Carrier drone or towed drone

Abstract

Method for operating an aircraft (5), (145) characterized in that the aircraft (5), (145) is equipped with at least one attachable and detachable towed drone (10ae), (10mk), (10mkae) with wings (120), (180) on which drives are attached to booms (50), (55) or pylons above or below the wings (120, 15), consisting of a motor (30) and a propeller (40), is connected indirectly by a tow rope (9) or tow bar or directly on fuselage (140), nose (190) of the aircraft (5), (145) or directly on the wing (20) of the aircraft (5), (145) and that the aircraft (5,145) is towed by the connected towing drone (10ae), (10mk), (10mkae) Push or It receives thrust and lift.

Description

[0001] The major problem with electric flight is the low energy content of current batteries. The energy density of robust lithium iron phosphate batteries is approximately 100 Wh / kg. Currently, the maximum energy density for the more sensitive lithium iron polymer batteries is approximately 200 Wh / kg.

[0002] A great deal of energy is consumed during takeoff. The batteries required for this put a strain on the aircraft during cruise flight. The question is: How can the weight of the batteries be kept as low as possible during cruise flight?

[0003] The state of the art is the so-called hybrid drives, which have a relatively small battery for the energy-intensive takeoff, which is charged during cruise flight by a generator connected to an internal combustion engine.

[0004] Fuel cells are now also being used as alternatives to electrical power.

[0005] Self-propelled gliders are usually launched with launch winches or by aerotow. Applied to the starting problem of electric flight, this means that electric aircraft should be launched with external aids that do not impede later cruise flight. It is conceivable to launch an electric aircraft using a winch launch or an aerotow. The disadvantages of this approach are the complex infrastructure required for a winch launch and the fact that, with an aerotow, the entire tow aircraft, including the pilot, must be lifted into the air.

[0006] Towing model aircraft is also state of the art.

[0007] Connecting two aircraft to each other is also state-of-the-art, for example, the transport of the space shuttle on a jumbo jet or the German Mistel project during World War II. The release of missiles from an aircraft is also state-of-the-art.

[0008] For drones, one can base their design on existing concepts, which are controlled either by varying thrust (thrust vector control) like multicopters or by aerodynamic rudder like an aircraft (usually in a kite configuration). Landing can occur either vertically or in a horizontal descent. Since fixed-wing aircraft are significantly more energy-efficient than multicopters, the characteristics of fixed-wing aircraft (such as a kite configuration) should be considered for drones. Multicopter-like drones with fixed-wing flight characteristics are described in DE 10 2017 212 716 A1, DE 10 2011 000 651 A1, and DE 10 2016 120 671 A1.

[0009] The "thermik2go" process is familiar from Aero 2019. Drive units, including the accumulator, are slid onto the wings using scissors (www.thermik2go.de).

[0010] DE 10 2018 116 164 A1, filed by Porsche AG, proposes the principle of a multicopter battery drone without wings, which is intended to increase the efficiency and assist the take-off of a vertical take-off electric aircraft, eVTOL, by connecting it to the top of the eVTOL with a locking device.

[0011] US 2007 / 0145 182 A1 describes a one-way launch system for a winged aircraft, consisting of a motor with a battery and motor controller, but without wings or aerodynamic control. This launch system is positively attached to the nose of the aircraft and jettisoned after takeoff. It is essentially a two-stage aircraft system, similar to those used in rockets or spacecraft.

[0012] US 2014 / 0 158 812 A1 also presents a two-stage launch system for aircraft, both for small UAVs and very large spacecraft. The aircraft are connected along a common fuselage centerline. However, each stage is also individually flight-capable and reusable.

[0013] US 2019 / 0 152 605 A1, filed by Boeing, describes a detachable fixed-wing drone that functions as a flying electrical power source, a type of battery-powered drone, that is attached to or inside an aircraft. After delivering power to the aircraft, the detachable battery-powered drone flies to a recharging station.

[0014] US 2016 / 0288 918 A1 proposes the use of both jettisonable and in-flight dockable batteries to increase the range of electric aircraft. One embodiment of these batteries is a winged UAV with or without its own propulsion, i.e., a battery drone. These battery drones supply electrical energy to the aircraft via various connection types. However, the connections between the battery drone and the aircraft are only designed to be mechanically stable enough to serve as a towed connection between the two aircraft in special cases. The drives of these battery drones and the aircraft described are only in the Fig. 5d and are located as propellers in the nose of the fuselage. To ensure ground clearance for larger propellers during takeoff with this propeller arrangement, a launch carriage with a high landing gear that can be detachable at the moment of takeoff is proposed. For landing the aircraft with very low landing gear, the propellers must be positioned parallel to the cowling or the wing. Other propulsion systems for the aircraft and the towing drones, not shown in the drawings, are therefore located in the area of ​​the leading edge of the wing. Due to this configuration, changes in the center of gravity can occur when releasing the battery-powered drones, which must be compensated for by an internal balancing system.

[0015] The advantages of a towed drone with drives on booms above or below the wings are explained in more detail in the following description. Description:

[0016] The invention therefore proposes launching gliders, especially older glider types that have seemingly become obsolete in the age of self-launching aircraft, such as Bergfalke III, Ka-8, etc., but also larger aircraft, such as electric commercial aircraft, while towing one or more drones. This type of drone could be synonymously referred to as a towing drone, launch carrier, carrier drone, launch-assistance drone, or launch drone. These towing drones are connected to the aircraft for takeoff, are released after reaching altitude, and fly—like a normal tow aircraft—to the starting point or another destination.

[0017] The concept of a towed drone is, of course, not limited to electric propulsion with batteries. Towed drones with heat engines, such as piston engines or turbines, pressurized storage propulsion systems, such as superheated steam or compressed air, or other forms of chemical energy conversion, such as rocket engines, are also conceivable.

[0018] The state of the art for a tow connection is the tow rope.

[0019] The connection between the towing drone and the aircraft can be rigid, loose (only by tension), dampened, variable-length, or elastic. For example, a tow bar could be used, similar to that used in a car, which can be rigid, elastic, variable-length, or dampened.

[0020] Towing is usually done in the direction of the aircraft's longitudinal axis. Towing an aircraft in the direction of its vertical axis is equivalent to vertically lifting the entire mass of the towed assembly and is certainly as energy-wasting as transporting goods with multicopter parcel drones.

[0021] In normal aero-tows, the term "tow train" is used. In general, the extended term "tow system" should be used for the connection between an aircraft and a towing drone.

[0022] A fundamental advantage of the towed drone as an external, non-manned component is the lower safety requirements and thus the lower manufacturing and operating costs, since this component can be detached from the main aircraft at any time. The fire source of an ignited battery can then be jettisoned, so to speak.

[0023] Lower requirements for reliability and the elimination of the tow pilot mean, on the one hand, a lower weight for towed drones compared to conventional tow aircraft, but it also means that the towed aircraft can have a lower flight mass or an increased payload or range.

[0024] Since the towed drone can be assembled from many identical units, so to speak as a modular system, this modular system achieves a level of redundancy through the large number of units that can compensate for the lower reliability of the individual units.

[0025] The variability of the drone in a kind of modular system means easy manufacturability and thus cost-effective production and easy replacement of defective units during operation, which in turn results in low operating costs.

[0026] The drone as an electric propulsion system can certainly represent a self-sufficient, environmentally friendly and, in the long term, cost-effective and sustainable alternative to the current heat engine-based aviation, especially at airfields and gliding sites without a power connection, in combination with photovoltaic systems or wind turbines to generate electricity.

[0027] As a classic design for a towed drone, it's conceivable to attach a large towed drone to the fuselage, for example, at the wing-fuselage junction. This can be based on the classic four-point wing-fuselage connection. If the drone has a wing, it can be considered an additional wing. The towed system is then a multi-plane.

[0028] It is also conceivable to install detachable towing drones on the wings. These drives could be slid onto the airfoil from the front like gloves, located on the top or bottom of the wing, or on the trailing edge of the wing. The drone mount can also be slid onto the wing like a scissor, thus ensuring no structural changes. The towing drone is then connected to this slid-on mount.

[0029] A problem with attachment to the wings can be the wing bending moment at the wing root, which can become excessive with additional lift bodies and increased lift. The maximum towing speed should be adjusted accordingly. Alternatively, flaps could be installed on the wings of towed drones to control the amount of lift. In extreme cases, the towed drone is designed and controlled in such a way that only thrust is applied, and the drone's lift force just compensates for the additional weight force on the wing. The drone then only generates lift for itself.

[0030] Thinking further, new aircraft can of course be designed to accommodate the increased wing bending moment created by lift-enhancing drones on the wings, whereby the use of towed drones can increase both thrust and lift.

[0031] The tow drone can be a conventional multicopter drone that is pushed onto the nose of the fuselage, onto the wings, or onto the tail fins using a form-fitting attachment contour that can be removed from the aircraft. After release, this type of drone rotates 90° and flies as a "classic" multicopter drone using the lift of the rotor blades. To minimize drag during towing, the drone's central body and the rotor mounts should be profiled. If a multicopter drone with a wing-based central body is used, this drone can also return to the starting airfield in horizontal flight – thus more energy-efficient than a conventional drone – which increases the range of the overall system. Biplane or even multiplane configurations are also conceivable.

[0032] The landing of these drones can then take place vertically but in principle also horizontally.

[0033] Instead of the kite configuration, a towing drone in the form of a flying wing, a canard, or a tandem configuration with or without sweep can also be useful, especially if there is no space for a long fuselage as a tail boom for the corresponding towing application.

[0034] The towed drone can also be equipped with a paraglider that opens after release or before landing, so that the drone has a lower wing loading for landing.

[0035] If aerodynamically controlled drones are used, they can be attached to the fuselage or wings, for example on the upper or lower side of the wing. The glider or even a commercial aircraft is then towed by smaller aircraft connected to it, i.e. towed drones. For model aircraft, this means that a glider is towed by, for example, one or two towed drones, which are in a sense special model aircraft. Since there are legal weight limits for model aircraft and drones in Germany, e.g. 25 kg, 150 kg, it can be useful to split the towed drones into several lighter units. From takeoff to release, these aircraft are controlled by the towed aircraft. Model aircraft pilots can then continue to control these aircraft after the towed aircraft has been released until landing, which could certainly create a new connection between these air sports.

[0036] It is also conceivable, however, that the entire towing process with towed drones, i.e., drone towing, takes place in such a way that the pilot controls the towed drones from takeoff until they are released, for example, the thrust. After release, the towed drones, or rather the towed drone, then fly autonomously to the starting point or another destination. It is also conceivable that the towed drone could fly autonomously to another airfield to tow an aircraft there.

[0037] In gliders, the release mechanism in the cockpit could be used to actuate the release. Electromechanical, mechanical, electromagnetic, or pneumatic release mechanisms are conceivable for coupling the aircraft to the towing drone.

[0038] Connecting the aircraft and towing drone changes the center of gravity and the air attack point of the towing system. During operation, care must be taken to ensure that the system remains inherently stable or is kept stable by suitable control devices.

[0039] One can distinguish between three focal points and air attack points: a) the aircraft, b) the towed drones c) the towed system. Control of the system:

[0040] Depending on the type of towing system, various control and regulation methods are conceivable: a) Control during towing using only the controls of the towed aircraft; b) Control during towing using controls of both the towed drone and the aircraft; c) Control using only the controls of the towed drone (e.g., vertical towing of a fixed-wing aircraft). The control elements used here include the aerodynamic rudder and thrust vector control.

[0041] The dimensions of tow drones can also vary considerably. Tow drones for commercial aircraft must be correspondingly larger than those for small aircraft. Depending on the purpose of the tow drone, a distinction can be made between pure takeoff drones, i.e., those that can tow an aircraft as high as possible near an airfield, and cruise drones, which, in addition to takeoff, are also used as propulsion for a specific portion of the cruise flight to increase the range of the overall system.

[0042] When it comes to the takeoff procedure, a distinction can be made between towing drones that load the aircraft and its landing gear with their weight before takeoff and those that stand on their own landing gear and therefore do not transfer any additional weight force to the aircraft being towed.

[0043] The release process can be based on the release process in gliding or the release of missiles.

[0044] The released towed drones should return to their departure or destination airfield in special flight corridors or on special flight surfaces, especially if above FL100.

[0045] In the case of towing drones that have towed commercial aircraft from controlled airfields, control or steering can also be carried out directly by air traffic control. Alternatively, a dedicated towing center at commercial airports could be established, which would be responsible for taxiing the towing drones to the aircraft to be taken off, engaging, taking off, towing, releasing, returning, landing, and taxiing to the towing drone parking area.

[0046] It is also conceivable that the towed drone could be reconnected to the aircraft before landing. Using the towed drone for takeoff and landing has the significant advantage that the aircraft only needs to be configured for cruise flight. A critical scenario, of course, is that the aircraft cannot find a landing drone for landing. In this case, the aircraft would have to touch down at a higher speed than when coupled with a landing drone. The aircraft's lift-enhancing capabilities, as well as emergency braking devices, such as a drogue parachute, would naturally have to be designed for this emergency.

[0047] The towed drone then replaces, in a way, the high-lift system required for takeoff and landing, either completely or partially.

[0048] The use of retractable drives can be useful for both towed drones and towed aircraft; a) because high-speed drives are not suitable for takeoff, b) because a retracted drive cannot be damaged during the release or re-engagement process, and c) because retracted drives do not offer any resistance.

[0049] The propulsion systems of towed drones can be mounted on booms or pylons, allowing the drive to be tailored to the specific characteristics of the aircraft being towed or the towing system, such as the center of gravity and air attack point. Of course, propulsion systems for towed drones can also be mounted as impellers in or near the wings.

[0050] The power supply of the towing drones can be located in the central body, the wings, the tail booms or the fuselage. Various forms of power supply for the towing system can be implemented. In the simplest case, the towing drone and the towed aircraft have two independent and separate power supplies. In order to keep the range of the aircraft as long as possible, part or all of the propulsion energy from the towing drone's energy reserves can be supplied to the aircraft's engines during the towing process. In this case, the power supplies of the towing drone and the aircraft are, in a sense, connected to one another. In addition to a towing connection, the towing system also requires a detachable connection for the power flow, comparable, for example, to the connections between batteries and chargers in cordless screwdrivers.

[0051] If the towing drone also supplies the aircraft with energy during takeoff, its weight and thus its size will increase. Drones with wings are certainly more efficient for this solution.

[0052] For safety reasons, the release mechanism can detach the drone from the towed aircraft, as well as detach the towed aircraft from the drone. The connection is essentially an intermediate component into which both aircraft engage. Typically, this intermediate component remains on the towed drone.

[0053] Of course, a simple, detachable connection between the towing drone and the aircraft is also conceivable. For safety reasons, the connection could be severed by a "destructible" connection, e.g., a cutting device like those used in winch launches in gliders, or by explosive cartridges.

[0054] For gliders, one could also imagine a towing drone that is attached to the nose of the aircraft. Its connection to the aircraft is most easily achieved through a positive fit on the nose and via the nose coupling. Additional couplings are, of course, conceivable. Such a drone would make the overall system more nose-heavy, so this drone would need to have buoyancy devices to balance its own weight so that the towed aircraft is neither too nose-heavy nor too tail-heavy. This drone could be a biplane or ring-wing multicopter drone capable of both horizontal and vertical landing.

[0055] The connection of power supply and towing power transmission can be made in two separate units or in one unit. Drawings Fig. Figure 1 shows the three axes of an aircraft 5 in kite configuration: the longitudinal axis 1, the transverse axis 2, and the vertical axis 3. In this aircraft, the wings run approximately in the direction of the transverse axis 2. The wing axis 7 runs approximately in the direction of the transverse axis 2. The X-axis is assigned to the transverse axis 2, the Y-axis to the longitudinal axis 1, and the Z-axis to the vertical axis 3. This aircraft 5 is connected to the cable boom 6 of the towing drone 10ae via the nose coupling 8 and a tow rope 9. This boom also symbolizes the longitudinal axis 1 of the towing drone. This tow combination, consisting of the glider 5 and the towing drone 10ae, is still strongly based on the classic aerotow. The towing drone 10ae consists of a wing 120 that rolls on the landing gear 60. The towed drone is powered by motors 30 mounted on booms 50, which drive propellers 40. The propeller circle is also designated 40 in the following. The towed drone is controlled via tail booms 70, which extend from each engine boom 50 beyond the trailing edge 80 of the wing. Additionally, control surfaces acting as ailerons, elevators, or flaps could be attached to the trailing edge 80 of the wing. Steering around the vertical axis 3 of the towed drone can also be achieved using thrust vector control. In Fig. 2 shows a towed drone 10mk, which is pushed onto the wing nose 25 of the wing 20 with its center body 15. Booms 50 are attached to the top and bottom of the fuselage or center body 15 of the towed drone 10mk. These booms carry the drive motors 30, which in turn drive the propellers 40. The center of gravity of the (towed) drone is marked 90d, that of the aircraft is marked 90f, and that of the drone-aircraft system is marked 90s. Attaching a mass in front of the center of gravity relative to the Y-axis 1 makes the overall system more top-heavy. The center of gravity of the overall system, 90s, is located to the left of the aircraft's center of gravity, 90f. Fig. 3 shows the towed drone 10mk of Fig. 2 in perspective view. You can see 2 rows of drives on the top 100o and bottom 100u of the Center body 15 of the 10mk towed drone. 40 denotes both the propeller and the corresponding propeller circle. Starting with a drive module consisting of boom 50, motor 30, and propeller 40 with a short center body 15, the ten-motor drive system shown here can be constructed modularly. Fig. 4 shows the towed drone 10mk of the Fig. 2 and Fig. 3 in vertical flight. Rigid or extendable landing struts 110 are located beneath the motors 30 located on the booms 50, so that the propellers 40 are not damaged during a vertical landing. The center body 15 of the drone is designed so that it is flush with the lower edge 210 defined by the landing struts 110 and does not protrude beyond it. Fig. Figure 5 shows a drone 10ae with a center body 15 that can be slid onto a wing and features only one upper drive train 100o. Additional tail units 70 extend rearward from the booms 50 that support the motors 30, allowing this towed drone to be aerodynamically controlled. The center body 15 then acts as a not necessarily very good wing profile. Landing is possible on fixed or retractable skids or landing gear, which are not shown in the drawing. Fig. 6. shows the towing drone 10ae of Fig. 5 in side view. Landing gear or skids are not shown. Fig. 7 shows a towing drone comparable to Fig. 5 in a side view. Here, the center body is a profiled wing 120. The tail boom 70 could be even longer to increase the lever arm of the tail units 75. Additionally, the trailing edge 80 of the wing 120 can be equipped with control surfaces 130 for elevator or aileron control. The fastening elements for connecting to the wing or fuselage of the aircraft to be towed are not shown. Fig. 8 shows a towed drone 10ae comparable to that of Fig. 7 in perspective view. In this version, the tail booms 70 are significantly extended beyond the trailing edge 80 of the wing 120. Fig. 9 shows a towed drone 10ae comparable to that of Fig. 7, which is latched onto the fuselage 140 of a commercial aircraft with the wing 20 and the flight direction 150. The connection between the towed drone and the aircraft is made via a transition element 160, to which the landing gear 60 and the latching device 170 are attached. Fig. 10 shows the situation of Fig. 9 from the front. The latching device 170 consists of bolts that can be moved in the direction of the X-axis, i.e., the transverse axis 2, outward for engaging and inward for disengaging. The landing gear 60 is slightly offset from the fuselage 140. The transition element 160l,r is split and functions both as the landing gear support and as a receptacle for the latching device 170. Additionally, a detachable electrical connection for supplying the aircraft with power from the drone batteries could be provided here. This is not shown. Fig. Figure 11 shows a towed drone 10mkae, which is a hybrid of a multicopter and a fixed-wing aircraft. Two wing profiles 120o,u are connected by a center body 15 and are positively mounted on a wing 20 such that the center of gravity of the drone 90d and the center of gravity of the aircraft 90f are very close together, or rather, on top of each other. The center body 15 does not have to be in Fig. 2 and Fig. 3 extend over the entire span of the wings 120o,u, but can be made very slim, e.g. comparable to the connecting body 160 of Fig. 9 and Fig. 10. The motors 30 are mounted on outriggers 50 on the wings 120o,u and drive the propellers 40. In principle, this drone could also be controlled in horizontal flight using thrust vectoring alone. However, control surfaces 130 can also be provided on the trailing edges of the wings. Fig. Figure 12 shows the towed drone 10mkae unlatched. The landing struts 110, necessary for vertical landing, are extended. Fig. Figure 13 shows the towed drone 10mkae in vertical flight. The struts 50 pointing outward from the wings 20o,u enable large propeller circles 40, represented here by the dashed double arrows. Fig. Figure 14 shows a towed drone 10ae mounted beneath the fuselage 140 of an aircraft with wing 20 and driven by the propulsion arrays 100. The aircraft's propulsion and tail assembly are not shown. These may be mounted, for example, on the tail or on the wings 20, or retracted. The landing gear of the aircraft 65 and the drone 60 are extended. The landing gear struts are not shown. Fig. 15 shows the towed drone 10ae of Fig. 14. The center section of the towing drone 160 connects the two wings 120 and is shaped to suit the aircraft to be towed or the contour to which it is coupled. Fig. 16 shows the towing system of Fig. 14 from the front with the landing gears of aircraft 65 and the towing drone 60 extended. The engine rows 100 are located approximately centrally in front of the wings 20 of aircraft 145. Fig. 17 -19 show different positions of the towing drone 10ae from Fig. 14 under an airplane 145. Fig. 17 shows the towing system of Fig. 14 from the side. The center of gravity 90d of the towing drone 10ae is located in front of the center of gravity 90f of the mid-wing aircraft 145. The overall system becomes more nose-heavy, and the center of gravity of the towing system 90s moves in front of the center of gravity of the aircraft 90f. A location for the engines of the aircraft 145 (not shown) would be on wing 20. Fig. Figure 18 shows a towing system consisting of towing drone 10ae and aircraft 145 from the side. The center of gravity 90d of towing drone 10ae is located behind the center of gravity 90f of the mid-wing aircraft 145. The overall system becomes more tail-heavy, and the center of gravity of towing system 90s moves behind the center of gravity of aircraft 90f. Space for the engines of aircraft 145 (not shown) would be on wing 20 or on the leading edge 25. Traditional engine mounts on pylons under the wings with the intake opening well forward of the nose would also be conceivable here. Fig. Figure 19 shows a side view of a towing system consisting of a towing drone 10ae and a high-wing aircraft 145. The center of gravity 90d of the towing drone 10ae is located approximately below the center of gravity 90f of the aircraft 145 but at approximately the same Y-position along the longitudinal axis 1. The center of gravity of the entire system 90s is located lower than the center of gravity 90f of the aircraft with respect to the vertical axis 3. A location for the engines of the aircraft 145 (not shown) would be on the wing 20 or on or below the leading edge 25. Fig. Figure 20 shows a 10mkae towing drone for a 145-inch glider (shown without tail section and tail unit), which is latched onto the aircraft nose 190 in a side view. The abbreviation for the 10mkae towing drone is intended to express "multicopter-like and aerodynamic" controllability. The 145-inch glider has a center landing gear 65. This 10mkae towing drone carries its weight on the ground via its own landing gear 60 and in the air via the ring wing 180 (shown here in section), to which aerodynamic rudders can also be attached to control lift. These are not shown here. The 10mkae towing drone is positively connected to the aircraft nose 190 via the center body 15. The center body 15 is in the Fig. 20-22 are cut open in the middle to clearly show the form fit to the aircraft nose 190. An adapter body (not shown here) can be provided between the center body 15 and the aircraft nose 190 to enable a form fit connection between the towing drone and the respective aircraft type. The latching device is not shown. A connection 200 runs from the center body to the booms 50 of the drive motors 30, which drive the propellers 40. The ring wing is attached via the extension 55 of the booms 50. In principle, the towing drone 10mkae can land both horizontally and vertically. Vertical landing struts should be provided for vertical landing. These are not shown or are retracted. The landing gear struts for the landing gear of the drone 60 and the glider 65 have been shown for clarity. Fig. 20 - Fig. 22 omitted. Fig. 21 shows the towed drone 10mkae and the aircraft 145 of Fig. 20 in a perspective view obliquely from the side. The central body 15 and the annular wing 180 are cut open. Fig. 22 shows the towed drone 10mkae with complete ring wing 180 but still half-cut central body 15 in an oblique front view.

[0056] The use cases listed here demonstrate that the towed drone concept can be applied to many types of aircraft. This towed drone concept can also be applied to aircraft with heat engines, or implemented using heat engines. The major advantage of distributed propulsion, and thus the greater design flexibility and controllability offered by thrust vectors, only becomes fully apparent when electric motors are used. The use of hydraulic motors to implement distributed propulsion in towed drones also suffers from the lower efficiency of hydraulic energy transmission via turbomachinery instead of power lines.

[0057] The towed drone is therefore a consequence and necessity for electric flight - at least as long as the energy density of the batteries is still so low.

[0058] The center of gravity, or rather the air attack point, of the towing system can be adjusted using the drone's own wings, so that the drone transfers virtually no weight force to the aircraft, but only thrust. The center of gravity can be kept within the aircraft's permissible limits by securing the towing drone near the center of gravity.

[0059] On the ground, one can distinguish between the case where the towing drone has its own landing gear or where it has no landing gear of its own and places a load on the landing gear of the aircraft when stationary and taxiing.

[0060] For the connection of the drone to the aircraft, different adapters can be provided for each aircraft type for the positive connection, for example on the tip of the fuselage or wing nose or on the top or bottom of the fuselage, so that many different aircraft types can be towed with one drone. Designations ae aerodynamic F-tow aircraft tow mk multicopter mkae multicopter aerodynamically mixed SD tow drone 1 Longitudinal axis - Y-axis 2 Transverse axis - X-axis 3 Vertical axis - Z-axis 5 aircraft 6 rope booms 7 wing axis 8 Bow coupling 9 Tow rope 10ae,mk,mkae carrier drone aerodynamic, multicopter-like and combination 15 Fuselage or midbody of the drone 20 wing profile, wing aircraft 25 wing nose 30 engine 40 propeller or propeller circle 50 booms 55 Extension boom to ring fl 60 landing gear drone 65 landing gear aircraft 70 tail boom with tail unit 75 tail unit 80 wing trailing edge 90d,g,f Focus on drone, overall system, aircraft 100; 100o,u series of drives; top, bottom 110 landing struts 120 wing drone 130 rudder area 140 fuselage commercial aircraft 145 Airplane, Glider 150 Flight direction 160,160l,r transition element drone-aircraft, left,right 170 latching device 180 ring wings 190 Aircraft nose 200 Connection from the center body to the drives 210 bottom edge

Claims

[1] Procedures for the operation of an aircraft (5), (145) characterized by that the aircraft (5), (145) is provided with at least one towed drone (10ae), (10mk), (10mkae) which can be engaged and disengaged and has wings (120), (180) to which drives are attached to booms (50), (55) or pylons above or below the wings (120, 15), consisting of an engine (30) and a propeller (40), is connected, indirectly by a tow rope (9) or a tow bar or directly to the fuselage (140), the fuselage nose (190) of the aircraft (5), (145) or directly on the wing (20) of the aircraft (5), (145) and that the aircraft (5,145) is connected to the towed drone (10ae), (10mk), (10mkae) thrust or receives thrust and lift. [2] Method according to claim 1 characterized bythat the towed drone (10ae, 10mk, 10mkae) has an aerodynamic control by means of rudder surfaces (130) or thrust vector control. [3] Method according to claims 1 and 2 characterized by that the connection between the towed drone (10ae, 10mk, 10mkae) and the aircraft (145, 5) is made by means of positive locking in conjunction with a mechanical, pneumatic or electrical latching device. [4] Method according to claims 1 to 3 characterized by that the towed drone (10ae, 10mk, 10mkae) carries its own weight on the ground through its own landing gear (60). [5] Method according to claims 1 to 4 characterized by that the towed drone (10ae, 10mk, 10mkae) carries its own weight in the air by means of its own wings (120). [6] Method according to claims 1 to 5 characterized by that the towing drone (10ae, 10mk, 10mkae) provides additional lift for the aircraft (145, 5), thus carrying more than its own weight. [7] Method according to claims 1 to 6 characterized by that the towed drone (10ae, 10mk, 10mkae) is attached close to the center of gravity (90f) of the towed aircraft (145, 5). [8] Towed drone according to claims 1 to 7 characterized by that the center of gravity (90d) of the towing drone (10ae, 10mk, 10mkae) is located between the drives attached to booms (50, 55) or the propeller circles (55) of the drives, so that the towing drone can land vertically on the landing struts (110) after being released, rotated by 90°. [9] Towed drone according to claims 1 to 8 characterized by that the towed drone (10ae, 10mk, 10mkae) is controlled via the towed aircraft (145, 5). [10] Towed drone according to claims 1 to 9 characterized by that the towed drone (10ae, 10mk, 10mkae) can be adapted to different aircraft types using adapters.

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