WO2015019255A1

WO2015019255A1 - Boxwing aircraft

Info

Publication number: WO2015019255A1
Application number: PCT/IB2014/063592
Authority: WO
Inventors: Claudio BOTTONI; Andrea CECCHI; Maurizio DI CATTERINA
Original assignee: Bottoni Claudio; Cecchi Andrea; Di Catterina Maurizio
Priority date: 2013-08-08
Filing date: 2014-07-31
Publication date: 2015-02-12
Also published as: ITPI20130073A1

Abstract

Boxwing aeroplane (1) comprising a fuselage (20) defining for said boxwing aeroplane (1) a preferred axis of development (1a), a prow (1b) and an ending (1c); a boxwing wing structure (30) comprising front wings (31) suitable to be coupled to said prow (1b) and rear wings (32) suitable to be coupled to the ending (1c), and connectors (33) suitable to structurally connect said wings (31, 32); propulsion units (5) each defining a propulsion axis (5a); each of said wings (31, 32) comprises a through hole (31a, 32a) where the propulsion units (5) are housed varying the angle between propulsion axes (40a) and preferred axis of development (1a).

Description

"BOXWI NG AI RCRAFT"

D E S C R I P T I O N

The present invention relates to a boxwing aircraft or boxwing airplane as defined in the preamble of the first claim.

In particular, the invention relates both to an internally controlled aircraft that is adapted to be driven by an operator present in the airplane, and to a remotely controlled aircraft characterized by the absence of any human driver on the airplane. The flight can be controlled by a computer located on the aircraft, or by way of preset trajectories, or be under the remote control of a navigator or driver.

As it is known, the boxwing airplane includes a fuselage; a wing structure defining a closed profile/perimeter, i.e. closed wings defining a ring; and one or more propulsion units secured under the wing structure or, in some cases, to the fuselage.

Said wing structure is characterized by the presence of two half-wings connected by bulkheads so as to define said closed ring profile. In detail, this wing structure is defined by the presence of two projecting half-wings anchored to the fuselage; and two bulkheads, or connectors, each of which connecting the two half-wings so as to make the entire wing structure globally hyperstatic, unlike a conventional wing structure. This known structure mentioned above has some important drawbacks.

A first drawback is the fact that, because of the particular wing structure, the boxwing aircraft presents low maneuverability.

In fact, due to the particular air flow generated by the wing structure, boxwing airplane presents considerable difficulties of/in steering.

Another drawback is represented by the fact that it is often difficult to be manufactured or designed.

In this situation, the technical object underlying the present invention is to devise an boxwing airplane capable of substantially obviating the mentioned drawbacks, or at least one of the mentioned drawbacks, or which may introduce new features and/or functionality.

Within said technical object it is also an important task of the invention to have an aircraft easy to be maneuvered.

Another object of the invention is to design an boxwing airplane and, in detail, an boxwing aircraft characterized by simplicity of construction and design.

The technical object and the specified tasks can be achieved by a boxwing airplane as claimed in annexed claim 1 .

Preferred embodiments are defined in the dependent claims or in the embodiments described below in this description.

In particular, according to an aspect of the present invention, one or more propulsion units of the aircraft can be rotated or tilted (around a pitch axis, which extends in the wingspan direction from left to right) compared to a longitudinal axis of the aircraft so as to allow the aircraft to move according to various directions, for instance to allow for vertical or substantially vertical takeoff, and a forward or backward movement, or a condition of stationary flight. For example a vertical takeoff like that of a four copter can be obtained by providing four or more propulsion units pivotally mounted in their seats, and then different angles and movements of the aircraft can be further obtained by turning the propulsion units properly around respective pivotal axes.

In particular, in one embodiment of the present invention, the propulsion units can be rotatable around a transverse axis, that is to say an axis which crosses the fuselage in a transverse direction (short side) with respect to a longitudinal direction (long side) allowing in this way to contribute to a horizontal propulsion of the aircraft in the desired direction. In fact, to this end, in a first condition, the one or more propulsion units are in a position in which an propulsion axis of the propulsion unit is substantially perpendicular to the longitudinal axis of the fuselage, for example in a vertical direction, so as to provide a take off like a helicopter. Subsequently the one or more propulsion units are in a position in which the propulsion axis form an angle different from 90° with respect to the longitudinal axis of the fuselage, for example, inclined down towards a prow area to allow a forward movement.

According to another aspect of the present invention, to increase the maneuverability of the aircraft, the one or more propulsion units are partially housed in a respective wing. In this way, when rotated around its pivotal axis, at least a part of the propulsion unit may protrude from the wing and/or from the respective seat, and contribute to control movement directions, and thus allowing to reduce number of additional movable surfaces, such as bulkheads or other movable parts, on the aircraft, which are normally provided in conventional aircraft to determine movement direction.

It follows that an aircraft according to an embodiment of the present invention can present the one or more of the following characteristics:

• Ability to vertically take-off like an helicopter;

• Ability to horizontally fly like an airplane;

• Higher load capacity compared to a generic four copter or multicopter (in case the propulsion units of each half-wing are more than one) since the carrying capacity determined by the propulsion units may be added to that provided by the wings during a horizontal flight;

• Increased capacity to maneuver with respect to a conventional aircraft, obtained by the presence of the propulsion units partially received in the respective seats, which may also allow a rotation around the vertical axis of the aircraft during stationary flight;

• chance of avoiding some movable surfaces for controlling movement directions like in conventional aircraft.

Further characteristics and advantages of the invention are clarified below by the detailed description of a preferred embodiment of the invention, with reference to the accompanying drawings, in which:

Fig. 1 shows a boxwing aircraft according to one embodiment of the invention;

Fig. 2 illustrates a section of the boxwing airplane of Figure 1 ; Fig. 3 illustrates a boxwing airplane in a different configuration with respect that of Fig.

2;

Fig. 4 shows a further configuration of the boxwing airplane of Fig. 1 ;

Figs. 5-8 illustrate additional views of a boxwing airplane according to one embodiment of the invention in respective operating positions.

With reference to the above-mentioned Figures, the boxwing airplane according to one embodiment of the present invention is globally indicated with the number 1.

It includes a body 20 defining a preferred axis of development 1 a, 1 b for the aircraft 1 , a bow and a tail/ending 1 c; a boxwing wing structure 30; and one or more propulsion units 40 each of which defines a propulsion axis 40a. In other words, a fuselage 20 has a preferred axis of development 1 a which corresponds to a longitudinal axis, or which extends along a longitudinal direction (or the direction of the long side) between the bow 1 b and the tail 1 c and corresponding to a prevailing extension of fuselage 20. The fuselage 20, which can be made, for example, of steel, wood, glass fiber or carbon, comprises a central body 21 defining the bow 1 b and an internal chamber housing objects/persons to be transported with the aircraft 1 ; a tail cone 22 defines the tail 1 c; and at least one fin 23 protruding from the tail cone 22 in a direction nearly transverse to axis 1 a and having a appropriately tapered section.

Preferably the fuselage 20 comprises two fins 23 placed on the side opposite to the tail cone 22 and having, preferably, different extension and section.

At least one of the fins 23 and, preferably, only the fin 23 of maximum extension may comprise a rudder 23a, i.e. a portion weakly bound to the rest of the fin 23 so as to rotate with respect to an axis of rotation substantially perpendicular to the preferred axis of development 1 a.

The internal chamber of the body 21 may be adapted to house the control system, such as a cabin in the case of aircraft with internal driver, or remote control systems (wireless), in the case of remotely controlled aircraft. The wing structure 30 can be made of the same structural material of the fuselage 20, namely steel, wood, glass fiber or carbon.

The wing structure 30 is a boxwing structure, therefore, includes front half-wings 31 adapted to be coupled integrally to the fuselage 20 from opposite sides with respect to the axis 1 a and 1 b at the bow; rear half-wings 32 adapted to be rigidly constrained to the fuselage 20 from opposite sides with respect to the preferred axis 1 a and at the tail 1 c; and connectors 33 structurally connecting the front half-wings 31 to the rear half- wings 33.

Preferably, the wing structure 30 includes two front half wings 31 integral with the main body 21 ; two wings 32 integral with the rear tail cone 22; and two connectors 33. More preferably, the structure 30 includes wings 31 and 32 defining for the aircraft 1 , the same wingspan and substantially the same tapered section.

The wings 31 and 32 have axes of prevailing extension substantially transverse to the axis 1 a, i.e. axes extending from opposite sides with respect to the longitudinal axis 1 a, in a direction of short side. Conveniently, the preferred axes of development of the wings 31 and 32 define, with respect to the preferred axis 1 a angles substantially comprised between 45° and 90°, preferably, substantially comprised between 60° and 90 ° and, more preferably, substantially equal to 70°. In particular, the angle between the axes of extension of the front half-wings 31 and development axis 1 a is substantially opposite to the angle between the extension axes of the rear wings 32 and development axis 1 a.

Also, preferably, the half-wings 31 and 32 define almost flat rest surfaces and substantially parallel to the axis of preferred development 1 a and, suitably, distinct from each other. To this end, the front half wings 31 are coupled to the body 21 and the rear wings 32 are coupled to fin 23 and, in detail, at the extreme distal end of the fin 23 of the main/central body 21.

Advantageously, each wing 31 and 32 has at least one through seat 31 a and 32a and, preferably, one through seat 31 a and 32a.

The through seats 31 a and 32a can be made symmetrically to the axis 1 a and preferably substantially equal to each other and conforming to the outer profile of the propulsion unit 40.

They have extension axes substantially perpendicular to the rest surfaces of the wings 31 and 32 and to the preferred axis of development 1 a and, preferably, substantially equidistant from the axis 1 a.

The connectors 33 connect with each other the distal ends of the wings 31 and 32 distally from the fuselage 20 and have essentially a wing profile characterized by a substantially constant section and similar to that of the distal ends of the wings 31 and 32.

Preferably, the connectors 33 define directions of extension lying on planes substantially perpendicular to the rest surfaces of the wings 31 and 32 and defining, with respect to the axis 1 a, an angle substantially comprised between 30° and 90°, in particular, substantially comprised between 45° and 60° and, more accurately, substantially equal to 45°.

The wing structure 30 may also present pitch control surfaces 33b designed to control the pitch of the aircraft 1 and bulkheads 34 designed to control the roll of the boxwing airplane 1 . The pitch control surfaces 33b and the bulkheads 34 identify portions of wing 31 and/or 32 adapted to rotate with respect to the relative half-wing around an axis lying almost on the rest surface of the relative half-wing 31 and 32 and almost transverse to the axis 1 a.

Preferably, the pitch control surfaces 33b and bulkheads 34 are formed symmetrically with respect to the axis 1 a and arranged, respectively, in the vicinity of the central body 21 or one fin 23, and of the connectors 33, as illustrated in Fig. 1.

Preferably, the wing structure 30 has two pitch control surfaces 33b formed on the rear wings 32 and two bulkheads 34 formed on the front half-wings 31. More preferably, the structure 30 has four pitch control surfaces 33b, two of which present on the two rear wings 32 and two of which present on the front half wings 31 and adapted to rotate in a direction opposite to the surface of the rear wings 32; and two bulkheads 34 present on the front half wings 31 and on the rear wings 32.

The boxwing airplane 1 presents propulsion units 40 suitably anchored to the wings 31 and 32. More specifically, each of the propulsion units is at least partially housed in a through seat 31 a and 32a and is connected to the control system so as to allow an independent control of their operation.

Preferably, the aircraft has four propulsion units 40 places symmetrically with respect to the axis 1 a. The propulsion units 40 may therefore have respective propulsion axes 40a lying on two distinct planes substantially parallel to, and spaced apart from, said axis 1 a. More preferably, the mutual distance between the propulsion axes 40a and, therefore, between the extension axes of the seats 31 a and 32a is substantially less than 50% and, in particular, substantially equal to 30% of the wing extension of the boxwing airplane 1 .

The propulsion units 40 can be, for example, propellers, and preferably duce fan propellers, almost conforming to the through seats 31 a and 32a and, in particular, having a thickness, calculated along the propulsion axis 40a, substantially similar to the thickness/height of the seats 31 a and 32a so as to be almost entirely housed in the seats when the propulsion axis 40a is almost parallel to the axis of the seats 31 a and 32a.

In other words, one or more propulsion units are housed or received in a respective through seat so as to stand completely inside the through seat in at least one operating position. For example, with reference to the figures, the one or more propulsion units are housed or received substantially completely in a respective through seat when the propulsion axis 40a of the one or more propulsion units is substantially vertical. Preferably each propulsion unit 40 comprises one or more blades 41 adapted to rotate around the propulsion axis 40a; an axial motor 42, preferably an electric motor, adapted to control said rotation of said blades 41 and disposed on the axis 40a; an outer ring 43 adapted to contain the blades 41 and, thus, defining the outer profile of the propulsion unit 40; and arms 44 adapted to connect the outer ring 43 to the motor 42 and suitably spaced apart, along the propulsion axis 40a, from the blades 41 so as not to interfere with their rotation.

According to an aspect of the present invention, the propulsion units 40 are innovatively hinged to the seats 31 a and 32a so as to rotate with respect to the wings 31 and 32 by varying the angle between the propulsion axis 40a and the preferred axis of development 1 a and, consequently, the motion and/or the trajectory of the boxwing airplane 1. In other words, the power units 40 are connected to the respective wings 31 and 32 so as to rotate at least partially in the respective seats 31 a, 31 b and to tilt the propulsion axis 40a.

It follows that the engine 40 can rotate around an axis of rotation or pivoting axis from a condition in which the propulsion axis 40a is for example substantially vertical, and thus substantially perpendicular to the longitudinal axis 1 a, to a condition in which the propulsion axis 40a forms an angle different from 90° with respect to the longitudinal axis 1 a. In the illustrated embodiment, this movement causes a partial protrusion of the propulsion unit 40 with respect to the seat 31 a, 32a in which it is received. It should be understood that other angular displacements different from those illustrated may be provided as part of the present invention.

Preferably, the two propulsion units 40 of the rear half-wings 32 and the two propulsion units 40 of the front half wings 31 are adapted to rotate independently of each other obtaining a high number of possible combinations of inclinations of each propulsion axis 40a with respect to the longitudinal axis 1 a. In other words, the four propulsion units 40 are adapted to rotate independently to each other thus varying the mutual inclination between the propulsion axes 40a.

To this end, the aircraft 1 comprises, for each propulsion unit 40, a rotating organ 50 adapted to constrain the engine 40 to a through seat 31 a or 32a and defining, for the propulsion unit 40, a rotation axis 50a lying on a plane substantially parallel to the development axis 1 a and the rest surfaces of the wings 31 and 32. Preferably, the axis of rotation 50a of each propulsion unit 40 is substantially parallel to that of the other propulsion units 40 and almost transverse and, more preferably, substantially perpendicular to the development axis 1 a.

Advantageously, the axes of rotation 50a of the propulsion units 40 tied to the front wings 31 or the rear wings 32 are substantially the same.

Preferably, as illustrated in the figures, each rotating organ 50 includes pins 51 adapted to constrain the outer ring 43 to the seat 31 a or 32a defining the axis of rotation 50a; and a preferably electric rotational motor 52 located in the wings 31 and 32 and connected to the control system, thus allowing a control of the rotation of the propulsion unit 40 independently from the other propulsion units 40.

Finally, the boxwing airplane 1 can comprise at least one drive motor 60 firmly fastened to the fuselage 20 and/or the wing structure so as to define a propulsion axis substantially parallel to the development axis 1 a.

Said drive motor 60 can be, for example, a helix associated with the central body 21 in correspondence of the bow 1 b or to the tail cone 22 at the tail 1 c (Fig. 1 ).

Alternatively or in addition, the aircraft 1 has two propulsion organs, for example turbofan, anchored to one fin 23 or to the wings 31 and 32, symmetrically with respect to the axis 1 a.

The operation of the boxwing airplane, structurally described above, is as follows. Initially, the aircraft 1 is resting on the ground, and presents the propulsion units 40 with propulsion axis 40a substantially perpendicular to the preferred axis of development 1 a and, more accurately, substantially parallel to the gravity gradient. The operator, through the control system, turns the propulsion units 40, which, consequently, determine propulsion of the boxwing airplane 1 allowing a vertical takeoff.

Reached the desired height, the operator controls the advancement of the aircraft 1 through organs 50 that, by arranging the propulsion axes 40a oblique with respect to the development axis 1 a and the gravitational gradient, causes the propulsion units determine a boost of vertical component, i.e. parallel to the gradient gravitation, substantially equal to the weight of the aircraft 1 and a propulsion having the horizontal component adapted to define a forward motion (Fig. 2) or backward motion (Fig. 3). Preferably, the aircraft 1 may provide driving the drive motors 60 so as to increase the speed of advance.

When the boxwing airplane 1 reaches the desired position, the operator can decide either to actuate the switching off of the drive motors 60 and the rotation of the propulsion units 40 by placing the propulsion axes 40a substantially perpendicular to each other thereby defining a stationary flight (Fig. 4) or to keep the drive motors 60 switched on in case of need for additional propulsion.

If the operator desires a flight substantially stationary and, at the same time, rotate the boxwing airplane 1 , thanks to the rotation organs 50, the propulsion axes 40a can be arranged in such a way that the propulsion forces of the propulsion units 40 generate a vertical propulsion of resultant forces substantially equal to the weight of the aircraft 1 , and without any resulting horizontal propulsion, but defining a rotational moment on the boxwing airplane 1.

With reference to Figures 5-8, additional features and functionality of an aircraft according to an embodiment of the present invention are provided. The aircraft of Figures 5-8 includes the same structural characteristics of the aircraft described above with reference to Figures 1 -4.

In particular for example, with reference to figure 5, a mode for vertically going up. Alternatively in order to pitch up the aircraft, power can be given to the two propulsion units placed in the front wings. To turn right or left, more power can be just given to the pair of propulsion units located on the left-hand side or on right-hand side relative to the axis of the aircraft.

The combination of these forces thus allows complete freedom of movement in space. In addition, in the case all the propulsion units can rotate around their axis transverse with respect to the airplane, one can obtain a rotation whiteout any displacements/shifts during vertical flight, as shown in Figure 6.

In relation to a horizontal propulsion, such propulsion can be obtained in two ways, such as by tilting forward the propulsion units placed in the wings, as shown in Figures 7 and 8, or by inserting other two engines (not shown in the drawings) located at the sides of the fuselage and which are actuated only during horizontal flight. The invention allows important advantages.

A first advantage is the fact that the boxwing airplane 1 presents an extremely high maneuverability.

In fact, thanks to the possibility to vary the inclination of the propulsion axes 40a respect to the preferred axis of development 1 a, it has the ability to switch alternately and quickly from a vertical flight, currently impossible for the known boxwing airplanes, to horizontal/advance flight.

This aspect has been further increased by the particular arrangement of the propulsion units 40 in the seats 31 a and 32a which allows to optimize the action of the same propulsion units 40 and thus, for example, easily obtaining a stable stationary flight, a vertical takeoff, or a rotation with almost no radius.

An important advantage is the high maneuverability of the aircraft 1 that, for example, is able to rotate in a limited space.

This aspect has been innovatively obtained thanks to the possibility of varying the mutual inclination of the propulsion axes 40a. It was also increased thanks to the possibility of controlling the power and the tilt of the propulsion units 40 independently from each other.

Another advantage is that the arrangement of propulsion units 40 provides high aerodynamic efficiency and, therefore, reduced fuel consumption of the aircraft 1 . One of the most important advantages is therefore identifiable in the fact that the boxwing airplane 1 , especially for remote controlled aircrafts, ensures at the same time both a controllability/maneuverability at least comparable to that of helicopters and carrying capacity at least equal to that of the aircraft.

A not secondary advantage is given by the presence of four control surfaces of the pitch 33b and four bulkheads 34 that allow a more effective and rapid stabilization of the aircraft 1 .

The invention is susceptible of variations within the scope of the inventive concept. All the elements described and claimed are replaced by equivalent elements; moreover details, materials, shapes and dimensions can be of any sort.

Claims

1. Boxwing aeroplane (1) comprising a fuselage (20) defining for said boxwing aeroplane (1 ) a preferred axis of development (1 a) corresponding to a longitudinal axis of the fuselage (20), a prow (1 b) and an ending (1 c); propulsion units (40) each one defining a propulsion axis (40a); a boxwing wing structure (30) comprising front wings (31 ) suitable to be coupled in correspondence of said prow (1 b) and rear wings (32) suitable to be coupled in correspondence of said ending (1 c), and connectors (33) suitable to structurally connect said wings (31 , 32), characterized in that each of said wings (31 , 32) comprises at least one through hole (31 a, 32a); and in that said propulsion units (40) are at least partially housed in said through holes (31 a, 32a) and wherein said propulsion units (40) are hinged to said wings (31 , 32) so as to rotate with respect to said wings (31 , 32) varying the angle between said propulsion axes (40a) and said preferred axis of development (1 a).

2. Boxwing aeroplane (1) according to claim 1 , wherein said propulsion units (40) are suitable to rotate with respect to said wings (31 , 32) independently from each other and so as to vary the mutual inclination between said propulsion axes (40a).

3. Boxwing aeroplane (1) according to one or more of the previous claims, wherein each of said propulsion units (40) define, with respect to said wing (31 , 32), a rotation axis (50a) lying on a plane substantially parallel to said preferred axis of development (1 a).

4. Boxwing aeroplane (1) according to the previous claim, wherein said rotation axis (50a) is substantially perpendicular to said preferred axis of development (1 a).

5. Boxwing aeroplane (1) according to one or more of the previous claims, wherein said propulsion units (40) are duce fan propeller.

6. Boxwing aeroplane (1) according to one or more of the previous claims, wherein said through holes (31a, 32a) are substantially complementarily shaped to said propulsion units (40).

7. Boxwing aeroplane (1) according to one or more of the previous claims, wherein said propulsion axes (40a) are substantially equidistant with respect to said preferred axis of development (1a).