Geared counterrotating turbine/fan propulsion system

An axial flow fan jet engine comprising:

• at least one set of fan blades for providing by-pass air and thrust;
• a core portion for generating hot combustion gases, the core portion including a high pressure compressor for providing compressed air, a combustor for combusting the compressed air with fuel to produce the combustion gases, and a turbine for driving the high pressure compressor;
• counterrotating turbine means mounted rearwardly of the engine core portion and disposed to be driven by the hot combustion gases exiting said engine core portion, said counterrotating turbine means including at least one set of first turbine blades configured and mounted to rotate in one angular direction relative to the engine axis, and at least one set of second turbine blades positioned axially adjacent said first blade set and configured and mounted to rotate in the opposite angular direction;
• high speed shaft means operatively connected to said counterrotating turbine means and extending axially to a position forward of the engine core portion, said high speed shaft means including at least two counterrotating shaft members each connected to be driven by a respective one of said first blade set and said second blade set;
• and
• reduction gear means positioned forwardly of the core engine portion and operatively connected to be driven by both of said two shaft members, said reduction gear means including output means operatively connected to drive said fan blades at a rotational speed less than the rotational speed of either of said two shaft members;
• wherein said reduction gear means includes a pair of cooperating planetary gear assemblies, each of said assemblies having a rotatable sun gear, a ring gear, and set of planetary gears disposed between the the respective ring gear and sun gear, each of said sun gears being operatively connected to be driven by a respective one of said two shaft members.