FOLDABLE TANDEM WING AIRCRAFT

This invention relates in general to UAV technology but more particularly to foldable tandem wing aircraft.

It is currently common in the market of using UAVs or Unmanned Aerial Vehicles to carry variety of loads and perform various aerial tasks particularly in photography, spraying, aerial delivery, fire disaster, security and safety which are widely used.

Multirotor UAVs are currently known in the market to do majority of tasks than fixed wing UAVs because of its advantages in mobility, precision in movement, VTOL or vertical takeoff and landing capability and portability of the vehicle. One of the disadvantages of multirotor UAV lies relatively short time that they can remain airborne. When the aircraft is in horizontal flight, some energy from the motors is utilized for its horizontal movement. Therefore, certain models of multirotor aircraft include wings to enhance energy efficiency in horizontal flight. These models are the vertical take-off and landing (VTOL) fixed wing aircraft or so-called hybrid UAV.

For conventional fixed wing UAV, it is mostly used for fast and smooth flight but limited to lightweight load capacity because the higher the load requires larger wing area for higher lift. Fixed wing UAV cannot perform vertical take-off and landing because it needs rolling, takeoff and landing distance with flat and smooth terrain.

Many fixed wing UAV models are in monoplane configuration, these are aircrafts with single main wing plane. Although this wing configuration has the highest efficiency and lowest drag than tandem wing configuration, monoplanes require a certain stretch for a single wing plane, which takes up a lot of space and gives its packaging and transportation even more difficulties. In order to adapt to market development while meeting the performance of both multirotor UAV and fixed wing UAV, we need to improve the wing configuration so that the packaging, storage and transportation can save more space, improve portability, packaging and transport efficiency. The present invention is to solve the aforementioned technical problems by technical solutions as follows:

The foldable tandem wing aircraft; a hybrid UAV comprising a body or the fuselage with attached two main wings, with one located forward and the other to the rear, this is called an aircraft with tandem wing configuration. The aircraft's wings are foldable using kinematic chain assembly with structures and mechanical bearings attached between each side of the wing and the fuselage.

The forward and rear part of the fuselage are respectively provided with structural members, these members are connected to the end portion of the said kinematic chain assembly which is then connected to the wing. The wing structure from root to tip also comprises of main structural members connecting other internal structures such as ribs (airfoil shaped structures where wing skin is attached), engine mountings, etc., the structural members in the wing structure are also connected to the other end of the kinematic chain assembly. The mechanical bearings act as pivot points for the rotation of the foldable wing relative to the fuselage.

The internal structures of the wing as described above are also connected to the engine mount structure or the fixing brackets of a propulsion device. As described, each wing is provided with a front pull motor, each motor is attached on each wing segment providing vertical thrust for vertical takeoff and landing capability and horizontal thrust for horizontal flight.

This foldable wing segment allows convenient packaging and transporting of the aircraft as well as providing more efficient horizontal flight than multirotor UAV carrying the same load capacity. When all aircraft's wings are expanded and positioned perpendicular to the fuselage, the aircraft is in flight position. On the other hand, if the aircraft's wings are folded and positioned parallel to the fuselage, the aircraft is in storage position.

The beneficial effects of the present invention are: the present invention foldable tandem wing aircraft, by folding the forward and rearward wing structural members provide narrow width for the aircraft when not in flight using simple mechanism. This foldable tandem wing has obvious advantages in terms of portability, space saving, packaging, storing and transportation as well as utilization of lift produced by tandem wings which gives great convenience, energy and cost savings for the user. The forward wings are extended outwards by an extendable mechanism or the kinematic chain assembly that separates the wing away from the fuselage then folded towards and parallel to the fuselage by a mechanical bearing. When deploying the aircraft for operation, maintenance, inspection or flight position, the wings are positioned perpendicular to the fuselage then rotating the wing at certain angle to connect with the locking mechanism.

It is therefore the tandem wing element of the present invention to provide an aerial vehicle that reduces the thrust required from the motor whi le in horizontal flight by approximately 70% less than conventional high lift multirotor UAV.

Still the wing element is to provide an aerial vehicle which not only reduces motor thrust requirement but also an operational cost saver, saving energy consumption which in result increases operational flight time.

Moreover, the mechanism or the kinematic chain assembly between the wings and the fuselage provides a foldable feature which makes this UAV unique and more convenient to carry for user than other monoplane fixed wing UAV models with the same load capacity.

Other parts and advantages of the present invention will be apparent upon reading the following description taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a perspective view of the aircraft in storage position;

Figure 2 is a sectional view taken along line 2-2 of Fig. 1;

Figure 3 is perspective view of the aircraft as wings separated from fuselage;

Figure 4 is a perspective view of the aircraft in flight position;

Figure 5 is a sectional view taken along line 25-25 of Fig. 4. Referring now to the several views of the drawings wherein like reference numerals designated same parts throughout, there is shown my invention for foldable tandem wing aircraft.

As shown, the said foldable tandem wing aircraft 20, comprising a fuselage 6, further comprising forward wing segments 5 and 7, rear wing segments 3 and 4, respectively. Both forward and rear part of the fuselage 6 is provided with structural members 23 and 24 attached to the skin and other internal structures supporting the shape of fuselage 6.

The rear wing segments 3 and 4 and forward wing segments 5 and 7 are all connected to the fuselage 6 with kinematic chain assembly comprising mechanical bearing 9 coupled to carbon structure 22 which is then inserted to the fuselage 6 through the mechanical bearing 27, the carbon structure 8 of the kinematic chain assembly is inserted to the mechanical bearing 9 and connected to the carbon structure 21 and 28. The mechanical bearing 9 is responsible for wing's rotation about the vertical axes (v, t, y, and i), and the mechanical bearing 27 is responsible for wing's rotation about the lateral axes (n and a) during folding and unfolding.

Only the rear wing segments 3 and 4 has the carbon structure 22 of the pivot assembly that can be pulled outwards along lateral axis a from the internal structures of the fuselage 6, while the carbon structure 22 of forward wing segments 5 and 7 are fixed in the internal structure of fuselage 6. The carbon structure 22 pulled outwards so that the rear wings can make longer distance between fuselage 6 and rear wing segments 3 and 4.

The distance E of the structural members 8 of the kinematic chain assemblies at the rearward side of the fuselage 6 is greater than the distance S of forward wing segments to ensure clearance to fold after forward wing segments are folded.

Rear wing segment 4 is coupled to engine 11 with propeller 1 to produce lift and propulsion for left hand and rearward part of the fuselage 6. Rear wing segment 3 is coupled to engine 12 with propeller 15 to produce lift and propulsion for right hand and rearward part of the fuselage 6. Forward wing segment 5 is coupled to engine 14 with propeller 17 to produce lift and propulsion for left hand and forward part of the fuselage 6. And the forward wing segment 7 is coupled to engine 16 with propeller 13 to produce lift and propulsion for right hand and forward part of the fuselage 6.

After operation or flight position, the wings are then folded to storage position wherein, forward wing segments 5 and 7 are folded first before the rear wing segments parallel to the longitudinal axis r and closer to the surface of fuselage 6 than the rearward wing segments 3 and 4 which is also folded parallel to the longitudinal axis r.

Lastly in flight position, the rear wing segments 3 and 4 are unfolded outwards from the storage position first before wing segments 5 and 7 which are also unfolded outwards from the storage position. The rear and forward wings are then positioned to flight position by aligning the rear wing segments 3 and 4 along the lateral axis a and perpendicular relative to the longitudinal axis r and the forward wing segments 5 and 7 which are aligned along the lateral axis n and perpendicular relative to the longitudinal axis r. This allows the tandem wings to be folded when the aircraft is not in use or in storage position and then unfolded when the aircraft will be used for flight or in flight position.