Helicopter landing overload retarding device

Abstract

The invention belongs to the technical field of helicopter landing, and particularly relates to a helicopter landing overload retarding device. The device comprises a gas cylinder arranged in a cabin of the helicopter, a manual triggering device arranged in an inflation cabin and one or more inflatable buoys arranged at the bottom of the helicopter, and each buoy is connected with the gas cylinder through a pipeline; before the helicopter is landed, the buoys collide with the water surface before the bottom of the helicopter body, the water surface is split by means of the buoys at the bottom of the helicopter body, the landing characteristic similar to that of a ship body configuration helicopter is formed, and overload relieving of helicopter water forced landing is achieved.

Description

Technical Field

[0001] This invention belongs to the field of helicopter water landing technology, and particularly relates to a helicopter water landing overload mitigation device. Background Technology

[0002] With the development of helicopter technology, their applications in daily life are becoming increasingly widespread, and helicopters are undertaking more and more missions at sea, thus increasing the probability of helicopter water landings. If the normal overload of the fuselage at the moment of water entry during a forced landing can be reduced, the probability of impact injuries to the occupants can be greatly reduced. At the same time, reducing the water landing overload can reduce the load on the fuselage during the forced landing, which can improve the structural integrity of the helicopter after the forced landing and facilitate the escape of the people on board.

[0003] Modern helicopter designs tend to incorporate external fuel tanks, wide fuselages, and open tail doors. This effectively reduces the overall height of the helicopter, increases interior space, and meets the needs of transporting large cargo and rapid loading and unloading. However, this wide fuselage design significantly increases the surface area in contact with water during landing, increasing the impact of the water. This increases the G-forces during landing, amplifying the impact on the helicopter and its occupants, making them more susceptible to injury and structural damage. For wide helicopters, inflatable floats are typically placed on the front and rear sides of the fuselage to improve stability during landing and floating, but this does not reduce the G-forces experienced during landing.

[0004] Helicopters with a ship-hull configuration, due to their wedge-shaped bottom, can split the water surface upon landing, reducing the helicopter's water load. However, the wedge-shaped configuration occupies a large amount of space at the bottom of the fuselage, causing the overall floor / cargo compartment and above of the helicopter to be taller, which greatly increases the structural weight of the helicopter. At the same time, due to its wedge-shaped bottom, it will greatly increase its drag during flight, reducing the helicopter's performance. This is an important reason why modern shipborne helicopters and helicopters operating on water rarely use ship-hull configurations. Summary of the Invention

[0005] Purpose of the invention: Currently, there is no water-landing overload mitigation device for helicopters with flat bottom configurations. This invention mitigates the overload during the water-landing process by changing the shape of the bottom of the helicopter fuselage before it enters the water.

[0006] The present invention provides a helicopter water landing overload mitigation device, which includes a gas cylinder installed in the helicopter cabin and a manual triggering device in the inflation chamber, as well as one or more inflatable floats installed at the bottom of the helicopter, each float being connected to the gas cylinder through a pipe; Before the helicopter lands, the floats collide with the water surface before the bottom of the fuselage. The floats at the bottom of the fuselage split the water surface, forming a landing characteristic similar to that of a helicopter with a ship hull, thus mitigating the overload of the helicopter's forced landing on water.

[0007] Furthermore, during normal flight, the floats are folded and embedded in the float compartment under the bottom skin of the helicopter. The float compartment is covered with fabric or skin, or the floats are installed close to the skin.

[0008] Furthermore, the diameter of the pontoons is between 300mm and 500mm, and the upper limit of the pressure that the pontoons can withstand is designed to be above 60kPa.

[0009] Furthermore, the ratio of the length to the diameter of the pontoon is between 4 and 9.

[0010] Furthermore, the pontoon adopts a compartmentalized design, dividing the compartment into three sections: front, middle, and rear, with pontoon mounting straps arranged at the compartments, giving the pontoon better rigidity during water landing.

[0011] Furthermore, when deploying multiple pontoons, the pontoons can be arranged in a straight line, a triangular arrangement, or a two-by-two arrangement.

[0012] Furthermore, the volume of the pontoon shall not exceed 20% of the volume of the main pontoon.

[0013] Furthermore, the distance between the midpoint of the float and the side of the fuselage should be no less than one float diameter.

[0014] In summary, the beneficial effects of the present invention are as follows: The core function of this invention is to reduce the water overload during helicopter water landing, reduce the water load on the aircraft, reduce the probability of injury to personnel on board during water landing, and at the same time reduce the waterline when the helicopter is floating, thereby increasing the probability of escape after a forced landing. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the bottom single float of a helicopter water landing overload mitigation device according to the present invention; Figure 2 This is a schematic diagram of the arrangement of a single float at the bottom of a helicopter water landing overload mitigation device according to the present invention; Figure 3 This is a schematic diagram of the bottom float arrangement of a helicopter water landing overload mitigation device according to the present invention; Figure 4 This is a schematic diagram of the bottom float arrangement of a helicopter water landing overload mitigation device according to the present invention; Figure 5 This is a schematic diagram of the retracted float of a helicopter water landing overload mitigation device according to the present invention. Figure 6This is a side view of the inflated and deployed float of a helicopter water landing overload mitigation device according to the present invention. Figure 7 A schematic diagram illustrating the water overload mitigation effect of the present invention when the water is vertically immersed in still water. Figure 8 A schematic diagram illustrating the water-landing overload mitigation effect of this invention when flying over water in the presence of still water. Figure 9 This diagram illustrates the effect of the invention on mitigating water overload when the device is in sea state 5 and facing the waves. Detailed Implementation

[0016] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0017] This invention addresses the water landing characteristics and operational environment requirements of flat-bottomed helicopters by adding one or more devices to the helicopter's underside that can alter the shape of the fuselage bottom. These devices include one or more inflatable floats, an air cylinder, and a manually operated trigger mechanism inside the inflation chamber. The floats are connected to the air cylinder via pipes, and the pilot inside the chamber can easily access the inflation trigger mechanism. During normal flight, the inflatable floats are folded and installed at corresponding positions on the fuselage bottom. Because the device is installed on the fuselage bottom, its aerodynamic impact on the helicopter is minimal, regardless of whether it protrudes from the bottom. Where installation space exists, the floats are embedded within the float chamber beneath the bottom skin. The float chamber is covered with fabric or skin, which is riveted to the fuselage using fixed-force rivets. Where installation space is limited, the folded floats can be directly installed on the outside of the bottom skin and connected to the fuselage bottom using fasteners. When a helicopter malfunctions and needs to make an emergency water landing, the inflation device is manually triggered during the approach to the water surface. The inflatable floats inflate, unfolding the fabric or skin of the float compartment. Once unfolded, they form floats or float assemblies that fit snugly against the bottom of the fuselage. Before the helicopter touches the water, the floats collide with the water surface, using the floats on the fuselage bottom to cleave the water, creating a landing characteristic similar to a ship-shaped helicopter. This mitigates the overload during the water landing. Because the floats on the fuselage bottom are relatively small, the manual inflation device and air cylinders can be shared with the emergency flotation system, simplifying the water landing overload mitigation system. This system would then only consist of the bottom floats, their mounting structure, and the inflation piping.

[0018] (1) This invention applies to helicopters with a flat-bottom configuration that require water landing, especially helicopters with a wide bottom design, such as those shown in the attached diagram. Figure 5 As shown; (2) The air cylinder and manual inflation triggering device of the float can be shared with the emergency flotation system, simplifying the design of the whole system. Compared with the helicopter with the emergency flotation system installed, the system only needs to add a few small floats. (3) The device is installed on the bottom of the helicopter using an inflatable airbag or airbag assembly. During normal flight, it is folded and embedded in the float compartment under the bottom skin (see attached). Figure 5 The floats are covered with fabric or skin, and the skin is riveted to the fuselage with fixed force rivets. If the space at the bottom of the fuselage is limited and it is difficult to install them inside the skin after folding, the floats can also be installed close to the skin. (4) When a helicopter needs to make an emergency landing on water, the cabin inflation device should be manually activated during the approach to the water surface. The floats will be fully inflated and deployed before landing (see attached document). Figure 6 ); (5) In order to ensure that the pontoon can withstand the huge water pressure during the landing process, the upper limit of the pressure that the pontoon can withstand should be designed to be above 60 kPa, so as to ensure that it will not be damaged when subjected to water load impact. (6) As attached Figure 1 As shown, the diameter of the bottom float should be controlled, and the diameter of the bottom float should be controlled between 300mm and 500mm. This size is the clearance between the bottom of most flat-bottomed helicopters and the ground. (7) As attached Figure 1 As shown, the basic shape of the pontoon is cylindrical. In order to reduce the resistance when it touches the water, the diameters at both ends can be reduced to make its shape more streamlined. (8) As attached Figure 1 As shown, to ensure the rigidity of the pontoon, the length-to-diameter ratio of the pontoon is between 4 and 9.

[0019] (9) As attached Figure 1 As shown, in order to increase the design rigidity of the pontoon, the bottom pontoon should adopt a compartment design. The compartment can be divided into three sections: front, middle and rear, according to the length. The pontoon mounting straps are arranged at or near the compartments to give the pontoon better rigidity during the water landing process.

[0020] (10) The same materials and processes are used as the main buoy. The initial inflation pressure of the buoy can be the same as that of the main buoy, or it can be 1 to 2 times the inflation pressure of the main buoy.

[0021] (11) As attached Figure 2 , 3 As shown in Figure 4, the float assembly can be arranged in a straight line, a triangular arrangement, or a two-by-two arrangement. The specific arrangement can be optimized according to the bottom structure design of the fuselage, equipment installation, and space layout.

[0022] (12) When designing the volume of the pontoon, the total volume at the bottom should generally not exceed 20% of the volume of the main pontoon. Otherwise, if the pontoon on one side fails to deploy and touch the water, it may affect the floating stability of the helicopter. (13) As attached Figure 4To ensure that the floats do not slide off the bottom of the fuselage due to lateral forces when the helicopter sideslips into the water, the midpoint of the floats should be a certain distance from the side of the fuselage, not less than one float diameter.

[0023] (14) For helicopters that need to use the buoyancy of the floats to lift the waterline when the helicopter is floating on the water, the arrangement of the floats can be comprehensively considered according to the waterline design, and the arrangement is not limited to the arrangement described in key point 11.

[0024] The core function of this invention is to reduce the water overload during helicopter water landing, reduce the water load on the aircraft, reduce the probability of injury to personnel on board during water landing, and at the same time reduce the waterline when the helicopter is floating, thereby increasing the probability of escape after a forced landing.

[0025] 1) This invention can greatly reduce the water landing overload when a helicopter enters water vertically.

[0026] A vertical water entry simulation analysis was conducted using a speed of 1.5 m / s, considering 2 / 3 of the rotor lift. The initial distance between the bottom of the fuselage and the water surface was 0.86 m. Comparisons with and without overload mitigation devices are attached. Figure 7 As shown, it can reduce the maximum overload during the water contact process from 7.4g to 4.6g.

[0027] 2) This invention can reduce the overload by 1g when the water is flying in front of still water.

[0028] Analyzing the situation with a forward velocity of 15.4 m / s and a vertical velocity of 1.5 m / s, considering the overload after water entry at 2 / 3 of the rotor's lift, such as... Figure 8 As shown: This invention reduces the water overload from 4.2g to 3.1g.

[0029] 3) This invention can reduce the water overload under wave-facing water-landing conditions by 2g.

[0030] The overload mitigation during sea state 5, when landing against the waves, was analyzed. Using this invention, the maximum overload during landing against the waves in sea state 5 can be reduced from 6g to 4g.

[0031] 4) This invention lowers the waterline when the helicopter is floating, which is beneficial for the escape of the pilot and passengers.

[0032] Because the buoyancy generated by the floats of this invention is located at the bottom of the fuselage, it can raise the waterline of the helicopter, as shown in the attached figure. Figure 9 As shown, the three floats can generate 15% of the total weight of the aircraft. When the helicopter is floating at its maximum weight, the waterline is about 700mm above the bottom of the fuselage. This invention generates 15% of the total weight of buoyancy at the bottom of the fuselage, which can lower the waterline by 90mm, making it easier for the pilot and crew to escape.

[0033] 5) The system of the present invention is simple. For helicopters equipped with an emergency flotation system, the inflation source and inflation control can be the same system as the main flotation system. Only a few floats need to be added to the bottom of the fuselage to draw air from the gas cylinder to the floats. The system is simple and highly reliable. At the same time, it does not have to bear the weight increase caused by adding gas cylinders and control systems, thus saving system costs.

[0034] 7) The float arrangement of the present invention adopts multiple floats distributed in a way that can be flexibly adjusted according to the shape of the bottom of the fuselage and the equipment installation, and has great feasibility.

[0035] 8) When the pontoon of this invention is impacted by water, the internal pressure of the pontoon will increase significantly due to the impact force. However, because the diameter of the pontoon is small, the tension generated on the surface of the pontoon will not exceed the range of use of the pontoon material. Therefore, it can use the same materials and processes as the main pontoon, without the need to develop additional pontoon materials and manufacturing processes.

[0036] 9) The mounting point of this invention is at the bottom of the fuselage. When it is not possible to design an internal float pod, its protruding part is small in shape and at the bottom, so it will hardly affect the aerodynamic characteristics and flight speed of forward flight, and has good compatibility with helicopters.

[0037] 10) When the float is inflated and deployed, its flight trajectory will not interfere with the rotor and tail rotor because the inflation port cover opens downwards, thus ensuring high safety.

[0038] 11) The volume of a single float in this invention is small. If a single float fails to inflate and deploy, its small size will not have a significant impact on the landing and floating stability of the helicopter. Therefore, when this invention is used, it will not have a significant impact on the overall floating system design of the helicopter. It can be directly modified on helicopters that have already installed a floating system to reduce the maximum overload of helicopters during water landing.

Claims

1. A helicopter water-landing overload mitigation device, characterized in that, The device includes a gas cylinder located inside the helicopter cabin and a manually triggered device inside the inflation chamber, as well as one or more inflatable floats located at the bottom of the helicopter, each float being connected to the gas cylinder via a pipe. Before the helicopter lands, the floats collide with the water surface before the bottom of the fuselage. The floats at the bottom of the fuselage split the water surface, forming a landing characteristic similar to that of a helicopter with a ship hull, thus mitigating the overload of the helicopter's forced landing on water.

2. The helicopter water-landing overload mitigation device according to claim 1, characterized in that, During normal flight, the floats are folded and embedded in the float compartment under the bottom skin of the helicopter. The float compartment is covered with fabric or skin, or the floats are installed close to the skin.

3. The helicopter water-landing overload mitigation device according to claim 1, characterized in that, The diameter of the pontoons is between 300mm and 500mm, and the upper limit of the pressure that the pontoons can withstand is designed to be above 60kPa.

4. The helicopter water-landing overload mitigation device according to claim 1, characterized in that, The ratio of the length to the diameter of the pontoon is between 4 and 9.

5. A helicopter water-landing overload mitigation device according to claim 1, characterized in that, The pontoon adopts a compartmentalized design, dividing the compartment into three sections: front, middle, and rear. The pontoon mounting straps are arranged at the compartments, giving the pontoon better rigidity during water landing.

6. A helicopter water-landing overload mitigation device according to claim 1, characterized in that, When deploying multiple pontoons, they can be arranged in a straight line, a triangular arrangement, or a two-by-two arrangement.

7. A helicopter water-landing overload mitigation device according to claim 1, characterized in that, The volume of the pontoon shall not exceed 20% of the volume of the main pontoon.

8. A helicopter water-landing overload mitigation device according to claim 1, characterized in that, The distance between the midpoint of the float and the side of the fuselage should be no less than one float diameter.

9. A helicopter, characterized in that, The helicopter is equipped with the device as described in any one of claims 1-8.

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