Control systems for gas turbine engines

Claim 1

A GAS TURBINE JET PROPULSION ENGINE OF THE NON-REHEAT SINGLE SPOOL TYPE COMPRISING AN AIR INTAKE DESIGNED TO RECEIVE AN AIR FLOW AT SUPERSONIC VELOCITIES, A COMPRESSOR, A COMBUSTION SYSTEM, A TURBINE AND A JET NOZZLE DESIGNED FOR OPERATION UNDER SUPERSONIC FLIGHT CONDITIONS ARRANGED SEQUENTIALLY IN THE DIRECTION OF FLOW; MEANS FOR VARYING THE JET NOZZLE AREA; A FUEL SUPPLY TO SAID COMBUSTION SYSTEM; AN OPEN LOOP CONTROL SYSTEM COMPRISING A NOZZLE CONTROL CONNECTED TO VARY THE AREA OF SAID JET NOZZLE SO AS TO VARY THE PROPULSIVE THRUST; A CLOSED LOOP CONTROL SYSTEM SEPARATE FROM SAID OPEN LOOP CONTROL SYSTEM AND COMPRISING A FUEL CONTROL FOR VARYING SAID FUEL SUPPLY AND GOVERNING MEANS INDEPENDENT OF SAID NOZZLE CONTROL AND OPERABLE IN RESPONSE TO ENGINE ROTATIONAL SPEED TO AUTOMATICALLY ADJUST SAID FUEL CONTROL SO AS TO VARY THE FUEL SUPPLY IN A SENSE TO MAINTAIN ENGINE ROTATIONAL SPEED SUBSTANTIALLY CONSTANT OVER AT LEAST PART OF THE ENGINE OPERATING RANGE; AND MEANS OPERABLE IN RESPONSE TO COMPRESSOR INLET TEMPERATURE T1 TO IMPOSE A MINIMUM LIMIT ON THE JET NOZZLE AREA, SAID LIMIT INCREASING WITH T1 OVER SAID PART OF THE ENGINE OPERATING RANGE.