In this paper, we present a computer-aided design (CAD) system for broadcloth composite part layout. Major applications of this system involve simulating the layout of broadcloth composites used to reinforce the structural frames in aircraft and other vehicles. We first focus on several requirements that such a CAD system must meet. The requirements include: (1) an accurate model of broadcloth composite sheets, (2) a flexible model for 3D surfaces, (3) a mapping method between 2D broadcloth space and 3D surface space, (4) a method for obtaining 2D plane developments, (5) a method for handling "darts", and (6) a method for predicting and preventing anomalies, such as wrinkles and breaks. We then describe our solutions to each of these requirements. Finally, we present simulation examples, emphasizing how the resulting layout and the deformation of a given broadcloth composite sheet on a 3D surface is greatly affected by initial conditions. We also show an example of removing wrinkles by inserting a dart.