升力风扇垂直起降飞机属于一种特殊的固定翼飞行器，兼有直升机式的悬停状态、固定翼状态，以及特殊的过渡状态。在这三种状态下，两套升力部件（直接升力部件和气动升力部件）只共用一套动力源，使得动力源工作状态差异很大，导致各总体参数之间的匹配关系与常规固定翼飞机甚为不同。为此，基于螺旋桨动量理论推导了升力风扇垂直起降飞机全机升阻、功率特性的估算模型；并针对整个过渡过程，分析了各总体参数对过渡态功率、阻力特性的影响，进而得到各总体参数的合理匹配方法以满足减小＂富余功率＂和节省过渡阶段的燃油消耗量的设计要求，提高巡航经济性。所研究的成果能为升力风扇垂直起降飞机概念设计提供有效地指导原则。%Lift-fan VTOL aircraft is a special type of fixed wing aircraft , whose three modes are: helicopter-like hover, fixed-wing, and special transition.Among these three modes, aerodynamic lift system and direct lift system share only one engine system.The working conditions of the two lift systems differ apparently .Consequently, the relationships among conceptual parameters of lift -fan VTOL aircraft are different from those of conventional aircraft . On the basis of classical momentum theory , we established a preliminary model for analyzing characteristics of lift , drag and power.Then we assessed the impacts of the conceptual parameters exerted on characteristics of total drag and power consumed.We gave feasible methods for so selecting and weighing the conceptual parameters as to meet the requirements of reducing "surplus power"and saving more fuel during transition for cruising efficiency .The three conclusions in section 4 of the full paper, in our opinion, can provide effective guidance for the preliminary design of lift-fan VTOL aircraft.
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