This chapter presents a dynamic model of a flexible wing as the main component of an airborne wind energy system for crosswind operations. The basic components are rigid plates that are interconnected by gimbal joints and allow for rotational degrees of freedom which mimic the basic deformations of a C-shaped kite. Realistic steering is accomplished through length-varying bridle lines that are actuated by a kite control unit. This suspended cable robot is connected to the ground by a tether model which uses linked rigid line elements and allows for reel out at a constant speed. The simulation results show that the developed model is robust and that the steering behavior of a C-shaped kite can be reproduced. The main deformation modes are captured and the model has the potential to run real-time, making it suitable for control simulation purposes.