IXV Re-entry Guidance, Control & DRS Triggering: Algorithm Design and Assessment

Abstract

The Intermediate eXperimental Vehicle (IXV) re-entry GNC is tasked with stabilising and manoeuvring the IXV from the Entry Interface Point (EIP, 120 km altitude) suborbital trajectory conditions to the deployment of a 3 stage (supersonic drogue, subsonic drogue and a main parachute) parachute system. The re-entry GNC is comprised of the Guidance, Navigation and Control functions, which are scheduled via a Flight Management function that interfaces the GNC with the vehicle’s mode vehicle management (MVM). Within reentry GNC responsibilities there is also the design and validation of the Descent and Recovery System (DRS) triggering algorithm, which autonomously triggers the extraction of the supersonic parachute. The IXV is a lifting body with a lift-to-drag ratio of 0.7 in the hypersonic regime and, distinct from other re-entry vehicles such as ARD and Orion, is actuated through the combination of two body flaps mounted at the aft windward side of the vehicle and RCS thrusters. The challenges for the IXV re-entry GNC system design are common to those for re-entry vehicles performing a first flight, with the re-entry GNC required to be robust to high levels of uncertainty in the vehicle dynamics. This paper describes the IXV re-entry G&C and DRS triggering algorithms at the current IXV programme status of Phase D, including the assessment of the re-entry GNC performance using the IXV functional engineering simulation developed for the IXV programme.