Electric propulsion systems for aircraft require electric motors with high power density and high efficiency. This paper presents the design and analysis of a 300 kW slotless permanent magnet synchronous motor for electric aircraft propulsion. The machine consists of a Halbach PM-array structure and an air-cooled slotless stator with custom litz wire formed using cured, ceramic-filled resin. The proposed motor is designed considering multi-physics performance based on electromagnetic field, thermal and mechanical analysis. However, the resulting motor specifications and detailed dimensions are changed for economies of scale and ease of manufacturing by altering the magnet segment number, magnet shape and litz wire shape. The impacts of changing these parameters are addressed in this paper.