This paper presents a methodology for the concurrent first-stage preliminary design and ascent trajectory optimization, with application to a Vega-derived light launch vehicle. The reuse as first stage of an existing upper-stage (Zefiro 40) requires a redesign of the propellant grain geometry, in order to account for the mutated operating conditions. An optimization code based on the parallel running of several differential evolution algorithms is used to find the optimal law of the internal pressure during first-stage operation, together with the optimal thrust direction and other relevant flight parameters of the entire ascent trajectory. The payload injected into a target orbit is maximized, while meeting multiple design constraints, either involving the alone solid rocket motor or dependent on the actual flight trajectory. Numerical results for sun-synchronous orbit injection are presented.

本文提出了一种同时进行的第一阶段初步设计和上升轨迹优化的方法，并将其应用于源自Vega的轻型运载火箭。作为现有上级（Zefiro 40）的第一级的再利用，需要重新设计推进剂颗粒的几何形状，以解决变化的工况。使用基于几种微分进化算法的并行运行的优化代码来查找第一阶段操作期间内部压力的最佳规律，以及整个上升轨迹的最佳推力方向和其他相关飞行参数。射入目标轨道的有效载荷将最大化，同时满足多个设计约束，这些约束可能涉及单独的固体火箭发动机，也可能取决于实际飞行轨迹。