A method for testing the floatability of an aircraft simple runway

Abstract

The application belongs to the technical field of determining the floatability of an aircraft simple runway, and particularly relates to a test method for determining the floatability of an aircraft simple runway, which is designed to determine the passing number of the aircraft on the simple runway in a simulation test mode, can accurately evaluate the floatability of the simple runway, can provide accurate evaluation of the simple runway for aircraft test flight, thereby effectively shortening the test flight period, reducing the test flight cost, avoiding the situation that the aircraft is trapped in the runway and cannot normally slide, and ensuring the safety of the aircraft test flight.

Description

Technical Field

[0001] This application belongs to the technical field of determining the buoyancy of simple aircraft runways, and specifically relates to a test method for the buoyancy of simple aircraft runways. Background Technology

[0002] Aircraft test flights are mostly conducted on makeshift runways. These makeshift runways are not paved and are only simply treated. The surface materials may include turf, gravel, soil, pebbles, sand, asphalt, coral, metal paving, etc.

[0003] Buoyancy is a measure of an aircraft's ability to operate on a runway of a given strength, typically expressed as the number of passes. The pavement material of a simple aircraft runway is a complex, inhomogeneous polymer, usually neither elastic nor plastic, making it difficult to establish a mathematical model for accurate calculations.

[0004] Currently, the assessment of the buoyancy of simple runways is mainly based on the calculation of "Estimation of the buoyancy of aircraft landing gear for take-off and landing at airports without paved soil", which includes the following steps:

[0005] 1) Calculate the contact area of ​​the aircraft tires with the ground;

[0006] 2) Calculate the aircraft tire contact pressure;

[0007] 3) Calculate the equivalent single-wheel load;

[0008] 4) Determine the number of coverage passes;

[0009] 5) Calculate the number of passes for each coverage;

[0010] 6) The number of passes is determined by multiplying the number of coverage passes by the number of passes per coverage pass;

[0011] 7) Calculate the passage numbers for both the nose landing gear and the main landing gear, and take the smaller number.

[0012] Because it is impossible to identify all soft areas when testing the strength of a makeshift runway, nor can it identify the impact of aircraft bounce on the runway surface on uneven surfaces, it is difficult to accurately determine the number of times an aircraft passes on a makeshift runway using the above methods. The number of passes obtained often differs significantly from the actual number of passes. Using this as an evaluation result for a makeshift runway and conducting aircraft test flights may result in damage after only a few taxiing runs, requiring maintenance, which would prolong the test flight cycle, increase test flight costs, and even lead to aircraft getting stuck on the runway and unable to taxi normally, resulting in danger.

[0013] This application is made in view of the aforementioned technical deficiencies.

[0014] It should be noted that the above background information is only used to assist in understanding the inventive concept and technical solution of this application, and it does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0015] The purpose of this application is to provide a simplified runway buoyancy test method for aircraft to overcome or mitigate at least one of the known technical defects.

[0016] The technical solution of this application is:

[0017] A simplified runway buoyancy test method for aircraft includes:

[0018] Step 1: Lay the test track. The two ends of the test track are dry cement track sections, and the middle is a simple track section. The simple track section includes multiple sections, each with a different load-bearing ratio (CBR).

[0019] Step 2: Calculate the equivalent single-wheel load of the aircraft's main wheels;

[0020] Step 3: Install the two aircraft main wheels onto the test vehicle, and load counterweights onto the test vehicle so that the load on each aircraft main wheel is the equivalent single-wheel load of the aircraft main wheel;

[0021] Step 4: Use a towing vehicle to tow the test vehicle with the main wheels of the aircraft on the dry concrete runway section, accelerate the test vehicle to the test speed, and then pass through each section of the simple runway at a constant speed.

[0022] Step 5: Repeat step 4 and record the wheel rut depth of the aircraft main wheels each time the test vehicle passes through each section of the makeshift runway until the wheel rut depth of the aircraft main wheels reaches the damage standard, and obtain the number of times the aircraft main wheels pass through each section of the makeshift runway.

[0023] Step 6: Calculate the equivalent single-wheel load of the aircraft's nose wheel;

[0024] Step 7: Install the two aircraft nose wheels onto the test vehicle, load counterweights onto the test vehicle, and make the load on each aircraft nose wheel equal to the equivalent single-wheel load of the aircraft nose wheel.

[0025] Step 8: Install the aircraft's nose wheel towing test vehicle on the cement dry runway section using a towing vehicle, accelerate the test vehicle to the test speed, and then pass through each section of the simple runway at a constant speed.

[0026] Step 9: Repeat step 8 and record the depth of the aircraft's nose wheel ruts each time the test vehicle passes through each section of the makeshift runway until the depth of the aircraft's nose wheel ruts reaches the damage standard, and obtain the number of times the aircraft's nose wheel passes through each section of the makeshift runway.

[0027] Step 10: Compare the number of times the aircraft's main wheels and nose wheels pass through each section of the makeshift runway, and take the smaller value as the number of times the corresponding aircraft's takeoff and landing weight passes through each section of the makeshift runway.

[0028] According to at least one embodiment of this application, in the above-described method for testing the buoyancy of an aircraft makeshift runway, the length of each makeshift runway segment is 10m.

[0029] Each section of the dry cement running track is 50m long.

[0030] According to at least one embodiment of this application, in the above-described simplified runway buoyancy test method for aircraft, the calculation of the equivalent single-wheel load of the aircraft's main wheels is specifically as follows:

[0031]

[0032] in,

[0033] SWL m The equivalent single-wheel load of the aircraft's main landing gear;

[0034] W represents the weight of the aircraft;

[0035] D n This is the distance from the aircraft's nose wheel to its center of gravity.

[0036] D0 is the distance between the aircraft's nose wheel and main landing gear;

[0037] n m The number of main landing gears on the aircraft;

[0038] K m This is the amplification factor for the equivalent single-wheel load of the aircraft's main wheels;

[0039] The calculation of the equivalent single-wheel load of the aircraft's nose wheel is as follows:

[0040]

[0041] in,

[0042] SWL n This is the equivalent single-wheel load of the aircraft's nose wheel;

[0043] W represents the aircraft's takeoff and landing weight;

[0044] D m This is the distance from the main landing gear to the aircraft's center of gravity.

[0045] D0 is the distance between the aircraft's nose wheel and main landing gear;

[0046] n n The number of the aircraft's front wheels;

[0047] K nThis is the amplification factor for the equivalent single-wheel load of the aircraft's nose wheel.

[0048] According to at least one embodiment of this application, in the above-described method for testing the buoyancy of an aircraft simple runway, the wheel track of the tractor is different from that of the test vehicle, so that the wheel tracks of the tractor do not coincide with those of the test vehicle.

[0049] According to at least one embodiment of this application, in the above-described method for testing the buoyancy of an aircraft simple runway, in step ten, a minimum number of adaptive passes is further determined, and the minimum load ratio CBR corresponding to the aircraft takeoff and landing weight adaptation is the one with the number of passes closest to the load ratio CBR of the simple runway section.

[0050] This application has at least the following beneficial technical effects:

[0051] This invention provides a method for testing the buoyancy of a simplified runway. The method is designed to determine the number of times an aircraft passes on a simplified runway through a simulation test, which can accurately assess the buoyancy of the simplified runway. This provides an accurate assessment of simplified runways used for aircraft flight testing, thereby effectively shortening the flight test cycle, reducing flight test costs, and avoiding dangerous situations where the aircraft gets stuck on the runway and cannot taxi normally, thus ensuring the safety of aircraft flight tests. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the aircraft landing gear wheel arrangement provided in an embodiment of this application;

[0053] Figure 2 This is a schematic diagram of the test track laying provided in an embodiment of this application;

[0054] Figure 3 This is a schematic diagram of a test vehicle being towed by a tractor, provided in an embodiment of this application.

[0055] To better illustrate this embodiment, some parts in the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual size of the product. Furthermore, the accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent. Detailed Implementation

[0056] To make the technical solution and advantages of this application clearer, the technical solution of this application will be described in a clearer and more complete manner below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of this application, and are only used to explain this application, not to limit this application. It should be noted that, for ease of description, only the parts related to this application are shown in the accompanying drawings. Other related parts can be referred to the general design. In the absence of conflict, the embodiments and technical features in the embodiments of this application can be combined with each other to obtain new embodiments.

[0057] Furthermore, unless otherwise defined, the technical or scientific terms used in this application description shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "upper," "lower," "left," "right," "center," "vertical," "horizontal," "inner," and "outer," etc., used in this application description to indicate relative direction or positional relationship are used only to indicate relative orientation or positional relationship, and do not imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. When the absolute position of the described object changes, its relative positional relationship may also change accordingly, and therefore should not be construed as a limitation on this application. The terms "first," "second," "third," and similar terms used in this application description are used only for descriptive purposes to distinguish different components, and should not be construed as indicating or implying relative importance. The terms "a," "one," or "the," etc., used in this application description should not be construed as an absolute limitation on quantity, but should be construed as indicating the existence of at least one. The terms "including," "comprising," etc., used in this application description mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects.

[0058] Furthermore, it should be noted that, unless otherwise explicitly specified and limited, terms such as “installation,” “connection,” and “linkage” used in the description of this application should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; or it can be a connection within two components. Those skilled in the art can understand its specific meaning in this application according to the specific circumstances.

[0059] The following is in conjunction with the appendix Figures 1 to 3 This application provides a further detailed description of the simplified runway buoyancy test method for aircraft provided in this application.

[0060] Step 1: Laying the test track:

[0061] The test track consists of dry cement track sections at both ends and a simple track section in the middle. The simple track section can have multiple segments, each with a different load-bearing ratio (CBR). The length of each segment should be approximately 10m. The length of each dry cement track segment should be approximately 50m.

[0062] Step 2: Calculate the equivalent single-wheel load of the aircraft's main wheels:

[0063] Based on the aircraft's takeoff and landing weight, center of gravity position, and landing gear structure on the makeshift runway, the load borne by the aircraft's main wheels on the makeshift runway, i.e., the equivalent single-wheel load, is calculated as follows:

[0064]

[0065] in,

[0066] SWL m The equivalent single-wheel load of the aircraft's main landing gear;

[0067] W represents the weight of the aircraft;

[0068] D n This is the distance from the aircraft's nose wheel to its center of gravity.

[0069] D0 is the distance between the aircraft's nose wheel and main landing gear;

[0070] n m The number of main landing gears on the aircraft;

[0071] K m This is the amplification factor for the equivalent single-wheel load of the aircraft's main wheels. It is related to the landing gear structure, and the load distributed to each wheel may be different. Please refer to the relevant manual for determination.

[0072] Step 3: Install the two main aircraft wheels onto the test vehicle, load counterweights onto the test vehicle, and ensure that the load on each main aircraft wheel is the equivalent single-wheel load of the main aircraft wheel, and that the air pressure of each main aircraft wheel is consistent with the requirements of the simple runway.

[0073] Step 4: Use a towing vehicle to tow the test vehicle with the main wheels of the aircraft on the cement dry runway section, accelerate the test vehicle to the test speed, referencing the aircraft's taxiing speed, and then pass through each section of the simple runway at a constant speed.

[0074] The tractor is much lighter than the test vehicle, and the wheel tracks of the tractor do not coincide with the wheel tracks of the aircraft's main wheels, so the width of the tractor can be designed to be smaller.

[0075] Step 5: Repeat Step 4 and record the wheel rut depth of the aircraft's main wheels each time the test vehicle passes through each section of the makeshift runway until the wheel rut depth of the aircraft's main wheels reaches the damage standard, thus obtaining the number of times the aircraft's main wheels pass through each section of the makeshift runway.

[0076] Step Six: Calculate the equivalent single-wheel load of the aircraft's nose wheel:

[0077] Based on the aircraft's takeoff and landing weight, center of gravity position, and landing gear structure on the makeshift runway, the load borne by the aircraft's nose wheel on the makeshift runway, i.e., the equivalent single-wheel load, is calculated as follows:

[0078]

[0079] in,

[0080] SWL n This is the equivalent single-wheel load of the aircraft's nose wheel;

[0081] W represents the aircraft's takeoff and landing weight;

[0082] D m This is the distance from the main landing gear to the aircraft's center of gravity.

[0083] D0 is the distance between the two front wheels of the aircraft;

[0084] n n The number of the aircraft's front wheels;

[0085] K n This is the amplification factor for the equivalent single-wheel load of the aircraft's nose wheel.

[0086] Step 7: Install the two aircraft nose wheels onto the test vehicle, load counterweights onto the test vehicle so that the load on each aircraft nose wheel is the equivalent single-wheel load of the aircraft nose wheel, and the air pressure of each aircraft nose wheel is consistent with the requirements of the aircraft simple runway.

[0087] Step 8: Install the aircraft's nose wheel towing test vehicle on the cement dry runway section using a towing vehicle, accelerate the test vehicle to the test speed, referencing the aircraft's takeoff speed, and then pass through each section of the simple runway at a constant speed.

[0088] Step 9: Repeat step 8, and record the depth of the aircraft's nose wheel ruts each time the test vehicle passes through each section of the makeshift runway, until the depth of the aircraft's nose wheel ruts reaches the damage standard, and obtain the number of times the aircraft's nose wheel passes through each section of the makeshift runway.

[0089] Step 10: Compare the number of passes of the main wheels and nose wheels of the aircraft on each section of the makeshift runway. The smaller value is taken as the number of passes of the corresponding aircraft takeoff and landing weight on each section of the makeshift runway. A minimum number of passes can be further determined. The minimum load ratio CBR of the makeshift runway section with the number of passes closest to it is taken as the minimum load ratio CBR of the corresponding aircraft takeoff and landing weight.

[0090] Step 11: For different takeoff and landing weights of the aircraft, perform steps 1 to 10 to obtain the number of times the aircraft passes on each section of the simple runway with different takeoff and landing weights, and its minimum load ratio (CBR).

[0091] In one specific embodiment, the aircraft landing gear is a tricycle type, with two nose wheels, eight main wheels, and four wheels on each side, arranged as follows: Figure 1 As shown, the buoyancy is determined using the simplified runway buoyancy test method disclosed in the above embodiments, as detailed below.

[0092] Step 1: Laying the test track:

[0093] The test track consists of dry concrete sections at both ends and a simple earthen track section in the middle. Each dry concrete section is 50m long. The simple earthen track section comprises 10 sections, each 10m long, with bearing ratios (CBRs) of 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12, designated as 1#, 2#, 3#, 4#, 5#, 6#, 7#, 8#, 9#, and 10#. Figure 2 As shown.

[0094] Step 2: Calculate the equivalent single-wheel load of the aircraft main wheels.

[0095] Step 3: Install the two main aircraft wheels onto the test vehicle, and load counterweights onto the test vehicle so that the load on each main aircraft wheel is the equivalent single-wheel load (SWL) of the main aircraft wheel. m Furthermore, the air pressure of each aircraft's main landing gear must be consistent with the requirements of the simple runway.

[0096] Step 4: Use a tow truck to pull the test vehicle with the aircraft's main wheels installed on the concrete dry runway section, accelerating the test vehicle to the test speed, referencing the aircraft's takeoff speed, and then passing through each section of the makeshift runway at a constant speed, such as... Figure 3 As shown.

[0097] Step 5: Repeat Step 4 and record the wheel rut depth of the aircraft main wheels each time the test vehicle passes through each section of the makeshift runway until the wheel rut depth of the aircraft main wheels reaches the damage standard of 76mm, and obtain the number of times the aircraft main wheels pass through each section of the makeshift runway.

[0098] If the rut depth of the right main wheel of the test vehicle is 72mm after 5 passes on the No. 1 makeshift runway section, and 78mm after 6 passes, then the number of passes of the right main wheel on the No. 1 makeshift runway section is determined to be 5. Similarly, the number of passes of the left main wheel on the No. 1 makeshift runway section is determined to be 6. Therefore, the total number of passes of the main wheels on the No. 1 makeshift runway section is determined to be 5. Based on this, the number of passes of the main wheels on makeshift runway sections No. 2 to No. 10 can be further determined.

[0099] Step 6: Calculate the equivalent single-wheel load of the aircraft's nose wheel.

[0100] Step 7: Install the two aircraft nose wheels onto the test vehicle, load counterweights onto the test vehicle so that the load on each aircraft nose wheel is the equivalent single-wheel load of the aircraft nose wheel, and the air pressure of each aircraft nose wheel is consistent with the requirements of the aircraft simple runway.

[0101] Step 8: Install the aircraft's nose wheel towing test vehicle on the cement dry runway section using a towing vehicle, accelerate the test vehicle to the test speed, referencing the aircraft's takeoff speed, and then pass through each section of the simple runway at a constant speed.

[0102] Step 9: Repeat step 8, and record the depth of the aircraft's nose wheel ruts each time the test vehicle passes through each section of the makeshift runway, until the depth of the aircraft's nose wheel ruts reaches the damage standard, and obtain the number of times the aircraft's nose wheel passes through each section of the makeshift runway.

[0103] Step 10: Compare the number of times the main wheels and nose wheels of the aircraft pass through each section of the makeshift runway. Take the smaller value as the number of times the corresponding aircraft take-off and landing weight passes through each section of the makeshift runway. Determine the minimum number of passes to be 5. Take the load ratio CBR of the makeshift runway section with the closest number of passes to 5 as the minimum load ratio CBR for the corresponding aircraft take-off and landing weight.

[0104] The aircraft simple runway buoyancy test method disclosed in the above embodiments is designed to determine the number of times an aircraft passes on a simple runway through a simulation test. It can accurately assess the buoyancy of the simple runway and provide an accurate assessment of the simple runway used for aircraft flight test. This can effectively shorten the flight test cycle, reduce flight test costs, avoid situations where the aircraft gets stuck on the runway and cannot taxi normally, thus ensuring the safety of aircraft flight tests.

[0105] The technical solution of this application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A simplified runway buoyancy test method for aircraft, characterized in that, include: Step 1: Lay the test track. The two ends of the test track are dry cement track sections, and the middle is a simple track section. The simple track section includes multiple sections, each with a different load-bearing ratio (CBR). Step 2: Calculate the equivalent single-wheel load of the aircraft's main wheels; Step 3: Install the two aircraft main wheels onto the test vehicle, and load counterweights onto the test vehicle so that the load on each aircraft main wheel is the equivalent single-wheel load of the aircraft main wheel; Step 4: Use a towing vehicle to tow the test vehicle with the main wheels of the aircraft on the dry concrete runway section, accelerate the test vehicle to the test speed, and then pass through each section of the simple runway at a constant speed. Step 5: Repeat step 4 and record the wheel rut depth of the aircraft main wheels each time the test vehicle passes through each section of the makeshift runway until the wheel rut depth of the aircraft main wheels reaches the damage standard, and obtain the number of times the aircraft main wheels pass through each section of the makeshift runway. Step 6: Calculate the equivalent single-wheel load of the aircraft's nose wheel; Step 7: Install the two aircraft nose wheels onto the test vehicle, load counterweights onto the test vehicle, and make the load on each aircraft nose wheel equal to the equivalent single-wheel load of the aircraft nose wheel. Step 8: Use a towing vehicle to install the aircraft's nose wheel test vehicle on the cement dry runway section, accelerate the test vehicle to the test speed, and then pass through each section of the simple runway at a constant speed. Step 9: Repeat step 8 and record the depth of the aircraft's nose wheel ruts each time the test vehicle passes through each section of the makeshift runway until the depth of the aircraft's main nose wheel ruts reaches the damage standard, and obtain the number of times the aircraft's nose wheel passes through each section of the makeshift runway. Step 10: Compare the number of times the main landing gear and nose wheel of the aircraft pass through each section of the makeshift runway, and take the smaller value as the number of times the corresponding aircraft take-off and landing weight passes through each section of the makeshift runway. The calculation of the equivalent single-wheel load of the aircraft main wheels is as follows: ； in, The equivalent single-wheel load of the aircraft's main landing gear; For the weight of the aircraft; This is the distance from the aircraft's nose wheel to its center of gravity. This is the distance between the aircraft's nose wheel and main landing gear; The number of main landing gears on the aircraft; This is the amplification factor for the equivalent single-wheel load of the aircraft's main wheels; The calculation of the equivalent single-wheel load of the aircraft's nose wheel is as follows: ； in, This is the equivalent single-wheel load of the aircraft's nose wheel; This is the distance from the main landing gear to the aircraft's center of gravity. The number of the aircraft's front wheels; This is the amplification factor for the equivalent single-wheel load of the aircraft's nose wheel; In step ten, a minimum number of adaptive passes is further determined, and the minimum load ratio CBR corresponding to the aircraft takeoff and landing weight adaptation is the one with the number of passes closest to the load ratio CBR of the simplified runway section.

2. The simplified runway buoyancy test method for aircraft according to claim 1, characterized in that, Each section of the makeshift running track is 10 meters long. Each section of the dry cement track is 50m long.

3. The simplified runway buoyancy test method for aircraft according to claim 1, characterized in that, The track width of the tractor is different from that of the test vehicle.

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