Gravity Compensation Design Method Based on Similarity Law for Free Flight Test

Abstract

The invention provides a free flight test similarity law gravity compensation design method. The method comprises the steps that (1) according to the acceleration and initial separation speed of an aircraft during actual flight, gravitational acceleration a1 and initial separation speed v1 required by a froude number similar test are determined, and the ideal motion trajectory s1 of the aircraft under test conditions is determined; (2) a separation interference position l is determined according to the flight attack angle of the aircraft in combination with the shape of the aircraft; and (3) the motion trajectory s2 of the aircraft is determined under the test conditions, wherein the acceleration of the motion trajectory is the gravitational acceleration, and the initial separation speed of the aircraft is adjusted, so that the motion trajectory is the same as the time when the ideal motion trajectory in the step (1) reaches the separation interference position. According to the invention, the non-correspondence between model line displacement and angular displacement is reduced; the test reliability is improved; and line displacement is improved.

Description

technical field [0001] The invention relates to the parameter design of a free flight test, in particular to a design method for similarity law gravity compensation of a free flight test, which belongs to the field of aerospace engineering. Background technique [0002] The aircraft model wind tunnel test plays an important role in the initial stage of aircraft development. A major feature of the wind tunnel test is that various parameters of the real aircraft are similarly scaled, and the test is carried out on the scaled model. The data obtained from the test are reversed by the similar scale formula. All kinds of aerodynamic parameters of the real aircraft can be obtained through directional calculation. In the wind tunnel free flight model test, the size of the model is often much smaller than that of the real aircraft. In practice, it is often necessary to scale down a real missile several meters long into a test model of the size of a ballpoint pen. Although the wind ...

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Problems solved by technology

Therefore, the previous tests did not fully meet the requirements of the similarity law, resulting in a certain deviation in the displacement trajectory in the vertical direction during the separation process of the model, which has a certain impact on the prediction accuracy of the test results.

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