Gas turbine engine

A gas turbine engine comprising:

• a turbomachine comprising a compressor section, a combustion section, and a turbine section arranged in serial flow order, the turbomachine defining an engine inlet to an inlet duct, a fan duct inlet to a fan duct, and a core inlet to a core duct;
• a primary fan driven by the turbomachine;
• and
• a secondary fan located downstream of the primary fan within the inlet duct,
• the gas turbine engine defining a thrust to power airflow ratio between 3.5 and 100 and a core bypass ratio between 0.1 and 10,
• wherein the thrust to power airflow ratio is a ratio of an airflow through a bypass passage over the turbomachine plus an airflow through the fan duct to an airflow through the core duct, and wherein the core bypass ratio is a ratio of the airflow through the fan duct to the airflow through the core duct,
• wherein during operation of the gas turbine engine in an operating condition, the gas turbine engine defines an advance ratio greater than 3.3 and less than 9.0 and a net efficiency of at least 0.8 and less than 1.