System and method for controlling engine RPM of a ducted fan aircraft
View Patent ↗An aircraft including a ducted fan and an engine for driving the ducted fan includes a plurality of vanes movably mounted to the aircraft at a substantially rectangular exhaust end of the aircraft. Each of the plurality of vanes is substantially rectangular or square. The plurality of vanes are configured to alter an exit area of the exhaust end. The aircraft includes a sensor circuit for detecting a RPM of the engine and for outputting a RPM signal. The aircraft includes a control circuit coupled to the sensor circuit and the plurality of vanes. The control circuit is configured to actuate the plurality of vanes to alter the exit area of the exhaust end to vary a pressure load on the ducted fan to control the RPM of the engine in response to the RPM signal.
1. An aircraft including a ducted fan and an engine for driving the ducted fan, comprising:
a plurality of vanes movably mounted to the aircraft at a substantially rectangular exhaust end of the aircraft,
wherein each of the plurality of vanes is substantially rectangular, and
wherein the plurality of vanes are configured to alter an exit area of the exhaust end;
a sensor circuit configured to detect a RPM of the engine and to output a RPM signal;
a control circuit coupled to the sensor circuit and the plurality of vanes,
wherein the control circuit is configured to actuate the plurality of vanes to alter the exit area of the exhaust end to vary a pressure load on the ducted fan to control the RPM of the engine in response to the RPM signal; and
a first servo mechanism configured to balance pressure loads on the plurality of vanes, wherein
the first servo mechanism comprises a high force, low speed servo;
a second servo mechanism configured to actuate the plurality of vanes, wherein
the second servo mechanism comprises a low force, high speed servo; and
a linkage configured to couple the first and second servo mechanisms to the plurality of vanes.
2. The aircraft of claim 1 , wherein the control circuit is configured to control the RPM of the engine to maintain a maximum power of the engine for full-throttle flight.
3. The aircraft of claim 1 , wherein the control circuit is configured to control the RPM of the engine to maintain the RPM within a substantially narrow range of values.
4. The aircraft of claim 1 , wherein the control circuit is configured to control the RPM of the engine to operate the ducted fan at a substantially optimal forward-speed-to-tip-speed ratio of the ducted fan.
5. The aircraft of claim 1 , comprising:
a plurality of control surfaces movably mounted on an interior of the aircraft fore of the plurality of vanes mounted to the aircraft at a substantially rectangular exhaust end of the aircraft.
6. The aircraft of claim 5 , comprising:
at least two additional control surfaces movably mounted within the aircraft fore of the plurality of vanes mounted to the aircraft at a substantially rectangular exhaust end of the aircraft and substantially flush with respective interior walls of the aircraft,
wherein the at least two additional control surfaces are coupled to the plurality of control surfaces such that a trailing edge of one of the at least two additional control surfaces moves into an interior of the aircraft when trailing edges of the plurality of control surfaces, adjacent to the one of the at least two additional control surfaces, are deflected away from the respective interior wall of the aircraft.
7. The aircraft of claim 1 , comprising:
a plurality of control surfaces movably mounted on an exterior of the aircraft.
8. The aircraft of claim 1 , comprising:
a plurality of control surfaces movably mounted on outer corner edges of the exhaust end.
9. The aircraft of claim 1 , comprising:
a plurality of sets of control surfaces movably mounted on outer corner edges of the exhaust end.
10. The aircraft of claim 9 , wherein the plurality of sets of control surfaces are staggered along the outer corner edges of the exhaust end.
11. The aircraft of claim 9 , wherein at least one set of control surfaces is configured for differential deflection.
12. The aircraft of claim 11 , wherein the at least one set of control surfaces comprises a split at substantially a middle of a span of the at least one set of control surfaces.
13. The aircraft of claim 9 , wherein a first set of control surfaces is mounted fore of a second set of control surfaces.
14. The aircraft of claim 13 , wherein a trailing edge of the first set of control surfaces is substantially aligned with a hinge edge of the second set of control surfaces.
15. The aircraft of claim 9 , wherein a hinge edge of a first set of control surfaces on an outer corner edge of the exhaust end is substantially aligned with a hinge edge of a second set of control surfaces on an adjacent outer corner edge of the exhaust end, and
wherein the first and second sets of control surfaces are configured to allow unobstructed deflection between the first and second sets of control surfaces.
16. The aircraft of claim 1 , comprising:
a plurality of sets of control surfaces,
wherein at least a first set of control surfaces is movably mounted on outer corner edges of the exhaust end, and
wherein at least a second set of control surfaces is movably mounted within the aircraft fore of the plurality of vanes mounted to the aircraft at a substantially rectangular exhaust end of the aircraft.
17. The aircraft of claim 1 , comprising:
a plurality of control surfaces movably mounted within the aircraft fore of the plurality of vanes mounted to the aircraft at a substantially rectangular exhaust end of the aircraft in respective openings in walls of the aircraft,
wherein the plurality of control surfaces seal the openings when closed,
wherein the plurality of control surfaces divert air flow from inside the aircraft to outside the aircraft through the openings when open, and
wherein the control circuit is configured to actuate the plurality of control surfaces to control a reverse thrust of the aircraft.
18. The aircraft of claim 1 , wherein a duct of the aircraft comprises a substantially circular portion at a location of the ducted fan of the aircraft.
19. The aircraft of claim 1 , wherein the aircraft comprises a vertical take off and landing (VTOL) ducted fan aircraft.
20. The aircraft of claim 1 , wherein the aircraft comprises a substantially square exhaust end, and wherein each of the plurality of vanes is substantially square.
21. A system for controlling a RPM of an engine for driving a ducted fan of an aircraft, comprising:
a plurality of substantially rectangular control surfaces movably mounted to the aircraft at a substantially rectangular exhaust end of the aircraft,
wherein the plurality of control surfaces are configured to alter an exit area of the exhaust end;
a sensor configured to sense the RPM of the engine and to output a RPM indication signal;
an actuator coupled to the sensor and the plurality of control surfaces,
wherein the actuator is configured to actuate the plurality of control surfaces to alter the exit area of the exhaust end to vary a pressure load on the ducted fan to control the RPM of the engine in response to the RPM indication signal;
a first servo mechanism configured to balance pressure loads on the plurality of control surfaces, wherein
the first servo mechanism comprises a high force, low speed servo; a second servo mechanism configured to actuate the plurality of control surfaces, wherein
the second servo mechanism comprises a low force, high speed servo; and
a linkage configured to couple the first and second servo mechanisms to the plurality of control surfaces.
22. A method of controlling a RPM of an engine for driving a ducted fan of an aircraft, comprising the steps of:
a.) detecting the RPM of the engine to generate a RPM signal;
b.) actuating a plurality of substantially rectangular control surfaces movably mounted to the aircraft at a substantially rectangular exhaust end of the aircraft in response to the RPM signal; and
c.) altering an exit area of the exhaust end using the plurality of control surfaces to vary a pressure load on the ducted fan to control the RPM of the engine, wherein the step of altering is performed by
a first servo mechanism configured to balance pressure loads on the plurality of control surfaces, wherein
the first servo mechanism comprises a high force, low speed servo;
a second servo mechanism configured to actuate the plurality of control surfaces, wherein
the second servo mechanism comprises a low force, high speed servo; and
a linkage configured to couple the first and second servo mechanisms to the plurality of control surfaces.
23. The method of claim 22 , comprising the step of:
d.) controlling the RPM of the engine to maintain a maximum power of the engine for full-throttle flight.
24. The method of claim 22 , comprising the step of:
d.) controlling the RPM of the engine to maintain the RPM within a substantially narrow range of values.
25. The method of claim 22 , comprising the step of:
d.) controlling the RPM of the engine to operate the ducted fan at a substantially optimal forward-speed-to-tip-speed ratio of the ducted fan.