The invention is a propulsion
system for a V / STOL aircraft. In detail, the invention includes a turbo-fan engine having a fan section with a variable
pitch fan, a compressor section, a
combustion section, a
turbine section, said
turbine section having a low-pressure
turbine portion coupled to and driving the fan section and a high-pressure turbine portion coupled to and driving the compressor section. The engine further having a selectable
operating point wherein a portion of the power generatable by the low-pressure turbine at a selected operating
power setting is extracted to drive the fan section. A turbine outlet duct is included for directing the turbine section exhaust gases. A first angular shaped
nozzle section is co-incident with the turbine outlet duct for directing exhaust from the fan section. A second
nozzle section mounted to the first angular shaped
nozzle section between the fan section and the compressor section. A
system is included to shift said selectable
operating point of said engine to a second
operating point at the selected
power setting increasing the power extracted by the low-pressure turbine portion of the turbine section; such that power extracted by the low-pressure turbine portion and applied to the fan section can be increased without changing the selected
power setting and the
pitch of the blades of the variable
pitch fan section can be increased to absorb the increased power.