Search Results (3)

Under the European Space Agency (ESA) support, INCAS has taken the initiative to develop an Ascent and Descent Autonomous Maneuverable Platform (ADAMP) which will serve as an in-flight testing platform for reusable space technologies. This paper is focusing on activities aimed at assessing the robustness of the control system of the ADAMP in the presence of aerodynamic disturbances, with an emphasis on stability and disturbance rejection. Considering the ADAMP’s inherent aerodynamic instability, the way aerodynamic forces and moments are incorporated in the control design formulation plays a critical role in the effectiveness of the adopted control solution in the presence of wind gusts and potential interaction with sloshing modes. To showcase these phenomena, two alternative control design methodologies are employed in the paper: the baseline strategy relies on robust self-scheduled structured H-Infinity optimization, while the second approach is based on nonlinear sliding mode theory. Different structured H-Infinity controllers are designed and analyzed in the frequency domain, providing a clear understanding of the impact of the aerodynamic effects in terms of stability margin degradation. These controllers are then thoroughly compared with the sliding mode alternative via nonlinear worst-case simulation of typical ascent and descent flights in the presence of strong wind gusts. Full article

The development of modern reusable launchers, such as the Themis project with its LOX/LCH4 Prometheus engine, CALLISTO—a reusable VTVL-launcher first-stage demonstrator with a LOX/LH2 RSR2 engine, and SpaceX’s Falcon 9 with its Merlin 1D engine, underscores the need for advanced control algorithms to ensure reliable engine operation. The multi-restart capability of these engines imposes additional requirements for throttling, necessitating an extended controller-validity domain to safely achieve low thrust levels across various operating regimes. This capability also increases the risk of component failure, especially as engine parameters evolve with mission profiles. To address this, our study evaluates the dynamic reliability of reusable rocket engines (RREs) and their subcomponents under different failure modes using multi-physics system-level modelling and simulation, with a particular focus on turbopump components. Transient condition modelling and performance analysis, conducted using EcosimPro-ESPSS software (version 6.4.34), revealed that turbopump components maintain high reliability under nominal conditions, with turbine blades demonstrating significant fatigue life even under varying thermal and mechanical loads. Additionally, the proposed predictive model estimates the remaining useful life of critical components, offering valuable insights for improving the longevity and reliability of turbopumps in reusable rocket engines. This study employs deterministic, thermally dependent structural simulations, with key control objectives including end-state tracking of combustion chamber pressure and mixture ratios and the verification of operational constraints, exemplified by the LUMEN demonstrator engine and the LE-5B-2 engine class. Full article

Vertical takeoff and vertical landing (VTVL) vehicles, based on throttling liquid rocket engines, are attracting increasing attention for their validation of guidance and control techniques during landing. However, validation requires the vehicle to fly in a special trajectory with multiple constraints. Propellant consumption should be carefully calculated for the purpose of carrying more experimental devices during the flight, which makes conducting minimum-propellant trajectory optimization a necessity. This study focuses on the optimization of VTVL vehicles based on a throttling liquid rocket engine. Three flight scenarios applicable to this vehicle are proposed, namely, VTVL vehicles without horizontal movement, VTVL vehicles with horizontal movement, and vertical takeoff and autonomous landing with horizontal movement. Trajectory optimization using the Gauss pseudospectral method (GPM) was conducted during the abovementioned flight scenarios. The results show that the GPM provides excellent solutions for trajectory optimization in the different scenarios. In VTVL vehicles with horizontal movement, vertical takeoff, and autonomous landing with horizontal movement scenarios, the thrust appears in a similar bang–bang control. Meanwhile, in VTVL vehicles without a horizontal movement scenario, the thrust appears like a segmented bang–bang control, which we call regulative bang–bang control. Moreover, by introducing the thrust derivative into the optimization objective using a weighted method, thrust fluctuation can be restrained. To ensure the compatibility of switching the flight among the three scenarios, the carried propellant mass should be decided based on the third flight scenario. Full article