A vertical take-off and landing aircraft that uses a fixed forward tilt rotor to simulate rigid wing aerodynamics

Abstract

A vertical take-off and landing (VTOL) aircraft uses fixed rotors for both vertical take-off and landing (VTOL) and forward flight operations. The rotors are arranged to form a composite wing and achieve high span efficiency. The rotors are arranged to distribute lift evenly across the span of the composite wing. The composite wing may also have narrow forward and aft airfoil sections, or a single center wing, which may provide structural support as well as lift during forward flight. The wing rotors are angled forward to provide forward thrust during level flight.

Description

[Technical field]

[0001] The present invention relates to an airborne vehicle that uses rotors to simulate the aerodynamics of a rigid wing.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 62 / 850,943, filed May 21, 2019 by Mikic, which is incorporated herein by reference in its entirety. This application is a continuation-in-part of U.S. Provisional Patent Application No. 15 / 802,386, filed November 2, 2017 by Mikic et al., which claims priority to U.S. Provisional Patent Application No. 62 / 416,168, filed November 2, 2016 by Mikic et al., which is incorporated herein by reference in its entirety. Summary of the Invention

[0003] A vertical take-off and landing (VTOL) aircraft that uses fixed rotors for both VTOL and forward flight operations. The rotors are arranged to form a composite wing and achieve high wingspan efficiency. The rotors are arranged to uniform lift across the span of the composite wing. The wing rotors are canted forward to provide forward thrust during level flight. The wing rotors may be fixed in a forward-swept configuration. [Brief description of the drawings]

[0004] [Figure 1A] 1 is a shaded rendering of an airborne vehicle with composite wings that uses stacked counter-rotating propellers, according to some embodiments of the present invention. [Figure 1B] 1 is a shaded rendering of an airborne vehicle with composite wings that uses stacked counter-rotating propellers, according to some embodiments of the present invention. [Figure 1C] 1 is a shaded rendering of an airborne vehicle with composite wings that uses stacked counter-rotating propellers, according to some embodiments of the present invention. [Figure 1D]1 is a shaded rendering of an airborne vehicle with composite wings that uses stacked counter-rotating propellers, according to some embodiments of the present invention. [Figure 2A] 1 is a diagram of an air vehicle with composite wings using stacked counter-rotating propellers according to some embodiments of the present invention. [Figure 2B] 1 is a diagram of an air vehicle with composite wings using stacked counter-rotating propellers according to some embodiments of the present invention. [Figure 2C] 1 is a diagram of an air vehicle with composite wings using stacked counter-rotating propellers according to some embodiments of the present invention. [Figure 2D] 1 is a diagram of an air vehicle with composite wings using stacked counter-rotating propellers according to some embodiments of the present invention. [Diagram 3] FIG. 1 illustrates an airborne vehicle solution in forward flight according to some embodiments of the present invention. [Figure 4A] 1 is a shaded rendering of an airborne vehicle with composite wings, according to some embodiments of the present invention. [Figure 4B] 1 is a shaded rendering of an airborne vehicle with composite wings, according to some embodiments of the present invention. [Figure 5A] 1 is a diagram of an airborne vehicle with composite wings, according to some embodiments of the present invention. [Figure 5B] 1 is a diagram of an airborne vehicle with composite wings, according to some embodiments of the present invention. [Figure 5C] 1 is a diagram of an airborne vehicle with composite wings, according to some embodiments of the present invention. [Figure 6A] 1 is a lift-drag curve for various parameter values. [Figure 6B] 1 is a lift-drag curve for various parameter values. [Figure 6C] 1 is a lift-drag curve for various parameter values. [Figure 6D] 1 is a lift-drag curve for various parameter values. [Figure 6E]1 is a lift-drag curve for various parameter values. [Figure 6F] 1 is a lift-drag curve for various parameter values. [Figure 6G] 1 is a lift-drag curve for various parameter values. [Figure 7] FIG. 1 illustrates an air vehicle with composite wings using longitudinally staggered rotors according to some embodiments of the present invention. [Figure 8] FIG. 1 is a diagram of an air vehicle with composite wings using vertically staggered rotors according to some embodiments of the present invention. [Figure 9A] 1 is a diagram illustrating lift uniformity for different vehicle configurations. [Figure 9B] 1 is a diagram illustrating lift uniformity for different vehicle configurations. [Figure 9C] 1 is a diagram illustrating lift uniformity for different vehicle configurations. [Figure 9D] 1 is a diagram illustrating lift uniformity for different vehicle configurations. [Figure 9E] 1 is a diagram illustrating lift uniformity for different vehicle configurations. [Figure 10A] 1 is a diagram of a rotor according to some embodiments of the present invention. [Figure 10B] 1 is a diagram of a rotor according to some embodiments of the present invention. [Figure 11A] 1 is a diagram of an airborne vehicle with a wingtip rotor according to some embodiments of the present invention. [Figure 11B] 1 is a diagram of an airborne vehicle with a wingtip rotor according to some embodiments of the present invention. [Figure 11C] 1 is a diagram of an airborne vehicle with a wingtip rotor according to some embodiments of the present invention. [Figure 11D] 1 is a diagram of an airborne vehicle with a wingtip rotor, according to some embodiments of the present invention; [Figure 12A] 1 is a side view of an airborne vehicle with a wingtip rotor according to some embodiments of the present invention. [Figure 12B]1 is a side view of an airborne vehicle with a wingtip rotor according to some embodiments of the present invention. [Figure 13A] 2 is a diagram of a cowling of a rotor according to some embodiments of the present invention. [Figure 13B] 2 is a diagram of a cowling of a rotor according to some embodiments of the present invention. [Figure 13C] 2 is a diagram of a cowling of a rotor according to some embodiments of the present invention. [Figure 14A] FIG. 2 illustrates a rotor with cowling and blades according to some embodiments of the present invention. [Figure 14B] FIG. 2 illustrates a rotor with cowling and blades according to some embodiments of the present invention. [Figure 14C] FIG. 2 illustrates a rotor with cowling and blades according to some embodiments of the present invention. [Figure 15A] FIG. 2 is a diagram of a spar and rotor assembly according to some embodiments of the present invention. [Figure 15B] FIG. 2 is a diagram of a spar and rotor assembly according to some embodiments of the present invention. [Figure 15C] FIG. 2 is a diagram of a spar and rotor assembly according to some embodiments of the present invention. [Figure 15D] FIG. 2 is a diagram of a spar and rotor assembly according to some embodiments of the present invention. [Figure 15E] FIG. 2 is a diagram of a spar and rotor assembly according to some embodiments of the present invention. [Figure 16A] FIG. 1 is a diagram of an airborne vehicle with stacked rotors, according to some embodiments of the present invention. [Figure 16B] FIG. 1 is a diagram of an airborne vehicle with stacked rotors, according to some embodiments of the present invention. [Figure 16C] FIG. 1 is a diagram of an airborne vehicle with stacked rotors, according to some embodiments of the present invention. [Figure 16D] FIG. 1 is a diagram of an airborne vehicle with stacked rotors, according to some embodiments of the present invention. [Figure 17A] 1 is a diagram of an air vehicle with a forward wingtip rotor and an aft wingtip rotor according to some embodiments of the present invention. [Figure 17B] 1 is a diagram of an air vehicle with a forward wingtip rotor and an aft wingtip rotor according to some embodiments of the present invention. [Figure 17C] 1 is a diagram of an air vehicle with a forward wingtip rotor and an aft wingtip rotor according to some embodiments of the present invention. [Figure 17D] 1 is a diagram of an air vehicle with a forward wingtip rotor and an aft wingtip rotor according to some embodiments of the present invention.

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[0025] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] In some embodiments of the invention, an airborne vehicle has an array of rotors configured to function as a composite or pseudo-wing. The rotors are positioned relative to the airborne vehicle body and relative to each other such that the lift of the rotor array has a relatively uniform lift along the span of the pseudo-wing. The composite wing produces a (relatively) uniform lift, and a relatively uniform trailing vertical velocity (wash). Any swirling motion that occurs is concentrated at the wing tip, similar to a conventional aerofoil wing.

[0027] In some embodiments, the rotors are fixedly mounted to a structure coupled to the airborne vehicle body. The rotors may be staggered along a longitudinal axis of the airborne vehicle such that differential thrust along the longitudinal axis allows the vehicle to pitch forward to provide a forward thrust component from the rotors. In some aspects, pitch control may also be achieved using other means, such as elevator control. In some embodiments, the rotors may have several distinct aspects. In some aspects, the aircraft controls pitch, roll, and yaw without other control surfaces by differential thrust of the rotors. In some aspects, the aircraft has no other control surfaces for attitude control.

[0028] In some embodiments, the rotor arrangement, which constitutes a composite wing, may have a short-chord forward wing in front of the rotor. Because the air vehicle uses the rotor for vertical thrust during takeoff, the air vehicle does not require significant lift from a conventional wing during takeoff operations. The short-chord forward wing allows lift in forward flight during operation at higher airspeeds. The air vehicle may also have a short aft wing behind the rotor. The aft wing with a short chord may provide lift during forward flight operation at higher speeds. The aft wing may also make the wash of the pseudo-wing more uniform. The forward and aft wings may be used as structural elements to support the struts that support the rotor. The forward and aft wings may merge at the outer ends, which may allow for increased strength and stability. Additionally, the forward and aft wings, which are placed in position (in the horizontal plane) near the outside of the rotor arrangement, provide a safety element for users and ground personnel as a shield around the rotating blades of the rotor.

[0029] In some embodiments, there may be only rear wings (trailing edge wings). In some embodiments, there may be only forward wings (leading edge wings). In some embodiments, there are both forward and rear wings. In some embodiments, there is a center wing that may have rotors forward and aft of the wings.

[0030] In some embodiments, one or more rotors are used to provide forward thrust. In some aspects, a single propulsive rotor may be used at the rear of the airborne vehicle. In some embodiments, the rotational axis of the wing rotor may be inclined relative to vertical. In some embodiments, the wing rotor may be inclined forward. The forward-swept wing rotor contributes to the forward thrust of the airborne vehicle during forward flight. In some embodiments, the total forward thrust during forward flight is derived from a combination of the forward-swept wing rotor and one or more conventional rotors with spin axes parallel to the roll axis of the airborne vehicle.

[0031] The airborne vehicle may be constructed such that lift is provided by both the wings and the wing rotors in forward flight, and forward thrust is provided by the tail propeller and the forward-swept wing rotors.

[0032] The efficiency (lift / drag ratio) of an aircraft in forward flight may be sought to be as high as practicable while balancing other aircraft parameters. For example, the ratio of the tip speed of the rotating wing rotor in forward flight to the speed of the aircraft in forward flight is an important ratio to consider when designing for efficiency. Also, the percentage of lift provided by the wing rotor to the total lift (wing plus wing rotor) is an important ratio to consider when designing for efficiency. Also, the power distribution between the wing rotors and the ratio of the total power delivered to both the wing rotor and a traditional forward thrust propeller (e.g., the tail rotor) are important ratios to consider when designing for efficiency. The relationships between these ratios may be complex and may not lend themselves to explicit optimization. The underlying design parameters are that the wing rotor provides sufficient vertical thrust during vertical takeoff and landing to allow the aircraft to take off and land safely.

[0033] An airborne vehicle according to an embodiment of the invention is adapted for vertical take-off and landing using wing rotors. For take-off, the wing rotors are spun up to a speed in the range of their hovering RPM. In an embodiment where the wing rotors have a spin axis tilted forward relative to the horizontal axis of the airborne vehicle, the airborne vehicle will raise its nose during take-off and landing so that the plane of the wing rotors is horizontal. After take-off, while the wing rotors are still under power, the airborne vehicle may spin a propeller that pushes (or pulls) forward, such as a tail rotor. As the airborne vehicle gains forward speed, lift is generated by the leading and trailing edge wings, or in other embodiments by the center wing, and the proportion of lift provided by the wing rotors decreases. As the aircraft approaches its cruising speed, the wing rotors typically reduce their RPM, but the wing rotors remain powered and provide a portion of the total lift of the airborne vehicle. In some aspects, the wing rotors provide little lift, but may be rotated and spun up rapidly to provide attitude control for the aircraft. Power can be increased or decreased. This is also fine.

[0034] An airborne vehicle according to an embodiment of the present invention may be capable of hovering, taking off, landing, and engaging in forward flight, including all necessary maneuvering and attitude adjustments, by manipulating the speed of the individual rotors, and without the need for any additional control surfaces. In some embodiments, the airborne vehicle may not have ailerons, elevators, or any other controllable control surfaces. In such situations, where fixed tilt rotors are used for attitude control, the total simplicity of the design and system is a significant advantage. In some embodiments, the wing rotors for each wing are arranged along a straight line or along a curve, with each rotor extending further out from the aircraft body. The wing rotors may also be configured swept forward or aft, such that the rotors are at different positions along the roll axis of the aircraft. In other embodiments, the forward and aft rotors are respectively forward and aft of the wing and the center of mass of the aircraft. By being at different positions along the roll axis, the wing rotors can then provide control about the pitch axis. By being spaced a distance further out from the aircraft body, the wing rotors can provide control about the roll axis.

[0035] In some aspects, some of the rotors on each side of the aircraft rotate in a first direction and others rotate in the opposite direction. In such situations, yaw may be controlled by varying the speed and / or torque of the rotors rotating in the first direction relative to the opposite rotation. In some aspects, the rotors on each side of the aircraft body may be set at slightly different forward tilt angles. In such situations, yaw control may be achieved by varying the relative speed and / or thrust of the different rotors and the slightly different tilt angles.

[0036] In some embodiments, as seen in the shaded renderings of Figures 1A-1D and the line drawings of Figures 2A-2D, an airborne vehicle 100 has a body 101 coupled to starboard and starboard composite wings 102, 103 that use stacked counter-rotating propellers. In this exemplary embodiment, a short-chord leading edge wing 107 and a short-chord trailing edge wing 108 have multiple rotor assemblies 104 mounted along their wingspan. The rotor assemblies 104 are mounted on span supports 109 that are coupled to the leading edge wing 107 and the trailing edge wing 108. Wing tips 110 join the leading edge wing 107 to the trailing edge wing 108.

[0037] The rotor assembly 104 may have a first propeller 105 and a second propeller 106. In some aspects, the first propeller 105 and the second propeller 106 rotate in opposite directions. In such a configuration, the leading edge of one propeller leads forward on the outside of the rotor spin axis and the leading edge of the other propeller leads forward on the inside of the propeller spin axis. In a forward flight mode, the propeller blades will have more thrust when entering the prevailing airspeed wind than when retreating against the prevailing airspeed wind. With counter-rotating coaxial propellers, the downward thrust is equalized on the inside of the rotor shaft and on the outside of the rotor shaft.

[0038] In an exemplary embodiment, the airborne vehicle may accommodate one passenger and have a take-off mass of 315 kg. The wingspan may be 6 m, and the vehicle may be 3.5 m long and 1.5 m tall. The pseudo-wings may each be four coaxial rotor assemblies, each with a pair of counter-rotating propellers. Each propeller has three blades, where the blade chord is 0.05 m at the 75% radius. The airborne vehicle has a short-chorded front wing with a 0.5 m average chord, and a short-chorded rear wing with a 0.75 m average chord. The idealized cruise speed is 100 knots (about 51.4 m / s), with a maximum cruise speed of 150 knots (about 77.2 m / s). The power consumption in ideal cruise is 20 kW, and in hover mode is 80 kW. The battery mass is 50 kg and the vehicle's range is 50 miles (about 80.5 km).

[0039] In some embodiments of the composite wing, the rotors are configured to provide relatively uniform thrust along the span of the composite wing. One approach is that the counter-rotating propellers of the rotor assembly are positioned adjacent to each other along the span of the pseudo wing, as described above. Another approach that does not use coaxial counter-rotating propellers is to have propellers with overlapping swept-back and advanced-forward blade regions. For example, a rotor may be positioned with forward-forward blades on the outer side of the wing and swept-back blades on the inner side of the wing. Just inboard of this rotor there may be another rotor with forward-forward blades on the outer side of the wing. The rotors may be spaced vertically at regular intervals to allow for this overlap. In some embodiments, the rotors may be spaced vertically at regular intervals to allow for this overlap.

[0040] FIG. 3 illustrates the functional aspects of a composite wing, using an airborne vehicle with three counter-rotating rotor assemblies on either side of the vehicle body as an exemplary embodiment. The left side of the figure shows the vertical velocity behind the wing, and the right side of the figure shows the magnitude of the vortex motion. The goal of the composite wing design is to reduce the variation of lift across the span of the composite wing. The reduction of the variation of lift along the span of the wing may be revealed by modeling the vertical velocity behind the wing. The left side of the figure shows a relatively stable amount of vertical velocity along the span, demonstrating that the composite wing using three counter-rotating rotor assemblies functions in an aerodynamic sense as a typical wing constructed using a solid airfoil shape.

[0041] The right side of the figure shows the magnitude of vortex motion along the wing span and at the wing tip. The uniformity of the vertical velocity along the wing span should, to a first approximation, indicate a uniform uniformity of the vortex motion magnitude, as discussed above. When using rotors arranged in a composite wing, it is indeed possible to introduce high vortex points along the wing span. The position of the rotor is very important to minimize the magnitude of vortex motion that occurs along the wing span.

[0042] While the results seen in FIG. 3 represent the output for a modeled composite wing, it is understood that there is some time-dependent variation in the output related to the variation of the blade position over time.

[0043] In some embodiments, as seen in the shaded renderings of Figures 4A-4B and the line drawings of Figures 5A-5C, the air vehicle 200 has a body 201 coupled to a right composite wing 202 and a left composite wing 203 using wing-mounted rotors. In this exemplary embodiment, multiple wing rotor assemblies 204 are installed along the wingspan length with short-chord leading edge wing 207 and short-chord trailing edge wing 208. The wing rotor assemblies 204 are mounted on wing span supports 209 coupled to the leading edge wing 207 and trailing edge wing 208. Wing tips 210 join the leading edge wing 207 to the trailing edge wing 208. The air vehicle 200 does not use counter-rotating, stacked rotor assemblies. Although a stacked assembly may have distinct advantages in terms of load distribution in some embodiments (where the percentage of lift delivered by the rotors during level flight is lower), efficient flight may be achieved with a single rotor such as the air vehicle 200. Additionally, a single rotor allows for reduced cost and complexity.

[0044] In some aspects, the wing rotor assembly 204 is canted forward at an angle 212 other than perpendicular to the aircraft's constant altitude cruise plane. In some aspects, the rotors are canted forward at an angle between 5 and 20 degrees. In some aspects, the rotors are canted forward at an angle between 5 and 15 degrees. In some aspects, the rotors are canted forward at an angle between 8 and 20 degrees. In some aspects, the rotors are canted forward at an angle between 8 and 12 degrees. In an exemplary embodiment, the rotors are canted at 10 degrees. The cant angle may be defined as the angle between the rotor axis and the aerodynamic mean chord line of the largest wing, which in some embodiments may be the trailing edge wing.

[0045] Airborne vehicle 200 has a horizontal thrust aft rotor assembly 211 adapted to provide horizontal thrust during normal flight. Size and configuration details of an exemplary embodiment of airborne vehicle 200 are found in Table 1. Figures 10A-10B show rotor 204 with its central hub 221 (which may include an electric motor) and blades 220. Central hub 221 may have an electric motor therein and may have an exterior surface adapted for low drag when in a forward flight configuration.

[0046] In some aspects, the wing rotor assembly 204 has a rotating propeller with an electric motor. In some aspects, the horizontal thrust aft rotor assembly 211 has an electric motor. In some aspects, the motor is powered by a power source, such as a battery or batteries. [Table 1]

[0047] The use of a forward-swept wing rotor assembly allows forward thrust to be provided partly by the wing rotor assembly and partly by a conventional horizontal thrust propeller. A factor to consider in sharing this forward thrust is the proportion of total power delivered to the wing rotor relative to the total power delivered to both the wing rotor and the conventional propeller during forward cruise flight.

[0048] Another factor to consider is the percentage of lift delivered by the wing rotors relative to the total lift provided by both the wing and the wing rotors during forward flight. In embodiments where all attitudinal control, including roll control, is induced or maintained by manipulation of the motor speed of the wing rotors, the percentage of lift provided by the wing rotors must be high enough so that manipulation of the wing rotors can be effective to control aircraft attitude. In some aspects, the percentage of lift provided by the wing rotors at cruise speed is greater than 0.2. In some aspects, the percentage of lift provided by the wing rotors is greater than 0.25. In some aspects, the percentage of lift provided by the wing rotors is greater than 0.3. In some aspects, the percentage of lift provided by the wing rotors is greater than 0.1. The percentage of lift provided represents the sum of all wing rotors during nominal forward flight relative to the wing, although in some aspects certain rotors may be spun down to lower speeds to support aerodynamic control of the aircraft. In some aspects, one or more rotors may generate temporary negative lift to support certain control maneuvers.

[0049] Another factor to consider is the ratio of the tip speed of the wing rotor to the speed of the aircraft during forward flight. This factor may come into play when slowing down one or more wing rotors to reduce lift on one of the wings and induce a roll. In such a maneuver, the wing rotors on the other wing may be rotated up to increase lift. Nominally, there is a risk of stall for the retreating rotor blades when operating at a low multiple of the aircraft speed. In some aspects, the nominal cruise wing rotor tip speed is 2.0 times greater than the aircraft cruise speed. In some aspects, the nominal cruise wing rotor tip speed is 2.5 times greater than the aircraft cruise speed. In some aspects, the nominal cruise wing rotor tip speed is greater than 1.5 times the aircraft cruise speed. In some aspects, the nominal cruise wing rotor tip speed is greater than 1.0 times the aircraft cruise speed. In some aspects, the nominal cruise blade rotor tip speed may be as low as more than 0.5 times the aircraft's cruise speed, where tip speed is understood to be the blade's angular velocity multiplied by its radial length.

[0050] The above factors have been modeled to determine the lift to drag ratio L / De (effective drag) for the air vehicle 200 as a function of wing tip speed versus aircraft forward speed for the aircraft's angle of attack, and this data is presented graphically. The lift to drag ratio can be seen as a color-coded representation of the lift to drag ratio. The lift to drag ratio (effective drag) is the total shaft power of the aircraft divided by the forward speed of the aircraft. Overlaid on this color-coded are contours representing the other factors discussed above, including the percentage of total power delivered to the wing rotor, the percentage of lift delivered by the wing rotor, and also the aircraft's speed. The lift to drag ratio is modeled at different forward inclination angles for the wing rotor, and also with different wing rotor blade pitching. As seen in FIG. 6A, by encircling the portion of the graph during the cruise speed range of the aircraft 200 (50-75 m / s) and by reviewing the region having wing rotor tip speed to aircraft speed ratios greater than 2.0, it was discovered that the parameters in the non-obvious range provide the operating mode with the highest lift to drag ratio. A wing rotor tip speed to aircraft speed ratio of 2.0 coincides with a line for a lift ratio ration of 0.1 of the lift provided by the wing rotor to the total lift of the rotor and wing (i.e., a lift ration where the wing rotor provides an amount of lift that allows sufficient aircraft attitude control). The preferred result is to have a lift to drag ratio of greater than 8, within the constraints mentioned above, where a higher ratio of 9 or 10 is even more desirable. As seen in FIG. 6A, the aircraft analyzed with a rotor forward tilt of 10 degrees can operate with a tip speed ratio of greater than 2, a lift ratio of greater than 0.1 (or more), and an L / De ratio of greater than 8 at various aircraft speeds over a range of aircraft speeds.

[0051] 6A-6G are computational fluid dynamics (CFD) results comparing the above-mentioned parameters for different versions of the air vehicle. FIG. 6A shows the results for the above-mentioned air vehicle 200. Contour 601 forms a boundary around the region bounded by cruise speeds of 50 m / s and 75 m / s and where the ratio of rotor tip speed to aircraft speed exceeds 2.0. As can be seen, there is a significant region where L / De exceeds 8, including a significant region where it exceeds 9, and several significant regions where it exceeds 10. This indicates that the vehicle with a 10 degree forward-swept wing mounted rotor can achieve these L / De ratios for various operating scenarios.

[0052] Figure 6B shows a similar vehicle with rotors with 0 degrees forward sweep. As can be seen, there is almost no region above the 2.0 speed ratio line with L / De as high as 9.

[0053] Figure 6C shows a similar vehicle with rotors at 20 degrees of inclination. As can be seen, there is no region with L / De higher than 8 where operation within range is available. By contrasting L / De at 0 and 20 degrees forward inclination, as seen in Figures 6B and 6C, respectively, one can see the advantage of, for example, 10 degrees of inclination. Within the contour region 601, other design tradeoffs are made to arrive at an optimized design based on flight use considerations.

[0054] Figure 6D shows a similar vehicle with rotor blades with 0 degrees forward sweep, but with 5 degrees more pitching than in Figure 6B. As can be seen, there is almost no region above the 2.0 speed ratio line with L / De as high as 8.

[0055] Figure 6E shows a similar vehicle with rotor blades with 10 degrees forward pitch, but with 5 degrees more pitch than in Figure 6A. As can be seen, there is almost no area above the 2.0 speed ratio line with L / De as high as 8, although this appears to be optimal compared to the other cases with rotor blades with 5 degrees more pitch.

[0056] Figure 6F shows a similar vehicle with rotor blades with a 20 degree forward sweep, but with a pitch of 5 degrees more than in Figure 6C. As can be seen, there are few regions above the 2.0 speed ratio line where L / De is as high as 9, especially in the region of level flight (0 degree angle of attack).

[0057] In some embodiments of the invention, as seen in FIG. 7, an air vehicle 200 with a left composite wing 202 (right composite wing not shown) has rotors staggered along a longitudinal axis. The inboard rotor 207 has a forward side 208 and a return side 209 with respect to its propeller. The return side 209 of the inboard rotor 207 significantly overlaps with the forward side of the next rotor 204 along the span of the pseudo wing 202. This is repeated for the subsequent rotors 205, 206. This significant overlap of adjacent rotors on the forward and return sides evens out the lift provided during forward flight because forward flight speed enhances lift for the forward moving portion of the propeller rotation.

[0058] In some embodiments of the invention, as seen in FIG. 8, an air vehicle 300 with a left composite wing 301 and a right composite wing 302 has rotors vertically staggered along the span of the composite wing. The inboard rotor 303 has a forward side 307 and a return side 308 for its propeller. The return side 308 of the inboard rotor 303 significantly overlaps the forward side of the next rotor 304 along the span of the composite wing 301. This is repeated for the following rotor, and the rotors 305, 306 of the other wing. This significant overlap of adjacent rotors on the forward and return sides evens out the lift provided during forward flight, since forward flight speed enhances lift for the forward moving portion of the propeller rotation.

[0059] 9A-9E show the spanwise lift distribution for a conventional wing and a composite wing. FIG. 9A shows a hypothetical uniform spanwise lift distribution, as would be seen for a conventional wing. FIG. 9B-9E show the lift distribution profiles for various types of composite wings, each contrasted with an elliptical ideal lift distribution (visible as a dotted line). A rotor arrangement with a more uniform spanwise lift distribution would give a lower induced drag ratio compared to an ideally loaded, solid airfoil wing. In embodiments using a greater number of smaller rotors, as opposed to fewer and larger rotors, there is less total blade area and less drag for a given span length. In general, the mean blade chord does not change with the number of rotors for a given total lift and tip speed, so the smaller rotors have a more favorable aspect ratio (ratio of radius to mean chord).

[0060] FIG. 9B shows a four rotor system (two rotors per composite wing). The load variation is 20% due to the rotor configuration. The ratio of the induced drag of this configuration to the induced drag of an ideally loaded wing is 1.22. FIG. 9C shows an eight rotor system (four rotors per composite wing). The load variation is 20% due to the rotor configuration. The ratio of the induced drag of this configuration to the induced drag of an ideally loaded wing is 1.43.

[0061] FIG. 9D shows a four rotor system (two rotors per composite wing). The load variation is 40% due to the rotor configuration. The ratio of the induced drag of this configuration to the induced drag of an ideally loaded wing is 1.88. FIG. 9E shows an eight rotor system (four rotors per composite wing). The load variation is 40% due to the rotor configuration. The ratio of the induced drag of this configuration to the induced drag of an ideally loaded wing is 2.71.

[0062] 10A-10B show a rotor 221 according to some embodiments of the invention. As can be seen, there is a significant radius of the rotor 221 at the inboard end of the rotor blades 220 (as dimensioned in Table 1). In such a configuration, the inboard end of the rotor blades 220 is less likely to stall the retreating blades compared to configurations where the blades follow a path further towards the spin axis. This central region of the rotor allows for placement of individual motors (or pairs of motors in a counter-rotating blade configuration) within the outer surface of the rotor. Thus, the rotor blades may begin radially closer to the tip (relative to the spin axis) of the motor itself. The diameter of the rotor may be larger than the outer diameter of the motor in some aspects.

[0063] In some embodiments, as seen in Figures 11A-11D and 12A-12B, the airborne vehicle 400 utilizes forward tilt rotors in accordance with other embodiments of the present invention. The airborne vehicle 400 has a vehicle body 441 with a left wing 447 and a right wing 446. As seen in the top view of Figure 11C, the left wing 447 has an inboard section 447a and an outboard section 447b. The right wing 446 has an inboard section 446a and an outboard section 446b. The wings 446, 447 may be partial forward-swept wings with the inboard sections 446a and 447a curving forward and the outboard sections 446b and 447b curving aft. The configuration of the wings 446, 447 shown allows the aerodynamic center of the wing to be aft of the center of gravity of the airborne vehicle, which may enhance control and stability of the airborne vehicle during forward flight. It may also be desirable to couple the wings to the body of the airborne vehicle aft of the pilot's position. In some embodiments, there are internal structural elements that connect the wings to the body and to each other, which may traverse the interior of the air vehicle body. These internal structural elements may also be on top of the aircraft body, as the wings may be structurally connected to the aircraft body at or near the top of the aircraft body. This higher connection and associated internal structural support may require the wings to be connected to the aircraft body behind the pilot's head when the pilot is seated in the aircraft body. The forward curved inner portion 446a, 447a allows the wings to be connected aft, taking into account the above considerations. The swept-back wing change in the outer portion 446b, 447b then serves to bring the overall longitudinal aerodynamic center of the wing aft, taking into account control and stability considerations. This wing configuration also supports a compact design, which will be discussed below.

[0064] The aircraft 400 has a body 441 coupled to a right wing 446 and a left wing 447, and has multiple wing-mounted rotor assemblies. A right forward wing inner rotor assembly 448 and a right aft wing inner rotor assembly 452 are attached to a span support 463 coupled to the right wing 446. A right wing outer rotor assembly 456 is at the tip of the right wing 446. The blades 457 of the right wing outer rotor assembly 456 provide lift in forward flight in an outer region 461 of the fixed wing 446, which increases the effective span of the wing. A left forward wing inner rotor assembly 450 and a left aft wing inner rotor assembly 454 are attached to a span support 462 coupled to the left wing 447. A left wing outer rotor assembly 458 is at the tip of the left wing 447. Blades 459 of the left wing outer rotor assembly 458 provide lift in forward flight in a region 460 outside the fixed wing 447, which increases the effective span of the wing.

[0065] As seen in the plan view of FIG. 11C, the blade disks 449, 451, 453, 455, 457, 459 form a hexagon 463. The centers of the wing outer rotors 456, 458 and their blade disks 457, 459 are seen slightly forward of the leading edges of the aft-swept outer parts 446b, 447b of the wings 446, 447. The centers of the wing outer rotors 456, 458 and their blade disks 457, 459 may be on or near the longitudinal center of gravity of the airborne vehicle when stowed for flight. As seen in the figure, the hexagon 463 represents the external configuration limit of the aircraft, and this hexagon 463 represents a very compact design, being almost completely occupied by either the blade disks, the wings, or the aircraft body. This increases the disk loading and improves the hovering efficiency of the aircraft. It is also clear that the configuration of the wings contributes to the compactness of the design, as previously mentioned. It is further seen that each rotor has a counterpart on the opposite side of the aircraft body, on a line substantially across the aircraft's center of gravity and at or near the same distance from the center of gravity. This configuration allows for very rapid control compensation in the event of a rotor failure during a vertical takeoff or landing maneuver, as the counterpart of the failed motor can be powered down almost instantly to maintain aircraft attitude. In some embodiments, the remaining four rotors can be spun up to compensate for the overall loss of lift caused by the failure of the rotor and the powering down of its counterpart.

[0066] In some aspects, the wing rotor assemblies 448, 450, 452, 454, 456, 458 are tilted forward at an angle other than perpendicular to the aircraft's constant altitude cruise plane. In some aspects, the rotors are tilted forward at an angle between 5 and 20 degrees. In some aspects, the rotors are tilted forward at an angle between 5 and 15 degrees. In some aspects, the rotors are tilted forward at an angle between 8 and 20 degrees. In some aspects, the rotors are tilted forward at an angle between 8 and 12 degrees. In an exemplary embodiment, the rotors are tilted at 10 degrees. The tilt angle may be defined as the angle between the rotor axis and the mean aerodynamic chord line of the wing. In some aspects, the wing rotor assemblies may be fixed at the tilt angles described above and may not have articulating aspects.

[0067] The airborne vehicle 400 has a horizontal thrust aft rotor assembly 443 adapted to provide horizontal thrust during normal flight. Aft support structures 444, 445 extend down from the aft of the wing outer rotor assembly and span supports. These are also used as airfoil sections to provide yaw axis stability for the aircraft.

[0068] 12A-12B show aspects of an air vehicle 400 according to some embodiments of the present invention. The wing inner rotor assembly is supported by span supports 462, 463 and may be considered to have a forward portion 462a, 463a and an aft portion 462b, 463b, although the span supports themselves may be continuous supports. The span supports 462, 463 are coupled to the wings 446, 447. The forward wing inner rotor assembly 448 may have a top cover 448a and an aft portion 448b adapted for aerodynamic drag minimization. Similarly, the wing outer rotor assembly 456 may have a top cover 456a and an aft portion 456b, and the aft wing inner rotor assembly 452 may have a top cover 452a and an aft portion 452b. Aspects of the aft portions 448a, 456b, 452b are described below. As seen in the side view of FIG. 12B, blade disks 449, 457, 453 are angled forward relative to the horizontal of the aircraft.

[0069] Among the design factors that have been considered for aircraft 440 are the configuration used for vertical takeoff and landing and the control it provides, the longitudinal location of the wing's aerodynamic center of lift for control stability, the higher blade tip speeds required for control versus the desire to reduce tip speed to reduce drag, and maintaining relatively uniform lift along the wingspan. The interplay of these factors does not lead to an obvious optimization.

[0070] In some embodiments having forward and aft wing inner rotor assemblies and only a single wing outer rotor assembly on each wing, the lift provided by the individual wing inner rotor assemblies during forward flight may be lower than the lift of the wing outer rotor assemblies, whose total lift provides a more even lift distribution along the wing.

[0071] In some aspects, the wing rotor assembly has a rotating propeller with an electric motor. In some aspects, the horizontal thrust aft rotor assembly has an electric motor. In some aspects, the motor is powered by a power source, such as a battery or batteries.

[0072] 13A-13C show rotor assembly 470 with top cover 470a and extended aft portion 470b, which is the lower cowling. The rotor assembly maintains a forward tilt from vertical of, for example, 10 degrees, or another value discussed above, so that the extended aft portion 470b facilitates the pressure recovery area to avoid flow separation. In some aspects, the extended aft portion, which is the lower cowling, may be part of a continuous aerodynamic structure that joins with the outer surface of the aerodynamic boom. In some aspects, the extended aft portion, which is the lower cowling, may be more distinct from adjacent structures, as seen in FIG. 13B. In an exemplary embodiment, a motor, which may be an electric motor, is present within rotor assembly 470.

[0073] 14A-14C show a rotor assembly 470 with blades 472. A top cover 470a rotates with the blades, and an extended rear portion 470b of the rotor assembly remains fixed to the aircraft body. A different aspect of the rotor assembly 470 is the ratio of the radius 473 of the rotor top cover 470a to the radius 474 of the blade disk. As mentioned above, a rotor cap 470a with a larger radius spreads the inner ends of the blades 472 and reduces the situation where a retreating blade may stall during forward flight. In some embodiments, the ratio of the radius of the rotor cap to the radius of the blade disk is greater than 0.25. In some embodiments, the ratio of the radius of the rotor cap to the radius of the blade disk is greater than 0.30. In some embodiments, the ratio of the radius of the rotor cap to the radius of the blade disk is greater than 0.20.

[0074] 15A-15E show an exemplary double rotor assembly 480 with an aerodynamic boom 483. The forward rotor assembly 482 has a top cover 482a and an extended rear section 482b. The aft rotor assembly 481 has a top cover 281a and an extended rear section 481b. An aft support structure 484 may extend downwardly from the aft area of ​​the aerodynamic boom 483. As can be seen in the cross section of FIG. 15C from a section 485 made along the aerodynamic boom 483, an airfoil section is used to reduce drag during forward flight as well as during vertical takeoff and landing operations.

[0075] In some embodiments, as seen in Figures 16A-16D, an airborne vehicle 500 utilizes forward tilt rotors in accordance with other embodiments of the present invention. The airborne vehicle 500 has a vehicle body 501 with a left wing 502 and a right wing 503. As seen in the plan view of Figure 16C, the left wing 502 has an inboard section and an outboard section. The right wing 503 has an inboard section and an outboard section. The wings 502, 503 may be partial forward-swept wings, with the inboard section curving forward and the outboard section curving aft. The wing configuration as shown allows the aerodynamic center of the wing to be aft of the center of gravity of the airborne vehicle, which may enhance control and stability of the airborne vehicle during forward flight. It may also be desirable to couple the wings to the body of the airborne vehicle aft of the pilot's position. In some aspects, there are internal structural elements that couple the wings to the body and to each other, which may traverse the interior of the body of the airborne vehicle. These internal structural elements may also be on top of the aircraft body, as the wing may be structurally connected to the aircraft body at or near the top of the aircraft body. This higher connection and associated internal structural support may require the wing to be connected to the aircraft body behind the pilot's head when the pilot is seated in the aircraft body. The forward curvature inboard allows the wing to be connected aft, allowing for the above considerations. The outboard swept-back wing change then acts to bring the overall longitudinal aerodynamic center of the wing aft, allowing for control and stability considerations. The horizontal thrust propeller 516 is adapted to propel the aircraft forward in horizontal flight in conjunction with the forward thrust components of the wing-mounted rotor assemblies described above.

[0076] The aircraft 500 has a body 501 coupled to a right wing 503 and a left wing 502, and has multiple, wing-mounted, stacked, double rotor assemblies. A right forward upper rotor assembly 506 and a right forward lower rotor assembly 507, and a right aft upper rotor assembly 504 and a right aft lower rotor assembly 505 are mounted to span supports coupled to the right wing 503. A left forward upper rotor assembly 508 and a left forward lower rotor assembly 509, and a left aft upper rotor assembly 510 and a left lower rotor assembly 511 are mounted to span supports coupled to the left wing 502. In this configuration, it can be seen that each rotor has a counterpart on the opposite side of the aircraft body, on a line substantially across the center of gravity of the aircraft, and at or near the same distance from the center of gravity. In this configuration, if a rotor fails during vertical takeoff and landing maneuvers, the counterpart of the failed motor can be powered down almost instantly to maintain the aircraft's attitude, allowing for very rapid control compensation. In some aspects, the remaining rotor may be spun up to compensate for the overall loss of lift caused by the failure of said rotor and the powering down of the control rotor.

[0077] In some aspects, the wing rotor assemblies 504, 505, 506, 507, 508, 509, 510, 511 are tilted forward at an angle other than perpendicular to the aircraft's constant altitude cruise plane. In some aspects, the rotors are tilted forward at a range of 5 to 20 degrees. In some aspects, the rotors are tilted forward at a range of 5 to 15 degrees. In some aspects, the rotors are tilted forward at a range of 8 to 20 degrees. In some aspects, the rotors are tilted forward at a range of 8 to 12 degrees. In an exemplary embodiment, the rotors are tilted at 10 degrees. The tilt angle may be defined as the angle between the rotor axis and the mean aerodynamic chord line of the wing. In some aspects, the wing rotor assemblies may be fixed at the above mentioned tilt angles and may not have articulating aspects.

[0078] As shown in the side view of FIG. 16B, rotor assemblies 504, 505, 506, 507 are supported by rotors with extended rear portions 512, 513, 514, 516 that facilitate pressure recovery regions to avoid flow separation.

[0079] In some embodiments, as seen in FIGS. 17A-17D, the airborne vehicle 600 utilizes forward tilt rotors in accordance with other embodiments of the present invention. The airborne vehicle 600 has a vehicle body with left and right wings. As seen in the plan view of FIG. 17C, the left wing has an inboard section and an outboard section. The right wing has an inboard section and an outboard section. The wings may be partial forward swept wings, with the inboard section curving forward and the outboard section curving aft. The wing configuration as shown allows the aerodynamic center of the wing to be aft of the center of gravity of the airborne vehicle, which may enhance control and stability of the airborne vehicle during forward flight. It may also be desirable to couple the wings to the body of the airborne vehicle aft of the pilot's position. In some aspects, there are internal structural elements that couple the wings to the body and to each other, which may traverse the interior of the body of the airborne vehicle. These internal structural elements may also be on top of the aircraft body, as the wings may be structurally coupled to the aircraft body at or near the top of the aircraft body. This higher attachment and associated internal structural support may require that the wing be attached to the aircraft body behind the pilot's head when the pilot is seated in the aircraft body. The forward curved inboard portion allows the wing to be attached aft, allowing for the above considerations. The outboard portion swept-back wing change then acts to bring the wing's overall longitudinal aerodynamic center aft, allowing for control and stability considerations. The horizontal thrust propeller, in conjunction with the forward thrust components of the wing-mounted rotor assemblies described above, is adapted to propel the aircraft forward in horizontal flight.

[0080] The aircraft 600 has a body coupled to right and left wings and has multiple wing-mounted rotor assemblies. A wing inboard right hand forward rotor assembly 605 and a wing inboard right hand aft rotor assembly 606 are mounted on span supports coupled to the right wing. A wing outboard right hand forward rotor assembly 607 and a wing outboard right hand aft rotor assembly 608 are mounted on span supports coupled to the right wing. A wing inboard left hand forward rotor assembly 603 and a wing inboard left hand aft rotor assembly 604 are mounted on span supports coupled to the left wing 503. A wing outboard left hand forward rotor assembly 601 and a wing outboard left hand aft rotor assembly 602 are mounted on span supports coupled to the left wing. The blades of the left wing outboard rotor assemblies 601, 602 provide lift for forward flight in an area 610 outside the fixed wing, which increases the effective span of the wing. The blades of the right wing outer rotor assembly 607, 608 provide lift for forward flight in the outer region 611 of the fixed wing, which increases the effective span of the wing.

[0081] In this configuration, if a rotor fails during a vertical takeoff and landing maneuver, the counterpart rotor of the failed motor can be powered down almost instantly to maintain aircraft attitude, allowing for very rapid control compensation. In some aspects, the remaining rotors can be spun up to compensate for the overall loss of lift caused by the failure of the rotor and the powering down of the counterpart rotor.

[0082] In some aspects, the wing rotor assemblies 601, 602, 603, 604, 605, 606, 607, 608 are tilted forward at an angle other than perpendicular to the aircraft's constant altitude cruise plane. In some aspects, the rotors are tilted forward at a range of 5 to 20 degrees. In some aspects, the rotors are tilted forward at a range of 5 to 15 degrees. In some aspects, the rotors are tilted forward at a range of 8 to 20 degrees. In some aspects, the rotors are tilted forward at a range of 8 to 12 degrees. In an exemplary embodiment, the rotors are tilted at 10 degrees. The tilt angle may be defined as the angle between the rotor axis and the mean aerodynamic chord line of the wing. In some aspects, the wing rotor assemblies may be fixed at the above mentioned tilt angles and may not have articulating aspects.

[0083] As shown in the side view of FIG. 17D, rotor assemblies 601, 602, 603, 604, 605, 606, 607, 608 are supported by rotors with extended rear pressure recovery areas that facilitate avoiding flow separation.

[0084] As is apparent from the above description, numerous and varied embodiments may be constructed from the description given herein, and additional advantages and modifications will readily occur to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general invention.

Claims

1. 1. An airborne vehicle adapted for vertical takeoff and horizontal flight using rotors to simulate the aerodynamics of conventional wings, comprising: a vehicle body, a right wing assembly, a left wing assembly, and a horizontal thrust aft rotor assembly, the right wing assembly comprising: The right wing and a plurality of right wing rotor assemblies; Equipped with the left wing assembly comprising: The left wing and a plurality of left wing rotor assemblies; Equipped with the horizontal thrust aft rotor assembly: adapted to provide horizontal thrust during normal flight; the plurality of starboard wing rotor assemblies comprising: the spin axis of each of the starboard wing rotor assemblies is tilted forward in a fixed position relative to the aircraft structure while in a horizontal forward flight configuration; and [0023] adapted to maintain power during forward flight; each of the right wing rotor assemblies has a propeller with three or more blades; a right front wing inner rotor assembly coupled to an inner wing portion of the right wing and forward of the right wing; a right aft wing inner rotor assembly coupled to an inner wing portion of the right wing and aft of the right wing; a right wing outer rotor assembly coupled to the right wing tip, the plurality of port wing rotor assemblies comprising: the spin axis of each of the port wing rotor assemblies is tilted forward in a fixed position relative to the aircraft structure while in a horizontal forward flight configuration; and [0023] adapted to maintain power during forward flight; each of the left wing rotor assemblies includes a propeller having three or more blades; a left forward wing inner rotor assembly coupled to an inner wing portion of the left wing and forward of the left wing; a left aft wing inner rotor assembly coupled to an inner wing portion of the left wing and aft of the left wing; a left wing outer rotor assembly coupled to the left wing tip, the spin axis of said right wing rotor assembly is tilted forward at an angle in the range of 5 to 20 degrees relative to a normal to the horizontal flight line of the airborne vehicle in normal forward flight; the spin axis of the rotor assembly of said left wing being tilted forward at an angle in the range of 5 to 20 degrees relative to a normal to the horizontal flight line of the airborne vehicle in normal forward flight; An aerial vehicle characterized by:

2. 2. The aerial vehicle of claim 1, the spin axis of said right wing rotor assembly is tilted forward at an angle in the range of 8 to 12 degrees relative to a normal to the horizontal flight line of the airborne vehicle in normal forward flight; the spin axis of the rotor assembly of said port wing being tilted forward at an angle in the range of 8 to 12 degrees relative to a normal to the horizontal flight line of the airborne vehicle in normal forward flight; An aerial vehicle characterized by:

3. 2. The aerial vehicle of claim 1, the spin axis of said starboard wing rotor assembly is tilted forward at an angle in the range of 5 to 15 degrees relative to a normal to the horizontal flight line of the airborne vehicle in normal forward flight; the spin axis of the rotor assembly of said left wing is tilted forward at an angle in the range of 5 to 15 degrees relative to a normal to the horizontal flight line of the airborne vehicle in normal forward flight; An aerial vehicle characterized by:

4. 3. The aerial vehicle of claim 2, further comprising: the airborne vehicle has no controllable flight control surfaces; An aerial vehicle characterized by:

5. 3. The aerial vehicle of claim 2, further comprising: the right wing rotor assembly and the left wing rotor assembly, An electric motor; an upper central hub coupled to a rotating portion of the electric motor; three or more blades coupled to the central hub; An aerial vehicle comprising:

6. 6. The aerial vehicle of claim 5, further comprising: the upper central hub being a flattened hub; An aerial vehicle characterized by:

7. 6. The aerial vehicle of claim 5, further comprising: a ratio of a diameter of the upper central hub to a diameter of a circle traversed by the vanes is greater than 0.25; An aerial vehicle characterized by:

8. 6. The aerial vehicle of claim 5, further comprising: a ratio of a diameter of the upper central hub to a diameter of a circle traversed by the vanes is greater than 0.30; An aerial vehicle characterized by:

9. 6. The aerial vehicle of claim 5, further comprising: the right wing rotor assembly and the left wing rotor assembly each include a lower cowling extending aft of the upper central hub; An aerial vehicle characterized by:

10. 9. The aerial vehicle of claim 8, further comprising: the right wing rotor assembly and the left wing rotor assembly each include a lower cowling extending aft of the upper central hub; An aerial vehicle characterized by:

11. 2. The aerial vehicle of claim 1, further comprising: each of said plurality of right wing rotor assemblies has a mating left wing rotor assembly that is approximately equidistant from a centerline of said airborne vehicle on a line passing through approximately the center of gravity of said airborne vehicle; An aerial vehicle characterized by:

12. 3. The aerial vehicle of claim 2, further comprising: each of said plurality of right wing rotor assemblies has a mating left wing rotor assembly that is approximately equidistant from a centerline of said airborne vehicle on a line passing through approximately the center of gravity of said airborne vehicle; An aerial vehicle characterized by:

13. 4. The aerial vehicle of claim 3, further comprising: each of said plurality of right wing rotor assemblies has a mating left wing rotor assembly that is approximately equidistant from a centerline of said airborne vehicle on a line passing through approximately the center of gravity of said airborne vehicle; An aerial vehicle characterized by:

14. 1. An airborne vehicle adapted for vertical takeoff and horizontal flight using rotors to simulate the aerodynamics of conventional wings, comprising: a vehicle body, a right wing assembly, a left wing assembly, and a horizontal thrust aft rotor assembly, the right wing assembly comprising: The right wing and a plurality of right wing rotor assemblies; Equipped with the left wing assembly comprising: The left wing and a plurality of left wing rotor assemblies; Equipped with the horizontal thrust aft rotor assembly: adapted to provide horizontal thrust during normal flight; the plurality of starboard wing rotor assemblies comprising: the spin axis of each of the starboard wing rotor assemblies is tilted forward in a fixed position relative to the aircraft structure while in a horizontal forward flight configuration; and [0023] adapted to maintain power during forward flight; each of the right wing rotor assemblies has a propeller with three or more blades; a right front wing inner rotor assembly coupled to an inner wing portion of the right wing and forward of the right wing; a right aft wing inner rotor assembly coupled to an inner wing portion of the right wing and aft of the right wing; a right front wing outer rotor assembly coupled to a wing outer section of the right wing and forward of the right wing; a right aft wing outer rotor assembly coupled to a wing outer section of the right wing and aft of the right wing, the plurality of port wing rotor assemblies comprising: the spin axis of each of the port wing rotor assemblies is tilted forward in a fixed position relative to the aircraft structure while in a horizontal forward flight configuration; and [0023] adapted to maintain power during forward flight; each of the left wing rotor assemblies includes a propeller having three or more blades; a left forward wing inner rotor assembly coupled to an inner wing portion of the left wing and forward of the left wing; a left aft wing inner rotor assembly coupled to an inner wing portion of the left wing and aft of the left wing; a left forward wing outer rotor assembly coupled to a wing outer section of the left wing and forward of the left wing; a left aft wing outer rotor assembly coupled to the wing outer section of the left wing and aft of the left wing, the spin axis of said right wing rotor assembly is tilted forward at an angle in the range of 5 to 20 degrees relative to a normal to the horizontal flight line of the airborne vehicle in normal forward flight; the spin axis of the rotor assembly of said left wing being tilted forward at an angle in the range of 5 to 20 degrees relative to a normal to the horizontal flight line of the airborne vehicle in normal forward flight; An aerial vehicle characterized by:

15. 15. The airborne vehicle of claim 14, the spin axis of said starboard wing rotor assembly is tilted forward at an angle in the range of 8 to 12 degrees relative to a normal to the horizontal flight line of the airborne vehicle in normal forward flight; the spin axis of the left wing rotor assembly is tilted forward at an angle in the range of 8 to 12 degrees relative to a normal to the horizontal flight line of the airborne vehicle in normal forward flight; An aerial vehicle characterized by:

16. 15. The airborne vehicle of claim 14, the spin axis of said starboard wing rotor assembly is tilted forward at an angle in the range of 5 to 15 degrees relative to a normal to the horizontal flight line of the airborne vehicle in normal forward flight; the spin axis of the rotor assembly of said port wing being tilted forward at an angle in the range of 5 to 15 degrees relative to a normal to the horizontal flight line of the airborne vehicle in normal forward flight; An aerial vehicle characterized by:

17. 16. The aerial vehicle of claim 15, further comprising: the airborne vehicle has no controllable flight control surfaces; An aerial vehicle characterized by:

18. 16. The aerial vehicle of claim 15, further comprising: the right wing rotor assembly and the left wing rotor assembly, An electric motor; an upper central hub coupled to a rotating portion of the electric motor; three or more blades coupled to the central hub; An aerial vehicle comprising:

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