灭火飞机投水动响应特性

大型灭火飞机投水飞行时,短时间内大吨位水量的投放会引起载机的动力响应问题.为此,采用小孔出流理论进行飞机投水量的数值模拟,以静气动弹性配平结果为初始条件,考虑飞机的刚体模态和弹性模态,用最小状态拟合技术进行非定常气动力建模,分析了飞机投水飞行时的响应特性;并以投水结束后的飞行状态为初始条件,以飞行操纵产生的舵偏角为输入,分析了飞机退场爬升时的响应特性.结果显示,灭火飞机投水时,飞行姿态和载荷会发生较小变化;退场爬升时,飞行姿态和载荷会发生显著变化.分析结果为大型灭火飞机的结构设计和飞行操纵提供了参考.

Dynamic response analysis of water dropping for firefighting aircraft

A mass of water dropping for a time of large firefighting aircraft can produce dynamic response problem in flight. The variational process of water quality was deduced by applying hydromechanical simulation of fenestral outflow.Considering rigid-body modes and elastic modes, dynamic response analysis of water dropping for a firefighting aircraft was presented by applying minimum-state approximation formula of unsteady aerodynamics, in which the results of trim analysis were defined as the initial conditions. And the dynamic response characteristic of high pitch angle in exit flight was studied when the pilot input command was defined by elector deflection angle, in which the flying gesture after water dropping was the initial condition. Results show that flying gesture and loads of firefighting aircraft are slightly changed continuously, but they are changed obviously when in climbing exit flight with high angle. It provides future reference for the structural design and the pilot input command of large firefighting aircraft.