A Research On The Ballistic Characteristics Of Projectile Flying At High Altitude Environment

The firing range of conventional projectile is becoming further and further with the application of new and advanced technology. It was found that the experimental firing range differ fairly from the calculated firing range in the research process of ultra range projectile designed basing on the classical ballistic and aerodynamic theory. The cause of these phenomena is that the span and altitude range the rocket experienced is so large that on the one hand the traditional method used to calculate the gravity, aerodynamic forces and trojectory cause non-negligible error, on the other hand the aerodynamic forces and moments vary greatly during the flight and leading the projectile to behave different characteristics compared with the projectiles flying at low altitude. It is necessary to make a further study on the aerodynamic and ballistic characteristics for the projectile experiencing high altitude environment so that we can provide the theoretical basis for developing it.This paper is devoted to the research of the following content according to the phenomena observed in the development of ultra range rocket.(1) Referencing to the Artillery Standard Atmosphere and other available atmosphere data, the Artillery Standard Atmosphere is extended to the high altitude basing on its definition, characteristic and purpose.(2) Basing on the gravimetric theory, a new method for calculating normal gravity is proposed. Basing on this method, the various gravity calculation model introduced in ballistics is compared and their application range is analyzed. The calculation result show that the constant value gravity model with g= 9.8m/s2 is appropriate for trajectory calculation when the range is short. With the increase of the trajectory range, the sphere earth gravity model should be adopted. For ultra range trajectory, adopting normal gravity model makes for trajectory calculation precision.(3) Basing on the theory of aerodynamic and rarified aerodynamic, the variation of aerodynamic coefficient versus height and its effect on ballistics is analyzed for conventional projectile experiencing high altitude environment. The result shows that the effect of aerodynamic variation versus height on trajectory calculation should be considered while its effect on angular motion analyzation is negligible.(4) The calculation model fit for ultra range projectile is built. The calculation method for flying height and curve earth surface range is researched. The effect of different earth surface model, different gravity model and the variation of aerodynamics vesurs height on trajectory calculation are discussed. The result shows that the above mentioned factor may affect trajectory calculatin quite a little. They should be considered to improve the precision of trajectory calculation.(5) The angular motion model suitable for both low and high altitude environment is built. The nuance of angular motion model introduced in different ballistics is compared and the cause of this difference is analyzed. The effect of coefficient variation on the stability of angular motion is analyzed; the engineering stablility of projectile flying at high altitude environment is researched. With the hypothesis that the aerodynamics coefficient is linear inδ2, the square of attach angle amplitude, the nonlinear angular motion model is derived. The result shows that the nonlinear angular motion model also contain item relative to (δ2). Basing on the new derived nonlinear angular motion model, the criterion of dynamical stability is researched considering algebra and aerodynamic nonlinearity. The research results achieved are of important reference to the calculation and designation of projectile experiencing high altitude environment.