Fixed-wing aircraft non-airport take-off and landing adaptability evaluation method based on test flight performance data

Abstract

The invention discloses a fixed-wing aircraft non-airport take-off and landing adaptability evaluation method based on test flight performance data, and belongs to the field of aviation aircraft design. Comprising typical difference analysis of a non-airport environment and an airport environment, takeoff and landing sliding tolerance analysis of the unmanned aerial vehicle in the non-airport environment and takeoff and landing lateral deviation tolerance analysis of the unmanned aerial vehicle in the non-airport environment. The non-airport take-off and landing adaptive capacity of the airplane is analyzed through take-off and landing data of previous test flights. Key differences and possible problems faced by taking off and landing in the non-airport environment are found out by comparing the test flight airport environment with the non-airport environment, and key constraints of taking off and landing in the non-airport environment are formed; taking-off and landing taxiing section flight parameters in the test flight data are extracted, conformity analysis is carried out from all constraint dimensions, and the conformity analysis comprises analysis of taxiing tolerance based on grounding point deviation and analysis of taxiing feasibility of all levels of roads based on taxiing side offset distance probability distribution; whether field cleaning work needs to be carried out or not during taking-off and landing is evaluated by combining airplane height and highway guardrail design standard comparison.

Description

Technical Field

[0001] The present invention belongs to the field of aviation aircraft design, and in particular relates to a non-airport take-off and landing adaptability assessment method based on scientific research test flight data. Background Art

[0002] During the aircraft design process, flight tests are a common method for assessing aircraft performance. Based on the aircraft's capabilities, corresponding flight test subjects are designed to verify the aircraft's capabilities step by step. The flight test process requires a gradual approach, and the difficulty of achieving and verifying capabilities varies. In the initial stages of flight testing, subjects that are easy to implement and require a gentle flight process are generally prioritized for verification. Subjects that are difficult to implement and require intense maneuvers are postponed or selected for verification.

[0003] Taking off and landing in non-airport environments is a key capability requirement for drones. Being able to successfully launch and recover drones on roads and in the wild will significantly expand their usable range and lower the barrier to entry. However, during the scientific research test flight phase, it is unrealistic to directly select non-airport environments to arrange test flight subjects for testing. Although it is impossible to directly conduct test verification of this capability, takeoff and landing are a necessary process for every aircraft test flight. Through the accumulation of test flights, a large number of flight parameters for takeoff and landing can be obtained. There is an urgent need to propose a systematic method to conduct a predictive assessment of the test aircraft's adaptability to non-airport takeoffs and landings by analyzing the flight parameters of airport takeoffs and landings. Summary of the Invention

[0004] The present invention proposes a method for evaluating the adaptability of an aircraft for non-airport takeoff and landing based on conventional airport test flight data to solve the problems existing in the prior art.

[0005] The technical solution of the present invention:

[0006] A method for evaluating the suitability of fixed-wing aircraft for non-airport takeoff and landing based on flight test performance data includes the following three parts of analysis:

[0007] (1) Analysis of typical differences between non-airport environment and airport environment

[0008] By referring to the design standards for airport runways and non-airport environments, and comparing the differences between airport and non-airport environments at all levels, we extracted parameters that affect takeoff and landing. Based on this comparison, we conducted a non-airport takeoff and landing adaptability analysis. Parameters affecting takeoff and landing include pavement length, pavement width, and the coefficient of friction between the pavement and the wheels.

[0009] Furthermore, a comparative analysis is conducted on the length, width and aircraft parameters allowed for takeoff and landing at airports of different levels, and the width requirements for roads of different levels, to determine which level of road width is closest to the runway width of the lowest-level airport. Highways above that level are then selected to evaluate the adaptability of non-airport takeoffs and landings.

[0010] Furthermore, by comparing the friction coefficient between the runway and the wheel in non-airport environments, it is analyzed whether it can be used for subsequent take-off and landing taxiing tolerance analysis and take-off and landing sideslip tolerance analysis.

[0011] Furthermore, since the friction coefficient of highway pavement is higher than that of airport runways under the same natural conditions, it is reasonable and has a certain margin to use the taxiing distance of airport runways in the test flight data for analysis. Therefore, in terms of the friction coefficient between the pavement and the wheels, highways can be used for takeoff and landing taxiing tolerance analysis and takeoff and landing lateral tolerance analysis.

[0012] (2) Analysis of takeoff and landing tolerance of UAV in non-airport environment

[0013] Factors influencing taxiing margins need to be analyzed, including touchdown point deviation and post-touchdown taxiing distance analysis. Touchdown point deviation refers to the positional deviation between the nominal touchdown point and the actual touchdown point. By comparing the friction coefficient of non-airport runways with that of airport runways under the same meteorological conditions, the difference in taxiing distance after touchdown between the two environments is analyzed.

[0014] Furthermore, the upper limit of the taxiing tolerance for highway takeoffs and landings is determined by the length of the highway's straight sections. By analyzing and comparing the design speeds of various highway classes, the straight lengths for each class are determined. The required highway class is selected as the lower limit, and the average straight length (L meters) of that class is used as the analysis criterion for highway takeoff and landing feasibility.

[0015] The ideal landing point of the drone is D1, the nominal landing point is D2, and the actual landing point is D3. The distance between the ideal landing point and the nominal landing point is L 12 , the distance between the ideal grounding point and the actual grounding point is L 13 , the distance between the nominal grounding point and the actual grounding point is L 23 After the drone touches the ground, the two-wheel rolling distance is X1, the three-wheel rolling distance is X2, and the sliding tolerance is X.

[0016] S2.1. Distance L between the ideal grounding point and the nominal grounding point 12 The value of is determined by the control strategy;

[0017] S2.2. Determine the distance L between the ideal touchdown point and the actual touchdown point by observing the change in the glide distance during the test landing. 13 , then calculate L by the following formula 23 :

[0018] L 23 =L 13 -L 12 ;

[0019] S2.3. By reading the taxiing data and wheel load data from the test flight, the two-wheel taxiing distance is X1, and the three-wheel taxiing distance is X2. Calculate X using the following formula:

[0020] X=X1+X2+L 23

[0021] S2.4. Determine whether the X calculated in step 2.3 satisfies the taxiing tolerance constraint requirements of the following formula, and analyze whether the non-airport meets the takeoff and landing requirements based on the friction coefficient between the pavement and the wheels:

[0022] X <L。

[0023] (3) Analysis of lateral deviation tolerance of UAV takeoff and landing in non-airport environment

[0024] The lateral deviation data of the take-off and landing process obtained from previous scientific research test flights of UAVs was used to obtain the probability distribution of lateral deviation distance using statistical methods. Combined with the aircraft size, aircraft altitude, lateral deviation distance of taxiing, non-airport roadbed width, and excess object height, an analysis of the lateral deviation tolerance for take-off and landing in non-airport environments was implemented.

[0025] Furthermore, the upper limit of the side deviation distance for highway takeoff and landing depends on the width of the highway. When side deviation occurs, the possibility of collision between the highway guardrail and the aircraft wing should also be considered:

[0026] The maximum side deviation distance generated by the UAV during the taxiing process is C, the UAV's top-view width is W, the road width is Wr, the UAV's wingtip height is Hw, and the guardrail height is Hr. Then the above variables satisfy:

[0027]

[0028] If C satisfies the above formula, but There is a possibility that the wingtip will collide with the guardrail, and additional requirements must be met:

[0029] H w ≤n2+H r

[0030] Where n1 is the cornering safety factor and n2 is the wing collision safety margin.

[0031] The present invention has the following beneficial effects: The aircraft's adaptability to non-airport takeoffs and landings is analyzed using takeoff and landing data from previous test flights. By comparing the test flight airport environment with the non-airport environment, key differences and potential issues faced in non-airport takeoffs and landings are identified, forming key constraints for non-airport takeoffs and landings. Flight parameters for the takeoff and landing run segments are extracted from the test flight data, and compliance analysis is conducted from various constraint dimensions. This includes analyzing taxiing tolerance based on touchdown point deviation and feasibility of takeoffs and landings on various highways based on the probability distribution of runway side offset. Furthermore, the need for clearing the area during takeoff and landing is assessed by comparing aircraft altitude with highway guardrail design standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the relative position relationship between the "ideal grounding point" and the "nominal grounding point".

[0033] Figure 2 Changes in the distance to be flown during the landing process—data source 1.

[0034] Figure 3 Changes in the distance to be flown during the landing process—data source 2.

[0035] Figure 4 Changes in the distance to be flown during the landing process—data source 3.

[0036] Figure 5 Changes in the distance to be flown during the landing process—data source 4.

[0037] Figure 6 Changes in lateral offset during takeoff—data source 1.

[0038] Figure 7 The change of lateral offset during takeoff—data source 2.

[0039] Figure 8 The change of lateral offset during takeoff—data source 3.

[0040] Figure 9 The change of lateral offset during takeoff—data source 4.

[0041] Figure 10 This is a box plot of the side deviation during takeoff.

[0042] Figure 11 It is the probability distribution histogram of the lateral deviation during the takeoff process.

[0043] Figure 12 Changes in lateral offset during landing—data source 1.

[0044] Figure 13 Changes in lateral offset during landing—data source 2.

[0045] Figure 14 Changes in lateral offset during landing—data source 3.

[0046] Figure 15 Changes in lateral offset during landing—data source 4.

[0047] Figure 16 This is a box plot of the side deviation during the landing process.

[0048] Figure 17 It is the probability distribution histogram of the side deviation during the landing process. DETAILED DESCRIPTION

[0049] Based on the above technical method and in conjunction with the accompanying drawings, a typical embodiment of the present invention is described as follows, taking a highway as an example:

[0050] 1. Refer to the design standards of airport runways and highways, compare the environmental differences of airports and highways at all levels, extract key parameters such as length, width, and friction coefficient, and propose an airport environmental assessment method based on the comparison of key parameters.

[0051] The design runway lengths of airports at all levels and the corresponding aircraft parameters allowed to take off and land are shown in Table 1.

[0052] Table 1 Length / width of different levels of airports and aircraft parameters allowed to take off and land

[0053]

[0054] The width standards of highways of different levels are shown in Table 2:

[0055] Table 2 Width requirements for highways of different levels

[0056]

[0057] The friction coefficients of airport runways at different levels are shown in Table 3:

[0058] Table 3 Airport runway friction coefficient

[0059]

[0060]

[0061] The friction coefficients of different levels of roads are shown in Table 4:

[0062] Table 4 Road friction coefficient

[0063]

[0064] Comparing the data in Tables 1 and 2, the runway width of the lowest-level airport (18 meters) is similar to the width of a secondary highway with a design speed of 80 km / h (12 meters) and a primary highway with a design speed of 60 km / h (20 meters). Lower-level highways generally have a design width of no more than 10 meters. By the end of 2023, my country's secondary highway mileage reached 762,200 kilometers, a sufficient number and widespread distribution. Therefore, secondary and higher-level highways can be used as an example to assess the adaptability of non-airport takeoffs and landings.

[0065] According to the comparison between Table 3 and Table 4, it is believed that the friction coefficient of the highway pavement is slightly higher than that of the airport runway under the same natural conditions. Therefore, when analyzing the taxiing tolerance, it is reasonable to use the taxiing distance of the airport runway in the test flight data for analysis, and it has a certain margin.

[0066] 2. The upper limit of the glide tolerance for highway takeoffs and landings depends on the length of the straight section of the highway. Design speeds for expressways and first-class highways are typically 80 to 120 km / h. Straight sections generally do not exceed 20 times the design speed, meaning 1,600 to 2,400 meters. Design speeds for second-class highways are typically 60 to 80 km / h. Straight sections generally do not exceed 10 to 15 times the design speed. That is, the straight section of a second-class highway with a design speed of 80 km / h is 800 to 1,200 meters. This example uses a second-class highway with a design speed of 80 km / h as the lower limit, and the corresponding average glide tolerance is 1,000 meters as the analysis criterion for highway takeoff and landing feasibility.

[0067] The components of the rollout margin include the touchdown point deviation and the rollout distance.

[0068] When designing the landing process of a drone, the final approach glide path is a straight line, called the glide line. That is, after the drone is aligned with the runway, it glides at a fixed angle, and the intersection of the glide line and the runway is called the "ideal touchdown point." Before the drone touches down, it generally pulls the stick to raise the elevation angle in preparation for landing. This action process is called "leveling off." Due to the existence of the leveling off action, the drone's track before touching down will deviate from the glide line and be closer to the glide line. Under nominal no-wind conditions, the touchdown point obtained through simulation is the "nominal touchdown point." The relative position of the nominal touchdown point and the ideal touchdown point is related to the leveling off height and the control strategy of the leveling off stage. The higher the leveling off height, the more obvious the balance of the stick pull, and the closer the nominal touchdown point is. For the relative position relationship between the two, see Figure 1 During actual flight, the location where the aircraft touches down is called the "actual touchdown point." During a drone test flight and landing, due to uncertainties such as constant wind and airflow disturbances, the actual touchdown point generally deviates from the nominal touchdown point. When the leveling altitude and the control strategy for the leveling phase are determined, the relative position deviation between the nominal touchdown point and the ideal touchdown point can be controlled and determined. Therefore, the analysis of the glide tolerance mainly considers the position deviation between the actual touchdown point and the nominal touchdown point.

[0069] The ideal landing point of the drone is D1, the nominal landing point is D2, and the actual landing point is D3. The distance between the ideal landing point and the nominal landing point is L 12 , the distance between the ideal grounding point and the actual grounding point is L 13 , the distance between the nominal grounding point and the actual grounding point is L 23 , the two-wheeled rolling distance of the drone after landing is X1, the three-wheeled rolling distance is X2, and the sliding tolerance is X. Then the above variables satisfy:

[0070] L 23 =L 13 -L 12

[0071] X=X1+X2+L23

[0072] Based on the standard lower limit of 80 km / h for secondary roads, the coasting tolerance must meet the following requirements:

[0073] X<1000

[0074] Figures 2 to 5 The changes in the glide distance during the four landing flights are given. The value of the solid line tip and the intersection value of the dashed line and the solid line are read, and the distance L between the ideal landing point D1 and the actual landing point D3 of the UAV can be obtained by subtracting the two values. 13 .

[0075] The distance L between the ideal grounding point and the nominal grounding point 12 The value of is determined by the control strategy and its value is shown in Table 5.

[0076] Table 5 Distance L between ideal grounding point D1 and nominal grounding point D2 12

[0077]

[0078] Based on the L read in the attached figure 13 and L read in Table 5 12 , the distance between the nominal grounding point and the actual grounding point of different data sources can be calculated as L 23 , see Table 6.

[0079] Table 6 L of different data sources 12 , L 13 , L 23

[0080]

[0081] By reading the taxiing data and wheel load data of the test flight, the two-wheel taxiing distance X1 and the three-wheel taxiing distance X2 of different data sources are obtained (see Table 7).

[0082] Table 7 X1, X2, X from different data sources

[0083]

[0084] The calculated taxiing tolerances, X, in Table 7 all meet the constraint requirement of X < 1000. Considering the comparative analysis of friction coefficients between highways and airport runways in Tables 3 and 4, the friction coefficient for taxiing on highways is greater. Consequently, the actual X1 and X2 values ​​for the corresponding highways are smaller than those directly collected from the data source. Therefore, from the perspective of taxiing tolerance, the analyzed object possesses the capability to take off and land on a secondary highway.

[0085] 3. The upper limit of the highway takeoff and landing lateral offset is determined by the highway width. According to the design specifications in Table 2, the width of a secondary highway with a design speed of 80 km / h is generally 12 meters, with a minimum of 10 meters.

[0086] When a lateral deviation occurs, the possibility of the highway guardrail colliding with the aircraft wing should also be considered. The guardrail construction standards for different levels of highways are shown in Table 8:

[0087] Table 8 Guardrail construction standards for highways of different levels

[0088]

[0089] Guardrails on secondary roads are primarily Class A and B. The 94-standard A(Am) guardrail has a total post length of 185cm, a 110cm deep embedment (with 75cm of the post exposed), and a 60cm beam-slab height. The 06-standard A(Am) guardrail has a total post length of 215cm, a 140cm deep embedment (with 75cm of the post exposed), and a 60cm beam-slab height. The 17-standard A(Am) guardrail has a total post length of 235cm or 250cm, a 140cm or 165cm deep embedment (with 95cm or 85cm of the post exposed), and a 69.7cm beam-slab height. The maximum height of the three A(Am) guardrail standards is 95cm.

[0090] The maximum side deviation distance generated by the UAV during the taxiing process is C, the UAV's top-view width is W, the road width is Wr, the UAV's wingtip height is Hw, and the guardrail height is Hr. Then the above variables satisfy:

[0091]

[0092] If C satisfies the above formula, but There is a possibility that the wingtip will collide with the guardrail, and additional requirements must be met:

[0093] H w ≤n2+H r

[0094] Where n1 is the cornering safety factor, which allows for a margin of safety even after the aircraft corners. In this embodiment, it is set to 1.5. n2 is the wing collision safety margin. Because the wing will vibrate up and down during taxiing, with the amplitude gradually increasing from the wing root to the wingtip, a sufficient safety margin is required. The value of this factor is related to the wing geometry and stiffness. In this embodiment, it is set to 0.5. Considering that the maximum guardrail height on a secondary highway is 95 cm, the guardrail height Hr, converted to standard units, is 0.95.

[0095] Figures 6 to 9The variation in lateral deviation during the takeoff roll of four flights is presented. While lateral deviation control accuracy is extremely high (±0.5 meters) at low indicated airspeeds in the early stages of takeoff, extreme lateral deviation values ​​are mostly observed at high indicated airspeeds. Due to the reduced pressure on the nose wheel at high indicated airspeeds, control efficiency decreases, and the lateral force generated by the crosswind increases, some increase in lateral deviation is normal and within a controllable range. Based on the above test data, the aircraft's lateral deviation control accuracy during takeoff at low and medium speeds is ±0.5 meters, and during short dynamic takeoff rolls at high speeds, the lateral deviation control accuracy is ±1.5 meters.

[0096] Figure 10 Box plots of all the lateral deviation data during the takeoff roll of four flights are given. Through box plot analysis, the median of the lateral deviation distance during the entire takeoff process of all flights is between -0.5 and 0; the upper and lower quartiles are between -0.5 and 0.5; the extreme value of the box distribution is between -0.5 and 0.5; and the actual extreme value of the data is between -1.5 and 1. Figure 11 The probability distribution histogram of all the lateral deviation data during the takeoff and rolling of four flights is given. Through distribution probability analysis, the lateral deviation distance is concentrated in the range of -0.5 to 0.5.

[0097] Figures 12 to 15 The variation of the sideways deviation during the landing roll of four flights is presented. Analysis of the time-domain data shows that the sideways deviation during landing exhibits a small oscillation around zero, with the amplitude of the oscillation not exceeding ±2 meters. Based on these test data, the aircraft's landing roll sideways deviation control accuracy is ±2 meters.

[0098] Figure 16 Box plots of all the lateral deviation data during the landing roll of four flights are given. Through box plot analysis, the median of the lateral deviation during the entire landing process of all flights is between -0.5 and 0.5; the upper and lower quartiles are between -1.5 and 1; the extreme values ​​of the box distribution are between -2 and 2; and the actual extreme values ​​of the data are between -2 and 2. Figure 17 The probability distribution histogram of all the lateral deviation data during the landing roll of four flights is given. Through distribution probability analysis, the lateral deviation distance is concentrated in the range of -1 to 1.

[0099] In summary, the extreme value of the lateral deviation in this embodiment is ±2 meters. Assuming the road width Wr = 10 meters, n1 = 1.5, it satisfies The wingtip height of the drone is 2.5 meters, the guardrail height Hr is 0.95 meters, n2 = 0.5 meters, and H w ≤n2+H r Therefore, from the perspective of lateral tolerance, the analyzed object has the ability to take off and land on a secondary highway.

Claims

1. A method for evaluating the adaptability of fixed-wing aircraft for non-airport takeoff and landing based on flight test performance data, characterized in that: The analysis includes the following three parts: (1) Analysis of typical differences between non-airport environment and airport environment Referencing the design standards of airport runways and non-airport environments, comparing the differences between airport and non-airport environments at all levels, extracting the parameters that affect takeoff and landing, and conducting a non-airport takeoff and landing adaptability analysis based on the comparison of the parameters that affect takeoff and landing; the parameters that affect takeoff and landing include pavement length, pavement width, and the friction coefficient between the pavement and the wheels; (2) Analysis of takeoff and landing tolerance of UAV in non-airport environment It is necessary to analyze the factors that affect the glide tolerance, including the touchdown point deviation analysis and the glide distance analysis after touchdown; Touchdown point deviation refers to the positional difference between the nominal touchdown point and the actual touchdown point. By comparing the friction coefficient of non-airport runways with that of airport runways under the same meteorological conditions, the difference in taxiing distance after touchdown under the two environments is analyzed. (3) Analysis of lateral deviation tolerance of UAV takeoff and landing in non-airport environment The lateral deviation data of the take-off and landing process obtained from previous scientific research test flights of UAVs was used to obtain the probability distribution of lateral deviation distance using statistical methods. Combined with the aircraft size, aircraft altitude, lateral deviation distance of taxiing, non-airport roadbed width, and excess object height, an analysis of the lateral deviation tolerance for take-off and landing in non-airport environments was implemented.

2. The method for evaluating the adaptability of fixed-wing aircraft for non-airport takeoff and landing based on flight test performance data according to claim 1, characterized in that: In the analysis of typical differences between non-airport and airport environments, the length, width, and aircraft parameters permitted for takeoff and landing at different levels of airports are compared and analyzed, along with the width requirements for different levels of highways. The width of the lowest-level airport runway is determined to be similar to the width of the highway at that level, and highways at or above that level are selected to assess the suitability of non-airport takeoffs and landings. By comparing the friction coefficient between the runway and the wheel in non-airport environments, it is analyzed whether it can be used for subsequent take-off and landing taxiing tolerance analysis and take-off and landing sideslip tolerance analysis.

3. The method for evaluating the adaptability of fixed-wing aircraft for non-airport takeoff and landing based on flight test performance data according to claim 2, characterized in that: Since the friction coefficient of highway pavement is higher than that of airport runways under the same natural conditions, it is reasonable and has a certain margin to use the taxiing distance of airport runways in the test flight data for analysis. Therefore, in terms of the friction coefficient between the pavement and the wheels, highways can be used for takeoff and landing taxiing tolerance analysis and takeoff and landing sideslip tolerance analysis.

4. The method for evaluating the adaptability of fixed-wing aircraft for non-airport takeoff and landing based on flight test performance data according to claim 1, characterized in that: In the glide tolerance analysis of UAV takeoff and landing in non-airport environments, the upper limit of the glide tolerance for highway takeoff and landing depends on the length of the straight section of the highway; By analyzing and comparing the design speeds of various levels of highways, the straight length of each level of highway is determined, and the highway level that meets the requirements is selected as the standard lower limit. The average straight length L meters of the highway of this level is used as the analysis criterion for the feasibility of highway take-off and landing. The ideal landing point D1, the nominal landing point D2, and the actual landing point D3 of the drone are recorded; the distance between the ideal landing point and the nominal landing point is L 12 , the distance between the ideal grounding point and the actual grounding point is L 13 , the distance between the nominal grounding point and the actual grounding point is L 23 , the two-wheel rolling distance of the UAV after landing is X1, the three-wheel rolling distance is X2, and the sliding tolerance is X; S2.

1. Distance L between the ideal grounding point and the nominal grounding point 12 The value of is determined by the control strategy; S2.

2. Determine the distance L between the ideal touchdown point and the actual touchdown point by observing the change in the glide distance during the test landing. 13 , then calculate L by the following formula 23 : L 23 =L 13 -L 12 ; S2.

3. By reading the taxiing data and wheel load data from the test flight, the two-wheel taxiing distance is X1, and the three-wheel taxiing distance is X2. Calculate X using the following formula: X=X1+X2+L 23 S2.

4. Determine whether the X calculated in step 2.3 satisfies the taxiing tolerance constraint requirements of the following formula, and analyze whether the non-airport meets the takeoff and landing requirements based on the friction coefficient between the pavement and the wheels: X <L。 5. The method for evaluating the adaptability of fixed-wing aircraft for non-airport takeoff and landing based on flight test performance data according to claim 1, characterized in that: In the analysis of the lateral deviation tolerance of UAVs taking off and landing in non-airport environments, the upper limit of the lateral deviation distance for highway takeoff and landing depends on the width of the highway. When lateral deviation occurs, the possibility of collision between the highway guardrail and the aircraft wing should also be considered: The maximum side deviation generated by the UAV during the taxiing process is C, the UAV's top-view width is W, the road width is Wr, the UAV's wingtip height is Hw, and the guardrail height is Hr; then the above variables satisfy: If C satisfies the above formula, but There is a possibility that the wingtip will collide with the guardrail, and additional requirements must be met: H w ≤n2+H r Where n1 is the cornering safety factor and n2 is the wing collision safety margin.

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