Flight control using pin-protuberances for blunted cones

Abstract

AbstractThis paper presents the concept of using cylindrical pins as short protuberances for trajectory control of a blunted cone in the supersonic and hypersonic regimes. Supersonic and hypersonic flow interactions for cylindrical protuberances, installed on a blunt cone are studied for their aerodynamic effects. The utility of these protuberances for aerodynamic control and trajectory shaping of a re-entry cone are explored. Static aerodynamic coefficients in the Mach range of 2–9·7 at various incidences are computed. The pressure distribution along the vehicle longitudinal axis in the presence of the pin-protuberance is studied using CFD analysis. With the altered pressure distribution, a net increase in the aerodynamic force is obtained which can be actively utilised for flight control and maneuvering of the vehicle during re-entry. After quantifying the aerodynamic effects of the protuberance, it is modelled and used as an effective actuation mechanism for flight feedback control. It is shown that this can work as an effective control device for Mach numbers less than five. An actuator design for insertion/retraction of the protuberance is presented and modelled, and a robust controller is synthesised which can in real time govern the position of the protuberance to control the flight attitude angle to achieve a desired trajectory. The controller takes in measurements of the vehicle’s pitch angle and actuates the pin height continuously to control the pitch angle to a desired value. The control performance is demonstrated on a high fidelity six degrees-of-freedom (6-DOF) nonlinear flight simulation.