Abstract—A new program package, DUCAD‐C, has been developed to assist in computer‐aided design of double‐mussel deflection coils. In contrast with the very abstract model of our existing package, DUCAD‐Y, this new package, DUCAD‐C, gives an exact description of a deflection coil based on the simulation of winding this coil in the mandrels. Since the coils calculated by DUCAD‐C agree very well with the corresponding real coil, DUCAD‐C is a very powerful tool for the development of new d