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A combined analytical and test program has been performed to develop a method of designing high-speed power turbine rotors to (1) minimize rotor- induced dynamic loads under normal operating conditions, (2) minimize rotor tip- to-shroud clearance to maintain high flow-path efficiency, and (3) minimize rotor deflections due to sudden abusive imbalance loads associated with blade loss. A design/prediction system was established for both synchronous and nonsynchronous rotor whirl and the best compromise design for a rotor subjected to these excitations. Two mathematical models were developed in the course of the program. First, a squeeze film damper model and subsequent computer program were developed to quantify the effects of end-seal leakage and inlet feedback on damper performance. Secondly, a spline coupling friction mathematical model and computer program were developed to predict the destabilizing forces which excite rotor nonsynchronous whirl. To verify the accuracy of the analytical models developed in the program and other existing rotor dynamic models, a comprehensive test program was run. This program included: (1) a high speed film damper test rig, (2) bearing flexible support testing, (3) a synchronous response rotor rig, and (4) a nonsynchronous response rotor rig. Using the results of the analytical models and experimental tests, a method of design optimization was developed to obtain the best trade-off between all the rotor design variables considered in this program. (Author)