Method and system for maintaining lateral control of an unmanned aerial vehicle during landing - Patents.com

Abstract

The system, apparatus, and method includes an unmanned aerial vehicle (UAV) (101), one or more inner wing panels (107) of the UAV, one or more outer wing panels (109) of the UAV, at least one inboard propeller (140) mounted to at least one engine (110) disposed on the one or more inner wing panels, at least one tip propeller (141) mounted to the at least one engine (110) disposed on the one or more outer wing panels, and at least one microcontroller (420), wherein the microcontroller is configured to determine an angular position of the at least one inboard propeller and to send a signal to stop rotation of the at least one inboard propeller such that the at least one inboard propeller is held in an attitude that provides clearance for the propeller blades to the ground upon landing.

Description

[Technical field]

[0001] The present embodiments relate generally to unmanned aerial vehicles (UAVs), and more particularly to maintaining lateral control of a UAV during landing with inboard propellers level.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62 / 945,815, filed December 9, 2019, the contents of which are incorporated herein by reference for all purposes. [Background technology]

[0003] Unmanned aerial vehicles (UAVs), such as high-altitude, long-endurance aircraft, are light aircraft capable of controlled, sustained flight. UAVs may associate with a ground operator for two-way communications. Summary of the Invention

[0004] One embodiment may include a system for maintaining lateral control of an unmanned aerial vehicle (UAV) during takeoff and landing with inboard propellers level, in one embodiment, the UAV is a high altitude, long endurance solar powered aircraft.

[0005] An embodiment of the system includes an unmanned aerial vehicle (UAV), one or more inboard wing panels of the UAV, one or more outer wing panels of the UAV, the one or more outer wing panels disposed on either side of the one or more inner wing panels and the one or more outer wing panels disposed at an upward angle relative to a plane formed by the one or more inner wing panels, at least one inboard propeller mounted to at least one engine disposed on the one or more inner wing panels, at least one tip propeller mounted to the at least one engine disposed on the one or more outer wing panels, and at least one microcontroller in communication with the at least one engine disposed on the one or more inner wing panels, the at least one microcontroller configured to determine an angular position of the at least one inboard propeller and to send a signal to stop rotation of the at least one inboard propeller such that the at least one inboard propeller is held in an attitude that provides ground clearance for the propeller blades upon landing.

[0006] In additional system embodiments, the UAV may be a high altitude long endurance aircraft. In additional system embodiments, the solar array may cover at least a portion of the one or more inner wing panels and the one or more outer wing panels. Additional system embodiments may further include one or more landing pods of the UAV, the one or more landing pods may be attached to the one or more inner wing panels of the UAV to assist in landing the UAV. In additional system embodiments, a distance (d1) from the center of the propeller hub to the tip of the at least one inboard propeller is greater than a height of the one or more landing pods, and the at least one inboard propeller may strike the ground during rotation of the at least one inboard propeller when the UAV is on the ground. In additional system embodiments, the at least one outboard propeller may be identical to the at least one inboard propeller, and the at least one outboard propeller may rotate freely when the UAV is on the ground.

[0007] Additional system embodiments may further include a position sensor in communication with the microcontroller, the position sensor detecting a position of the at least one inboard propeller. In additional system embodiments, the position sensor may be a Hall effect rotary position sensor. In additional system embodiments, the at least one microcontroller may be further configured to determine an altitude of the UAV and transmit a signal to stop rotation of the at least one inboard propeller if the determined altitude is below a threshold altitude. In additional system embodiments, the at least one microcontroller may be further configured to transmit a signal to adjust rotation of the at least one outboard propeller while the at least one inboard propeller is held in an attitude that provides ground clearance for the propeller blades. In additional system embodiments, the at least one microcontroller may be further configured to determine an altitude of the UAV and transmit a signal to start rotation of the at least one inboard propeller if the determined altitude is above a threshold altitude.

[0008] An embodiment of the method may include determining, by at least one microcontroller, an altitude of an unmanned aerial vehicle (UAV); determining, by at least one microcontroller in communication with at least one engine of the UAV, an angular position of at least one inboard propeller connected to the at least one engine, wherein the at least one inboard propeller is disposed on one or more inner wing panels; and sending, by the at least one microcontroller, a signal to stop rotation of the at least one inboard propeller such that the at least one inboard propeller is held in an attitude that provides ground clearance for the propeller blades if the determined altitude is below a threshold altitude, wherein the at least one inboard propeller may hit the ground during rotation of the at least one inboard propeller when the UAV is on the ground.

[0009] Additional method embodiments may further include transmitting, by the at least one microcontroller, a signal to adjust rotation of at least one outboard propeller connected to the at least one engine, while the at least one inboard propeller is held in an attitude that provides propeller blade to ground clearance upon landing, the at least one outboard propeller being disposed on one or more outer wing panels. In additional method embodiments, the at least one outboard propeller is identical to the at least one inboard propeller, and the at least one outboard propeller is free to rotate when the UAV is on the ground.

[0010] Another system embodiment includes an unmanned aerial vehicle (UAV), at least one inboard propeller mounted to at least one engine of the UAV, where at least a portion of the at least one inboard propeller may contact the ground surface during rotation of the at least one inboard propeller when the UAV is located on the ground surface, at least one tip propeller mounted to the at least one engine of the UAV, where the at least one tip propeller may rotate freely without contacting the surface during rotation of the at least one tip propeller when the UAV is located on the ground surface, and at least one microcontroller in communication with the at least one engine, configured to determine an angular position of the at least one inboard propeller and send signals to the at least one inboard propeller such that the at least one inboard propeller is held in an attitude that provides clearance between the propeller blades and the ground surface.

[0011] In additional system embodiments, the at least one microcontroller is further configured to send a signal to the at least one tip propeller to adjust thrust to guide the UAV for landing while the at least one inboard propeller is held in an attitude that provides ground clearance for the propeller blades, the at least one tip propeller maintaining lateral control of the UAV during landing. In additional system embodiments, the at least one microcontroller is further configured to send a signal to the at least one tip propeller to adjust thrust to guide the UAV for takeoff while the at least one inboard propeller is in an attitude that provides ground clearance for the propeller blades, the at least one tip propeller maintaining lateral control of the UAV during takeoff, the at least one microcontroller is further configured to send a signal to the at least one inboard propeller after takeoff to cause the at least one inboard propeller to begin rotating.

[0012] Additional system embodiments may further include one or more landing pods to aid in the safe landing of the UAV on the surface of the Earth, where a distance (d1) from the center of the propeller hub to the tip of the at least one inboard propeller is greater than a height (d2) of the one or more landing pods, and a distance (d1) from the center of the propeller hub to the tip of the at least one tip propeller is greater than or equal to a height (d3) from the center of the propeller hub of the at least one tip propeller to a bottom end of the one or more landing pods. Additional system embodiments may further include one or more inner wing panels of the UAV to which the at least one inboard propeller is attached, and one or more outer wing panels of the UAV, where the at least one tip propeller is attached to the one or more outer wing panels, the one or more outer wing panels are disposed on either side of the one or more inner wing panels, and the one or more outer wing panels are disposed at an upward angle relative to a plane formed by the one or more inner wing panels. Additional system embodiments may further include a position sensor in communication with the microcontroller, the position sensor detecting a position of the at least one inboard propeller. [Brief description of the drawings]

[0013] The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the present invention. Like numerals refer to corresponding parts throughout the various views. Embodiments are illustrated by way of example and not by way of limitation in the accompanying drawings. [Figure 1] FIG. 1 illustrates a system for maintaining lateral control of an unmanned aerial vehicle during landing with inboard propellers leveled, according to one embodiment. [Diagram 2] FIG. 2 illustrates a top perspective view of the unmanned aerial vehicle of FIG. [Diagram 3]Figure 3A shows a schematic diagram of a wing panel and associated propeller of the unmanned aerial vehicle of Figure 1. Figure 3B shows a schematic diagram of the wing panel and a two-bladed propeller held against the wing panel. Figure 3C shows a schematic diagram of the wing panel and a three-bladed propeller held against the wing panel. [Figure 4] FIG. 4 illustrates an exemplary top-level functional block diagram of an embodiment of a computing device. [Diagram 5] FIG. 5 shows a flow chart of the steps performed by the microcontroller for landing the UAV. [Figure 6] FIG. 6 shows a flow chart of the steps performed by the microcontroller for takeoff of the UAV. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Referring to FIG. 1, a system 100 for maintaining lateral control of an unmanned aerial vehicle (UAV) 101 during landing with inboard propellers leveled is shown. A UAV is an aircraft without an onboard pilot and can be flown autonomously or remotely. Larger UAVs can use landing pods for safe landing, which can create extra weight and drag. The UAV can use differential thrust from the UAV's propulsion system for lateral control in some flight regimes, including takeoff and landing. In one embodiment, the UAV 101 is a high altitude, long endurance aircraft. In one embodiment, the UAV 101 can have three or more motors, e.g., 3-40 motors, and have a wingspan of 100 feet to 400 feet. In one embodiment, the UAV 101 can have a wingspan of approximately 260 feet and can be propelled by multiple motors, e.g., 10 electric motors, driven by solar arrays covering the wing surfaces, thereby achieving zero emissions. The UAV101 is designed to fly above the clouds at an altitude of approximately 65,000 feet above sea level and conduct continuous, long-term missions of up to several months without landing.

[0015] The UAV 101 functions optimally at high altitudes and is capable of sustained flight for significant periods of time without resorting to landing. In one embodiment, the UAV 101 may have a weight of approximately 3,000 pounds.

[0016] The UAV 101 further includes at least one motor 110 coupled to the UAV 101 for propulsion of the UAV 101. In one embodiment, the motor 110 is a brushless DC motor of conventional configuration including an in-runner rotor electrically connected with windings in a Y configuration around a modified armature. The motor 110 may have a casing formed of steel or other high strength material to enclose and protect the motor. A stator is disposed around the outer periphery of the rotor, the stator having a backiron to contain the magnetic field of the stator. The rotor may be formed of any suitable magnets including permanent magnets such as neodymium or praseodymium, or electromagnets. The stator may have an armature constructed from layers of laminated electrical steel, such as silicon steel, with an oxide film disposed between each steel layer to reduce induced ring currents and increase the efficiency of the motor 110. Other armature materials may include iron or amorphous steel.

[0017] In one embodiment, the motor 110 is configured with windings wound around iron teeth. Additionally, there may be a layer of magnets on the outside of the motor 110 that remain attached to the motor 110 until temperatures drop to approximately -80° C. This is advantageous since the UAV 108 often flies in temperatures approaching -80° C. at night and at high altitudes.

[0018] Some motors in the art may be iron-free to avoid hysteresis and eddy current losses that waste energy in the form of heat. In one embodiment, the motor 110 may incorporate permendur, such as Hiperco®, a cobalt-iron soft magnetic alloy with equal parts iron and cobalt. Permendur has very low hysteresis and eddy current losses and often outperforms iron-free motors. Additionally, iron has some very important properties that iron-free motors do not have: (1) it provides mechanical support for the windings, (2) it provides inductance, thus eliminating the need for external inductors, (3) it provides a means to transfer heat away from the motor, (4) it provides a very thin air gap, so much less magnetic material is needed to create the magnetic field, and (5) it keeps the magnetic field away from the copper, where a lot of energy is lost when the magnetic field passes through it.

[0019] As shown in FIG. 2, the UAV 101 may include one or more inner wing panels 107 and one or more outer wing panels 109, a central panel 108, a plurality of inboard propellers 140 associated with each inner wing panel 107, and a plurality of tip propellers 141 associated with each outer wing panel 109. The UAV 101 may further include one or more landing pods 113 for assisting in the safe landing of the UAV 101 at a landing site (102, FIG. 1). The one or more inner wing panels 107 may be disposed on either side of the central panel 108. In some embodiments, the central panel 108 may not be present and only the inner wing panel 107 may be used. In other embodiments, the inner wing panel 107 may be identical to the central panel 107. The one or more outer wing panels 109 may be disposed on either side of the one or more inner wing panels 107 and / or the central panel 108. The one or more outer wing panels 109 may be disposed at an angle relative to a plane formed by the one or more inner wing panels 107 and / or central panel 108. In some embodiments, the one or more outer wing panels 109 may curve upwardly relative to the plane formed by the one or more inner wing panels 107 and / or central panel 108. In one embodiment, the UAV 101 has a wingspan of approximately 260 feet and is propelled by multiple motors, e.g., ten electric motors, driven by solar arrays covering the surface of each wing, resulting in zero emissions.

[0020] 3A, the inboard propeller 140 of the one or more inner wing panels 107 of the UAV 101 and the tip propeller 141 of the one or more outer wing panels 109 of the UAV 101 can each include a propeller hub 142, a propeller blade 144, and a propeller blade tip 146. In one embodiment, the propellers 140, 141 can each have two blades 144. In another embodiment, the propellers 140, 141 can each have more than two blades 144. In one embodiment, the propellers 140, 141 can be identical. In one embodiment, the distance from the center of the propeller hub 142 to the propeller blade tip 146 is d1. With respect to the inner wing panel 107, the landing pod 113 proximate to the associated propeller hub 142 has a height d2.

[0021] In general, it may be desirable to reduce the height of the landing pod 113 to reduce the weight of the landing pod 113 and the drag induced by the landing pod 113 on the UAV 101. However, reducing the height of the landing pod 113 may be limited by the distance d1. For example, if the height d2 of the landing pod 113 is too low such that the distance from the center of the propeller hub 142 to the propeller blade tip 146 is equal to or greater than the height d2 of the landing pod (e.g., d1≦d2), when the inboard propeller 140 rotates while the UAV 101 is on or near the ground 150, such as during takeoff or landing, the blade 144 may strike the surface 150, such as the ground, causing damage to the UAV 101.

[0022] In one embodiment, the inboard propeller 140 may be leveled such that the blades 144 are in an orientation that provides propeller blade clearance with respect to the ground 150 when the UAV 101 lands. In some embodiments, an orientation that provides propeller blade clearance with respect to the ground 150 is when the blades of a two-bladed propeller are maintained approximately parallel to a plane formed by the one or more inner wing panels. In other embodiments, an orientation that provides propeller blade clearance with respect to the ground 150 is when the blades of a two-bladed propeller are maintained at an angle with respect to a plane formed by the one or more inner wing panels, such as at an angle with respect to the plane and / or not substantially perpendicular to the plane, such that the propeller blades do not contact the ground 150. In some embodiments, an orientation that provides propeller blade clearance with respect to the ground 150 is when the blades of a three-bladed propeller are maintained such that none of the propeller blades contact the ground 150 and / or the top propeller blade is substantially perpendicular to the plane. In one embodiment, the inboard propeller 140 and the tip propeller 141 can each include a microcontroller 420. Each microcontroller 420 can be in communication with a respective motor for each propeller 140, 141. In some embodiments, one microcontroller 420 can control one or more propellers, such as all of the inboard propellers 140. In one embodiment, each propeller 140, 141 has an associated microcontroller 420. In another embodiment, a single microcontroller 420 controls all of the propellers 140, 141. In another embodiment, one microcontroller 420 controls the tip propeller 141 and another microcontroller 420 controls the inboard propeller 140.

[0023] As described below, the tip propeller 141 may continue to function for propulsion and control purposes during landing and takeoff. More specifically, the height of the landing pod 113 may be set such that a distance d1 from the center of the propeller hub 142 to the propeller blade tip 146 is equal to or greater than a height d3 from the center of the propeller hub 142 to the bottom edge of the landing pod 113 (e.g., d1≦d3).

[0024] 3B shows a schematic diagram of a wing panel 107 and a two-bladed propeller 140 held against the wing panel 107. Each inboard propeller 140 can include a propeller hub 142, propeller blades 144, and propeller blade tips 146. In one embodiment, the distance d1 is from the center of the propeller hub 142 to the propeller blade tips 146. With respect to the inboard wing panel 107, the landing pod 113 proximate to the associated propeller hub 142 has a height d2.

[0025] In one embodiment, the inboard propeller 140 may be maintained in an attitude that provides propeller blade clearance relative to the ground 150. The blades of the two-bladed propeller 140 may be maintained at an angle 160 relative to a plane formed by the one or more inner wing panels 107, such as at an angle 160 relative to the plane and / or not substantially perpendicular to the plane, such that the propeller blades 144 do not contact the ground 150.

[0026] 3C shows a schematic diagram of a wing panel 107 and a three-bladed propeller 141 held against the wing panel. Each inboard propeller 141 can include a propeller hub 142, propeller blades 145, and propeller blade tips 147. In one embodiment, the distance from the center of the propeller hub 142 to the propeller blade tips 147 is d1. With respect to the inboard wing panel 107, the landing pod 113 adjacent to the associated propeller hub 142 has a height d2.

[0027] In one embodiment, the inboard propeller 141 may be maintained in an orientation that provides clearance between each propeller blade 145 and the ground 150. The blades of the three-bladed propeller 145 may be maintained at an angle relative to the plane formed by the one or more inner wing panels 107 such that the propeller blades 145 do not contact the ground 150. In one embodiment, the topmost propeller blade (i.e., the propeller blade 145 of the three-bladed propeller 145 having the propeller blade tip 147 furthest from the ground 150) may be substantially perpendicular to the plane formed by the inner wing panel 107. In other embodiments, the topmost propeller blade may be held at an angle substantially perpendicular to the plane formed by the inner wing panel 107. The positioning of the three-bladed propeller 141 relative to the inner wing panel 107 is such that it provides clearance between each propeller blade 145 and the ground.

[0028] 4 illustrates an example of a top-level functional block diagram of a computing device embodiment 400. An exemplary operating environment is illustrated as a computing device such as a microcontroller 420 including a processor 424, such as a central processing unit (CPU), addressable memory 427, an external device interface 426, e.g., an optional USB port and associated processing, and / or an Ethernet port and associated processing, and an optional user interface 429, e.g., an array of status lights and one or more toggle switches, and / or a display, and / or a keyboard and / or a pointer-mouse system and / or a touch screen. Optionally, the addressable memory may include any type of computer-readable medium capable of storing data accessible by the microcontroller 420, such as magnetic hard and floppy disk drives, optical disk drives, magnetic cassettes, tape drives, flash memory cards, digital video disks (DVDs), Bernoulli cartridges, RAM, ROM, smart cards, etc. Indeed, any medium for storing or transmitting computer-readable instructions and data may be employed, including a connection port to or a node on a network, such as a LAN, a WAN, or the Internet. These elements may communicate with each other via a data bus 428. In some embodiments, a processor 424, via an operating system 425, such as supporting a web browser 423 and applications 422, may be configured to perform the process steps of establishing a communication channel and the processing steps of the embodiments described above.

[0029] The microcontroller 420 may further include at least one sensor 152, such as an external angular position sensor. In one embodiment, the sensor 152 may be a magnetic rotational position sensor, such as a Hall effect rotational position sensor. In another embodiment, the sensor 152 is a variable reluctance sensor. In another embodiment, the sensor 152 may be an optical sensor. In another embodiment, the sensor 152 may be a combination of a magnetic sensor and an optical sensor. In one embodiment, the combination of a magnetic sensor and an optical sensor can detect the current position of the blade 144, rather than just detecting the signal of the blade 144 at a particular position, such as a horizontal position.

[0030] With respect to the magnetic Hall effect sensor embodiment, a magnet may be attached to each blade 144 and a magnetic Hall effect sensor 152 may detect each magnet. The sensor 152 may then detect the angular position of the blade 144 and the processor 424 may perform steps to continuously control the angular position of the blades 144 attached to the motors 110. More specifically, as the UAV 101 approaches the ground 150 for landing and the UAV 101 descends below a threshold altitude, the flight control computer (FCC) may send command signals to each motor 110 associated with the inboard wing panel 107 to level, hold, and lock the blades 144 of the associated inboard propeller(s) 140. The microcontroller 420 controls the speed of the motors 110, thereby leveling, holding, and locking the blades 144. Additionally, the microcontroller 420 associated with the tip propeller 141 can control the speed of the motor 110 for landing and takeoff while the blades 144 associated with the inboard propeller 140 are leveled and locked.

[0031] When the inboard propeller 140 stops rotating, such as when the UAV 101 descends to the landing site 102, the tip propeller 141 continues to rotate, and the thrust from the motor 110 to the tip propeller 141 allows the tip propeller 141 to guide the UAV 101 for landing. At or near the ground 150, the distance d1 is greater than the distance d3 from the propeller hub 142 to the ground 150, because the outboard wing 109 points up, providing a safe distance between the tip propeller 141 and the ground 150 at all times. In this configuration, the non-leveled tip propeller 141 maintains lateral control of the UAV 101 while the inboard propeller 140 is maintained in a level position during landing.

[0032] During takeoff of the UAV 101, the inboard propeller 140 is initially oriented in an attitude that provides propeller blade clearance to the ground 105, while the tip propeller 141 can provide both sufficient thrust and control to enable the UAV 101 to take off and ascend above a threshold altitude. The inboard propeller 140 can then be used for additional thrust once the UAV 101 has ascended above the threshold altitude.

[0033] With reference to FIG. 5, a flow chart 500 of steps performed by a microcontroller, such as microcontroller 420, for landing a UAV, such as UAV 101, is shown. At step 502, a sensor may detect the angular position of the blades of the UAV's propellers. At step 504, a processor of the microcontroller may perform steps to continuously control the angular position of the blades attached to the motors. In one embodiment, each propeller (tip or inboard) has an associated microcontroller. In another embodiment, one microcontroller controls all the propellers. In another embodiment, one microcontroller controls the tip propellers and another microcontroller controls the inboard propellers. In one embodiment, the UAV has a wingspan of approximately 260 feet and is propelled by multiple motors, e.g., 10 electric motors, driven by solar arrays covering the surface of each wing, thereby achieving zero emissions.

[0034] As the UAV approaches the ground for landing and descends below a threshold altitude, a flight control computer (FCC) can send command signals to each motor associated with the UAV's inboard wing panels to level the blades of the associated propellers. In step 506, the motors receive the angular position of the blades and stop the propellers from rotating in an orientation that provides clearance of the propeller blades to the ground upon landing.

[0035] In step 508, when the propeller rotation is stopped as the UAV descends to the landing site, the tip propeller can continue to rotate, and the tip propeller can guide the UAV for landing by thrust from the motor to the tip propeller. In one embodiment, the distance from the center of the propeller hub to the propeller blade tip is d1. For the inner wing panel, the landing pod 113 adjacent to the associated propeller hub has a height d2. The landing pod is sufficiently tall that the distance d3 from the center of the propeller hub to the propeller blade tip is equal to or greater than the height d2 of the landing pod (e.g., d1≦d3). At or near the ground, the distance d1 is greater than the distance d3 from the propeller hub 142 to the ground. This is because the outer wing points up, always providing a safe distance between the tip propeller and the ground. So configured, in step 510, the non-leveled tip propeller retains lateral control of the UAV during landing, while the propeller is held in a level position. In some embodiments, a signal can be sent to the tip propeller to adjust its rotation by increasing rotation, decreasing rotation, or maintaining the current rotation. If it is desired to maintain the same thrust when the inner propeller is held, the tip propeller speed can be increased. In some embodiments, for control, the tip propeller rotation can be increased, stayed the same, or decreased as needed.

[0036] With reference to FIG. 6, a flow chart 600 of steps performed by a microcontroller, such as microcontroller 420, for takeoff of a UAV, such as UAV 101, is shown. The method 600 can include detecting an angular position of an inboard propeller blade by a sensor in communication with the microcontroller (step 602). The method 600 can then include the microcontroller processor performing a step of continuously communicating the angular position of the inboard blade to a motor (step 604). The method 600 can then include the motor receiving the angular position of the inboard blade at the microcontroller, and the microcontroller processor can verify that the inboard propeller blade is properly oriented (step 606). If the inboard propeller blade is not properly oriented during rotation, i.e., if the inboard propeller blade is not held in place, there is a risk that the rotating inboard propeller blade will strike the ground during takeoff. If the inboard propeller blades are not in the proper attitude relative to the inner wing panel, the microcontroller processor can take corrective action, such as sending a signal to stop takeoff or sending a signal to hold the propeller blades in the proper attitude. The method 600 can then include having the tip propeller hold lateral control of the UAV during takeoff while the inboard propeller is held in the proper attitude (step 610). The tip propeller can provide the thrust required for the UAV to take off while the inboard propeller is held in place to prevent it from hitting the ground during takeoff. The method 600 can then include the microcontroller starting rotation of the inboard propeller as the UAV ascends from the takeoff point while the tip propeller continues to rotate (step 608). In some embodiments, the thrust generated by the tip propeller can be reduced as the inboard propeller begins to rotate in order to balance the thrust generated by the sum of all of the tip and inboard propellers.

[0037] It is contemplated that various combinations and / or subcombinations of the specific features and aspects of the above-described embodiments may be made and still fall within the scope of the present invention. Thus, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed invention. Moreover, it is intended that the scope of the present invention, although disclosed herein by way of example, should not be limited by the specific disclosed embodiments described above.

Claims

1. Unmanned aerial vehicles (UAVs) and One or more inner wing panels of the UAV; at least one inboard propeller attached to at least one engine disposed on said one or more inner wing panels; at least one microcontroller in communication with at least one engine disposed in the one or more inner wing panels, determining an angular position of the at least one inboard propeller; at least one microcontroller configured to send a signal to stop rotation of the at least one inboard propeller such that the at least one inboard propeller is held in an orientation that provides propeller blade clearance to the ground upon landing; and Equipped with the at least one inboard propeller may strike the ground during rotation of the at least one inboard propeller when the UAV is on the ground; one or more outer wing panels of the UAV, the one or more outer wing panels being disposed on either side of the one or more inner wing panels, the one or more outer wing panels being disposed at an upward angle relative to a plane formed by the one or more inner wing panels; at least one tip propeller attached to at least one engine disposed on said one or more outer wing panels; The at least one microcontroller configured to transmit a signal to the at least one tip propeller to adjust thrust to guide the UAV for landing while the at least one inboard propeller is held in an attitude that provides propeller blade clearance relative to the ground; the at least one tip propeller maintains lateral control of the UAV during landing; The at least one microcontroller configured to transmit a signal to the at least one tip propeller to adjust thrust to guide the UAV for takeoff while the at least one inboard propeller is in an orientation that provides propeller blade clearance relative to the ground, the at least one tip propeller maintaining lateral control of the UAV during takeoff; 13. The system of claim 12, wherein the at least one microcontroller is further configured to send a signal to the at least one inboard propeller after takeoff such that the at least one inboard propeller begins rotating.

2. The system of claim 1 further comprising: and further comprising one or more landing pods for the UAV; the one or more landing pods are attached to the one or more inner wing panels of the UAV to assist in landing the UAV; a distance from a center of a propeller hub to a tip of the at least one inboard propeller is greater than a height of the one or more landing pods; 11. A system comprising: at least one outboard propeller, the at least one outboard propeller being identical to the at least one inboard propeller, the at least one outboard propeller being free to rotate when the UAV is on the ground.

3. 2. The system of claim 1, The system is characterized in that the UAV is a high-altitude, long-endurance aircraft.

4. The system of claim 1 further comprising: a solar array covering at least a portion of the one or more inner wing panels.

5. The system of claim 1 further comprising: a position sensor in communication with the microcontroller, the position sensor detecting a position of the at least one inboard propeller.

6. 6. The system of claim 5, The system according to claim 1, wherein the position sensor is a Hall effect rotary position sensor.

7. 2. The system of claim 1, The at least one microcontroller further comprises: Determining the altitude of the UAV; transmitting a signal to stop rotation of the at least one inboard propeller when the determined altitude is below a threshold altitude; 13. A system configured to transmit a signal to adjust rotation of the at least one outboard propeller while the at least one inboard propeller is held in a position that provides propeller blade clearance with respect to the ground.

8. 2. The system of claim 1, The at least one microcontroller further comprises: Determining the altitude of the UAV; 13. The system of claim 12, further comprising: a first inboard propeller configured to: transmit a signal to initiate rotation of the at least one inboard propeller when the determined altitude is above a threshold altitude.

9. determining, by at least one microcontroller in communication with at least one engine of an unmanned aerial vehicle (UAV), an angular position of at least one inboard propeller connected to the at least one engine, the at least one inboard propeller being disposed on one or more inboard wing panels; transmitting, by the at least one microcontroller, a signal to stop rotation of the at least one inboard propeller such that the at least one inboard propeller is held in an orientation that provides propeller blade clearance to the ground upon landing; the at least one inboard propeller may strike the ground during rotation of the at least one inboard propeller when the UAV is on the ground; the UAV comprises one or more outer wing panels of a UAV, the one or more outer wing panels being disposed on either side of the one or more inner wing panels, the one or more outer wing panels being disposed at an upward angle relative to a plane formed by the one or more inner wing panels; at least one tip propeller attached to at least one engine disposed on said one or more outer wing panels; The at least one microcontroller further comprises: configured to transmit a signal to the at least one tip propeller to adjust thrust to guide the UAV for landing while the at least one inboard propeller is held in an attitude that provides propeller blade clearance relative to the ground; the at least one tip propeller maintains lateral control of the UAV during landing; The at least one microcontroller configured to transmit a signal to the at least one tip propeller to adjust thrust to guide the UAV for takeoff while the at least one inboard propeller is in an orientation that provides propeller blade clearance relative to the ground, the at least one tip propeller maintaining lateral control of the UAV during takeoff; 20. The method of claim 1, wherein the at least one microcontroller is further configured to send a signal to the at least one inboard propeller after takeoff such that the at least one inboard propeller begins rotating.

10. The method of claim 9 further comprising: The method comprising determining, by the at least one microcontroller, an altitude of the UAV.

11. 11. The method of claim 10, a signal is sent to stop rotation of the at least one inboard propeller if the determined altitude is below a threshold altitude.

12. The method of claim 10 further comprising: transmitting, by the at least one microcontroller, a signal to adjust rotation of at least one outboard propeller connected to at least one engine while the at least one inboard propeller is held in an orientation that provides propeller blade clearance relative to the ground upon landing; the at least one outboard propeller is disposed on one or more outer wing panels; The method, wherein the at least one outboard propeller is identical to the at least one inboard propeller, and the at least one outboard propeller is capable of rotating freely when the UAV is on the ground.

13. In the system, at least one microcontroller in communication with at least one engine of an unmanned aerial vehicle (UAV); at least one inboard propeller is attached to the at least one engine of the UAV; The at least one microcontroller determining an angular position of the at least one inboard propeller; sending a signal to the at least one inboard propeller such that the at least one inboard propeller is held in an orientation that provides propeller blade clearance relative to the ground; When the UAV is located on a surface of the earth, at least a portion of the at least one inboard propeller may contact the surface of the earth during rotation of the at least one inboard propeller; the UAV further comprising at least one tip propeller attached to at least one engine of the UAV; when the UAV is located on a surface of the earth, the at least one tip propeller is capable of rotating freely without contacting the surface of the earth during rotation of the at least one tip propeller; The at least one microcontroller further comprises: configured to transmit a signal to the at least one tip propeller to adjust thrust to guide the UAV for landing while the at least one inboard propeller is held in an attitude that provides propeller blade clearance relative to the ground; the at least one tip propeller maintains lateral control of the UAV during landing; The at least one microcontroller configured to transmit a signal to the at least one tip propeller to adjust thrust to guide the UAV for takeoff while the at least one inboard propeller is in an orientation that provides propeller blade clearance relative to the ground, the at least one tip propeller maintaining lateral control of the UAV during takeoff; 13. The system of claim 12, wherein the at least one microcontroller is configured to send a signal to the at least one inboard propeller after takeoff such that the at least one inboard propeller begins to rotate.

14. 14. The system of claim 13, The system further comprises one or more landing pods to assist in the safe landing of the UAV on the ground, wherein the distance from the center of the propeller hub to the tip of the at least one inboard propeller is greater than the height of the one or more landing pods, and the distance from the center of the propeller hub to the tip of the at least one tip propeller is greater than or equal to the height from the center of the propeller hub of the at least one tip propeller to the bottom end of the one or more landing pods.

15. The system of claim 13 further comprising: one or more inner wing panels of a UAV, the one or more inner wing panels to which the at least one inboard propeller is attached; one or more outer wing panels of a UAV, the at least one tip propeller being attached to the one or more outer wing panels, the one or more outer wing panels being disposed on either side of the one or more inner wing panels, the one or more outer wing panels being disposed at an upward angle relative to a plane formed by the one or more inner wing panels; a position sensor in communication with the microcontroller, the position sensor detecting a position of the at least one inboard propeller.

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