Abstract In this paper, we propose a tandem tethered balloon scheme as a solution for increasing the operating altitudes of balloons to near-space altitudes of more than 20 km. By adding a middle balloon with a smaller volume than that of the top balloon in the middle weak wind zone, this scheme partially offsets the weight of the tether above the middle balloon, thereby greatly increasing the operating altitude of the tethered balloon. Another significant advantage of this scheme is that, when the working altitude exceeds 20 km, the opposite directions of the winds at high and low altitudes can be exploited to reduce the horizontal displacement of the top balloon, raising the safety factor and the wind-resistant capabilities of the tether. In this paper, a three-dimensional static model is established for the tandem ultra-high-altitude tethered balloon, and a static equilibrium governing equation of the tandem ultra-high-altitude tethered balloon is derived. In addition, a design method based on the principle of the tether safety factor has been proposed for the tandem tethered balloon. For the first time, a sensitivity analysis was conducted for the tether resistance coefficient, balloon resistance coefficient, and balloon lift coefficient for the design optimization and flight test stages. Finally, we analyzed the three-dimensional cross-sectional profile of the tether, the maximum tension of the tether, the length of the tether, and the variation of the angle between the ground end of the tether and the horizontal plane for a tandem tethered balloon system that remained airborne continuously for one month. This work confirms that the model is viable in complex and variable wind field environments and capable of long-duration flights.

中文翻译：

---

串联、长时程、超高空系留气球及其系统特性

摘要 在本文中，我们提出了一种串联系留气球方案，作为将气球的运行高度提高到 20 公里以上的近空高度的解决方案。该方案通过在中间弱风区增加一个体积比顶部气球体积小的中间气球，部分抵消了中间气球上方系绳的重量，从而大大增加了系绳气球的运行高度。该方案的另一个显着优点是，当工作高度超过20公里时，可以利用高低空相反的风向，减少顶气球的水平位移，提高安全系数和抗风能力。系绳的能力。在本文中，建立了串联式超高空系留气球的三维静态模型，推导出了串联式超高空系留气球的静平衡控制方程。此外，还提出了一种基于系绳安全系数原理的串联系留气球设计方法。首次对系绳阻力系数、气球阻力系数和气球升力系数进行了设计优化和试飞阶段的敏感性分析。最后，我们分析了系绳的三维横截面轮廓，系绳的最大张力，系绳的长度，以及连续悬空一个月的串联系留气球系统的系绳地面端与水平面之间角度的变化。这项工作证实了该模型在复杂多变的风场环境中是可行的，并且能够进行长时间飞行。