Patent Description:
A type of aircraft that can take off, hover, and land vertically is referred to as a VTOL aircraft. A VTOL aircraft has one or more rotors that produce vertical lift. Some VTOL aircraft also have fixed-wings that generate lift when the aircraft is propelled forward by a propeller, a jet engine, etc. When these fixed-wing aircraft convert from vertical flight to horizontal or cruise flight, the rotors are turned off. However, once the rotors are off, the rotors and any support structures associated with the rotors remain in the airflow around the aircraft, which can create drag.

<CIT> states, in accordance with its abstract, a fixed-wing aircraft on which retractable multi-rotor assemblies are mounted and which can perpendicularly take off and land. In the scheme of the fixed-wing aircraft, the fixed-wing aircraft comprises fixed-wing assemblies, retractable multi-rotor assemblies, a multi-rotor extending and retracting control mechanism, a multi-rotor hatch which can be opened and closed and a hatch opening and closing control mechanism. The fixed-wing aircraft is characterized in that when the aircraft is in a take-off stage or a landing stage or when the aircraft needs to hover in the air, the retractable multi-rotor assemblies in the lower part of an aircraft body are unfolded to provide a perpendicular take-off and landing capacity; when the aircraft cruises at a high speed, the multi-rotor assemblies are retracted in the aircraft body, the multi-rotor hatch is closed to keep the aerodynamic performance of the fixed-wing aircraft; and besides, when the fixed-wing aircraft is in perpendicular take-off and landing state, hovering state and cruising state at a high speed, the highest energy service efficiency can be obtained, so that the fixed-wing aircraft disclosed by the invention has a large perpendicular take-off and landing weight and a long range at the same time. According to this fixed-wing aircraft, a solution of a perpendicular take-off and landing fixed-wing unmanned aerial vehicle which is low in cost and high in energy efficiency is provided, is wide in application, and is particularly suitable for being applied to trades including point-to-point article transportation, long-distance cruise and the like.

<CIT> U states, in accordance with its abstract, that a VTOL fixed wing uavs belongs to VTOL unmanned air vehicle technique field. A VTOL fixed wing uavs includes the fuselage, set firmly in wing onthe fuselage and set firmly in the fin of afterbody still includes pairs of ailerons, to the rotatable setting of aileron in the side of fuselage, and pairs the aileron is located respectively the fuselage for the front end and the rear end of wing, it is every right the aileron symmetry set up in the both sides of fuselage, the fuselage corresponding to the storage tank has been seted upto aileron position department for, accomodates the stationary vane when flying to the aileron. The VTOL fixed wing uavs has the advantage of accomodating, expanding that the aileron can be convenient, and flight performance is good, the packing transportation is convenient.

<CIT> states, in accordance with its abstract, that an aircraft comprises a fuselage, a bearing area, and two drive rotors. The thrust direction of first drive rotor is arranged more temporarily in the horizontal direction. The second drive rotor is attached to a pivot arm through which the rotor is pivoted from the first position to the second position. In the first position, operation of drive rotor is carried out in the vertical sliding direction, and in the second position, operation of drive rotor is stopped, while the rotor rests against the fuselage and/or the bearing area.

<CIT> states, in accordance with its abstract, that an aircraft has a pair of drive rotor that are respectively provided in a horizontal thrust direction and a vertical thrust direction. The drive rotor is pivotably secured at a pivotal arm such that the driver rotor is pivoted from a first position into a second position. The drive rotor is accommodated in outside and/or a support surface of a hull in first position, and is accommodated in the hull and/or support surface in second position. The drive rotor and/or pivotal arm are connected with an outer portion of support surface and/or hull.

<CIT> states, in accordance with its abstract, an apparatus that includes a rotor blade assembly capable of generating vertical lift, one or more propulsion units capable of engaging and disengaging from the rotor blade assembly, an encapsulating housing, wherein the encapsulating housing is capable of containing the rotor blade assembly.

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.

According to the present disclosure, a method and a retractable propulsor assembly as defined in the independent claims are provided. Further embodiments of the claimed invention are defined in the dependent claims. Although the claimed invention is only defined by the claims, the below embodiments, examples, and aspects are present for aiding in understanding the background and advantages of the claimed invention.

The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments, further details of which can be seen with reference to the following description and drawings.

Some embodiments are now described, by way of example only, and with reference to the accompanying drawings.

The figures and the following description illustrate specific exemplary embodiments. It will be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles described herein.

Furthermore, any examples described herein are intended to aid in understanding the principles of the disclosure are to be construed as being without limitation. As a result, this disclosure is not limited to the specific embodiments or examples described below, but by the appended claims.

<FIG> are isometric views of retractable propulsor assemblies <NUM> for an aircraft <NUM> in various illustrative embodiments. In the embodiment illustrated in <FIG>, a fuselage <NUM> of aircraft <NUM> includes a compartment <NUM>, which is configured to house retractable propulsor assembly <NUM>. Retractable propulsor assembly <NUM> is configured to deploy from compartment <NUM> to provide lift to aircraft <NUM> for vertical flight, and to stow or retract into compartment <NUM> when aircraft <NUM> is in forward (e.g., cruise) flight.

In this embodiment, retractable propulsor assembly <NUM> includes an arm <NUM> having an end <NUM> (i.e., a first end) rotatably attached to fuselage <NUM> within compartment <NUM> and an end <NUM> (i.e., a second end) distal from end <NUM> that supports a propulsor <NUM>. Propulsor <NUM> provides lift to aircraft <NUM> during vertical flight operations. Propulsor <NUM> comprise any component, system, or device that generates vertical lift for aircraft <NUM>. In some embodiments, propulsor <NUM> comprises a motor <NUM> and a rotor <NUM> as illustrated in <FIG>, while in other embodiments, propulsor <NUM> comprises other combinations of reciprocating engines, turbines, one or more rotors, propellers, etc. In the deployed position illustrated in <FIG>, propulsor <NUM> generates lift as aircraft <NUM> vertically lands, vertically takes-off, and hovers. During forward flight (e.g., cruise flight) when lift is provided by other lift generating elements (e.g., control surfaces or wings, not shown in <FIG>), retractable propulsor assembly <NUM> is stowed in compartment <NUM> as illustrated in <FIG>.

To deploy retractable propulsor assembly <NUM> as illustrated in <FIG>, arm <NUM> pivots at end <NUM> (e.g., at axis <NUM>) and moves end <NUM> in the direction of arrow <NUM>. To stow retractable propulsor assembly <NUM> as illustrated in <FIG>, arm <NUM> pivots at end <NUM> (e.g., at axis <NUM>) and moves end <NUM> in the direction of arrow <NUM>.

In the embodiment illustrated in <FIG>, fuselage <NUM> includes a door <NUM> that is configured to selectively cover and uncover compartment <NUM>. Door <NUM> selectively uncovers compartment <NUM> prior to deploying retractable propulsor assembly <NUM> from compartment, and door <NUM> selectively covers compartment <NUM> in response to stowing retractable propulsor assembly <NUM> in compartment <NUM>. The use of compartment <NUM> and door <NUM> covering compartment <NUM> when retractable propulsor assembly <NUM> is stowed provides the technical effect of minimizing aerodynamic drag on aircraft <NUM> while aircraft <NUM> is in forward flight.

In some embodiments, retractable propulsor assembly <NUM> is spring-biased toward the deployed position illustrated in <FIG>. The use of spring biasing enables retractable propulsor assembly <NUM> to be deployed even in the case where a primary deployment system used to deploy retractable propulsor assembly <NUM> has failed. For example, mechanisms used to deploy retractable propulsor assembly <NUM> may include electric motors, hydraulic systems, pneumatic systems, etc., which may be inoperable in some cases due to failure. When inoperable, the spring biasing system is used to deploy retractable propulsor assembly <NUM>, thereby allowing aircraft <NUM> to perform a vertical landing.

The torque generated by a spring biasing system (not shown in this view) to pivot retractable propulsor assembly <NUM> out of compartment <NUM> and into the deployed position illustrated in <FIG> is selected to overcome the opposing torque generated on retractable propulsor assembly <NUM> due to an airflow generated when aircraft <NUM> is in forward flight. This ensures that the torque generated by the spring biasing system can effectively and reliably deploy retractable propulsor assembly <NUM> during forward flight in case of a failure of the primary deployment system. The use of spring-biasing toward the deployed position provides a higher level of safety than relying on the primary deployment system alone.

Various latching mechanisms may be used to selectively lock retractable propulsor assembly <NUM> in the deployed position to prevent arm <NUM> from rotating at end <NUM>, and to selectively unlock retractable propulsor assembly <NUM> when in the deployed position to allow arm <NUM> to rotate at end <NUM> to transition retractable propulsor assembly <NUM> to the stowed position illustrated in <FIG>. The latching mechanisms may include electric actuators, hydraulic actuators, manual actuators (e.g., slidable pins), or combinations thereof. During a failure of the primary deployment system for deploying retractable propulsor assembly <NUM>, a pilot, in one embodiment, utilizes a manual release mechanism to unlock arm <NUM> for rotation at end <NUM>, thereby allowing the spring biasing system to automatically pivot retractable propulsor assembly <NUM> out of compartment <NUM>. Once deployed, the pilot, in one embodiment, utilizes a manual lock mechanism to lock retractable propulsor assembly <NUM> in the deployed position illustrated in <FIG>.

In some embodiments, retractable propulsor assembly <NUM> is used as landing gear <NUM> for aircraft <NUM>, as illustrated in <FIG>. In this embodiment, end <NUM> of retractable propulsor assembly <NUM> includes landing gear <NUM>, which is configured to support fuselage <NUM> when aircraft <NUM> is on the ground. Landing gear <NUM> may retract into or pivot toward arm <NUM> as retractable propulsor assembly <NUM> is stowed in compartment <NUM> to achieve a more compact shape, and deploy out of or pivot away from arm <NUM> as retractable propulsor assembly <NUM> is deployed from compartment <NUM> in preparation for landing. Although the embodiment of <FIG> illustrates landing gear <NUM> as a wheel, landing gear <NUM> in other embodiments comprises other type of structures that contact the ground when aircraft <NUM> lands.

In some embodiments, retractable propulsor assembly <NUM> is stowed in compartment <NUM> in response to aircraft <NUM> landing in order to provide a more open path for the occupants of aircraft <NUM> to exit and enter aircraft <NUM>. In these embodiments, <FIG> may represent the configuration of aircraft <NUM> while on the ground, with retractable propulsor assembly <NUM> stowed in compartment <NUM>. When aircraft <NUM> is ready for flight operations, retractable propulsor assembly <NUM> is deployed as illustrated in <FIG> to allow aircraft <NUM> to perform vertical flight operations.

<FIG> depicts retractable propulsor assembly <NUM> in another illustrative embodiment. In particular, <FIG> illustrate compartment <NUM> through cut lines <NUM>-<NUM> of <FIG>. <FIG> illustrates retractable propulsor assembly <NUM> in the stowed position, <FIG> illustrates retractable propulsor assembly <NUM> in an intermediate position between stowed and deployed, and <FIG> illustrates retractable propulsor assembly <NUM> in the deployed position. Referring again to <FIG>, retractable propulsor assembly <NUM> is in the stowed position. In this view, compartment <NUM> includes a blade guide <NUM>, which is used to guide rotor <NUM> into the position illustrated in <FIG> as retractable propulsor assembly <NUM> transition from the deployed position to the stowed position. In this embodiment of retractable propulsor assembly <NUM>, retractable propulsor assembly <NUM> is mechanically driven between the stowed position and the deployed position using a primary deployment system <NUM>. Primary deployment system <NUM> may be referred to as a drive mechanism in some embodiments. Primary deployment system <NUM> comprises any component, system, or device that transitions retractable propulsor assembly <NUM> between the stowed position illustrated in <FIG> and the deployed position illustrated in <FIG>. Some examples of primary deployment system <NUM> include electric motor and gear assemblies, hydraulic actuators, pneumatic actuators, etc., which collectively comprise one or more power sources. In this embodiment, primary deployment system <NUM> comprises a main gear <NUM> that is engaged with a driving gear <NUM>. Main gear <NUM> is mechanically coupled to end <NUM> of arm <NUM>, and as driving gear <NUM> rotates in the direction of arrow <NUM>, main gear <NUM> rotates in the direction of arrow <NUM>. Driving gear <NUM> may be driven in rotation, for example, using an electric motor, a mechanical crank, etc. As main gear <NUM> rotates in the direction indicated by arrow <NUM>, arm <NUM> pivots out of compartment <NUM>, moving end <NUM> of arm <NUM> in the direction of arrow <NUM>.

<FIG> illustrates retractable propulsor assembly <NUM> in an intermediate position between stowed and deployed, and <FIG> illustrates retractable propulsor assembly <NUM> in the deployed position. When in the deployed position, retractable propulsor assembly <NUM> is operated to generate lift for aircraft <NUM>.

Referring again to <FIG>, arm <NUM> is rotatably coupled to main gear <NUM> in this embodiment, and is held in place relative to main gear <NUM> by a latching mechanism <NUM>. Latching mechanism <NUM> may be referred to as a locking mechanism in some embodiments. Latching mechanism <NUM> is illustrated as a locking pin in this embodiment. When latching mechanism <NUM> is released, a spring biasing system <NUM> generates a torque on end <NUM> of arm <NUM>, pivoting end <NUM> of arm <NUM> in the direction of arrow <NUM> to automatically deploy retractable propulsor assembly <NUM> from compartment <NUM>. Spring biasing system <NUM> operates independently of primary deployment system <NUM> to deploy retractable propulsor assembly <NUM>, thereby ensuring that retractable propulsor assembly <NUM> is deployed even if main gear <NUM> fails to rotate. Spring biasing system <NUM> comprises any component, system, or device that automatically transitions retractable propulsor assembly <NUM> from the stowed position to the deployed position independently of primary deployment system <NUM>. Some examples of spring biasing system <NUM> include pneumatic pistons, springs, spiral springs, helical torsion springs, etc..

<FIG> illustrates retractable propulsor assembly <NUM> in an intermediate position as spring biasing system <NUM> deploys retractable propulsor assembly <NUM>. In <FIG>, main gear <NUM> remains stationary as end <NUM> of arm <NUM> pivots. As arm <NUM> pivots due to disengagement of latching mechanism <NUM>, end <NUM> of arm <NUM> pivots away from a first retaining feature <NUM> in main gear <NUM> towards a second retaining feature <NUM> in main gear <NUM>.

In response to deploying retractable propulsor assembly <NUM> via spring biasing system <NUM>, latching mechanism <NUM> is activated to lock retractable propulsor assembly <NUM> in the deployed position by engaging latching mechanism <NUM> with second retaining feature <NUM>. <FIG> illustrates retractable propulsor assembly <NUM> in the deployed position independent of primary deployment system <NUM> using spring biasing system <NUM> in an illustrative embodiment.

<FIG> are perspective views of an aircraft <NUM> in various illustrative embodiments. The structure of aircraft <NUM> is merely provided as an example, and the concepts described herein for aircraft <NUM> apply to any aircraft. For example, aircraft <NUM> may comprise any type of air vehicle that utilizes retractable propulsor assemblies <NUM>. Such air vehicles may include rotors that generate lift during forward flight (e.g., one type of flight control surface) and therefore, aircraft <NUM> in some embodiments does not include wings <NUM>-<NUM>.

In this embodiment, aircraft <NUM> utilizes a pair of retractable propulsor assemblies <NUM>, which are located proximate to a nose <NUM> of aircraft <NUM>. In other embodiments, retractable propulsor assemblies <NUM> are located at other positions on aircraft <NUM>. <FIG> illustrates retractable propulsor assemblies <NUM> for aircraft <NUM> in the deployed position, and <FIG> illustrates retractable propulsor assemblies <NUM> for aircraft <NUM> in the stowed position.

In this embodiment, aircraft <NUM> includes propulsors <NUM> that provide thrust for forward flight. Some examples of propulsors <NUM> include engines, motors, rotors, ducted fans, turbines, etc. Aircraft <NUM> also includes wings <NUM>-<NUM> extending from opposite sides of a fuselage <NUM> to define a support plane for horizontal, forward, wing-born flight, or cruise flight.

To provide vertical flight (i.e., vertical take-off, hover, and vertical landing), aircraft <NUM> includes one or more fixed propulsor assemblies <NUM>, which are located aft of wings <NUM>-<NUM> in this embodiment, and retractable propulsor assemblies <NUM>, which are forward of wings <NUM>-<NUM> and proximate to nose <NUM> in this embodiment. As aircraft <NUM> transitions from vertical flight to forward flight, retractable propulsor assemblies <NUM> are stowed within fuselage <NUM>, and doors <NUM> are closed to allow aircraft <NUM> to achieve a more aerodynamic shape and reduce drag during forward flight (see <FIG>).

<FIG> is a flow chart of a method <NUM> of operating a VTOL aircraft in an illustrative embodiment. <FIG> are flow charts depicting additional details of method <NUM> in various illustrative embodiments. Method <NUM> will be described with respect to aircraft <NUM>, although method <NUM> may be performed by other aircraft. The steps of method <NUM> are not all inclusive, and may include other steps, not shown. The steps may be performed in an alternate order.

Prior to vertical take-off, doors <NUM> open (if equipped, see optional step <NUM> and <FIG>) and retractable propulsor assemblies <NUM> are deployed from compartments <NUM> (see step <NUM>). In some embodiments, deploying retractable propulsor assemblies <NUM> is performed utilizing one or more power sources (e.g., powering motors, engines, pneumatic pistons, , etc., see <FIG>, step <NUM>). Lift for aircraft <NUM> is generated by retractable propulsor assemblies <NUM> and fixed propulsor assemblies <NUM> to perform vertical take-off. In some embodiments, one or more power sources are utilized to operate retractable propulsor assemblies <NUM> to provide lift (see <FIG>, step <NUM>). Some examples of one or more power sources that may operate retractable propulsor assemblies <NUM> to provide lift include combinations of motors and rotors (e.g., motor <NUM> and rotor <NUM>), ducted fans, turbines, engines, generators, batteries, hybrid power sources, etc..

As aircraft <NUM> achieves an altitude above the ground, propulsors <NUM> drive aircraft <NUM> forward and aircraft <NUM> transitions from vertical flight to cruise flight (see step <NUM>). In some embodiments, one or more power sources are utilized to operate propulsors <NUM> of aircraft <NUM> to provide forward thrust for cruise flight (see <FIG>, step <NUM>).

When the lift generated by wings <NUM>-<NUM> is sufficient to maintain altitude, fixed propulsor assemblies <NUM> may be placed in a free-wheeling state. Retractable propulsor assemblies <NUM> are stowed in compartments <NUM> during cruise flight (see step <NUM>). For example, one or more power sources are utilized to stow retractable propulsor assemblies <NUM> in compartment <NUM> (see <FIG>, step <NUM>). Doors <NUM>, if present, close to cover compartments <NUM> while in cruise flight (see optional step <NUM>).

To transition out of cruise flight and into vertical flight, doors <NUM> open to uncover compartments <NUM> (see <FIG>, optional step <NUM>), and retractable propulsor assemblies <NUM> are deployed from compartments <NUM> (see <FIG>, step <NUM>). Fixed propulsor assemblies <NUM> are placed in operation and provide vertical lift. Rotors <NUM> of retractable propulsor assemblies <NUM> are driven in rotation and also provide vertical lift. Aircraft <NUM> transitions from cruise flight to vertical flight (see <FIG>, step <NUM>).

Retractable propulsor assemblies <NUM> are deployed independently of primary deployment system <NUM> (e.g., primary deployment system <NUM> is inoperable). In this embodiment, end <NUM> of arm <NUM> (see <FIG>) is disengaged from primary deployment system <NUM> (see <FIG>, step <NUM>), and spring biasing system <NUM> applies a torque to end <NUM> to deploy retractable propulsor assembly <NUM> from compartment <NUM> (see <FIG>, step <NUM>).

The use retractable propulsor assembly <NUM> allows aircraft <NUM> to take-off vertically, hover, and land vertically. When transitioning into cruise flight, retractable propulsor assemblies <NUM> are stowed, which minimizes drag on aircraft <NUM>. When on the ground, retractable propulsor assemblies <NUM> may also be stowed to allow passengers to enter and exit aircraft <NUM> more easily. Further, various embodiments of retractable propulsor assemblies <NUM> are deployable using spring biasing system <NUM>, which operates independently of primary deployment system <NUM>. Further, still, selectively powering retractable propulsor assemblies <NUM> during vertical flight operations, while suspending such powering during forward or cruse flight improves the endurance of aircraft utilizing retractable propulsor assemblies <NUM> by reducing the electrical loads and/or fuel usage during forward or cruise flight.

Any of the various control aspects shown in the figures or described herein may be co-implemented along with any mechanical system described, as hardware, a processor implementing software, a processor implementing firmware, or some combination of these. For instance, the mechanical systems described herein for deploying and stowing retractable propulsor assemblies <NUM>, in some embodiments, are controlled by one or more flight controllers, which may be implemented in combinations of hardware and software.

In another example, a control aspect may be implemented as dedicated hardware.

Also, a control aspect may be implemented as instructions executable by a processor or a computer to perform the functions of the element.

Claim 1:
A method (<NUM>) of operating a Vertical Take-Off and Landing, VTOL, aircraft (<NUM>; <NUM>), the method comprising:
deploying (<NUM>) a retractable propulsor assembly (<NUM>) from a compartment (<NUM>) of a fuselage (<NUM>) of the VTOL aircraft to provide lift for vertical flight, wherein the retractable propulsor assembly (<NUM>) comprises: an arm (<NUM>) having a first end (<NUM>) rotatably coupled to the fuselage (<NUM>); a propulsor (<NUM>) disposed at a second end (<NUM>) of the arm (<NUM>) and a drive mechanism (<NUM>) configured to deploy the arm (<NUM>);
transitioning (<NUM>) the VTOL aircraft from the vertical flight to cruise flight; and
stowing (<NUM>) the retractable propulsor assembly (<NUM>) in the compartment (<NUM>) during the cruise flight to reduce aerodynamic drag on the VTOL aircraft,
wherein deploying the retractable propulsor assembly (<NUM>) comprises:
in case where the drive mechanism (<NUM>) configured to deploy the arm (<NUM>) has failed or is inoperable, disengaging the first end (<NUM>) of the arm (<NUM>) from the drive mechanism (<NUM>); and
applying a torque to the first end (<NUM>) of the arm (<NUM>) to deploy the arm (<NUM>) and the propulsor (<NUM>) from the compartment (<NUM>) independently of the drive mechanism (<NUM>).