Aircraft with folding mechanism

1. An aircraft with a folding mechanism, the aircraft comprising:

a fuselage;

multiple longitudinal beams attached to the fuselage with multiple lifting units attached to each of the longitudinal beams, the longitudinal beams extending parallel to one another, extending parallel to a first axis of the aircraft, and being offset from one another in a direction perpendicular to the first axis in a locked configuration for flights, the longitudinal beams being rotatably attached to the fuselage by at least one respective first pivot joint that is configured to pivot the longitudinal beams around a respective first pivot axis to a pivoted position, wherein the respective first pivot axis is parallel to the first axis of the aircraft; and

a crossbeam attached to the fuselage that extends at a right angle with respect to the longitudinal beams in the locked configuration for flights, with multiple other lifting units being attached to the crossbeam, the crossbeam being rotatably attached to the fuselage by at least one second pivot joint that is configured to pivot the crossbeam around a second pivot axis to a pivoted position.

2. The aircraft of claim 1 , wherein said lifting units comprise at least one respective rotor, said rotors being arranged in a common rotor plane, for at least one of said longitudinal beams or said crossbeam, respectively.

3. The aircraft of claim 1 , wherein said crossbeam is arranged above said longitudinal beams along a vertical axis of the aircraft.

4. The aircraft of claim 1 , wherein said longitudinal beams have multiple branches, said lifting units being located at least at one of respective branching points or end-points of said branches.

5. The aircraft of claim 4 , wherein the lifting units are located in at least one triangular configuration.

6. The aircraft of claim 1 , wherein said crossbeam has multiple branches, said lifting units-being located at least at one of respective branching points or end-points of said branches.

7. The aircraft of claim 6 , wherein the lifting units are located in at least one triangular configuration.

8. The aircraft of claim 1 , wherein the lifting units comprise rotors attached to said longitudinal beams and said crossbeam in a pivoted position relative to said longitudinal beams and said crossbeam, respectively.

9. The aircraft of claim 8 , wherein the rotors located on said longitudinal beams are attachable with their blades oriented in parallel with said longitudinal beams, and the rotors located on said crossbeam are attachable with their blades oriented in parallel with said crossbeam, transversely to said longitudinal beams.

10. The aircraft of claim 1 , further comprising a plurality of connector elements for interconnecting one of said longitudinal beams with said crossbeam or one of said longitudinal beams with another one of said longitudinal beams.

11. The aircraft of claim 10 , wherein at least one said connector element is rotatably attached either to one of said longitudinal beams or to said crossbeam by a third pivot joint configured for rotating said connector element against said one of said longitudinal beams or said crossbeam.

12. The aircraft of claim 11 , further comprising a quick release mechanism configured to secure said connector elements on said crossbeam, said quick release mechanism comprising a pin for passing through alignable through-holes in said connector elements and said crossbeam or respective brackets attached to said crossbeam.

13. The aircraft of claim 1 , wherein said longitudinal beams, in a pivoted position thereof, enclose said fuselage.

14. The aircraft of claim 1 , further comprising an attachment configured to fix said crossbeam to said longitudinal beams in said pivoted positions.

15. The aircraft of claim 1 , further comprising at least one of a payload or a landing gear attached to said fuselage.

16. The aircraft of claim 1 , wherein the crossbeam is rotatable with respect to the fuselage and independent of the longitudinal beams.