Biplane flying device

1. A biplane flying device, comprising:

a fuselage;

an upper wing, connected to one side of the fuselage, wherein the upper wing has a first end and a second end opposite to each other;

a lower wing, connected to the fuselage and opposite to the upper wing, wherein the lower wing has a third end and a fourth end opposite to each other, the first end is opposite to the third end, and the second end is opposite to the fourth end;

a first propulsion assembly, connected between the first end, the third end and the fuselage; and

a second propulsion assembly, connected between the second end, the fourth end and the fuselage;

wherein the first end, the second end, the third end and the fourth end each have an arc-shaped wingtip structure, the arc-shaped wingtip structures at the first end and the third end are respectively bent toward the first propulsion assembly and connected to the first propulsion assembly, and the arc-shaped wingtip structures at the second end and the fourth end are respectively bent toward the second propulsion assembly and connected to the second propulsion assembly; and

the biplane flying device further comprises a first connecting member and a second connecting member, wherein the first connecting member is connected between the fuselage and the first propulsion assembly, and the second connecting member is connected between the fuselage and the second propulsion assembly.

2. The biplane flying device according to claim 1 , wherein the upper wing further has a chord line, the first propulsion assembly and the second propulsion assembly each have a central axis, there is an angle between the chord line and any of the central axes, and the chord line rises in a direction away from the fuselage, wherein the direction is defined as from a trailing edge of the upper wing to a leading edge of the upper wing.

3. The biplane flying device according to claim 2 , further comprising at least one wing-connecting member connected between the fuselage and the upper wing, wherein the at least one wing-connecting member keeps a distance between the fuselage and the upper wing, and the lower wing is directly connected to the fuselage.

4. The biplane flying device according to claim 1 , wherein the upper wing and the lower wing each have an airfoil, and the airfoils each have a curve.

5. The biplane flying device according to claim 1 , wherein the upper wing further comprises an aileron on a side of the upper wing close to a tail of the fuselage.

6. The biplane flying device according to claim 1 , wherein the first propulsion assembly and the second propulsion assembly each comprises a fan propeller and an air guide assembly, the air guide assembly is disposed at an exhaust port of the respective fan propeller, the fan propeller of the first propulsion assembly is connected between the first end, the third end and the fuselage, and the fan propeller of the second propulsion assembly is connected between the second end, the fourth end and the fuselage.

7. The biplane flying device according to claim 1 , further comprising a tail wing, wherein the tail wing and the lower wing are located on the same side of the fuselage, and the tail wing is located on a tail of the fuselage.

8. The biplane flying device according to claim 7 , further comprising a plurality of wheels disposed on the tail of the fuselage and the tail wing.