Rapid response attitude control logic for shaft-driven lift fan STOVL engine
AssigneeUnited Technologies Corporation
InventorsRichard A. Freese, Julio Perez
Life of this patent
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Abstract
A short take-off and vertical landing (“STOVL”) aircraft has a conventional gas turbine engine that is selectively mechanically connected to a vertically-oriented lift fan by a drive shaft when the aircraft operates in a vertical flight mode. An engine control provides for rapid response attitude control of the aircraft when the pilot initiates desired changes in the attitude (i.e., pitch, roll and/or yaw) of the aircraft. The control achieves the rapid response by varying both the inlet guide vanes of the lift fan and the area of the engine nozzle. These variations result in a substantially constant low rotor speed, which facilitates the desired rapid attitude response and corresponding aircraft control.
Claims20
A control system for a gas turbine engine disposed on an aircraft, the aircraft also having a lift fan, the engine being coupled to the lift fan during operation of the aircraft in a vertical mode of flight, the engine having a compressor and a turbine connected together in a rotatable spool, the engine having an exhaust nozzle with an opening that is controllable to thereby control an amount of thrust produced by the engine, the lift fan having airflow passing therethrough in a controlled manner, the lift fan also having a plurality of variable vanes that are controllable to control the airflow passing through the lift fan to thereby control an amount of thrust produced by the lift fan, the control system comprising:
- means for sensing a parameter indicative of a corresponding operating condition of the engine and for providing a sensed engine signal indicative thereof;
- means for sensing a parameter indicative of a corresponding operating condition of the lift fan and for providing a sensed lift fan signal indicative thereof;
- means, responsive to a desired change in attitude of the aircraft operating in a vertical mode of flight, for providing at least one commanded attitude signal indicative of the desired change in the attitude of the aircraft;
- and
- signal processing means, responsive to the sensed engine signal and to the sensed lift fan signal and to the commanded attitude signal, for controlling the opening of the exhaust nozzle and for controlling the amount of airflow passing through the lift fan, wherein the opening of the exhaust nozzle and the amount of airflow passing through the lift fan are both in an amount to keep substantially constant a speed of the rotatable spool, wherein by keeping substantially constant the speed of the rotatable spool the control system provides for relatively rapid response of the aircraft to the desired change in the attitude of the aircraft.
A control system for an aircraft operable in a vertical mode of flight and having a gas turbine engine and a lift fan, the engine being coupled to the lift fan during the vertical mode of flight, the engine having an exhaust nozzle with an opening that is controllable to thereby control an amount of thrust provided by the engine, the engine also having a compressor and a turbine connected together in a spool, the lift fan having airflow passing therethrough in a controlled manner to thereby control an amount of thrust provided by the lift fan, the control system comprising:
- first processing means, responsive to a signal indicative of an engine operating parameter and responsive to a signal indicative of a lift fan operating parameter and responsive to a signal indicative of a commanded thrust output of the engine, for controlling an amount of opening of the exhaust nozzle;
- and
- second processing means, responsive to a signal indicative of an engine operating parameter and responsive to a signal indicative of a lift fan operating parameter and responsive to a signal indicative of a commanded thrust output of the engine, for controlling the amount of airflow passing through the lift fan;
- wherein the amount of opening of the exhaust nozzle and the amount of airflow passing through the lift fan are both in an amount to keep substantially constant a speed of the compressor and turbine spool;
- wherein by keeping substantially constant the speed of the compressor and turbine spool the control system provides or relatively rapid response of the aircraft to a commanded attitude of the aircraft.
An attitude control system for an aircraft selectively operable in both horizontal and vertical modes of flight, the aircraft having a gas turbine engine and a lift fan disposed within the aircraft in a predetermined physical relationship, the engine being coupled to the lift fan during a vertical mode of flight, the engine having an exhaust nozzle with an opening that is controllable in a variable amount to thereby control an amount of thrust provided by the engine, the engine also having a compressor and a turbine connected together in a rotatable spool, the lift fan having airflow passing therethrough in a controlled manner to thereby control an amount of thrust provided by the lift fan, the control system comprising:
- first processing means, responsive to a signal indicative of a commanded attitude of the aircraft, for controlling the amount of thrust provided by the engine by controlling the amount of the variable opening of the exhaust nozzle, wherein the amount of the variable opening of the exhaust nozzle is in an amount to keep substantially constant a speed of the compressor and turbine spool;
- and
- second processing means, responsive to a signal indicative of a commanded attitude of the aircraft, for controlling the amount of thrust provided by the lift fan by controlling the a mount of airflow passing through the lift fan, wherein the amount of airflow passing through the lift fan is in an amount to keep substantially constant a speed of the compressor and turbine spool.
Dependencies are inferred from the claim text.