High-speed VTOL (Vertical Takeoff and Landing) aircraft

Abstract

This aircraft improves upon the shortcomings of the Osprey, offering a highly economical, high-speed VTOL aircraft that surpasses it in both performance and functionality. [Solution] By employing two types of propellers, a propeller and a main rotor, as thrusters for the VTOL aircraft of this invention, the structurally complex and heavy tilt rotor mechanism becomes unnecessary, simplifying the aircraft's structure and reducing manufacturing and operating costs. The lighter aircraft also improves maneuverability and extends the range. Furthermore, in fixed-wing mode, the main rotor is stopped, and the arms of the rotor fixing device mounted on the aircraft are extended to completely catch the main rotor and maintain an attitude that minimizes air resistance. By using the propeller as the thruster for horizontal flight and stopping the rotation of the main rotor, air resistance is minimized, making it possible to achieve a maximum speed exceeding that of the Osprey.

Description

Technical Field

[0001] The present invention relates to a high-performance and low-cost VTOL (Vertical Takeoff and Landing aircraft) equipped with the functions of both an airplane and a helicopter.

Background Art

[0002] For many years, there has been a demand for an aircraft that combines the high speed of an airplane and the vertical takeoff and landing function of a helicopter. As an aircraft that meets this requirement, the Osprey (see Figure 1) has emerged. The structure of this aircraft basically adopts a tilt-rotor system (tilted rotor system) that changes the angle of the propeller rotor (an intermediate propeller between a propeller and a rotor) shaft equipped at the tip of the main wing of a general high-wing airplane, so that it is possible to switch the characteristics of a fixed-wing aircraft and a rotary-wing aircraft (helicopter) during flight. It is a VTOL (Vertical Takeoff and Landing aircraft). The mode when this aircraft performs the same flight as an airplane (fixed-wing aircraft) is called the fixed-wing mode, and the mode when it performs the same flight as a helicopter (rotary-wing aircraft) is called the rotary-wing mode. Conventional helicopters have a maximum speed of about 300 km / h, but the Osprey is as high as 565 km / h and has a longer flight range. On the other hand, when compared with a propeller aircraft of the same size equipped with a normal main tail and propeller, it is clearly inferior in terms of flight speed and flight range.

[0003] One of the propeller aircraft of the same size as the Osprey is the E-2C medium surveillance aircraft. This aircraft has a very large air resistance with a huge radar dome with a diameter of more than 7 meters on the upper part of the fuselage supported by six struts. Although the engine output is 83% of that of the Osprey, it exhibits a flight speed of 625 km / h, which is more than 10% higher than that of the Osprey (see Figure 2).

[0004] Until the Osprey, which successfully made its first flight in 1989 and is currently the only high-speed VTOL in operation, appeared, the field of activity as a VTOL was dominated by helicopters, but the disadvantages of slow flight speed and short flight range have been raised.

[0005] To address the shortcomings of helicopters—their low speed and short range—many prototypes have been built and test-flewed over the years, but some of the main ones did not reach practical use.

[0006] Fairey FB-1 Gyrodyne, British-made, first flight in 1947. The aircraft is an experimental rotary-wing aircraft with a single lifting rotor and a tractor propeller mounted on the tip of the right wing stub wing, providing both thrust and counter-torque response. It has a maximum speed of 224 km / h and a length of 7.62 m.

[0007] Fairey Roddine, British-made, first flight 1957. During takeoff, the aircraft directs most of its engine power to the compressor, mixes fuel with the resulting compressed air, and injects the combustion gases from the rotor tips to rotate and take off vertically. After takeoff, all engine power is redirected to the propellers for forward flight, and the aircraft maintains level flight using the lift generated by the wings. During level flight, the unpowered rotors rotate in response to the airflow from the front, similar to an autogyro, assisting in lift. This system allowed for lower fuel consumption and higher speeds than helicopters. However, due to the loud noise during takeoff and landing, its inferiority to conventional passenger aircraft in terms of economy, and ultimately for political reasons, development of this compound helicopter was discontinued. It had a maximum speed of 343 km / h and a length of 18 meters.

[0008] Ka-22, Russian-made, first flight 1959. This aircraft is a fixed-wing aircraft equipped with engines, main rotors, and tractor propellers at the wingtips, with a top speed of 350 km / h and a total length of 27 meters. In rotary-wing mode, the propeller drive is deactivated, and in fixed-wing mode, the rotor is allowed to rotate freely, with flight control performed by the ailerons and tail.

[0009] Bell 533, American-made, first flight 1961. This experimental aircraft is based on a standard UH-1 helicopter, with a pair of turbojet engines added to the fuselage. It was designed to investigate the limits and conditions experienced by helicopter rotors, achieving a top speed of 508 km / h and having a total length of approximately 17 meters.

[0010] AH-56 Cheyenne, American-made, first flight in 1967. This aircraft was a compound helicopter with a main tail and a rear propeller, similar to a conventional helicopter, with a maximum speed of 394 km / h and a length of 16.66 m. Despite successful development, its adoption was canceled due to delays in development caused by technical problems, soaring development costs, and changes in tactical thinking.

[0011] Sikorsky X-wing aircraft completed in 1986. The aircraft is a research and development hybrid helicopter, the S-61, a medium-sized helicopter with a crew capacity of 18, equipped with small wings and a pair of turbofan engines for horizontal speed enhancement on the sides of its fuselage. The four blades of the main rotor, which lacked flexibility during high-speed flight, were fixed at the 1:30, 4:30, 7:30, and 10:30 positions. Completed in 1986, this 22-meter-long aircraft was intended to be used as the upper wing of a biplane, aiming for a top speed of 700 km / h. However, in reality, it was inferior to later tiltrotor aircraft in terms of speed, fuel efficiency, and range, and its complex structure and poor maintainability meant the project was abandoned in 1988 without ever being flown. In the final stages of the plan, the predicted maximum speed had dropped to 550 km / h.

[0012] X-49, American-made, first flight in 2007. This aircraft is an experimental composite helicopter with fixed wings attached to the underside of a standard SH-60 helicopter fuselage and a ducted fan attached to the tail. The ducted fan provides thrust and also has control fins that change the airflow direction to control torque, allowing the aircraft to reach a top speed of 270 km / h and have a total length of 19.76 m.

[0013] Eurocopter X3, European-made, first flight 2013. This aircraft is a compound helicopter, a Eurocopter EC155, with a pair of tractor propellers and small wings attached. It is a high-speed helicopter test aircraft designed to demonstrate the concept that the small wings contribute to lift, reducing the load on the main rotor and lowering its rotation speed, thereby reducing drag on the forward-facing blades and preventing stalls on the backward-facing blades. As the flight speed (forward speed) increases, the lift generated by the small wings also increases, reducing the main rotor rotation speed to a minimum of 15%, and the aircraft has a maximum speed of 472 km / h and a length of approximately 14 m.

[0014] Recent attempts to increase the speed of compound helicopters in the United States include a plan for a future vertical take-off and landing (VTOL) aircraft, initiated in 2009 by the U.S. Department of Defense, with the goal of developing a VTOL aircraft for military use from 2030 onwards. The requirements for the aircraft in the development goals are: ▲1▼Speed ​​of 425 kilometers per hour or more ▲2▼Operational radius of 415 km or more ▲3▼ Increase in internal payload ▲4▼Improved durability ▲5▼ Situational awareness This is the granting of [the right / the right]. While these were development goals, I believe that ▲1▼ and ▲2▼ are remarkably low by today's standards.

[0015] The aircraft participating in the above project is the SB-1 Defiant compound helicopter, which generates powerful lift by employing coaxial counter-rotating rotors and can fly at a speed of 467 km / h thanks to a propeller mounted at the rear of the fuselage. This aircraft, which lacks wings, has a coaxial counter-rotating rotor that continues to rotate even during high-speed flight. It is an 11-meter-long aircraft.

[0016] Bell's Invictus 360 is a helicopter equipped with short wings and an auxiliary power unit that can provide additional power. Bell highlights that the aircraft can be remotely controlled, has a top speed of 333 km / h, and is 14 meters long.

[0017] Bell's planned aircraft is a tilt-rotor aircraft, the V-280 Valor, which is slightly smaller than the V-22 Osprey and adopts a tilt (tilting) form only for the propeller rotor part. It has a maximum speed of 555 km / h and a total length of 20 m. It has outperformed other candidate aircraft and has been adopted by the US military.

[0018] In Japan, JAXA (Japan Aerospace Exploration Agency) is developing a next-generation compound helicopter with the goal of completing the world's fastest helicopter. However, with a target speed of 500 km / h, it is almost impossible to obtain the title of the world's fastest, and it is speculated that the speed needs to be increased by more than 100 km / h to achieve the goal.

Prior Art Documents

Patent Documents

[0019]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0020]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Non-Patent Document 5

Non-Patent Document 6

Non-Patent Document 7

Non-Patent Document 8

Non-Patent Document 9

Non-Patent Document 10

Non-Patent Document 11

Non-Patent Document 12

Non-Patent Document 13

[0021] The challenges to be addressed are that the V-22 Osprey, currently the only high-speed VTOL aircraft in actual operation, has lower performance and reliability compared to conventional propeller aircraft, as well as higher manufacturing and operating costs. [Means for solving the problem]

[0022] The Osprey is a tiltrotor aircraft that uses a prop rotor as its propulsion system. While the prop rotor can perform the dual functions of both a propeller and a main rotor, it is less efficient than a propeller in fixed-wing mode, resulting in a slower aircraft speed than a propeller aircraft. In rotary-wing mode, it is less efficient than a main rotor, resulting in lower lift capacity than a helicopter. Therefore, there is no further significant improvement in performance for tiltrotor aircraft, and we have no choice but to devise a new type of aircraft to solve the problem.

[0023] Helicopters, which were put into practical use as VTOL aircraft in the 1940s, have since been subjected to numerous attempts to increase speed by adopting the compound helicopter configuration, but have been blocked by the 400 km / h speed barrier. A close examination of the experimental records of these prototype machines reveals common problems. The fact is that the main rotor was still rotating even in fixed-wing mode, which allows for high-speed flight. In other words, the rotation of the main rotor was a hindrance to high-speed flight, and it can be said with certainty that this was the result of numerous designers who had worked on previous prototypes failing to consider this fact.

[0024] Looking back at aviation history from its early days to the present, the Italian Air Force's CR.42 (see Figure 17), a biplane with high air resistance that made its maiden flight in 1939, saw its top speed increase from 430 km / h to 520 km / h by replacing its engine from 840 hp to 1020 hp. Setting aside the issue of airframe strength, one might think that a top speed of 600 km / h wouldn't have been out of the question if the same aircraft had been fitted with a 2000 hp class engine. One could infer from this example that even an aircraft with somewhat high air resistance might be able to reach speeds of 600 kilometers per hour if it is equipped with high-performance propellers and a powerful engine to drive them.

[0025] Assuming that the Osprey's slow maximum speed is due to its prop rotor, the first characteristic of this invention is that it employs two types of thrusters: a propeller in fixed-wing mode and a main rotor in rotary-wing mode, thus eliminating the need for a tilt rotor mechanism.

[0026] In the fixed-wing mode of this proposed VTOL aircraft, the aircraft is lifted by the buoyancy of the main wings, making the main rotor a useless feature that creates significant air resistance. Solving this problem is the main challenge.

[0027] The second characteristic of this invention is that, in fixed-wing mode, the rotor is positioned to minimize air resistance before being stopped. This involves employing a fixing device attached to the aircraft to stop the main rotor during flight in fixed-wing mode and suppress vibrations of the main rotor. The fixing device previously patented in Spain is structurally complex and fragile, as it is integrated into the main rotor recess and rotor control device. More than 15 years have passed since the patent application, and not even a prototype has been manufactured, so it is presumed that the Spanish patent is impossible to realize. [Effects of the Invention]

[0028] In the fixed-wing mode of this VTOL design, the use of a propeller, which is more efficient than a prop rotor, makes it possible to achieve speeds in the 650 km / h range. On the other hand, in rotary-wing mode, the use of a main rotor, which is more efficient for rotary-wing flight than a prop rotor, enhances maneuverability. Next, by not adopting prop rotors, the tilt rotor mechanism becomes unnecessary, simplifying the aircraft's structure and significantly reducing manufacturing and operating costs. The reduced weight also improves maneuverability and extends the flight range. [Brief explanation of the drawing]

[0029] [Figure 1] This is a three-view drawing of the Osprey in fixed-wing mode with its prop rotors horizontal. (Maximum speed 565 km / h, engine output 12,300 hp) [Figure 2] This is a three-view drawing of the American-made E-2C medium patrol aircraft, which is equipped with a large radar dome on the upper fuselage. (Maximum speed 625 km / h, engine output 10,200 hp) [Figure 3] This is a three-view drawing of the small attack helicopter AH-1S. (Maximum speed 315 km / h, engine power 1,800 hp) [Figure 4] This is a three-view drawing of the rotor blade mode of Example 1. [Figure 5]This is a three-view drawing of the fixed-wing mode of Example 1. [Figure 6] This is a three-view drawing of the rotor blade mode in Example 2. [Figure 7] This is a three-view drawing of Example 2 in fixed-wing mode. [Figure 8] The electromagnetic main rotor fixing device is equipped with permanent magnets on the rotor side and an electromagnet on the top and a permanent magnet on the bottom of the fixing device, allowing for circular motion around a pivot point. In rotary-wing mode, the main rotor and fixing device are kept at a distance from each other to prevent contact, and in fixed-wing mode, they are brought into close contact and the main rotor is fixed by the force of the permanent magnet. The electromagnet is activated by energizing it when the main rotor and fixing device are separated, so it is not necessary to energize the electromagnet for most of the flight time. The upper diagram shows the rotary-wing mode and the lower diagram shows the fixed-wing mode. [Figure 9] This is a diagram of the mechanical main rotor fixing device in rotor blade mode. In rotor blade mode, a distance is maintained between the main rotor and the fixing device to prevent contact. The top diagram is a front view of the device, the middle diagram is a top view, and the bottom diagram is a side view. [Figure 10] This is a diagram of the mechanical main rotor fixing device in fixed-wing mode. In fixed-wing mode, the main rotor and the fixing device are in close contact to suppress vibrations of the main rotor. The top diagram is a front view of the device, the middle diagram is a top view, and the bottom diagram is a side view. For the VTOL main rotor fixing device of this invention, one of the two methods described above will be selected and equipped. [Figure 11] Head Rectifier This device reduces turbulence around the main rotor head that occurs when the main rotor is folded and the aircraft performs horizontal flight in the fixed-wing mode of Example 2. Compressed air is injected from a front compressed air injection device installed at the front of the main rotor head and a rear compressed air injection device installed at the rear of the main rotor shaft to reduce turbulence around the main rotor head and increase the aircraft speed. The top figure is a side view, the left middle figure is a front view of the front compressed air injection device, the right middle figure is a front view of the rear compressed air injection device, the left bottom figure is a top view of the front compressed air injection device, and the left bottom figure is a top view of the rear compressed air injection device. [Figure 12]Movable Winglets The aircraft designed in this invention is a biplane equipped with winglets at the wingtips of the upper and lower wings. The top two images show the winglets in fixed-wing mode, while the bottom two images show the winglets folded in rotary-wing mode to reduce the wind pressure downstream of the main rotor. [Figure 13] Cross-sectional view of a biplane wing. The aircraft of this design is a biplane with the upper wing positioned in front of the lower wing. The top two images in Figure 13 are cross-sectional views of the wing in fixed-wing mode, and the bottom two images show the state in rotary-wing mode where the leading-edge flaps of the upper wing are pointed straight down and the flaperons of the lower wing are pointed straight up to reduce the downstream wind pressure of the main rotor. [Figure 14] Movable tail fins in rotor mode: When in rotor mode, the movable tail fins do not use their function to maintain a horizontal position to avoid the tail rotor's wake. [Figure 15] Movable tail in fixed-wing mode: In fixed-wing mode, the movable tail functions as a V-tail, maintaining its attitude at a 45-degree angle. [Figure 16] This is a conceptual diagram illustrating how power is transmitted from the engine to the rotor and propeller. [Figure 17] This is a three-view drawing of the Italian Air Force biplane CR.32. A development of this aircraft was the CR.42, a biplane that achieved a top speed of 520 km / h, which was more than 10 km / h faster than the flight speed of the Zero fighter, a monoplane with retractable landing gear that reduced air resistance, when it was officially adopted by the Japanese Navy. [Modes for carrying out the invention]

[0030] This approach involves adding main and tail wings, control surfaces, and propellers to the basic structure of a typical helicopter equipped with one main rotor and a tail rotor, thereby creating a composite helicopter capable of VTOL (Vertical Take-Off and Landing). [Examples]

[0031] Figure 4 is a three-view drawing of a VTOL in rotary-wing mode, which implements this invention based on the general combat helicopter shown in Figure 3.

[0032] The combat helicopter airframe that serves as the basis for this design is equipped with main and tail wings and control surfaces.

[0033] This design is based on an aircraft with a pusher-type propeller mounted at the rear, along with associated friction clutches, brakes, and propeller gears.

[0034] The aircraft that forms the basis of this invention is equipped with either an electromagnetic or mechanical rotor fixing device. See Figures 8, 9, and 10.

[0035] The main rotor's rotating shaft is equipped with a friction clutch, a shaft assist rotation device, and a brake.

[0036] The tail rotor's rotating shaft is equipped with a friction clutch, a shaft assist rotation device, and a brake.

[0037] The VTOL in Example 1 has two flight modes: rotary-wing mode and fixed-wing mode.

[0038] In rotary-wing mode, the aircraft flies using both a main rotor and a tail rotor, similar to a conventional helicopter, and the propeller not in use during this flight is disconnected from the engine by a friction clutch. See Figures 4 and 16.

[0039] In fixed-wing mode, the aircraft flies using propeller thrust and wing lift, similar to a conventional airplane, and is controlled by flaperons and rudder / beta controls. The main rotor and tail rotor, which are not used in this mode, are disconnected from the engine by friction clutches. Each rotor is fixed in place by a rotor brake device, oriented parallel to the direction of the aircraft's movement, using a rotor shaft auxiliary rotation device. The main rotor's vibration is suppressed by a rotor fixing device. See Figures 8, 9, and 10.

[0040] The VTOL (Vertical Take-Off and Landing) system designed in this invention is capable of taking off and landing in both flight modes.

[0041] Switching from rotary-wing mode to fixed-wing mode involves connecting the propeller to the engine and rotating it once the aircraft reaches a safe takeoff speed in fixed-wing mode. When the propeller thrust is sufficiently generated and the aircraft reaches a speed at which it can fly using the lift of the main wings, the rotor is disconnected from the engine, stopped parallel to the aircraft's direction of travel using an axis assist rotation device, and the rotation axis is fixed with a brake. Finally, the main rotor is fixed with a rotor locking device, completing the flight mode switch.

[0042] Switching from fixed-wing mode to rotary-wing mode involves releasing the main rotor's locking mechanism and allowing it to rotate once the aircraft has reached a safe takeoff speed in fixed-wing mode. The propeller is then disconnected from the engine when the main rotor's thrust is sufficient and the aircraft is ready to fly, thus completing the flight mode switch. [Examples]

[0043] Example 2 is roughly identical to Example 1 in its basic operation. See Figures 6 and 7.

[0044] The difference between Example 2 and Example 1 is that Example 2 has three main rotor blades and is equipped with a main rotor head rectifier. Since there are three main rotor blades, it is necessary to fold the rotor to minimize air resistance in fixed-wing mode, so a mechanism similar to that described in [Non-Patent Document 16] is adopted. Furthermore, even if the main rotor has four or more blades, the high-speed VTOL of this invention can be achieved by applying the basic principles of this invention.

[0045] With three main rotor blades, the rotor blade mode requires unfolding the folded main rotor. In fixed-wing mode, the main rotor is closed and then fixed in place by a rotor locking device. Compressed air is then injected by the front and rear compressed air injection devices to prevent turbulence around the rotor head. [Explanation of Symbols]

[0047] 1 Torso 2 Main Wings 3 Movable tail wing 4. Movable winglets 5. Leading edge flag 6. Frapperon 7 Ladder Beta 8 engines 9 propellers 10 Main rotor 11 Tail rotor 12 rotorheads 14 Rotation axis 21 Rotor fixing device 22 Rotor fixing device head 23 Rotor fixing device arm 24 permanent magnets 25 Electromagnet 26 Rotor fixing device catch fitting 31 Front head rectifier 32 Rear head airflow rectifier 33 Compressed air nozzle 121 Reducer 122 Freewheel Clutch 123 Drive Gear 124 Drive shaft 125 Friction Clutch 126 Brake 127 Axis Auxiliary Rotating Device 128 Main Gear 130 Main rotor control unit 132 Tail rotor gear 133 Tail rotor control unit 134 Propeller gear 135 Propeller Control Unit 136 Gearbox 140 Auxiliary equipment

Claims

1. Rotor fixing device mounted on the outside of the main rotor mechanism To realize the VTOL of this invention, a device is needed to reliably hold the main rotor in an attitude that minimizes air resistance when flying in fixed-wing mode. While there are overseas patents for rotor fixing devices that utilize the framework of an umbrella, these have not been put into practical use because they further complicate the main rotor mechanism and are less durable. The rotor fixing device of the present invention is a highly durable and maintainable rotor fixing device because it is positioned outside the main rotor mechanism, and it reliably holds the main rotor in an attitude that minimizes air resistance when flying in fixed-wing mode. The details of the claim are as explained in Figures 8, 9, and 10.

2. Head rectifier This device reduces turbulence around the main rotor head when the main rotor is folded and the aircraft is flying horizontally in the fixed-wing mode of Example 2. The details of the claim are as described in Figure 11.

3. Movable winglets By adopting this design, the winglets can be folded between the upper and lower wings during vertical ascent and descent, minimizing the main rotor's wake across the entire wing. The details of the claim are as explained in [Figure 12].

4. The structure of the biplane with its front-to-back offset design and the operation method of the equipped leading-edge flaps and lavenders. The VTOL of this invention employs a biplane wing, with the upper wing positioned forward of the lower wing. The upper wing is equipped with leading-edge flaps that can be directed straight down during vertical ascent and descent, and the lower wing is equipped with flaperons that can be directed straight up during vertical ascent and descent, thereby minimizing the effect of the main rotor's wake across the entire wing. Details of the bill The details are as explained in [Figure 13].

5. Movable tail wing The present invention provides a movable tail fin that ensures high maneuverability in fixed-wing mode. This device is unnecessary in rotary-wing mode, so the tail fin is moved outside the wake area to avoid obstructing the tail rotor's wake. The details of the claim are as explained in Figures 14 and 15.

6. A composite helicopter, which is a conventional type of helicopter consisting of a main rotor and a tail rotor, with the addition of a propeller for horizontal flight, main and tail wings and control surfaces, wherein the flight mode can be changed during flight, and has a rotary-wing mode and a fixed-wing mode in which the main rotor can be completely stopped and the air resistance can be kept to a minimum. A high-speed VTOL composite helicopter manufactured with the above-mentioned claim 1 as an essential additional element and the other claims as optional additional elements, which can achieve a flight speed comparable to that of a propeller-driven aircraft.

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