Abstract: A turbofan-ramjet engine is provided with optional duct burning in the turbofan mode. A core engine is provided with a first annular passage therearound for directing airflow around the inlet of the core engine. A second annular passage having a fan directs air flow into the inlet of the core engine and said first annular passage. A third annular passage extends around the first and second annular passage with the first and third annular passage each directing their flow into a common annular combustion chamber. Variable vanes are provided in the first and third annular passages to provide for blocking off the passage or acting as swirl vanes depending on mode of operation. Blocking vanes are also provided in the annular exhaust passage of the core engine. Coannular nozzles are provided with one located at the exhaust of the core engine and an outer one located aft of the common annular combustion chamber.