Abstract
Unsteady aerodynamic system modeling is widely used to solve the dynamic stability problems encountering aircraft design. In this paper, single degree-of-freedom (SDF) vibration model and forced simple harmonic motion (SHM) model for dynamic derivative prediction are developed on the basis of modified Etkin model. In the light of the characteristics of SDF time domain solution, the free vibration identification methods for dynamic stability parameters are extended and applied to the time domain numerical simulation of blunted cone calibration model examples. The dynamic stability parameters by numerical identification are no more than 0.15% deviated from those by experimental simulation, confirming the correctness of SDF vibration model. The acceleration derivatives, rotary derivatives, and combination derivatives of Army-Navy Spinner Rocket are numerically identified by using unsteady N-S equation and solving different SHV patterns. Comparison with the experimental result of Army Ballistic Research Laboratories confirmed the correctness of the SHV model and dynamic derivative identification. The calculation result of forced SHM is better than that by the slender body theory of engineering approximation. SDF vibration model and SHM model for dynamic stability parameters provide a solution to the dynamic stability problem encountering aircraft design.
Highlights
In aircraft design and development, it is difficult and costly to achieve dynamic stability within the flight envelop
The analysis report on the first flight failure of X-43A points out that the specially structured aerodynamic forces of the aircraft have far greater than expected nonlinearity, and the inaccurate aerodynamic modeling is considered to be one of the critical failure aspects [9]
Single degree-of-freedom (SDF) vibration model and forced simple harmonic motion (SHM) model for dynamic derivative prediction is developed on the basis of modified Etkin model [5]
Summary
In aircraft design and development, it is difficult and costly to achieve dynamic stability within the flight envelop. In the aircraft design stage, it is hard to foresee the boundaries of dynamic operation stability and the severity level of dynamic problems, most of which are not discovered until in the flight test stage. Over the hundred years’ history of unsteady aerodynamic mathematic model, one after another, modified models targeting at the shortfalls of Bryan model have been introduced These include state space model [13] (differential equation model), indicating function model [14] (integral equation model), Etkin full-order model, and reduced-order model having gained rapid development over the past few years [15,16,17]. Single degree-of-freedom (SDF) vibration model and forced simple harmonic motion (SHM) model for dynamic derivative prediction is developed on the basis of modified Etkin model [5]. While the viscous flux vectors, FV, GV, and HV, contain terms of the heat flux and viscous forces exerted on the body and can be represented by
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