preliminary design phase meaning in English

初步设计阶段
初期设计阶段

The aircraft conceptual design is a whole design process . it proceeds from conceptual design phase to preliminary design phase with the purpose of offering a optimal aircraft project
飞机总体设计是指从概念设计到初步设计阶段，进行飞机总体方案设计的全过程，其最终的目标是给定最优的飞机总体方案。
That means data and graph are divided completely . author noticed that these days , many researches about the design of midship section are focused on the scantling of the component in the preliminary design phase
本人注意到现今国内外对船舯结构设计的研究多集中在初步设计上，即定出舯剖面的框架；而在局部设计中却鲜有作为。