Supersonic aircraft turbofan

A method of operating a supersonic aircraft having a turbofan engine which provides propulsive thrust to the aircraft over a range of flight operations including relatively high thrust transonic push operation during which the aircraft transitions from subsonic to supersonic flight and relatively low thrust supersonic cruise operation, the engine having:

• an engine core comprising in flow series a compressor, a combustor and a turbine;
• a fan located upstream of the engine core;
• a supersonic intake for slowing down incoming air to subsonic velocities at an inlet to the fan formed by the intake;
• a bypass duct surrounding the engine core, wherein the fan generates a core airflow to the engine core and a bypass airflow through the bypass duct;
• a mixer for mixing an exhaust gas flow exiting the engine core and the bypass airflow exiting the bypass duct;
• and
• a thrust nozzle rearwards of the mixer for discharging the mixed flows, the thrust nozzle having a variable area throat;
• the method including:
• performing a take-off operation with the aircraft, the engine providing propulsive thrust at a high level during the take-off operation by implementing a reduced area of the variable area throat;
• and
• transitioning the aircraft after the take-off operation to a subsequent climb operation in which the area of the variable area throat is increased.