VTOL AIRCRAFT

Abstract

A VTOL aircraft (1) having a fuselage (2) for transporting passengers and/or load, front and rear wings (3, 4) attached to the fuselage, a right connecting beam (5a) and a left connecting beam (5b), which connecting beams structurally connect the front wing and the rear wing, and which connecting beams are spaced apart from the fuselage, and at least two lifting units (M1-M6) on each one of the connecting beams. The lifting units each include at least one propeller (6b) and at least one motor (6a) driving the propeller, preferably an electric motor, and are arranged with their respective propeller axis in an essentially vertical orientation. The front wing, at least in portions thereof, has a sweep angle γ between γ=450 and γ=135°, and the rear wing, at least in portions thereof, has a forward sweep with sweep angle β≥30°.

Claims

1. A VTOL aircraft (1), comprising: a fuselage (2) for transporting at least one of passengers or load; a front wing (3) attached to the fuselage (2); a rear wing (4) attached to the fuselage (2), behind the front wing (3) in a direction of forward flight (FF); a right connecting beam (5a) and a left connecting beam (5b), said connecting beams (5a, 5b) structurally connect the front wing (3) and the rear wing (4), said connecting beams (5a, 5b) are spaced apart from the fuselage (2); and at least two lifting units (M1-M6) on each one of the connecting beams (5a, 5b), said lifting units (M1-M6) each comprise at least one propeller (6b) and at least one motor (6a) driving said propeller (6b), and are arranged with the respective propeller axis in an essentially vertical orientation (z); wherein the front wing (3), at least in portions thereof, has a sweep angle γ between γ=450 and γ=135°, and the rear wing (4), at least in portions thereof, has a forward sweep with sweep angle β≥30°.

2. The aircraft (1) of claim 1, wherein the front wing (3) has a wing area (S.sub.front) that is smaller than a wing area (S.sub.rear) of the rear wing (4).

3. The aircraft (1) of claim 2, wherein 60%<S.sub.front/S.sub.rear<100.

4. The aircraft (1) of claim 1, wherein the rear wing (4) is partly shaped as a V-Tail with a sweep angle (δ) greater than 90°.

5. The aircraft (1) of any claim 1, wherein in a plane perpendicular to a longitudinal axis (x) of the aircraft (1), the rear wing (4) extends sideways from the fuselage (2) such that respective wing halves (4a, 4b) of the rear wing form an angle (θ)<180°.

6. The aircraft (1) of claim 1, wherein the at least two lifting units (M1-M6) on each one of the connecting beams comprises three of the lifting units (M1-M6) on each one of the connecting beams (5a, 5b).

7. The aircraft (1) of claim 1, wherein the lifting units (M1-M6) are placed symmetrically about a longitudinal (x-z) and a lateral (y-z) plane, respectively, of the aircraft (1).

8. The aircraft (1) of claim 1, wherein attachments (A3, A4) of the front wing (3) and the rear wing (4), respectively, to the connecting beams (5a, 5b) are placed in between respective rotor planes (P1-P6) swept by the propellers (6b).

9. The aircraft (1) of claim 1, wherein the rear wing (4) is placed higher in vertical position (z) than the front wing (3).

10. The aircraft (1) of claim 1, wherein the front wing (3) incorporates a dihedral angle (λ).

11. The aircraft (1) of claim 1, wherein the dihedral angle (λ) is incorporated at respective tips of the front wing (3).

12. The aircraft (1) of claim 1, wherein the rear wing (4) incorporates an anhedral angle (ε), at least in an outer portion thereof, towards said connecting beams (5a, 5b).

13. The aircraft (1) of claim 1, wherein longitudinal aircraft stability, which is defined by a quantity Cm/α, is negative, Cm being a pitching moment coefficient and a being an angle of attack.

14. The aircraft (1) of claim 1, wherein a centre of actuation (CoA) is geometrically in a same longitudinal position (x.sub.CoA) as a centre of gravity (CoG) of the aircraft, and a neutral point (NP) is located aft of both the centre of actuation (CoA) and the centre of gravity (CoG).

15. The aircraft (1) of claim 1, further comprising at least one forward propulsion unit (F1, F2) connected thereto.

16. The aircraft (1) of claim 15, wherein the at least one forward propulsion unit includes at least one propeller and at least one motor driving said propeller.

17. The aircraft (1) of claim 16, wherein the at least one motor is an electric motor.

18. The aircraft (1) of claim 15, wherein the at least one forward propulsion unit (F1, F2) includes one of the forward propulsion units located on each side of the fuselage (2).

19. The aircraft (1) of claim 18, wherein The forward propulsion units are located below both the front wing (3) and the rear wing (4) and forward of the rear wing (4).

20. The aircraft (1) of claim 1, wherein the front wing (3) and the rear wing (4), when viewed along a longitudinal axis (x) of the aircraft (1), together form a closed loop shape.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Further characteristics and advantages of the present invention can be gathered from the following description of exemplary embodiments with reference to the appended drawings.

[0069] FIG. 1 shows a plan view of an aircraft according to the invention;

[0070] FIG. 2 shows a side view of an aircraft according to the invention;

[0071] FIG. 3 shows a front view of an aircraft according to the invention;

[0072] FIG. 4 shows a simplified version of FIG. 1;

[0073] FIG. 5 shows another front view of an aircraft according to the invention; and

[0074] FIG. 6 shows another plan view of an aircraft according to the invention.

DETAILED DESCRIPTION

[0075] FIG. 1 shows a VTOL aircraft 1 having a fuselage or fuselage body 2 for transporting passengers and/or load. x, y, and z denote the aircraft axes (longitudinal, transverse, and vertical, respectively, as detailed above). A front wing 3 is attached to the fuselage 2. Furthermore, a rear wing 4 is attached to the fuselage 2 behind the front wing 3 in a direction of forward flight (arrow FF) of the aircraft 1. A right connecting beam 5a and a left connecting beam 5b structurally connect the front wing 3 and the rear wing 4, which connecting beams 5a, 5b are laterally spaced apart from the fuselage 2. The aircraft 1 comprises six lifting units M1-M6, three of which are arranged on each one of the connecting beams 5a, 5b. The lifting units M1-M6 each comprise at least one propeller 6b and at least one motor 6a driving said propeller 6b, preferably an electric motor, and they are arranged with their respective propeller axis in an essentially vertical orientation (z axis). This is explicitly shown for only one (M6) of the lifting units M1-M6 in FIG. 1.

[0076] The lifting units M1-M6 are placed symmetrically about the longitudinal (x) and lateral (y) axes of the aircraft 1: Lifting units M1 and M5 are placed at equal distances (in x-direction) toward the front and the rear, respectively, when compared to lifting unit M3. The same holds for lifting units M2, M4, and M6. Furthermore, the three lifting units on each side of the aircraft 1 are placed at equal transverse distances (in y-direction) from the aircraft's longitudinal axis.

[0077] Reference numerals P1-P6 denote rotor planes that can be defined as respective areas swept by the rotating propellers 6b of lifting units M1-M6. Wing attachments to the connecting beams 5a, 5b are be placed in between and outside the rotor planes P1-P6. Said wing attachments are denoted A3 for front wing 3 and A4 for rear wing 4.

[0078] The front wing 3 and the rear wing 4, at least in portions thereof, i.e., the outer portion of the rear wing 4 with respect to the fuselage 2, both define a sweep angle (γ, β) which is less than 90° (forward sweep). Rear wing 4 has a backward sweep (angle δ) in a region close to the fuselage 2 (V-Tail), which helps to reduce the length of the fuselage 2 while keeping a sufficient rear surface wing area S.sub.rear (cf. below). Preferred values for these angles are: 45°<γ<135°, preferably γ=75°, 30°<β<90°, preferably β=65°, and 70°<δ<170°, preferably δ=110°.

[0079] Reference numerals F1 and F2 denote forward propulsion units (pushers) that are attached at the right side and at the left side of the fuselage 2, respectively, toward the rear of the aircraft 1 (in front of rear wing 4). The pushers can comprise at least one propeller and at least one motor driving said propeller (not shown).

[0080] The specific physical points of the aircraft 1, which were defined earlier, are denoted as CoG (centre of gravity), CoA (centre of actuation), CA (aerodynamic centre) and NP (neutral point). Also denoted are the individual aerodynamic centres of both the front wing 3 (CA.sub.Front) and the rear wing 4 (CA.sub.Rear), respectively, for that part of each wing which extends between fuselage 2 and right connecting beam 5a. The same applies to that part of each wing which extends between fuselage 2 and left connecting beam 5b (not shown in FIG. 1). As can be gathered from FIG. 1, the centre of actuation CoA of the aircraft 1 is geometrically in the same longitudinal position (x.sub.CoA) as the aircraft's centre of gravity CoG (at least approximately), while the neutral point NP is located well aft of both the centre of actuation CoA and the centre of gravity CoG due to the forward sweep of wings 3 and 4.

[0081] The front wing 3 has a wing area S.sub.front that is smaller than a wing area S.sub.rear of the rear wing 4. In the present example 60%<S.sub.front/S.sub.rear<70%. In sum, the rear wing 4 comprises the surface of a V-Tail (wing half 4b) and a classical lifting wing surface (wing half 4a), which will become apparent from FIGS. 3 to 5 below.

[0082] FIG. 2 shows a side view of the aircraft 1 of FIG. 1. Same elements are denoted by common reference numerals in all Figures.

[0083] The connecting beams (only beam 5b is visible in FIG. 2) are placed higher than (or above) the fuselage 2, i.e., in the z direction (cf. FIG. 1).

[0084] M1+2 denotes lifting units M1 and M2, which are located behind one another in the line of sight. Same applies to lifting units M3 and M4 as well as lifting units M5 and M6, respectively.

[0085] Reference numeral D denotes propeller downwash (only shown for one (M5+6) of the lifting units M1-M6). Said wing attachments (cf. FIG. 1) are located outside the downwash zones.

[0086] FIG. 3 shows a front view of the aircraft 1. As can be seen, in a plane perpendicular to a longitudinal axis (x) of the aircraft 1, the rear wing 4 extends sideways from the fuselage 2 such that respective wing halves 4a, 4b of rear wing 4 form an angle α<180°, preferably approximately 90° to 100°. The inner wing half 4b forms the surface of a V-Tail, while the outer half 4a represents a classical lifting wing surface.

[0087] Front wing 3 incorporates a dihedral angle (λ) which, combined with the above-mentioned sweep angle (γ<90°), positively affects lateral/directional stability of the aircraft 1. Said angle λ may increase toward respective tips of the wing 3. Additionally, the rear wing 4 incorporates an anhedral angle (ε) in order to create a high vertical offset VO in the region of higher downwash 7 (cf. FIG. 2) of the front wing 3 which occurs especially in the in-board portion of said wing 3 (spanwise). Said angle ε, too, may increase toward respective tips of the wing 4. In this way, the front wing 3 and the rear wing 4, when viewed along the longitudinal axis (x) of the aircraft 1, together form a closed loop shape.

[0088] FIG. 4 is a somewhat simplified version of FIG. 1 for to illustrate the front wing 3 with its area S.sub.front being smaller than area S.sub.rear of the rear wing 4. However, the rear wing surfaces produce less vertical lift due to the V-Tail configuration. Rear wing 4 comprises the surface of the V-Tail 4b and classical lifting wing surface 4a, which are illustrated by means of different shadings.

[0089] This is further illustrated in FIG. 5, which is another front view of the aircraft 1 (cf. FIG. 3 for additional details).

[0090] Finally, as illustrated in FIG. 6, the V-Tail sweep angle δ, δ>90°, also leads to an improved load transfer (dashed lines denoted by reference numeral 8) as the “V” configuration transfers loads from the connecting beam 5b via wing 4a and via the V-tail 4b into the fuselage 2.