Abstract: The operation of a twin spool turbojet under windmilling condition is analyzed and the windmilling characteristics are derived.The calculation method is based on theoretical analysis and experimental data. Using characteristics of components, including the compressor, the turbine and the combustion chamber, the windmilling characteristics are obtained. In calculating the high pressure rotor, the method is the same as that of the single rotor turbojet engine. When calculating low pressure rotor,the high pressure rotor is taken as a resistant component of the low pressure rotor.An example of the application of the method is presented, which shows good. agreement between the prediction and experimental data.

Key words: twin-spool turbojet, windmilling characteristics, high/low pressure rotor matching