FIELD OF THE INVENTION:

The present invention relates to an aerial vehicle. In particular, the present invention relates to a vertical rotor assembly in an aerial vehicle.

BACKGROUND:

Gravitational forces incident on an aerial vehicle are counteracted by generating lift forces in the aerial vehicle. The lift forces are provided by fixed wings which are designed to create a pressure differential to generate lift force during forward flight. Alternatively, a rotary wing can produce lift force as in the case of rotorcrafts. During vertical takeoff, landing, or hovering in the air, a set of rotors may be used to produce lift.

In hybrid aerial vehicles, both fixed wings and vertical rotors are used to generate lift. Ducted fans may also be used. Typically, the take-off and landing of the hybrid aerial vehicle may be strictly vertical (VTOL). In such an instance, the fixed wing does not produce any lift. To increase the amount of lift generated from the fixed wings, the hybrid aerial vehicle is inclined at an angle to the ground during take off, climb, landing and descent operations.

However, when the hybrid aerial vehicle is in an inclined position, the vertical rotors are also inclined. The inclined configuration of the vertical rotor results in reduced lift forces due to a horizontal component of the generated force when the vertical rotors are operated. Due to this, the increase in lift forces obtained from the fixed wing by inclination of the hybrid aerial vehicle is offset by the reduction in the lift forces generated from the vertical rotors. Also, the horizontal component of the VTOL engines acts in the direction of drag during the inclined climb and this VTOL engine induced drag force has to be accounted for and the forward flight engine must produce thrust accordingly, which ultimately leads to unnecessary energy consumption.

Developing solutions to maximize lift during inclined take-off, climb, landing and descent of the hybrid aerial vehicle will improve its efficiency.

OBJECTIVE OF THE INVENTION:

The primary objective of the present invention is to offset the loss in lift forces produced by the vertical rotors during inclined take-off and landing of a hybrid aerial vehicle.

The secondary objective of the present invention is to develop an automatic mechanism which operates to enable prevention of loos in lift forces from vertical rotors.

SUMMARY:

The present invention relates to a vertical rotor assembly for an aerial vehicle, comprising a rotor and a connecting element assembly attached to the rotor at one end and to a frame of the aerial vehicle at the other end. The connecting element assembly is disposed to orient, a central axis of the vertical rotor, perpendicular to the ground irrespective of the inclination of the aerial vehicle to the ground.

The aforementioned features of the present invention aid in the increasing the lift forces generated by a hybrid aerial vehicle with fixed wings and rotors during take off and landing. The response time, which is the time taken for changing the orientation of the vertical rotor in response to changes in the inclination of the vehicle, is also short. These objectives and advantages of the present invention will become more evident from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:

The objective of the present invention will now be described in more detail with reference to the accompanying drawing, wherein:

Figure 1 illustrates a vertical rotor assembly as an embodiment of the present subject matter.

Figure 2(a) illustrates a profile view of a vertical rotor assembly as an embodiment of the present subject matter.

Figure 2(b) illustrates a side view of a vertical rotor assembly as an embodiment of the present subject matter.

Figure 3(a) illustrates a profile view of a ducted fan attached to an air frame as an embodiment of the present subject matter.

Figure 3(b) illustrates a profile view of a ducted fan attached to an air frame as an embodiment of the present subject matter.

Figure 4 illustrates a profile view of a ducted fan attached to an air frame in different orientations with respect to the air frame (a) at 0 degrees, (b) at 45 degrees, and (c) at 90 degrees as an embodiment of the present subject matter.

OFT ATT FT) DESCRIPTION OF THE INVENTION:

During take-off, climb, landing and descent, a hybrid aerial vehicle comprising a fixed wing and vertical rotors is operated at an inclination to the ground for utilizing the lift forces obtained from the fixed wing. In the inclined configuration of the aerial vehicle, the vertical rotors, which are fixed to the airframe of the aerial vehicle, also incline with respect to a vertical direction.

A typical vertical rotor comprises a rotor, and a motor. A hub of the rotor is connected to a shaft of the motor at a first end of the motor. A second end of the motor is connected to a first end of a pod. A second end of the pod is connected to a frame of an aerial vehicle. By this assembly, the vertical rotor is operationally connected to the frame of the aerial vehicle through the pod. During a vertical take off and landing, the rotor is operated to generate a lift force. The pod transfers the lift force from the rotor to the frame. In the place of the pod, a strut may be placed to transfer the lift force from the rotor to the frame. Through this mechanism, the frame experiences a lifting force.

When the aerial vehicle is inclined, the vertical rotor is also in an inclined configuration with respect to the ground. In an inclined configuration, only the vertical component of the generated force from the vertical rotor can counteract gravity and act as the lifting force.

A ducted fan may also be used to produce lift forces. Similar to a vertical rotor, a duct in an inclined configuration will also exert only a vertical component of the total force.

In order to offset the loss in the lifting force produced by a lift generating device such as a vertical rotor or the ducted fan, the present invention discloses a vertical rotor assembly which can orient itself to maintain a central axis of the lift generating device in a vertical alignment with respect to the ground irrespective of the inclination of the aerial vehicle.

The vertical rotor assembly comprises a lift generating device and a connecting element assembly. The connecting element assembly is attached to the lift generating device at one end and to a frame of the aerial vehicle at the other end. The connecting element assembly is disposed to orient a central axis of the lift generating device, perpendicular to the ground irrespective of the inclination of the aerial vehicle to the ground. The connecting element assembly operates automatically under the influence of gravity.

Figure 1 illustrates a vertical rotor assembly as an embodiment of the present subject matter. A frame (100) of the aerial vehicle is partially seen in the figure 1. A connecting assembly is attached to the frame (100) at one end and to a vertical rotor (102) at the other end. In an embodiment, the connecting assembly comprises a pod (104), and a hinge (106). The hinge (106) may be in the form of a bearing. In an embodiment, the pod (104) may be attached to the frame (100) at one end and to the hinge (106) at the other end. The hinge (106) comprises a motor mount (108) attached to a motor (110) of the vertical rotor (102). Further, the hinge comprises a central rod (114) which provides the axis over which the motor mount (108) oscillates. A set of rotor blades of the vertical rotor (102) are connected to the motor (110). The rotor blades, the motor (110) and the motor mount (108) function as a single unit which is disposed to oscillate over the central rod (114).

When the hybrid aerial vehicle is inclined, the gravitational forces acting on the vertical rotor (102) pivot the motor mount (108) over the central rod (114) so as to ensure that the vertical rotor ( 102) is positioned along the vertical axis perpendicular to the ground. Further an actuator is provided to maintain the vertical configuration which actuates the alignment of the vertical rotor.

In another embodiment, a gimbaling mechanism operating about two axes is used to enable the vertical alignment in situation for controlled landing during cross winds and stringent landing space availability.

In another implementation of the present invention, a part of the frame can be adapted to provide an axis of rotation. Figure 2(a) illustrates a profile view of a vertical rotor assembly as an embodiment of the present subject matter. Figure 2(b) illustrates a side view of a vertical rotor assembly as an embodiment of the present subject matter. The connecting assembly comprises a hollow cylinder disposed on the part of the frame (100) to rotate about the axis of rotation. Further, the connecting assembly comprises a vertical rod (202) which on one end is attached to the hollow cylinder and at the other end is attached to the motor (110). The hollow cylinder, the vertical rod (202), the motor (110) and the rotor blades form a single unit which reorients under the effect of gravity till the vertical rotor (102) is positioned along the vertical axis perpendicular to the ground.

In another embodiment, the vertical rod may be replaced by two vertical rods (202) with a pod (104) positioned in between and connected to the vertical rods at either end. The pod (104) serves to transfer the lift forces generated by the vertical rotor (102) to the frame (100). In such a case, the hollow cylinder, the vertical rods (202), the pod (104), the motor (110), and the rotor blades form a single unit which reorients under the effect of gravity till the vertical rotor (102) is positioned along the vertical axis perpendicular to the ground

The pod (104) can be replaced by any other component which serves to transfer the lift forces. For example, a strut can be used in the place of the pod (104).

With the present invention, the rotors can pivot towards the direction of gravity when the hybrid aerial vehicle assumes an inclined orientation during climb from takeoff or approach to landing. Moreover, when the hybrid aerial vehicle transitions from cruise to hover mode, an inclined orientation may be assumed to cause stall of the wings thereby increasing the hybrid aerial vehicle’s drag, so the vertical rotors can pivot to allow for their full force to balance the weight of the hybrid aerial vehicle.

In case of the rotor being an electric ducted fan (EDF), the alignment of the ducted fan is adjusted. Figure 3(a) and 3(b) illustrates a profile view of a ducted fan attached to an air frame as an embodiment of the present subject matter. The surface of a ducted fan (300) is provided with a provision to attach a hinge (302). A hinge support (304) attaches the hinge (302) to the frame (100) of the aerial vehicle.

A linear actuator (306) is connected from the frame (100) of the aircraft wing using an actuator mount (308) and attached to the surface of the duct fan (300) through the hinge (302). The hinge (302) allows for the rotation of the duct (300) based on the motion of the actuator (306). The actuator (306) can be controlled to obtain a required position of the duct fan (300), enabling thrust vectoring. The required thrusts can be obtained from the individual EDFs (300) by controlling each of the actuators (306) separately.

Figure 4 illustrates a profile view of a ducted fan attached to an air frame in different orientations with respect to the air frame (a) at 0 degrees, (b) at 45 degrees, and (c) at 90 degrees as an embodiment of the present subject matter. At the 0 degrees configuration, the actuator is fully extended, and progressively retracting as the angle increases to reach a fully retracted configuration at 90 degrees configuration.

With the present invention, the rotors can pivot depending on the direction of actuation when the aerial vehicle assumes an inclined orientation during climb from takeoff or approach to landing. Further, when the terrain is not flat, lifting off causes a drift because the plane of the rotors is not matching that of the ground. The present invention enables the aircraft to take off and land perfectly vertically, without any drifts, even in case of uneven terrain by aligning the rotors with the ground.

During conditions where the vehicle needs to make an emergency landing or landing in a tightly packed environment, the rotors which are capable of gimbaling about two axes will be operative and hence make constant corrections in the touchdown trajectory to ensure proper landing. This feature would be extremely helpful to land during a heavy gust. The drift caused in case of having purely vertical rotors can be countered by a component of the force produced by aligning the rotors appropriately.

While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed.