Variable cycle turbofan-ramjet engine

A variable cycle turbofan-ramjet engine comprising:

• a annular inlet duct;
• a split fan assembly including a forward fan disposed in said inlet duct and an aft fan disposed downstream from said forward fan in flow communication therewith;
• a core engine disposed downstream from said aft fan and in flow communication therewith;
• a bypass channel surrounding said aft fan and said core engine and including:
• a forward bypass duct surrounding said aft fan having an inlet in selective flow communication with said forward fan;
• an intermediate bypass duct disposed between said aft fan and said core engine in selective flow communication with said aft fan;
• and
• an aft bypass duct surrounding said core engine and in flow communication with both said forward and intermediate bypass ducts;
• an augmenter disposed downstream from both said core engine and said bypass channel in flow communication therewith;
• an exhaust nozzle disposed downstream from said augmenter and in flow communication therewith;
• a mode selector valve disposed in said forward bypass duct and operable in an open position allowing air from said forward fan to enter said forward bypass duct and in a closed position preventing air from said forward fan from entering said forward bypass duct;
• and
• control means for controlling said turbofan-ramjet engine including said mode selector valve for operating said turbofan-ramjet engine in three modes of operation including:
• a first, single bypass, mode wherein said mode selector valve is positioned in said closed position and air is channeled through said forward fan and said aft fan and then through both said intermediate bypass duct and said core engine;
• a second, double bypass, mode wherein said mode selector valve is positioned in said open position and air is channeled from said forward fan to both said forward bypass duct and said aft fan, and air from said aft fan is channeled to both said intermediate bypass duct and said core engine;
• and
• a third, ramjet, mode wherein said mode selector valve is positioned in said open position, said core engine is shut down, and said augmenter is activated.