水上飞机浮筒外形设计的微机系统

A Microcomputer Program System for Seaplane Float Contour Design

本文介绍了一个水上飞机浮简外形设计的微机系统FCDS。浮筒外形是一张须满足流体静、动力等性能要求的复杂的三维曲面。FCDS以性能优良的库模型作为外形曲面生成的基础,使曲面的进一步设计有了一定的流体性能上的保证。系统用非均匀有理B样条来作曲线曲面的拟合和交互设计。不仅继承了普通多项式非均匀B样条重节点、重顶点等设计技巧,而且增加了形状调节的能力,同时可将二次曲线曲面统一在三次有理式中。系统提供了用穗坂卫法直接光顺空间曲线和曲面的功能,可对浮筒外形进行光顺处理,提供直接用于制造的数据。文中还对FCDS这类专业曲面CAD系统的设计构思、结构组成作了探讨。系统设计的通用性构思,使FCDS稍作修改即可用于其他飞机部件的外形设计。

This paper introduces a microcomputer program system for seaplane float contour design system——FCDS. A float contour is a complex 3-D curved surface which must satisfysome requirements about hydrostatical and hydrodynamical performances. In FCDS. a model picked from the model bank is taken as the foundation for generating a contour surface, which makes the further design of the surface have some warranties in hydrodynamics. A non-uniform rational B-spline is adopted to fit the cross designed curves and surfaces, on which not only the multiple-knot and multiple-vertex techniques based on a common polynomical non-uniform B-spline can be inherited, but also the ability of regulating shape will be increased. Besides, conies and conicoids can be integrated into a cubic ratio- nal expression. In the system. the function of fairing space curves and surfaces with the Hosaka method has been designed and the float contour can be faired so as to provide the contour data for direct application to manufacture.In this paper, it is also noted that the design conception and the structural form of CAD systems for specialized surface design such as FCDS are discussed. The universal conception of the system design makes FCDS possible be used for designing other aircraft component contours after being modified slightly.