concurrent optimization of launcher architectures and ascent trajectories with global optimization algorithms
- Paper number
IAC-08.C1.2.1
- Author
Mr. Francesco Castellini, Politecnico di Milano, Italy
- Coauthor
Dr. Sven Erb, European Space Agency (ESA), The Netherlands
- Coauthor
Dr. Michèle Lavagna, Politecnico di Milano, Italy
- Year
2008
- Abstract
In the context of a research work conducted on multi-objective global optimization techniques, the paper presents their application to the combined optimization of launcher architectures and ascent trajectories. The applicative scenario has been developed in two steps: first, the trajectory optimization has been implemented for existing launchers with fixed design parameters, and then the high level launcher architecture has been introduced in the optimization cycle. For the trajectory design, parameterized pitch and yaw angles have been used as control variables and a guidance strategy has been introduced to narrow the optimization boundaries. The total payload mass and the sum of the normalized quadratic errors on the target orbital parameters have been used as conflicting cost functions in multi-objective optimization, and hard constraints have been imposed on dynamic pressure, axial acceleration and peak heat flux during the ascent trajectory; geographical constraints dependant on the launch site have also been included in the model. In light of the upcoming sample return missions, environmental models of other Solar System bodies have been defined, so that the functionalities of the developed software are not restricted to Earth launchers. The proposed high level launcher architecture modelling is intended to provide a tool in the early stage of new conceptual design optimization and analysis for Earth or planetary launchers. Hence, the algorithms concentrate on the number and type of the stages, the presence of solid propellant boosters and the thrust and propellant mass of stages and boosters as optimization variables. The resulting search space is extremely vast; to restrain its boundaries a first guess analytical sizing module has therefore been developed that allows a rough but fast computation of the main launcher’s design parameters, to be used as reference values for the optimization. After a detailed comparison work of various optimization techniques, the well known NSGA-II and a newly developed version of Particle Swarm Optimization method, called DG-MOPSO (Double-Grid Multi-Objective Particle Swarm Optimization), have been selected for the applicative scenario. Two test cases have been chosen, a medium size launcher ascent optimization and the design of a new launcher for a Mars Sample Return mission. The paper presents the results obtained with the two optimization algorithms that are both consistent and very promising, proving the suitability of the developed tool for the early phases of launchers design. An open point of this work is the introduction of subsystem level optimization variables and sizing equations, that will turn the module into a versatile multi-disciplinary design software.
- Abstract document
- Manuscript document
IAC-08.C1.2.1.pdf (🔒 authorized access only).
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