KR102622742B1 - Hybrid vertical take-off and landing aircraft with improved flight stability - Google Patents

Abstract

The present invention is a composite vertical takeoff and landing aircraft that arranges a plurality of rotors on fixed wings used as main wings, configures some of the plurality of rotors in a tiltable form, and controls the attitude according to the situation to improve flight stability. It is about,
A plurality of inverted tilt units are installed symmetrically on both sides of the fuselage, including a straight tilt support installed on the main wing and a pair of tilt rotors installed at both ends of the tilt support in a form that can be tilted in different directions. It is provided with a plurality of fixed rotor parts symmetrically on both sides of the fuselage, including a straight fixed support installed on the main wing and a pair of lift rotors fixed to both ends of the fixed support, and an inversion tilt part. Each of the four or more tilt rotors that make up the tilt rotor and the four or more lift rotors that make up the fixed rotor section are spaced apart from each other in the longitudinal direction of the main wing and the longitudinal direction of the fuselage, so that the pitching moment arm and rolling moment arm, which are essential for controlling the attitude of the aircraft, are installed. It is characterized by being formed.

Description

Hybrid vertical take-off and landing aircraft with improved flight stability}

The present invention relates to a composite vertical takeoff and landing aircraft having fixed wings constituting the main wing and a plurality of rotors. More specifically, a plurality of rotors are arranged on the fixed wing used as the main wing, and some of the plurality of rotors are It relates to a complex vertical takeoff and landing aircraft that is configured in a tiltable form and controls its attitude depending on the situation to improve flight stability.

In general, in large cities such as Seoul, Korea, where overpopulation is a problem, severe traffic congestion and parking difficulties are becoming major problems, but normal methods such as expanding roads and expanding public transportation lines are no longer having a significant effect. We are reaching a difficult point.

Therefore, recently, urban air mobility (UAM, Urban Air Mobility), which combines the concept of a taxi with an electric propulsion multicopter drone equipped with multiple rotors, is attracting attention as a new alternative to solve the problem of traffic congestion. As the technology has advanced considerably, it is expected that commercialization will be possible in the near future.

In this way, if the commercialization of urban air mobility becomes a reality, safety is sufficiently proven, and the usage rate increases significantly, it is expected that traffic congestion in the city will be largely resolved.

However, in the commercialization of urban air mobility, the difficulties of long-term operation or long-distance flight of electric propulsion multicopter-type drones and issues related to flight safety remain issues that must be resolved.

In other words, it is necessary to improve the flight efficiency of multicopter-type drones, and in this regard, “Wing Tilt Drive System for Electric Vertical Takeoff and Landing Aircraft” in Korean Patent Publication No. 10-2020-0057057 and Korean Patent Publication No. 10-2021-0088052. Inventions such as Ho’s “vertical takeoff and landing air mobility” have been proposed and made public.

First, the “Wing Tilt Drive System for Electric Vertical Takeoff and Landing Aircraft” in Korean Patent Publication No. 10-2020-0057057 includes a pair of fixed wings and another pair of fixed wings at the front and rear of the aircraft, An invention has been proposed and disclosed regarding a composite vertical takeoff and landing aircraft, which is configured to have multiple tilt rotors on each fixed wing and enables vertical takeoff and landing.

In addition, the “vertical takeoff and landing air mobility” of Korean Patent Publication No. 10-2021-0088052 consists of four or more tilting rotors capable of tilting and two or more fixed lifting rotors installed on fixed wings, allowing vertical takeoff and landing. In addition, an invention regarding a composite vertical takeoff and landing aircraft that can reduce noise and vibration and can fly without problems even when some rotors are broken has been proposed and disclosed.

In other words, like the above-mentioned inventions, a composite vertical takeoff and landing device equipped with both fixed wings and rotors can be an alternative to multicopter-type drones, and has been developed by Archer in the United States, Vertical Aerospace in the United Kingdom, and Hyundai Motor Company in Korea. The concept for a composite vertical take-off and landing aircraft has also been released or is in development.

More specifically, the above complex vertical takeoff and landing aircraft has a form in which multiple rotors are arranged on the main wing (hereinafter referred to as main wing arrangement method) and a form in which a number of rotors are distributedly arranged in the main wing and tail wing (hereinafter referred to as tail wing). Among these, the main wing arrangement method can be divided into a form in which all rotors can tilt and a form in which only some rotors can tilt.

At this time, in the main wing arrangement method, a hybrid vertical takeoff and landing aircraft in which all rotors can be tilted has the problem of delaying the time to switch the rotor to the rotary wing state when the flight attitude is disturbed due to a disturbance or stall during flight in the fixed wing state. It happens.

In addition, a hybrid vertical takeoff and landing aircraft in which only some of the rotors are capable of tilting has fixed rotors arranged in a straight line along the length of the main wing, which makes it difficult to control the pitch of the aircraft in emergency situations such as the above. do.

In addition, in the tail wing distributed arrangement method, the rotor and motor placed on the tail wing create a structural burden on the aircraft, the pitching moment of inertia of the aircraft increases, and the thrust line of the aircraft is formed above the fuselage axis, so the use of fixed wings During flight, a problem arises in which pitch control of the aircraft becomes difficult.

In conclusion, in order to commercialize urban air mobility, a hybrid vertical takeoff and landing aircraft with improved flight efficiency than a multicopter type drone must be used, but improvement in safety is absolutely necessary.

Republic of Korea Patent Publication No. 10-2020-0057057 (May 25, 2020) Republic of Korea Patent Publication No. 10-2021-0088052 (July 14, 2021)

The hybrid vertical takeoff and landing device with improved flight stability according to the present invention is an invention proposed for the purpose of solving the problems of the known inventions as described above.

In a composite vertical takeoff and landing aircraft with tilt rotors placed on the main wings, when an emergency situation occurs in which the flight attitude is suddenly disturbed due to a disturbance such as a gust or stall during transition flight or fixed-wing flight in which all rotors are tilted, the aircraft returns to the rotor-wing state. There is a time delay in the transition, making it difficult to quickly restore posture.

In a hybrid vertical takeoff and landing aircraft in which the tilt rotor and lift rotor are arranged in a straight longitudinal direction on the main wing, the pitching moment arm between the rotors is not secured, which is a problem that prevents the pitching control power essential for flight safety in the above emergency situation from being secured. is occurring,

More fundamentally, in a form where the tilt rotor is arranged in series at the front and rear of the main wing, there is a problem that the decrease in thrust of the rear tilt rotor due to the wake of the front tilt rotor during fixed-wing flight cannot be resolved.

In addition, in a hybrid vertical takeoff and landing aircraft with multiple rotors distributed on the tail wings, the rotors and motors placed on the tail wings create a structural burden on the aircraft, increasing the pitching moment of inertia of the aircraft, and causing tail As the thrust line of the aircraft is formed upward of the fuselage axis by the tilt rotor installed on the wing, the problem of controlling the pitch of the aircraft becomes difficult when flying using fixed wings. Therefore, it is important to suggest a solution to this problem. It is for that purpose.

The present invention aims to achieve the above object,

In a complex vertical takeoff and landing aircraft having fixed wings constituting the main wing and a plurality of rotors,

A plurality of inverted tilt units are installed symmetrically on both sides of the fuselage, including a straight tilt support installed on the main wing and a pair of tilt rotors installed at both ends of the tilt support in a form that can be tilted in different directions. It is provided with a plurality of fixed rotor parts symmetrically on both sides of the fuselage, including a straight fixed support installed on the main wing and a pair of lift rotors fixed to both ends of the fixed support, and an inversion tilt part. Each of the four or more tilt rotors that make up the tilt rotor and the four or more lift rotors that make up the fixed rotor section are spaced apart from each other in the longitudinal direction of the main wing and the longitudinal direction of the fuselage, so that the pitching moment arm and rolling moment arm, which are essential for controlling the attitude of the aircraft, are installed. We present a composite vertical takeoff and landing aircraft with improved flight stability, which is characterized in that it is formed.

At this time, the reverse tilt unit is configured so that the pitch of the rear tilt rotor increases than the pitch of the front tilt rotor, so that the thrust of the rear tilt rotor decreases due to the generation of wake when moving and flying in fixed-wing mode or transition flight mode. It is characterized by preventing the occurrence of.

In addition, among the tilt rotors constituting the inversion tilt part of the complex vertical takeoff and landing aircraft, the front tilt rotor based on the main wing rotates in the same upward direction as the lift rotor so that thrust is formed upward, and the rear tilt rotor rotates toward the ground. It rotates so that thrust is formed upward in an attitude facing, but is characterized in that it is configured to take off and land vertically in a rotor mode in which adjacent rotors rotate in opposite directions.

In addition, the rotation of the lift rotor is stopped, but the front tilt rotor based on the main wing rotates while tilted toward the front, and the rear tilt rotor rotates in the opposite direction while tilted toward the rear, so that all tilt rotors It is characterized in that it is configured to move and fly in a fixed-wing mode that generates forward thrust.

In addition, with the front tilt rotor and rear tilt rotor rotating, the first transition flight mode is tilted forward and backward at the same speed, and the lift rotor also rotates, switching from rotary wing mode to fixed wing mode, and the front tilt rotor and rear The second transition flight mode, in which the tilt rotor rotates upward and downward at the same speed, and the lift rotor also rotates, switches from the fixed wing mode to the rotary wing mode, thereby maintaining flight stability.

In addition, when the composite vertical take-off and landing aircraft is moving and flying in fixed-wing mode and a disturbance acts on it and a fuselage inclination above the standard value is detected or a decrease in flight altitude due to a decrease in lift is detected above the standard value, the lift rotor rotates. It is characterized by being configured to switch to a mode and control the posture in the event of an additional emergency.

A composite vertical takeoff and landing aircraft with improved flight stability according to the present invention,

By distributing all the rotors in a square shape on the fixed wings that make up the main wing, unlike the case where rotors are installed on the tail wing, the effect is to prevent the weight burden from occurring on the tail wing and rear fuselage and to reduce the weight burden compared to the fuselage axis. In addition to preventing the upward formation of the thrust line, in contrast to the case of having a fixed rotor arranged only in a straight direction in the direction of the wing length and the case of having all rotors configured in a tilt type, as a result, the pitch problem, which is found in known inventions, is reduced. This has the effect of preventing an increase in the difficulty of control.

In addition, by implementing customized control for each tilting rotor and lift rotor that make up multiple rotors for each situation, not only is it easy to control the attitude of the vertical takeoff and landing aircraft, but it is also possible to quickly change the attitude of the aircraft even in emergency situations due to stall or disturbance. A stabilizing effect occurs.

Figure 1 is a perspective view showing the external appearance of a composite vertical takeoff and landing aircraft according to an embodiment of the present invention.
Figure 2 is a perspective view showing the external appearance of a composite vertical takeoff and landing aircraft according to another embodiment of the present invention.
Figure 3 is an example diagram showing the arrangement of a tilt rotor and a lift rotor for forming pitching moment arms (X1, X2) and rolling moment arms (Y1, Y2).
Figure 4 is an example showing the inverted rotor part, which constitutes a composite vertical take-off and landing aircraft with improved flight stability according to the present invention, installed on the main wing in a modular state that can be replaced.
Figure 5 is an example diagram showing a vertical takeoff and landing in a rotary wing mode of a composite vertical takeoff and landing aircraft with improved flight stability according to the present invention.
Figure 6 is an example diagram showing the process of converting the hybrid vertical takeoff and landing aircraft from rotary wing mode to fixed wing mode in the first transition flight mode.
Figure 7 is an example diagram showing the composite vertical takeoff and landing aircraft moving and flying in fixed-wing mode.
Figure 8 is an example diagram showing the posture control of the composite vertical takeoff and landing aircraft by switching to an emergency mode.

The present invention relates to a composite vertical takeoff and landing aircraft (100) having fixed wings constituting the main wing and a plurality of rotors,

It consists of a straight tilt support 111 installed on the main wing and a pair of tilt rotors 112 and 113 installed at both ends of the tilt support 111 in a form that can be tilted in different directions. A plurality of inversion tilt units 110 are symmetrically provided on both sides of the fuselage, and a straight fixed support 121 installed on the main wing and a pair of lift rotors fixed to both end portions of the fixed support 121 ( A plurality of fixed rotor units 120 including 122) are symmetrically provided on both sides of the fuselage,

Each of the four or more tilt rotors 112, 113 constituting the inversion tilt unit 110 and the four or more lift rotors 122 constituting the fixed rotor unit 120 are aligned in the longitudinal direction of the main wing and the longitudinal direction of the fuselage. It is characterized in that the pitching moment arm and the rolling moment arm, which are essential for controlling the attitude of the aircraft, are formed by being spaced apart from each other.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

First, as shown in FIG. 1, the composite vertical takeoff and landing aircraft 100 is configured in a shape including a pair of fixed wings constituting the main wing and a plurality of other fixed wings constituting the tail wing, and a plurality of rotors It is characterized by being symmetrically arranged on both main wings of the fuselage.

That is, the composite vertical take-off and landing aircraft 100 is a known VTOL (Vertical take-off and landing) type that is configured to move and fly using the main wings and tail wings, but can take off and land vertically using a plurality of rotors.

More specifically, the composite vertical takeoff and landing aircraft 100 includes a straight tilt support 111 installed on the main wing and a pair of tiltable supports 111 installed at both ends of the tilt support 111 in a form that can be tilted in different directions. A plurality of inversion tilt units 110 including tilt rotors 112 and 113 are configured to be symmetrically provided on both sides of the fuselage.

In addition, a plurality of fixed rotor units 120 including a straight fixed support 121 installed on the main wing and a pair of lift rotors 122 fixed to both end portions of the fixed support 121. It is configured to be symmetrically provided on both sides of the fuselage.

That is, as shown in FIG. 1, in the composite vertical takeoff and landing aircraft 100, a plurality of tilt rotors 112 and 113 are located inside a two-row transverse formation, and the remaining plurality of lift rotors 122 are located in a two-row transverse formation. It may be configured to be located on the outside of a large structure.

In addition, as shown in FIG. 2, the composite vertical takeoff and landing aircraft 100 may have a plurality of tilt rotors 112 and 113 located on the outside of the two-row transverse formation instead of being located on the inside. In this case, In this case, the remaining plurality of lift rotors 122 are located inside the two-row horizontal band.

That is, as shown in FIGS. 1 and 2, the composite vertical takeoff and landing aircraft 100 has a plurality of tilt rotors 112 and 113 located inside a two-row horizontal band and a plurality of lift rotors 122. Contrary to the first form, which is located on the outside, a plurality of tilt rotors (112, 113) are located on the outside of the two-row horizontal band and a number of lift rotors (122) are located on the inside. possible

In other words, the composite vertical takeoff and landing aircraft 100 includes four or more tilt rotors 112 and 113 constituting the inversion tilt unit 110 and four or more lift rotors 122 constituting the fixed rotor unit 120. It is configured to be spaced apart from each other in the longitudinal direction of the main wing and the longitudinal direction of the fuselage, allowing the formation of a pitching moment arm and a rolling moment arm that are essential for controlling the aircraft's attitude.

At this time, the plurality of tilt rotors and the plurality of lift rotors are arranged symmetrically on both sides of the fuselage, but do not need to be arranged at equal intervals from each other. As shown in Figure 3, the longitudinal direction (X direction) of the fuselage and the main wing By maintaining the distance between them in the longitudinal direction (Y direction), pitching moment arms (X1, X2) and rolling moment arms (Y1, Y2) can be formed by the thrust of the rotor.

In addition, as shown in FIGS. 1 and 2, the plurality of tilt rotors 112 and 113 are a pair of tilt rotors 112 at the front based on the main wing of the composite vertical takeoff and landing aircraft 100. It is installed in a vertical posture facing, and the rear pair of tilt rotors 113 are installed in a reverse posture facing the ground. However, in that posture, the thrust direction of the rotors is the same for all tilt rotors upward.

And the pair of tilt rotors 112 and 113 constituting the inversion tilt unit 110 and the pair of lift rotors 122 constituting the fixed rotor unit 120 have the weight of the composite vertical takeoff and landing aircraft 100. It must have a rotor diameter and specification suitable for the rotor.

Therefore, the inversion tilt unit 110 and the fixed rotor unit 120 have appropriate diameters and specifications corresponding to weight changes due to changes in the mission of the hybrid vertical takeoff and landing aircraft 100 or changes in payload including payload. It can be modularized as shown in FIG. 4 to enable replacement installation on the rotor.

At this time, the central side of the tilt support 111 constituting the inversion tilt unit 110 and the central side of the fixed support 121 constituting the fixed rotor unit 120 are respectively fastened to the main wing. A tool may be provided, and a fastening tool with a structure corresponding to the fastening tool may be provided at the bottom of the main wing.

Accordingly, the fastening tools can be firmly fastened to each other using a known method such as a bolt fastening method, and can be easily separated to enable replacement and installation with a rotor having a different diameter.

Thereafter, as shown in FIG. 5, the forward tilt rotor 112 based on the main wing among the tilt rotors 112 and 113 constituting the inversion tilt unit 110 of the composite vertical takeoff and landing aircraft 100 is used for lift. In the same way as the rotor 122, it rotates so that thrust is formed upward in an attitude facing the sky, and the rear tilt rotor 113 rotates so that thrust is formed upward in an attitude facing the ground, but adjacent rotors rotate in opposite directions. It can take off and land vertically in rotating rotor mode.

That is, among the rotors disposed on the main wing of the composite vertical takeoff and landing aircraft 100, one pair of forward tilt rotors 112 and all lift rotors 122 are in an attitude in which the thrust line is formed upward, that is, the rotors are in the sky. It is based on being placed in a facing posture.

However, the pair of rear tilt rotors 113 are basically arranged in a reverse attitude with the rotors facing the ground, and the entire rotor rotates simultaneously to form a sufficient degree of lift for takeoff of the composite vertical takeoff and landing aircraft 100. can do.

Therefore, the complex vertical takeoff and landing aircraft 100 can take off vertically from the ground and hover at a certain height, and in that state, a plurality of tilt rotors 112 and 113 are simultaneously operated to enable transition. It can be tilted.

That is, as shown in FIG. 6, the composite vertical takeoff and landing aircraft 100 tilts forward and backward at the same speed, respectively, with the front tilt rotor 112 and the rear tilt rotor 113 rotating, and the lift rotor (122) can also be switched from rotary wing mode to fixed wing mode with the first transition flight mode rotating.

At this time, the first transition flight mode is to generate sufficient thrust for mobile flight while maintaining the flight stability of the hybrid vertical takeoff and landing aircraft 100, and is a state in which the hybrid vertical takeoff and landing aircraft 100 is hovering, or Propel forward while flying forward in rotary wing mode to allow acceleration to occur until the speed reaches 1.2 times or more than the stall speed.

And in the first transition flight mode, all front tilt rotors 112 disposed on the main wings of the composite vertical takeoff and landing aircraft 100 are tilted forward, and all rear tilt rotors 113 are tilted rearward. As all the tilt rotors (112, 113) rotate in opposite directions to form a forward thrust, the torsion moments in different directions based on the elastic axes of each tilt rotor (112, 113) are canceled out. An effect similar to that of the overall weight of the composite vertical takeoff and landing aircraft 100 being lighter than when the tilt rotors are not arranged in series occurs.

Subsequently, as shown in FIG. 7, the combined vertical takeoff and landing aircraft 100 stops rotating the lift rotor 122, but the front tilt rotor 112 based on the main wing is tilted forward. It rotates, and the rear tilt rotor 113 rotates in the opposite direction while tilted toward the rear, so that all tilt rotors 112 and 113 can move and fly in a fixed-wing mode in which thrust is generated forward.

In other words, the plurality of lift rotors 122 maintain a rotating state until sufficient thrust is generated to enable the hybrid vertical takeoff and landing aircraft 100 to move and fly using fixed wings, thereby generating lift. , energy consumption can be reduced by stopping rotation after sufficient thrust is formed.

And in relation to the fixed wing mode, the inverted tilt unit 110 divides the speed (V) of the wake by the front tilt rotor 112 based on the main wing into the number of revolutions per second (n) of the rear tilt rotor 113. The pitch of the rear tilt rotor 113 is configured to increase than the pitch of the front tilt rotor 112 by the value divided by , causing the rear tilt rotor ( 113), the occurrence of a decrease in thrust can be prevented.

That is, in a state where the plurality of tilt rotors 112 and 113 are configured in series, the rear tilt rotor 113 is caused by the wake formation by the front tilt rotor 112 and the reduction of the angle of attack of the rear tilt rotor 113. A phenomenon occurs in which the formed thrust decreases.

At this time, despite the generation of wake by the front tilt rotor 112, in order to prevent a decrease in thrust of the rear tilt rotor 113, the pitch angle of the rear tilt rotor 113 must be increased by the inflow angle generated by the wake. Alternatively, you can increase the revolutions per minute (RPM).

However, the method of resolving the inflow angle by increasing the number of revolutions per minute of the rear tilt rotor 113 has the problem of limiting the number of revolutions of the motor that rotates the rear tilt rotor 113 and causing excessive energy consumption. , the method of increasing the pitch angle is more useful, and since it changes the installation angle of the blade, a more direct effect can be expected.

To verify the above configuration, using an RC Benchmark Series 1780 propeller thrust test device, the front and rear tilt rotors 112 and 113 were configured to have the same diameter of 15 inches and a pitch of 8 inches (Experiment 1). , A comparative experiment was conducted (Experiment 2) in which the front tilt rotor (112) was configured with a diameter of 15 inches and a pitch of 8 inches and the rear tilt rotor (113) was configured with a diameter of 15 inches and a pitch of 10 inches (Experiment 2). The results are as follows. same.

※ Experiment 1, front tilt rotor (diameter 15 inches, pitch 8 inches)

※ Experiment 1, rear tilt rotor (diameter 15 inches, pitch 8 inches)

※ Experiment 2, front tilt rotor (diameter 15 inches, pitch 8 inches)

※ Experiment 2, rear tilt rotor (diameter 15 inches, pitch 10 inches)

[Graph 1] - Rear tilt rotor thrust change graph of experiments 1 and 2

That is, as can be seen in Graph 1, when the pitch of the rear tilt rotor 113 is larger than that of the front tilt rotor 112, a decrease in the thrust of the rear tilt rotor 113 is prevented, and rather the front tilt rotor ( It can be confirmed that it is possible to form a thrust larger than 112).

At this time, the reason why the pitch of the rear tilt rotor 113 is 2 inches larger than the pitch of the front tilt rotor 112, which is 8 inches, is due to the following theoretical equation.

In other words, in the propulsion system of an aircraft rotor in which the front rotor and the rear rotor are configured in series, the decrease in thrust of the rear rotor due to the wake of the front rotor is caused by the front rotor flowing into the rear rotor when viewed based on the rotation surface of the rotor blades. This can be interpreted as the fact that the inflow angle formed by the wake speed of and the linear speed caused by the rotation of the rotor blades reduces the angle of attack of the rotor blades.

Therefore, if the pitch angle of the rear rotor blade is increased by this inflow angle, the rear rotor will have the angle of attack when there is no wake of the front rotor, thereby solving the problem of reduced thrust.

Additionally, at a distance r from the center of the rear rotor, the inflow angle ø can be expressed by the following equation.

(V: Wake velocity due to the front rotor, V _1: Linear velocity due to rotation of the rotor blades, n: Rotation per second of the rotor)

At this time, the inflow angle ø is equal to the pitch angle to be increased in the rear rotor, and by converting this to a pitch distance, the theoretical pitch distance ΔXp to be increased in the rear rotor can be derived as follows.

Meanwhile, in rotor products, the blade angle and width of the rotor, and the wake speed given to the blade change from the blade hub to the tip of the blade, and the pitch specified by the rotor manufacturer's product number is usually based on the blade angle at 75% from the blade hub. Since it is called , rather than directly applying the theoretically derived theoretical pitch increase amount, Δ It is useful to do

In addition, the distribution characteristic value, DF, has a specific value depending on the rotor manufacturer and the type of front and rear rotors. In the case of the APC 15x8 and 15x10 tilt rotors configured in (Experiment 2) above, the DF of the rear tilt rotor 113 is as follows As shown in Table 5 (Experiment 2, DF analysis of the rear tilt rotor), depending on the RPM and wake speed of the rear tilt rotor 113, they are distributed with similar values of 0.33 to 0.40, with an average value of 0.37. Therefore, in the case of Experiment 2, the DF of the rear tilt rotor 113 can be set to 0.37.

Front rotor (15x8) Wake speed Rear rotor (15x10) APC
Pitch increase theoretical
Pitch increase DF RPM Thrust(Kgf) V(m/s) RPM Thrust(Kgf) ΔP (inch) V/n (inch) 1532 0.13 3.9 1527 0.11 2 6.03 0.33 2005 0.22 5.0 2020 0.2 2 5.85 0.34 2501 0.34 6.1 2518 0.33 2 5.72 0.35 3017 0.50 7.3 3017 0.48 2 5.72 0.35 3498 0.67 8.0 3489 0.66 2 5.42 0.37 4006 0.88 9.1 4007 0.87 2 5.36 0.37 4502 1.12 9.7 4516 1.13 2 5.07 0.39 4992 1.37 11.5 5028 1.43 2 5.40 0.37 5498 1.68 12.3 5240 1.72 2 5.54 0.36 6001 1.99 13.2 6013 2.09 2 5.19 0.39 6503 2.37 13.8 6516 2.5 2 5.00 0.40 7017 2.71 15.9 6992 2.93 2 5.37 0.37 7490 3.10 15.9 7500 3.38 2 5.01 0.40

※ Experiment 2, DF analysis of rear tilt rotor

On the other hand, the induced speed, which is the speed of the air flow in the disk where the rotor rotates, occurs at a constant speed vertically throughout the disk surface, and assuming an ideal flow that does not rotate, it is determined by momentum theory as follows v ₁ And v ₂ , the wake velocity in the far field, an area sufficiently spaced from the rotor, is as follows.

Here, T is the thrust generated by the rotor, A is the disk area of the rotor, and ρ is the air density.

At this time, the wake speed in the actual flow accompanied by the rotational flow by the rotor, etc. can be determined as follows by introducing a correction factor CF (Correction Factor) with a value between 0.6 and 0.8.

At this time, the wake speed of the rotor varies depending on the rotor's thrust, T, but the wake speed can be determined by broadly dividing the design point into cruising flight conditions or maximum thrust conditions during transition acceleration flight.

Here, when the design point is set to the constant speed horizontal flight condition of cruising flight, the thrust T of the hybrid vertical takeoff and landing aircraft (100) is equal to the required thrust T _R corresponding to the drag force D, and the hybrid vertical takeoff and landing aircraft (100) When the speed is V, it can be determined from the harmful drag and induced drag equations as follows.

At this time, T _f , which is the thrust of the front tilt rotor 112 under consideration, is calculated by introducing SR (Share Ratio), which is the thrust sharing ratio of the front tilt rotor with respect to the required thrust of the combined vertical takeoff and landing aircraft 100, T _f = SR*T _R , and ΔXp, the theoretical pitch increase amount of the rear tilt rotor 113 connected in series by a support, can be determined as follows.

(v ₂ : wake speed of the front tilt rotor 112, n: revolutions per second of the rear tilt rotor 113, CF: correction coefficient, T _f : thrust of the front rotor, SR: thrust sharing ratio of the front rotor, Α: Disk area of the front rotor, ρ: Air density, C _Dp : Harmful drag of the hybrid vertical takeoff and landing aircraft (100), S: Area of the fixed wing, V: Speed of the hybrid vertical takeoff and landing aircraft (100), W: Complex vertical takeoff and landing aircraft ( 100) weight, e: wing efficiency coefficient, AR: aspect ratio of fixed wing)

In addition, when the design point is set to a transition acceleration flight condition, when the acceleration thrust by the front tilt rotor 112 is set to acc T _f (about 70% of the maximum thrust), the theoretical pitch increase amount of the rear tilt rotor 113 is ΔXp can be determined as follows.

(v ₂ : wake speed of the front tilt rotor 112, n: revolutions per second of the rear tilt rotor 113, CF: correction coefficient, accT _f : acceleration thrust of the front tilt rotor 112, A: front tilt rotor (112) disk area, ρ: air density)

In conclusion, based on the equation derived above, the pitch of the rear tilt rotor 113 is increased by ΔXp inches when based on the theoretical pitch compared to the pitch of the front tilt rotor 112, and when based on the product nominal pitch By increasing ΔP inches, it is possible to prevent the occurrence of a phenomenon in which the thrust of the rear tilt rotor 113 decreases.

In addition, the composite vertical take-off and landing aircraft 100 tilts upward and downward at the same speed with the front tilt rotor 112 and the rear tilt rotor 113 rotating, and the lift rotor 122 also rotates. The transition flight mode maintains flight stability and can be switched from fixed-wing mode to rotary-wing mode.

That is, the hybrid vertical takeoff and landing aircraft 100 can switch from fixed wing mode to rotary wing mode during flight to perform missions requiring rotary wing flight such as stationary flight or land vertically downward.

In addition, the composite vertical take-off and landing aircraft 100 is configured so that all rear tilt rotors 113 are tilted upward after landing in rotary wing mode is completed, thereby preventing accidents caused by the rear tilt rotor 113 facing the ground. It can be done as much as possible.

On the other hand, the composite vertical take-off and landing aircraft 100 is operated in fixed-wing mode when a disturbance such as a gust of wind is applied and a fuselage inclination above the standard value is detected or a decrease in flight altitude due to a decrease in lift is detected above the standard value. In a situation, as shown in FIG. 8, it can be configured to quickly control the attitude of the aircraft by switching to an emergency mode in which additional rotation of the lift rotor 122 occurs.

That is, as described above, the composite vertical takeoff and landing aircraft 100 has a pair of front tilt rotors 112 disposed in front of the fixed wing tilted toward the front, and another pair of rear tilt rotors disposed at the rear. (113) is tilted toward the rear and the rotation of all lift rotors (122) is stopped. It moves and flies in fixed-wing mode. When a stall occurs or a disturbance such as a gust of wind acts during mobile flight, the flight exceeds the standard value. Fuselage tilt may occur.

If the unstable state continues, the anxiety of passengers on board the composite vertical take-off and landing aircraft 100 may increase, and the possibility of a crash accident increases. Therefore, the present invention By allowing rotation of the lift rotor 122 for control, the state of the aircraft can be restored to a stable state.

That is, when the entire lift rotor 122 rotates simultaneously in a situation where the fuselage inclination above the reference value is detected, the lift force for the composite vertical takeoff and landing aircraft 100 is supplemented and the lift rotor arranged to have pitching and rolling rotation moment arms ( Due to the characteristics of 122), 3-axis posture control of front, rear, left and right balance, that is, pitching, rolling, and yawing, occurs immediately, making it possible to restore the posture to a stable state.

As a result, when flying in fixed-wing mode or a complex vertical takeoff and landing aircraft with lift rotors arranged in a straight line only in the longitudinal direction of the main wing without a pitching moment arm, all rotors are tilted forward, causing a time delay in switching to rotary wing mode. The instability factor of vertical takeoff and landing aircraft can be resolved.

As a result, the complex vertical take-off and landing aircraft 100 is capable of vertical takeoff and landing in the same way as a multicopter-type drone, and is capable of moving in a fixed-wing mode with improved flight efficiency than a multicopter-type drone, making it suitable for urban air mobility. In addition, it has the effect of solving both the flight stability problems and the structural burden of previously known complex vertical takeoff and landing aircraft.

Therefore, it can be expected that the successful commercialization of urban air mobility can be accelerated through the hybrid vertical takeoff and landing aircraft 100 proposed in the present invention.

The embodiments introduced above are provided as examples so that the technical idea of the present invention can be sufficiently conveyed to those skilled in the art to which the present invention pertains, and the present invention is limited to the embodiments described above. It is not limited and may be embodied in other forms.

In order to clearly explain the present invention, parts not related to the description are omitted from the drawings, and in the drawings, the width, length, thickness, etc. of components may be exaggerated or reduced for convenience.

Additionally, like reference numerals refer to like elements throughout the specification.

100: Complex vertical takeoff and landing aircraft
110: reverse tilt unit
→ 111: Tilt support
→ 112: Front tilt rotor
→ 113: Rear tilt rotor
120: fixed rotor part
→ 121: Fixed support
→ 122: Lift rotor

Claims (7)

In the complex vertical takeoff and landing aircraft (100), which has improved flight stability by having fixed wings constituting the main wings and a plurality of rotors,
It consists of a straight tilt support 111 installed on the main wing and a pair of tilt rotors 112 and 113 installed at both ends of the tilt support 111 in a form that can be tilted in different directions. A plurality of inversion tilt units 110 are symmetrically provided on both sides of the fuselage,
A plurality of fixed rotor units 120 consisting of a straight fixed support 121 installed on the main wing and a pair of lift rotors 122 fixed to both end portions of the fixed support 121 are installed on the fuselage. Equipped symmetrically on both sides,
Each of the four or more tilt rotors 112, 113 constituting the inversion tilt unit 110 and the four or more lift rotors 122 constituting the fixed rotor unit 120 are installed in the longitudinal direction of the main wing and the longitudinal direction of the fuselage. It is characterized in that the pitching moment arm and the rolling moment arm, which are essential for controlling the attitude of the aircraft, are formed by being spaced apart from each other,
The inversion tilt unit 110,
The pitch of the rear tilt rotor 113 is configured to increase than the pitch of the front tilt rotor 112, so that the thrust of the rear tilt rotor 113 is increased due to the generation of wake when moving and flying in fixed-wing mode or transition flight mode. A composite vertical takeoff and landing aircraft with improved flight stability, characterized by preventing the occurrence of deterioration phenomenon.
According to paragraph 1,
The inversion tilt unit 110 and the fixed rotor unit 120,
A hybrid vertical takeoff and landing aircraft with improved flight stability, characterized in that it is modularized to enable replacement and installation of rotors with a diameter corresponding to changes in the weight of the hybrid vertical takeoff and landing aircraft (100).
delete According to paragraph 1,
The composite vertical takeoff and landing aircraft (100),
Among the tilt rotors 112 and 113 constituting the inversion tilt unit 110, the front tilt rotor 112 based on the main wing rotates in the same upward direction as the lift rotor 122 so that thrust is formed upward. The rear tilt rotor 113 rotates so that thrust is generated upward in an attitude toward the ground, but is configured to vertically take off and land in a rotor mode in which adjacent rotors rotate in opposite directions,
The rotation of the lift rotor 122 is stopped, but the front tilt rotor 112 rotates while tilted toward the front, and the rear tilt rotor 113 rotates in the opposite direction while tilted toward the rear, so that all tilt rotors (112, 113) A composite vertical takeoff and landing aircraft with improved flight stability, characterized in that it is configured to move and fly in a fixed-wing mode that generates forward thrust.
According to paragraph 4,
The composite vertical takeoff and landing aircraft (100),
With the front tilt rotor 112 and the rear tilt rotor 113 rotating, the first transition flight mode tilts forward and backward at the same speed, and the lift rotor 122 also rotates, switching from rotary wing mode to fixed wing mode. do,
A second transition flight mode in which the front tilt rotor 112 and the rear tilt rotor 113 are rotated, tilting upward and downward at the same speed, and the lift rotor 122 is also rotating, switching from fixed wing mode to rotary wing mode. So,
A composite vertical takeoff and landing aircraft with improved flight stability, characterized in that flight stability is maintained.
According to paragraph 4,
The composite vertical takeoff and landing aircraft (100),
In case of an emergency in which additional rotation of the lift rotor 122 occurs when a fuselage tilt greater than the standard value is detected due to a disturbance while flying in fixed-wing mode, or when a decrease in flight altitude due to a decrease in lift is detected greater than the standard value, A composite vertical takeoff and landing aircraft with improved flight stability, characterized in that it is configured to control attitude by switching modes.
According to paragraph 4,
The composite vertical takeoff and landing aircraft (100),
A composite vertical takeoff and landing aircraft with improved flight stability, characterized in that all rear tilt rotors (113) are configured to tilt upward for the purpose of preventing accidents after landing in rotary wing mode is completed.