# US 11,027,837 B2 · Aircraft having thrust to weight dependent transitions > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,027,837 B2 - Document ID: US11027837B2 - Status: Granted - Kind: B2 - Application number: 16/154,359 - Filed: 2018-10-08 - Published: 2019-01-31 - Granted: 2021-06-08 - Earliest claimed: 2016-07-01 - Assignees: Textron Innovations Inc. - Applicants: Textron Innovations Inc. - Inventors: John Richard McCullough; Paul K. Oldroyd - Web page: https://patentgrep.com/patent/US11027837B2 ## CPC - B64C 11/46: Arrangements of, or constructional features peculiar to, multiple propellers {(B64C11/306 takes precedence)} - B64C 27/52: Tilting of rotor bodily relative to fuselage (of see-saw type construction B64C27/43) - B64C 27/57: automatic or condition responsive, e.g. responsive to rotor speed, torque or thrust - B64C 29/00: Aircraft capable of landing or taking-off vertically, e.g. vertical take-off and landing [VTOL] aircraft (rotorcraft B64C27/00) - B64C 29/0033: {the propellers being tiltable relative to the fuselage} - B64C 29/02: having its flight directional axis vertical when grounded - B64D 27/40: Arrangements for mounting power plants in aircraft - B64D 27/406: {Suspension arrangements specially adapted for supporting thrust loads, e.g. thrust links} - B64D 31/06: actuated automatically - B64U 50/18: Thrust vectoring - B64U 10/25: Fixed-wing aircraft (VTOL aircraft B64U10/20) - B64U 30/297: Tilting rotors - B64U 50/13: using external fans or propellers - B64U 50/19: using electrically powered motors - B64U 70/80: Vertical take-off or landing, e.g. using rockets (rotorcrafts B64U10/10; VTOL aircraft B64U10/20) - B64U 2101/60: for transporting passengers; for transporting goods other than weapons - B64U 2201/10: autonomous, i.e. by navigating independently from ground or air stations, e.g. by using inertial navigation systems [INS] - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - B64C: AEROPLANES; HELICOPTERS - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - B64U: UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract An aircraft includes an airframe having first and second wings with first and second pylons extending therebetween and having a two-dimensional distributed thrust array of outboard propulsion assemblies attached thereto. A flight control system is coupled to the airframe and is operable to independently control a rotor speed and a thrust vector of each propulsion assembly. In a low thrust to weight configuration, transitions from the VTOL orientation to the biplane orientation include establishing a pitch down flight attitude while engaging in collective thrust vectoring of the outboard propulsion assemblies to maintain hover stability followed collectively reducing the thrust vector angles to initiate forward flight. In a high thrust to weight configuration, transitions from the VTOL orientation to the biplane orientation include maintaining a level flight attitude while collectively increasing the thrust vector angles of the outboard propulsion assemblies to initiate forward flight. ## Claims ### Claim 1 An aircraft operable to transition between thrust-borne lift in a VTOL orientation and wing-borne lift in a biplane orientation, the aircraft comprising: an airframe having first and second wings with first and second pylons extending therebetween, the first and second wings each having first and second outboard nacelle stations; a two-dimensional distributed thrust array attached to the airframe, the thrust array including a plurality of outboard propulsion assemblies coupled to the first and second outboard nacelle stations of the first and second wings, the thrust array operable to provide thrust for the aircraft; and a flight control system coupled to the airframe and operable to independently control a rotor speed and a thrust vector of each of the propulsion assemblies; wherein the flight control system is configured to: select, based on whether the aircraft is in a low thrust to weight configuration or a high thrust to weight configuration, a transition procedure for transitioning the aircraft from the VTOL orientation to the biplane orientation; and implement the selected transition procedure to cause the aircraft to transition from the VTOL orientation to the biplane orientation; wherein, in the low thrust to weight configuration, the selected transition procedure comprises establishing a pitch down flight attitude while engaging in collective thrust vectoring of the outboard propulsion assemblies to maintain hover stability followed by collectively reducing the thrust vector angles to initiate forward flight; and wherein, in the high thrust to weight configuration, the selected transition procedure comprises maintaining a level flight attitude while collectively increasing the thrust vector angles of the outboard propulsion assemblies to initiate forward flight. ### Claim 2 (depends on 1) The aircraft as recited in claim 1 wherein the outboard propulsion assemblies further comprise unidirectional thrust vectoring propulsion assemblies. ### Claim 3 (depends on 1) The aircraft as recited in claim 1 wherein the outboard propulsion assemblies further comprise omnidirectional thrust vectoring propulsion assemblies. ### Claim 4 (depends on 1) The aircraft as recited in claim 1 wherein the low thrust to weight configuration further comprises a thrust to weight ratio of the aircraft below a predetermined threshold. ### Claim 5 (depends on 4) The aircraft as recited in claim 4 wherein the predetermined threshold is about 1.4. ### Claim 6 (depends on 1) The aircraft as recited in claim 1 wherein the low thrust to weight configuration further comprises a thrust to weight ratio of the aircraft between about 1.1 and about 1.4. ### Claim 7 (depends on 1) The aircraft as recited in claim 1 wherein the high thrust to weight configuration further comprises a thrust to weight ratio of the aircraft above a predetermined threshold. ### Claim 8 (depends on 7) The aircraft as recited in claim 7 wherein the predetermined threshold is about 1.7. ### Claim 9 (depends on 1) The aircraft as recited in claim 1 wherein the first and second wings each have first and second inboard nacelle stations; and wherein the thrust array further includes a plurality of inboard propulsion assemblies coupled to the first and second inboard nacelle stations of the first and second wings. ### Claim 10 (depends on 9) The aircraft as recited in claim 9 wherein the outboard propulsion assemblies are omnidirectional thrust vectoring propulsion assemblies and the inboard propulsion assemblies are non thrust vectoring propulsion assemblies. ### Claim 11 (depends on 9) The aircraft as recited in claim 9 wherein the outboard propulsion assemblies are longitudinal thrust vectoring propulsion assemblies and the inboard propulsion assemblies are lateral thrust vectoring propulsion assemblies. ### Claim 12 (depends on 9) The aircraft as recited in claim 9 wherein the first and second pylons each have an inboard nacelle station; and wherein the thrust array further includes an inboard propulsion assembly coupled to each of the inboard nacelle stations of the first and second pylons. ### Claim 13 (depends on 12) The aircraft as recited in claim 12 wherein the outboard propulsion assemblies are omnidirectional thrust vectoring propulsion assemblies and the inboard propulsion assemblies are non thrust vectoring propulsion assemblies. ### Claim 14 (depends on 1) The aircraft as recited in claim 1 wherein the pitch down flight attitude while engaging in collective thrust vectoring of the outboard propulsion assemblies to maintain hover stability further comprises a pitch down flight attitude of between about 10 degrees and about 20 degrees. ### Claim 15 (depends on 1) The aircraft as recited in claim 1 wherein the pitch down flight attitude while engaging in collective thrust vectoring of the outboard propulsion assemblies to maintain hover stability further comprises a pitch down flight attitude of between about 20 degrees and about 30 degrees. ### Claim 16 (depends on 1) The aircraft as recited in claim 1 wherein, in the low thrust to weight configuration, the selected transition procedure further comprises collectively reducing in the thrust vector angles and increasing the pitch down attitude until the thrust vectors are substantially horizontal and the wings are substantially horizontal. ### Claim 17 (depends on 1) The aircraft as recited in claim 1 wherein, in the high thrust to weight configuration, the selected transition procedure further comprises maintaining the thrust vector angles and increasing the pitch down attitude until the thrust vectors are substantially horizontal. ### Claim 18 (depends on 17) The aircraft as recited in claim 17 wherein, in the high thrust to weight configuration, the selected transition procedure further comprises collectively reducing thrust vector angles and increasing the pitch down attitude while maintaining the thrust vectors substantially horizontal until the wings are substantially horizontal. ### Claim 19 (depends on 1) The aircraft as recited in claim 1 wherein each of the propulsion assemblies furthest comprises an aerosurface and wherein, in the low thrust to weight configuration, the selected transition procedure further comprises collectively tilting the aerosurfaces to create a pitch down moment on the aircraft. ### Claim 20 An aircraft operable to transition between thrust-borne lift in a VTOL orientation and wing-borne lift in a biplane orientation, the aircraft comprising: an airframe having first and second wings with first and second pylons extending therebetween, the first and second wings each having first and second outboard nacelle stations; a two-dimensional distributed thrust array attached to the airframe, the thrust array including a plurality of outboard propulsion assemblies coupled to the first and second outboard nacelle stations of the first and second wings, the thrust array operable to provide thrust for the aircraft; and a flight control system coupled to the airframe and operable to independently control a rotor speed and a thrust vector of each of the propulsion assemblies; wherein the flight control system is configured to: select, based on whether the aircraft is in a low thrust to weight configuration or a high thrust to weight configuration, a transition procedure for transitioning the aircraft from the VTOL orientation to the biplane orientation; and implement the selected transition procedure to cause the aircraft to transition from the VTOL orientation to the biplane orientation; wherein, in the low thrust to weight configuration, the selected transition procedure comprises establishing a pitch down flight attitude while engaging in collective thrust vectoring of the outboard propulsion assemblies to maintain hover stability followed by collectively reducing the thrust vector angles to initiate forward flight followed by further collective reduction in the thrust vector angles and increasing the pitch down attitude until the thrust vectors and the wings are substantially horizontal; and wherein, in the high thrust to weight configuration, the selected transition procedure comprises maintaining a level flight attitude while collectively increasing the thrust vector angles of the outboard propulsion assemblies to initiate forward flight followed by maintaining the thrust vector angles and increasing the pitch down attitude until the thrust vectors are substantially horizontal followed by collectively reducing thrust vector angles and increasing the pitch down attitude while maintaining the thrust vectors substantially horizontal until the wings are substantially horizontal.