# US 11,305,872 B2 · Retractable propulsor assemblies for vertical take-off and landing (VTOL) aircraft > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,305,872 B2 - Document ID: US11305872B2 - Status: Granted - Kind: B2 - Application number: 16/524,547 - Filed: 2019-07-29 - Published: 2021-02-04 - Granted: 2022-04-19 - Earliest claimed: 2019-07-29 - Assignees: Aurora Flight Sciences Corporation - Applicants: The Aurora Flight Sciences Corporation - Inventors: Olivier Cornes - Web page: https://patentgrep.com/patent/US11305872B2 ## CPC - B64C 29/0033: {the propellers being tiltable relative to the fuselage} - B64C 1/14: Windows; Doors; Hatch covers or access panels; Surrounding frame structures; Canopies; Windscreens {accessories therefor, e.g. pressure sensors, water deflectors, hinges, seals, handles, latches, windscreen wipers}(fairings movable in conjunction with undercarriage elements B64C25/16; bomb doors B64D1/06) - B64C 25/04: Arrangement or disposition on aircraft - B64C 27/26: characterised by provision of fixed wings - B64C 27/30: with provision for reducing drag of inoperative rotor - B64C 29/0025: {the propellers being fixed relative to the fuselage} - B64C: AEROPLANES; HELICOPTERS ## Abstract Retractable propulsor assemblies for aircraft are described that generate lift during vertical take-off, hover, and vertical landing. The retractable propulsor assemblies are deployed from a compartment in a fuselage of the aircraft to transition the aircraft into vertical flight, and are stowed in the compartment during cruise flight to reduce aerodynamic drag on the aircraft. One embodiment comprises a method of operating a VTOL aircraft. The method comprises deploying the retractable propulsor assembly from the compartment of the fuselage to provide the lift for vertical flight. The method further comprises transitioning the VTOL aircraft from the vertical flight to cruise flight, and stowing the retractable propulsor assembly in the compartment during the cruise flight to reduce the aerodynamic drag on the VTOL aircraft. ## Claims ### Claim 1 A method of operating a Vertical Take-Off and Landing (VTOL) aircraft, the method comprising: deploying a retractable propulsor assembly from a compartment of a fuselage of the VTOL aircraft to provide lift for vertical flight; transitioning the VTOL aircraft from the vertical flight to cruise flight; and stowing the retractable propulsor assembly in the compartment during the cruise flight to reduce aerodynamic drag on the VTOL aircraft; wherein the retractable propulsor assembly comprises: an arm having a first end rotatably coupled to the fuselage; a propulsor disposed at a second end of the arm that is configured to generate lift for the aircraft; a drive mechanism configured to pivot the arm relative to the fuselage to transition the retractable propulsor assembly between a stowed position where the retractable propulsor assembly is stowed in the compartment, and a deployed position where the retractable propulsor assembly is deployed to perform vertical flight; a latching mechanism configured to selectively engage the arm with the drive mechanism, and disengage the arm from the drive mechanism; and a spring biasing system mechanically coupled to the first end of the arm; wherein deploying the retractable propulsor assembly further comprises: operating the latching mechanism to disengage the arm from the drive mechanism upon failure of the drive mechanism; and applying torque to the first end of the arm with the spring biasing system to pivot the arm out of the compartment and into the deployed position independently of the drive mechanism. ### Claim 2 (depends on 1) The method of claim 1, further comprising: deploying the retractable propulsor assembly from the compartment during the cruise flight; and transitioning the VTOL aircraft from the cruise flight to the vertical flight. ### Claim 3 (depends on 1) The method of claim 1, further comprising: opening a door that covers the compartment prior to deploying the retractable propulsor assembly. ### Claim 4 (depends on 3) The method of claim 3, further comprising: closing the door that covers the compartment while in cruise flight. ### Claim 5 An aircraft, comprising: a fuselage having control surfaces that are configured to provide lift during forward flight; and a retractable propulsor assembly, comprising: an arm having a first end rotatably coupled to the fuselage; a propulsor disposed at a second end of the arm that is configured to generate lift for the aircraft; a drive mechanism mechanically coupled to the first end of the arm that is configured to pivot the arm out of a compartment in the fuselage to transition the aircraft into vertical flight, and to pivot the arm into the compartment in response to the aircraft being in forward flight; a latching mechanism configured to selectively engage the arm with the drive mechanism, and disengage the arm from the drive mechanism; and a spring biasing system that operates independently of the drive mechanism to deploy the retractable propulsor assembly upon failure of the drive mechanism, the spring biasing system is mechanically coupled to the first end of the arm and is configured, in response to operating the latching mechanism to disengage the arm from the drive mechanism, to apply a torque to the first end of the arm to pivot the arm out of the compartment and into a deployed position. ### Claim 6 (depends on 5) The aircraft of claim 5, wherein the drive mechanism comprises: a main gear engaged with a driving gear; the main gear is mechanically coupled to the first end of the arm; the driving gear is driven in rotation to pivot the arm out of the compartment and into the deployed position. ### Claim 7 (depends on 6) The aircraft of claim 6, wherein: the arm is rotatably coupled to the main gear, and is held in place relative to the main gear by the latching mechanism; the second end of the arm, upon disengagement of the latching mechanism, pivots away from a first retaining feature in the main gear towards a second retaining feature in the main gear due to the torque applied by the spring biasing system; and the latching mechanism is configured to engage the second retaining feature in the main gear to lock the retractable propulsor assembly in the deployed position. ### Claim 8 (depends on 5) The aircraft of claim 5, further comprising: a door configured to selectively cover and uncover the compartment. ### Claim 9 (depends on 8) The aircraft of claim 8, wherein: the door is configured to cover the compartment in response to pivoting the retractable propulsor assembly into the compartment, and to uncover the compartment prior to pivoting the retractable propulsor assembly out of the compartment. ### Claim 10 (depends on 5) The aircraft of claim 5, further comprising: landing gear disposed on the arm that is configured to support the fuselage when the aircraft is on ground. ### Claim 11 (depends on 5) The aircraft of claim 5, wherein: the compartment in the fuselage is proximate to a nose of the aircraft. ### Claim 12 (depends on 5) The aircraft of claim 5, wherein: the retractable propulsor assembly comprises one of a plurality of retractable propulsor assemblies, each configured to generate a portion of the lift for the aircraft. ### Claim 13 (depends on 12) The aircraft of claim 12, wherein: the control surfaces comprise wings of the aircraft; and the plurality of retractable propulsor assemblies is disposed forward of the wings. ### Claim 14 A retractable propulsor assembly for aircraft, comprising: an arm having a first end rotatably coupled to a fuselage of the aircraft; a propulsor disposed at a second end of the arm that is configured to generate lift for the aircraft; a drive mechanism configured to pivot the arm relative to the fuselage to transition the retractable propulsor assembly between a stowed position where the retractable propulsor assembly is stowed in a compartment of the aircraft, and a deployed position where the retractable propulsor assembly is deployed to perform vertical flight operations; a locking mechanism configured to selectively engage the arm with the drive mechanism, and disengage the arm from the drive mechanism; and a spring biasing system that operates independently of the drive mechanism to deploy the retractable propulsor assembly upon failure of the drive mechanism, the spring biasing system is mechanically coupled to the first end of the arm and is configured, in response to operating the locking mechanism to disengage the arm from the drive mechanism, to apply a torque to the first end of the arm to pivot the arm out of the compartment and into the deployed position. ### Claim 15 (depends on 14) The retractable propulsor assembly of claim 14, wherein: the propulsor comprises a motor mechanically coupled to at least one rotor. ### Claim 16 (depends on 14) The retractable propulsor assembly of claim 14, wherein: the locking mechanism comprises a locking pin. ### Claim 17 (depends on 14) The retractable propulsor assembly of claim 14, further comprising: landing gear disposed on the arm that is configured to support the fuselage when the aircraft is on ground. ### Claim 18 (depends on 14) The retractable propulsor assembly of claim 14, wherein the drive mechanism further comprises: a main gear engaged with a driving gear; the main gear is mechanically coupled to the first end of the arm; the driving gear is driven in rotation to pivot the arm out of the compartment and into the deployed position. ### Claim 19 (depends on 18) The retractable propulsor assembly of claim 18, wherein: the arm is rotatably coupled to the main gear, and is held in place relative to the main gear by the locking mechanism; the second end of the arm, upon disengagement of the locking mechanism, pivots away from a first retaining feature in the main gear towards a second retaining feature in the main gear due to the torque applied by the spring biasing system; and the locking mechanism is configured to engage the second retaining feature in the main gear to lock the retractable propulsor assembly in the deployed position. ### Claim 20 (depends on 14) The retractable propulsor assembly of claim 14, wherein: the retractable propulsor assembly is proximate to a nose of the aircraft.