A Multibody Approach for Modelling of Rope Dynamics

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Kurzfassung

The ‘In-Air Capturing’ method is a novel approach for the recovery of space launch vehicles, where an airplane catches a winged rocket stage in mid-air and tows it back to the launch site. Since no descent propulsion system is required, the Reusable Launch Vehicle is less expensive than traditional techniques. During the In-Air Capturing maneuver, a capturing device attached to a rope is released from the towing aircraft. While the two vehicles are in close proximity to one another, this device autonomously connects the rocket to the airplane. For a successful capture, this device must move with agility and accuracy, despite the vibrations from the long rope (up to 300 m) and external disturbances. Therefore, modeling the flexible dynamics of the rope is essential to have a realistic understanding of the device’s maneuverability and the viability of the concept. Such highly flexible systems with significant deformation are difficult to model and manage and require intense computation. Driven by these requirements, we propose and examine a new multibody approach that provides a balance between accuracy and computation time. The rope can be modelled as a discretized chain of rigid bodies connected at the joints. The model also includes forces originating from the capturing device, the drag of the rope and the effect of the aircraft wake. To deal with rope features such as the bending stiffness and elongation, we adopt simplifying assumptions, with the goal to reduce the overall computational effort. Such assumptions are expected to hold, in the scenario of interest. To select rope fitting properties like material, diameter and length, we use the requirements imposed by the In-Air-Capturing application. Results show that the model provides a valid description of the underlying physics. Simulations of the In-Air-Capturing procedure demonstrate the capacity of the rope to sustain the loads associated with towing the rocket, while also allowing for large maneuverability for the capturing device. Overall, this thesis presents an accurate yet computationally efficient modelling approach for rope dynamics, with a special focus on the implications on the In-Air Capturing maneuver. This framework is also applicable to a wide range of dynamic simulations involving long, slender, flexible structures (such as air-to-air refueling).

Verfügbare Versionen dieses Eintrags

• A Multibody Approach for Modelling of Rope Dynamics. (deposited 21 Okt 2024 10:05) [Gegenwärtig angezeigt]