VTOL AIRCRAFT WITH A BATTERY ELECTRIC DRIVE AND AN INTERNAL COMBUSTION ENGINE

Abstract

A manned aircraft having wing parts, an internal combustion engine which is connected via a shaft to a left thrust nacelle and to a right thrust nacelle, which are pivotable from a vertical position for a hovering flight phase into a horizontal position for the forward flight phase, and having a left thrust unit and a right thrust unit which are driven by electric motors, and having a control unit which carries out a moment-dynamic flight control and which controls the thrust units to generate thrust for the hovering flight phase and at least partially stops them for the forward flight phase.

Claims

1. An aircraft comprising: a left wing part and a right wing part, each to generate aerodynamic lift during a forward flight phase of the aircraft; an internal combustion engine arranged in a fuselage of the aircraft, the combustion engine connected via a respective shaft to a left thrust nacelle arranged on the left wing part and to a right thrust nacelle arranged on the right wing part, wherein the left thrust nacelle and the right thrust nacelle each have at least one rotor or propeller to generate thrust via power transmitted by the shaft and are pivotable from a vertical position for a hovering flight phase of the aircraft into a horizontal position for the forward flight phase; a left thrust unit arranged on the left wing part and a right thrust unit arranged on the right wing part, each having at least one rotor or propeller and driven by electric motors that are electrically connected to a battery system; and a control unit configured to carry out a moment-dynamic flight control, wherein control variables of flight control in the forward flight phase comprise a flap control of aerodynamic surfaces of the wing parts and of a vertical stabilizer and horizontal stabilizer, wherein the control unit is configured to control the thrust nacelles to pivot into the vertical position for the hovering flight phase and to control the thrust units to generate thrust, and to at least partially stop the thrust units for the forward flight phase.

2. The aircraft of claim 1, wherein a respective thrust unit has exactly two rotors or propellers arranged one behind another, wherein a respective front rotor or propeller is arranged in front of the respective wing part and a respective rear rotor or propeller is arranged behind the respective wing part.

3. The aircraft of claim 2, wherein the front rotors or propellers of the thrust units are pivotable independently of one another from the vertical position for the hovering flight phase to the horizontal position for the forward flight phase in order to generate thrust in the hovering flight phase as well as in the forward flight phase, and wherein the rear rotors or propellers of the thrust units are fixed in the horizontal position, wherein the control unit is configured to control the rear rotors or propellers of the thrust units to generate thrust for the hovering flight phase and to stop the thrust units for the forward flight phase.

4. The aircraft of claim 1, wherein all rotors or propellers of the respective thrust unit are fixed in the horizontal position, wherein the control unit is configured to stop all rotors or propellers of the thrust units for the forward flight phase.

5. The aircraft of claim 1, wherein the control variables of the flight control in the hovering flight phase comprise speed changes of the rotors or propellers of the left thrust unit and the right thrust unit at a constant blade angle and/or a blade angle adjustment of the rotors or propellers of the left thrust unit and the right thrust unit.

6. The aircraft of claim 1, wherein the control unit is configured, in an autorotation phase by reversing a direction of torque on the left thrust nacelle and the right thrust nacelle and torque guided via the shaft to an electrical generator of the internal combustion engine, to supply electrical energy generated by the electrical generator to the battery system in order to charge the battery system using the electrical energy.

7. The aircraft of claim 1, wherein each of the electric motors of a respective thrust unit is individually connected to a respective battery unit of the battery system, wherein all battery units are capable of supplying electrical energy to their respective electric motor independently of one another.

8. The aircraft of claim 1, wherein the control unit is configured, in an event of a detected failure, malfunction, or discharge of the battery system, to supply a respective electric motor with electrical energy generated by an electrical generator of the internal combustion engine at least for the hovering flight phase.

9. The aircraft of claim 1, wherein the control unit is configured, in an event of a failure of the internal combustion engine detected at least in the forward flight phase, after a gliding phase with an aid of the left wing part and the right wing part and a subsequent low-level maneuver with continuous increase in the aerodynamic angle of attack while simultaneously reducing a horizontal speed, to control the thrust units to generate thrust immediately before the aircraft touches down on a ground.

10. The aircraft of claim 9, wherein the control unit is configured, during the gliding phase, to control the thrust nacelles to pivot into an autorotation position in order, by reversing a direction of torque on the left thrust nacelle and the right thrust nacelle and torque guided via the shaft to an electrical generator of the internal combustion engine, to supply electrical energy generated by the electrical generator to the battery system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In the drawings:

[0061] FIG. 1 shows an aircraft according to an example embodiment of the invention;

[0062] FIG. 2 shows the aircraft of FIG. 1 in a side view; and

[0063] FIG. 3 shows an aircraft according to a further example embodiment of the invention in a side view.

[0064] The illustrations in the figures are schematic and not to scale.

DETAILED DESCRIPTION

[0065] FIG. 1 shows an aircraft 1 for manned operation. It has four seats in a cabin in the fuselage 7. A left wing part 3 and a right wing part 5 are used to generate aerodynamic lift during a forward flight phase. Furthermore, an internal combustion engine 9 is arranged in the fuselage 7 of the aircraft 1, which is connected via a respective shaft 11 made of carbon-fiber-reinforced plastic to a left thrust nacelle 13 arranged on the left wing part 3 and to a right thrust nacelle 15 arranged on the right wing part 5. The internal combustion engine 9 includes a shaft gas turbine for generating torque on the shaft 11. The left thrust nacelle 13 and the right thrust nacelle 15 each have a rotor for generating thrust using the power transmitted by the shaft 11. They are also pivotable independently of one another from a vertical position for a hovering flight phase of the aircraft 1 to a horizontal position for the forward flight phase. Between the thrust nacelles 13, 15 and the fuselage, a left thrust unit 17 and a right thrust unit 19 are arranged on the wing parts 3, 5, each having two propellers arranged one behind the other. The thrust units 17, 19 therefore have a total of four propellers made of carbon-fiber-reinforced plastic arranged symmetrically to the fuselage 7. The propellers of the thrust units 17, 19 are driven by electric motors 21, which in turn are electrically connected to a battery system 23.

[0066] The respective front propeller is arranged in front of the respective wing part 3, 5 and is pivotable from the horizontal position to a vertical position for forward flight. The respective rear propeller is arranged behind the respective wing part 3, 5 and fixed in a horizontal position. In FIG. 1 and FIG. 2, the front propellers are shown in the vertical position. A control unit 25 carries out a moment-dynamic flight control with the aid of a PID basic controller. The PID basic controller relies, especially in the hovering flight phase, on the sensor signals of an inertial measuring unit, in particular, rotation angle rates with respect to a body-fixed coordinate system and orientation angles in relation to the earth. This involves orientation angle stabilization and rotation angle rate damping. Control variables for actuators of the aircraft 1 are generated as the output of the basic controller. The control variables include a blade angle adjustment of the rotors of the left thrust nacelle 13 and the right thrust nacelle 15 at an approximately constant speed in the hovering flight phase.

[0067] The rotational speed of the thrust nacelles 13, 15 is only adjusted depending on the flight condition and is essentially changed for the transition between the hovering flight phase and the forward flight phase with the IAS (English for indicated airspeed). However, during the hovering flight phase, the speed of the rotors of the thrust nacelles 13, 15 is maintained approximately constant. During this transition, the thrust gondolas 13, 15 are also pivoted from the vertical to a horizontal position by the control unit 25. In the reverse transition from the forward flight phase to the hovering flight phase, the thrust gondolas 13, 15 are transferred from the horizontal back to a vertical position by the control unit 25.

[0068] The control unit 25 also controls the electric motors 21 of the rear propellers in the hovering flight phase to generate thrust and brings them to a standstill in the forward flight phase. In this case, each of the electric motors 21 of a respective thrust unit 17, 19 is individually connected to a respective battery unit of a battery system 23, wherein all battery units can supply electrical energy to their respective electric motor 21 independently of one another. The front propellers are pivoted by the control unit 25 for the forward flight phase from the horizontal position to the vertical position for horizontal thrust in order to obtain, together with the thrust nacelles 13, 15 pivoted to the horizontal position, thrust to compensate for the aerodynamic drag.

[0069] However, when the cruising altitude is reached, the control unit 25 also moves the front propellers to the horizontal position and stops them, and transfers them to an aerodynamically favorable position to minimize aerodynamic drag. The rear and front propellers of the thrust units 17, 19 are only activated in their horizontal position (with vertical thrust vector) to generate thrust during the transition from the forward flight phase to the hovering flight phase. Furthermore, the following emergency procedures are stored in the control unit 25: [0070] If a failure or discharge of a battery unit of the battery system 23 is detected, the respective electric motor 21 connected to the failed battery unit is supplied with electrical energy generated by an electric generator of the internal combustion engine 9, at least for the hovering flight phase. [0071] If a failure of the internal combustion engine 9 is detected in the forward flight phase within a range having a minimum altitude dependent on a forward speed, the thrust nacelles 13, 15 are controlled to pivot into an autorotation position, an automatic gliding flight with a gliding phase assisted by the wing parts 3, 5 is initiated together with a warning to the pilot, and the thrust units 17, 19 are controlled to generate thrust immediately before the aircraft 1 touches down on the ground, even before a stall occurs due to an extended flare maneuver initiated by the pilot or the control unit 25.

[0072] FIG. 2 shows the aircraft 1 in side view, which is shown in FIG. 1 drawn from above.

[0073] FIG. 3 shows an alternative embodiment of the aircraft 1, wherein, in contrast to that shown in FIG. 1 and FIG. 2, all propellers of the respective thrust unit 17, 19 are fixed in a horizontal position. The control unit 25 then stops all propellers of the thrust units 17, 19 for the forward flight phase without pivoting them for the forward flight phase. In this case, the control variables of the flight control include speed changes of the propellers of the left thrust unit 17 and the right thrust unit 19 at a constant blade angle, as well as those mentioned above of the thrust nacelles 13, 15.

[0074] Although the invention has been further illustrated and described in detail byway of preferred example embodiments, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention. It is therefore clear that a variety of possible variations exists. It is also clear that embodiments mentioned as examples are really only examples, which are not to be construed in any way as limiting the scope of protection, the possible applications, or the configuration of the invention. Rather, the preceding description and the description of the figures enable a person skilled in the art to implement the example embodiments, wherein a person skilled in the art may make various changes knowing the disclosed inventive concept, for example with regard to the function or arrangement of individual elements cited in an example embodiment, without departing from the scope of protection as defined by the claims and their legal equivalents, such as more extensive explanations in the description.

LIST OF REFERENCE NUMERALS

[0075] 1 aircraft [0076] 3 left wing section [0077] 5 right wing section [0078] 7 fuselage [0079] 9 internal combustion engine [0080] 11 shaft [0081] 13 left thrust nacelle [0082] 15 right thrust nacelle [0083] 17 left thrust unit [0084] 19 right thrust unit [0085] 21 electric motors [0086] 23 battery system [0087] 25 control unit