Speaker
Mr
Marco Pallone
(Sapienza - University of Rome)
Description
Multistage launch vehicles of reduced size, such as “Super Strypi” or “Sword”, are currently investigated for the purpose of providing launch opportunities for microsatellites. Currently, microsatellites can be launched according to the time and orbital requirements of a main payload. The limited costs of microsatellites and their capability to be produced and ready for use in short time make them particularly suitable to face an emergency (responsive space), therefore small launch vehicles dedicated to microsatellites would be very useful. On the other hand, in order to reduce the launcher size without increasing too much the launch cost per kg of payload it is necessary to simplify the launch system as much as possible, including the guidance algorithms. A simple open-loop guidance strategy is proposed in this research and applied to the Scout rocket, a micro-launcher used in the past. Aerodynamics and propulsion are modeled with high fidelity through interpolation of available data. In order to simplify the open loop guidance law employed for the first three stages, the aerodynamic angle of attack is assumed constant for each stage. Unlike the original Scout, the terminal optimal ascent path is determined for the upper stage, using a firework algorithm in conjunction with the Euler-Lagrange equations and the Pontryagin minimum principle. Firework algorithms represent a recently-introduced heuristic technique inspired by the firework explosions in the night sky. The concept that underlies this method is relatively simple: a firework explodes in the search space of the unknown parameters, with amplitude and number of sparks determined dynamically. The succeeding iteration preserves the best sparks. With regard to the problem at hand, the unknown parameters are (i) the aerodynamic angles of attack of the first three stages, (ii) the coast time interval, (iii) the initial values of the adjoint variables conjugate to the upper stage dynamics, and (iv) the thrust duration of the upper stage. The numerical results unequivocally prove that the methodology at hand is rather robust, effective, and accurate, and definitely allows evaluating the performance attainable from multistage launch vehicles with accurate aerodynamic and propulsive modeling.
| Applicant type | First author |
|---|
Primary author
Mr
Marco Pallone
(Sapienza - University of Rome)
Co-authors
Dr
Mauro Pontani
(Sapienza - University of Rome)
Prof.
Paolo Teofilatto
(Sapienza - University of Rome)
