The Cognition And Modeling Of Near Space Atmosphere And Unmanned Air Vehiele Flight Simulation In Variable Wind Field

Near Space is the space scope from altitude 20km to 100km. Now it is an academic concept, there is no official definition. U.S. military has been called "cross-sectional area", Chinese academics called it that the "sub-space", "ultra-high", "high altitude". For a long time, most countries'military ignored the military value of near space. However, they have begun to pay attention to it, and develop aircraft in near space in recent years.At present, near space near aircraft mainly include stratospheric airships, floating air ball and unmanned aerial vehicles (UAV). UAV is a kind of aircraft that driven by motor power, which is unmanned, reusable. UAV is always designed by aircraft method, using solar energy, hydrogen fuel cells and other new types of energy. It is structure is light, relying on air power to achieve near space. They have long-range, long voyage, and highly integrated features.Therefore, the research of near-space UAV has important military-strategic significance. It costs much lower than satellite, only one-tenth or several percent of satellites. When in a task, the UAV can selected target region according to the commander's intent to surveillance, collect intelligence. The UAV needn't to consider the security issues. In a dangerous reconnaissance missions in the region, they do not have to risk their lives, and not to send escort for protection. UAV will conduct continuing aerial reconnaissance exploration during day and night. These are the strengths over people driving strategic reconnaissance plane.This paper is the research on this hot spot in near space.First, we get some basic awareness of near space environment and establish model for atmosphere, which include various parameters for the model. Then we focus on the wind field parameters of the model. We give the change rule of wind speed and the wind speed distribution by stratification. Then we use polynomial fitting the description of the data sets to obtain the sub-expression for the wind in different height. For the speed in a particular point, we get the estimated value by the speed curve interpolation. This paper presents a simulation model of the wind field.Secondly, based on some basic assumptions, we establish 6-DOF rigid nonlinear equation of motion for the UAV in body coordinate. At the same time, in order to study the impact of wind fields for UAV, we introduce the "4-point model". Then the initial model of UAV is modified for wind field parameters.Finally, we integrated the variable wind field model and the UAV model. The flight simulation is done. Then we discuss the response flight curve which bring by wind field. In the end, we Design the optimal climb trajectory of the UAV, and give the simulation of the result.