Abstract: Traditional reusable rocket landing relies on a vertical landing method. It requires a precise vertical attitude and both velocity and angular velocity close to zero. In contrast, tethered reusable rocket approaches offer improved stability by employing upper suspension, which tolerates a larger range of lateral velocity and attitude control deviations and experiences lower overloads. It requires the recovery hook to deploy rapidly just prior to landing to ensure the stability. What’s more, it’s required to provide substantial damping after capture to mitigate impact. To address this challenge, a novel dual-stage hydraulic damper is presented, incorporating a non-symmetric variable damping valve. This damper is designed to provide low damping during hook deployment, enabling rapid extension. Moreover, the damper provides high damping during retraction, implementing impact buffering and ensuring reliable tether capture without unhooking. A model of the proposed non-symmetric variable orifice dual-stage hydraulic extension damper rod has been developed and validated through both simulation and experimentation. The model accurately predicts the damper’s non-symmetric damping characteristics and the pressure impact during retraction. Finally, integrated simulations were conducted to evaluate the damper’s performance under realistic landing and tether capture conditions. Analyze the influence of different damping parameters on the tether capture process. The results demonstrate that the proposed damper achieves effective non-symmetric variable damping, ensuring reliable tether capture. These findings provide a theoretical foundation and technical support for the design and optimization of damper rods in tethered reusable rocket applications.

Key words: cable-type rocket recovery, two-stage telescopic hydraulic damper, asymmetric variable damping, pressure shock