High Speed PM Motors are popularly used in Spacecraft flywheel application. So, this paper proposes two different designs: one for classical sizing and the other for genetic one at 50 kW output power with 250 m/s tip speed. These two design trials of High Speed Permanent Magnet Synchronous Motors (HSPMSMs) are simulated with MATLAB, and Genetic Algorithm Toolbox. Then, the two design examples comparisons are introduced in analytical forms with study of machines waveforms, Total Harmonic Distortion (THD) and rotor losses. Finally, the effect of poles number on some sizing parameters and motor characteristics are illustrated in the form of charts with the waveforms. This is done at constant number of slots and phases with number of poles are 4, 6, and 12 at 50 kW output power and tip speeds of 250, 200, 150, and 100m/s