Conceptual and preliminary aircraft design codes have different geometry requirements. Conceptual design codes use component based models, while preliminary design codes require a more complete and integrated geometry. An automatic procedure to convert between the two types of models would prevent geometry inconsistencies and speed up the design process. This thesis describes some of the concepts and algorithms necessary to develop such a procedure. Specifically, the theory and development of C2 continuous fillets between aircraft components is discussed. B-spline surface generation from conceptual geometry data and the relimiting of e surfaces is also presented. / Master of Science