Abstract: An improved variable cycle turbofan-ramjet engine is disclosed. The engine includes a split fan assembly, a bypass channel surrounding a core engine and a mode selector valve for selectively bypassing air around an aft fan and the core engine. In a first, single bypass mode of operation, the mode selector valve allows air to flow through both a forward fan and the aft fan, and a portion of which bypasses the core engine. In a second, double bypass mode of operation, the mode selector valve allows air from the forward fan to bypass the aft fan and a portion of the air from the forward fan to bypass the core engine. In a third, ramjet mode of operation, the mode selector vane bypasses air around the aft fan and the core engine and the core engine is shut down for ramjet operation. In the preferred embodiment, the forward fan is allowed to windmill and powers a fuel pump connected thereto for providing fuel to a ram burner of the engine for ramjet operation.