Computer aided design has been applied in the design of high speed VSCF power generation systems in the areas of spray-oil cooling, structural stability, and rotor integrity under over-speed conditions. The application of aluminum and magnesium in the system to achieve light-weight is also covered.Thermal analysis using a finite difference program verifies the semiconductors critical temperatures upon which the heat sinks and the spray-oil flow are optimized. Finite element programs are used for stress analyses on the rotor and the structure. Attention is focused on weight reduction and stress concentration. Fracture toughness and fatigue analyses of an advanced rotor material have been used to determine the integrity of the system in terms of safety margin and service life.