In most normal conducting accelerating structures, the cell length is tailored for the particle velocity as the beam accelerates through the structure. However, because of the cost and difficulty in fabrication, superconducting structures are grouped into families in which each family is designed for a single beam velocity and then operated over a range of beam velocities. To calculate the optimum loaded Q for a superconducting cavity family, the transit time effects of the beam though the structure must be taken into account. This note will propose an equivalent RF circuit that accounts for transit time effects directly in the circuit.