Expansion of the airflow over a wing or rotor causes adiabatic cooling, and in terrestrial aviation a localized condensation cloud can form in moist air. The cold methane-nitrogen atmosphere of Titan is, in relative terms, rather close to the condensation point and the possibility of analogous condensation on the NASA Dragonfly rotorcraft mission is examined using simple first-principles models and Computational Fluid Dynamics. It is found that nominal near-ground flight will not trigger condensation, but fog formation may be expected on rotor upper surfaces and in tip vortices in some extremes of the flight envelope, notably during high-altitude meteorological profiling flights. Evaluation of droplet re-evaporation and tip vortex decay timescales suggests, however, that obscuration of navigation sensors is not likely to occur from the vehicle body or rotor wake, even in cross-wind hover.

机翼或旋翼上气流的膨胀会导致绝热冷却，在陆地航空中，潮湿的空气中会形成局部的凝结云。相对而言，泰坦的冷甲烷-氮气气氛相当接近凝结点，并且使用简单的第一性原理模型和计算流体动力学研究了NASA蜻蜓旋翼飞行器任务类似凝结的可能性。发现名义上的近地面飞行不会触发凝结，但是在飞行包线的某些极端情况下，尤其是在高海拔气象剖面飞行中，可能会在转子的上表面和尖端涡旋中形成雾气。但是，对液滴再蒸发和尖端涡旋衰减时间尺度的评估表明，