The Impact of Aeroelastic Effects on the Controllability of Conventional Launch Vehicles

Conference paper (2016)

Authors

E. Mooij Astrodynamics & Space Missions - Aerospace Engineering
D.I. Gransden Structural Integrity & Composites - Aerospace Engineering
Research Group
Astrodynamics & Space Missions (Aerospace Engineering) (TU Delft)
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Published Date

2016

Language

English

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Faculty

Aerospace Engineering

Department

Space Engineering

Research Group

Astrodynamics & Space Missions

Abstract

Sensor structural feedback and propellant sloshing have an adverse affect on the stability of conventional launch vehicles. Additionally, vehicle flight loads increase due to structural vibrations. However, in the conceptual design phase of a conventional launch vehicle, it is computationally expensive and undesirable to model the aeroelastic effects on its controllability, stability, and flightperformance. Therefore, this paper focusses on the assumed-modes method of analysing aeroelastic effects on a slender-bodied conventional launch vehicle.The general model consists of the structural stiffness and mass properties, discretised over the length of the launcher; flight mechanics, which are simplified to only the pitch-plane equations; and engine swivel, acting as a control (thrust and moment) actuator. The structural representation and flight dynamics are combined in a state-space model with a simple PD controller to evaluate the stability and control of the system, without attempting to optimize for performance. The response to a step-command, with and without turbulence, is examined and compared for rigid, flexible modes, and flexible modes with sloshing effects. Flexible modes and sloshing effects have a destabilising influence, which, if coupled with non-optimal feedback signals, may result in excessive flight loads.