This study investigates the microstructural evolution, crystallographic texture, and mechanical properties of a nickel-aluminium bronze (NAB)/410 NiMo martensitic stainless steel bimetallic structure fabricated via wire arc additive manufacturing (WAAM). The work provides a detailed assessment of the interfacial characteristics, phase transformations, and texture development across both alloys, as well as their impact on mechanical behaviour. Microstructural characterisation using optical microscopy, SEM, EBSD, and TEM revealed that the stainless steel region predominantly consists of martensite with minor fractions of δ-ferrite, α-ferrite, and retained austenite. A distinct Fe-rich interfacial layer was identified, from which columnar dendrites grow epitaxially into the NAB side. The NAB region exhibits α-phase grains with various k-phase precipitates whose distribution and morphology evolve with build height due to thermal cycling and dilution effects. Evidence of liquid metal embrittlement (LME) was observed at the interface. Texture analysis indicated a weak crystallographic texture in the stainless steel due to solid-state transformations, whereas the NAB exhibited a more textured structure, especially <101>//BD. Despite the presence of LME cracks at the interface, tensile testing consistently resulted in fracture within the NAB region, away from the interface, demonstrating effective load transfer across the interface under uniaxial tensile loading parallel to the building direction. The bimetallic structure achieved an ultimate tensile strength of 587 MPa and total elongation of ∼12%.

In-air capturing is a promising concept for recovering winged reusable launch vehicles (RLVs) using a towing aircraft (TA), without the need for any propulsion on board the RLV during descent. In this paper, the preliminary electromechanical design of an airborne device is presented, which is central to in-air capturing. The device is an autonomous system, towed by the TA, and docks with a boom attached to the nose of the RLV. A design space exploration and load analysis are performed using a simplified towing model, revealing significantly higher towing loads compared to previous estimates. The design of a probe-drogue docking mechanism is proposed, which uses a set of actuated wedges to lock the RLV boom in place. Actuator and sensor solutions are studied, aiming at a redundant and robust mechanism design. Based on reference commercial-off-the-shelf components, the size, weight, and power footprints of essential avionics are estimated, and a preliminary dimensioning of the required battery system is performed. Finally, a comprehensive, electromechanical computer-aided design model is developed, with which the overall inertial properties of the vehicle are estimated. The position of its centre of gravity is studied, revealing the need for a forward trim mass. Compared to previous design studies, the estimated total mass is increased to 175.44 kg, while the design’s overall safety factor grows to 1.51.