The Extensive Use of Splines at Boeing

Splines are used extensively at Boeing and throughout much of the industrial world. There are very few remaining areas in either manufacturing or engineering in which these interesting functions have yet to play a role, and their use continues to grow at a rapid rate. A spline, for the purposes of this article, is defined as any function made up of one or more polynomial pieces joined together to satisfy given (and possibly different) differentiability requirements. At Boeing, these functions are used not only to represent geometric designs, by modeling curves and surfaces that describe the edges and faces of geometric solids, but also to model engineering analysis and performance data. As an example of the latter, splines can be used to model airplane drag as a function of mach number, the speed of the airplane with respect to the free stream airflow.