CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a U.S. National Phase Patent Application and claims priority to and the benefit of International Application Number PCT/SG2017/050356, filed on on Jul. 18, 2017, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

Embodiments generally relate to an asymmetric aerial vehicle, a method of assembling an asymmetric aerial vehicle and a kit of parts for assembling an asymmetric aerial vehicle.

BACKGROUND

Aerial vehicle capable of Vertical Take-Off and Landing (VTOL), for example tail-sitter aircraft such as XFV-1 of the 1950s, typically uses the same set of flight controls for both vertical and horizontal flight and represents the most direct way of achieving transition flight. However, with the pilot facing upwards during vertical flight, making visual assessments, e.g. during landing, can be difficult.

Further, tail-sitter aircrafts have other technical issues. For example, they tend to be susceptible to toppling, e.g. when landing in a wind. This is due to a high centre of gravity relative to the size of the tail base. To address this issue, landing gears of wide span may be installed or span of the tail base may be enlarged to cover a wider area on the ground. These measures typically add weight and aerodynamic drag which in turn compromise the performance (e.g. cruise endurance) of the aircraft.

Another aerial vehicle capable of VTOL would be aircraft with tilt-wings or tilt-rotors configurations. These aircrafts typically remain horizontal during transition. Thus, these configurations would render the aircraft suitable for carrying passengers. However, aircraft with tilt-wings or tilt-rotors configurations would need separate sets of flight controls for helicopter-mode and airplane-mode flight, resulting in high complexity in their development and implementation.

On the other hand, unmanned aerial vehicle (UAV) or drones do not carry passengers or pilots. Hence passenger- and pilot-related limitations of aircraft capable of VTOL are not applicable to UAVs.

However, there are further issues related to the development of autonomous transition for UAV. A typical transition maneuver typically spans a wide range of airspeeds and angle-of-attack. The presence of variables which cover a wide range of values, when multiplied in combinations with the other variables, can potentially result in massive aerodynamic databases for adequate coverage of the transition envelope. This would incur significant effort and cost to generate by means such as wind tunnel testing, CFD etc., when developing autonomous transition. In addition, highly nonlinear aerodynamic characteristics and changes in stability characteristics over the high angle-of-attack range would need complex, non-linear control strategies and algorithms to be developed, further adding to the complexity of development efforts.

A known quad-rotor unmanned aerial vehicle is disclosed in PCT International Publication number WO2013/048339. The quad-rotor unmanned aerial vehicle described may be capable of Vertical Take-Off and Landing (VTOL) as well as transition between a vertical flight mode (or a helicopter-mode) and a horizontal flight mode (or an airplane-mode). However, an operational limitation of the quad-rotor unmanned aerial vehicle is that in the event of failure of one of the propellers, a total loss of controllability occurs for the respective control axis.

An unmanned aerial vehicle is disclosed in PCT International Publication number WO2015/099603 which is proposed to provide redundancy to address the scenario of propeller failure by having three pairs of coaxial and contra-rotating propellers. However, complex mechanisms are involved for each pair of motors driving each pair of coaxial and contra-rotating propellers. The three pairs of coaxial and contra-rotating propellers configuration disclosed also has an operational limitation in that it has weak control authority in yaw during hovering or helicopter-mode flight, which is also the roll control in the airplane-mode flight. The yaw control during hovering may be weak because yaw control may only use differential torque. The weak control authority in yaw during helicopter-mode (or roll during airplane-mode) tends to deteriorate the controllability of the aircraft, particularly when hovering in a crosswind, which is an important practical operating scenario.

SUMMARY

According to various embodiments, there is provided an aerial vehicle including a first wing structure and a second wing structure which intersects the first wing structure perpendicularly at a position offset from a midpoint of a transverse axis of the first wing structure in a direction towards a first wingtip of the first wing structure. The aerial vehicle may further include a first set of at least two propellers with respective propeller rotational axes disposed side-by-side along a portion of the first wing structure extending between the midpoint of the transverse axis of the first wing structure and a second wingtip of the first wing structure. The aerial vehicle may further include a second set of at least two propellers with respective propeller rotational axes disposed side-by-side along a first portion of the second wing structure extending from a first surface of the first wing structure. The aerial vehicle may further include a third set of at least two propellers with respective propeller rotational axes disposed side-by-side along a second portion of the second wing structure extending from a second surface of the first wing structure.

According to various embodiments, there is provided a method of assembling an aerial vehicle. The method may include providing a first wing structure and providing a second wing structure which intersects the first wing structure perpendicularly at a position offset from a midpoint of the first wing structure towards a first wingtip of the first wing structure. The method may further include providing a first set of at least two propellers with respective propeller rotational axes disposed side-by-side along a portion of the first wing structure extending between a midpoint of the first wing structure and a second wingtip of the first wing structure. The method may further include providing a second set of at least two propellers with respective propeller rotational axes disposed side-by-side along a first portion of the second wing structure extending from a first surface of the first wing structure. The method may further include providing a third set of at least two propellers with respective propeller rotational axes disposed side-by-side along a second portion of the second wing structure extending from a second surface of the first wing structure.

According to various embodiments, there is provided a kit for assembling an aerial vehicle. The kit may include a first wing structure and a second wing structure adapted to intersect the first wing structure perpendicularly at a position offset from a midpoint of the first wing structure towards a first wingtip of the first wing structure. The kit may further include a first set of at least two propellers adapted to be disposed with respective propeller rotational axes side-by-side along a portion of the first wing structure extending between a midpoint of the first wing structure and a second wingtip of the first wing structure. The kit may further include a second set of at least two propellers adapted to be disposed with respective propeller rotational axes side-by-side along a first portion of the second wing structure extending from a first surface of the first wing structure. The kit may further include a third set of at least two propellers adapted to be disposed with respective propeller rotational axes side-by-side along a second portion of the second wing structure extending from a second surface of the first wing structure.

