal Tail

Abstract

In this thesis, we explore the aerodynamic merits of replacing the vertical tail of the conventional aircraft with a rotary horizontal tail and identify the potential instability within the dynamics. The rigid body dynamics of a conventional aircraft and its vertical tailless version have been modeled for stability and control analysis. The nonlinear dynamics is linearized at trimmed flight conditions. For the conventional model, its spiral mode is unstable. For the vertical tailless model, its spiral mode and Dutch roll mode are unstable. A linear quadratic regulator is designed to resolve the instability. The aerodynamic data have been collected via software and wind tunnel to find the drag coefficient reduction. To ensure that we are comparing apples to apples, we have created three different flight scenarios where the force and moment coefficients of the conventional and vertical tailless aircraft are matched to the greatest extend. Results have shown that the total drag coefficient of the vertical tailless model is reduced by an average of 3.18% comparing to its conventional version during steady flight, 3.25% for steady level turn, and 10.4% for selected control surface deflection angles.