Abstract: To address issues such as aerodynamic coordination design, challenges in matching fundamental frequencies, conservative load design, and over-testing in ground experiments exposed by the traditional independent design mode of spacecraft and launch vehicles when dealing with large-scale spacecraft, an integrated spacecraft-launch vehicle collaborative design method is proposed. For joint optimization of aerodynamic configuration: by comparing and analyzing the pulsating pressure distribution of the self-escape and launch escape tower configurations, the optimal solution is determined. For collaborative dynamic characteristics design: a coupled spacecraft-launch vehicle dynamics model is established. To address the ultra-low fundamental frequency of the spacecraft (2.8Hz) and the dense elastic frequencies of the launch vehicle, a combination of structural stiffness enhancement and control system optimization method is adopted. For engineering extrapolation of external force functions during liftoff: based on jet flow simulations, external load identification, and historical flight data, an extrapolation method from noise to external forces is developed.For refined load design: a load analysis method integrating surface aerodynamic distribution, static overload, and dynamic acceleration is proposed. Dynamic response analysis is conducted based on the mechanical conditions of module interfaces, replacing the traditional centroid-equivalent overload method. The application of this method has yielded clear results. In terms of aerodynamics, the peak pulsating pressure at key locations of the launch escape tower configuration is reduced by approximately 50% compared with the self-escape configuration. In terms of dynamic characteristics, after optimization, the first and second elastic frequencies of the launch vehicle are effectively separated. The amplitude of the first three elastic frequency domains in the attitude control system is reduced by up to 4.10dB, significantly improving stability. In terms of loads and testing, the test load spectrum generated based on module interface conditions is reduced by an average of approximately 20% compared with traditional fixed-base conditions for the complete vehicle, effectively mitigating ground over-testing issues. The integrated spacecraft-launch vehicle design method proposed in this paper achieves multidisciplinary optimization across aerodynamic configuration, structural dynamics, attitude control design, and load environment, breaking through the limitations of traditional interface-segmented design. Its core value lies in providing systematic solutions for addressing ultra-low fundamental frequency compatibility and complex load prediction, while offering an effective approach for spacecraft weight reduction and reliability improvement through margin sharing and refined design.

Key words: integrated design, dynamics, load conditions, aerodynamic configuration optimization, mechanical environment