A method for measuring the visibility distance of a helicopter cabin occupant during a snowfield takeoff and landing phase

Abstract

The present application provides a kind of test method for measuring the visible distance of helicopter cabin passengers during take-off and landing stage in snowfield, belongs to the field of helicopter flight test.The purpose is to solve the problem that the technical field of the severity of the existing helicopter flight in snowfield and the evaluation of snow blindness causes the obstruction of the field of view in the cockpit has not carried out relevant research.The present application includes the following steps: S1 selects test environment and test site that meet the test conditions;S2 determines flight conditions;S3 test flight practice;S4, install test equipment;S5 set up identification target;S6 paste identification on the fuselage;S7 measure the physical properties of snow in the test site;S8 pre-flight inspection;S9 carry out test;S10 test end check helicopter state;S11 end parameter measurement;S12 equipment arrangement after test;S13 analyze data.Through the present application, an operable and followable flight test method and requirement can be provided for helicopter flight in snowfield and snow blindness research, which has important engineering application and guiding value.

Description

TECHNICAL FIELD

[0001] The present application relates to flight test technology, in particular to a method for measuring the visual distance of cabin passengers during the take-off and landing of a helicopter in a snowy area, and belongs to the field of helicopter flight tests. BACKGROUND

[0002] With the wide application of helicopters in various special environment transportation and rescue tasks, when taking off and landing or hovering near the ground in the polar region or other snow-covered scenes, the main rotor and the ground interference form a complex unsteady flow field, and the strong downwash airflow under the rotor will cause the snow particles near the rotor to be lifted up, inducing snow blindness of the helicopter, reducing the visibility outside the cockpit, and blocking the line of sight of the pilot and other passengers in the cockpit, which seriously endangers the safety of helicopter flight.

[0003] At present, the technical solutions for flight safety problems in low-visibility environments mostly focus on the extension of the pilot's visual range through airborne sensing devices such as laser radar, infrared camera, etc., or rely on specific flight procedures to avoid ground obstacles. In the technical field of helicopter snowfield flight and evaluation of the severity of the visual obstruction caused by snow blindness in the cockpit, no relevant research has been conducted. Therefore, it is of great significance to provide a test research method that can measure the visual distance of passengers in the cockpit during the take-off and landing process in the snowfield, and to conduct in-depth research on the impact of snow blindness in different working conditions on the visual field of passengers in the cockpit when the helicopter flies in the snowfield environment, and to provide visual distance measurement data under different environmental parameters. SUMMARY

[0004] In the following, a brief summary of the present application is given in order to provide a basic understanding of some aspects of the present application. It should be understood that this summary is not an exhaustive overview of the present application. It is not intended to identify key or important parts of the present application nor is it intended to limit the scope of the present application. Its purpose is merely to present some concepts in a simplified form as a prelude to the more detailed description to be discussed later.

[0005] In view of this, in order to solve the problem that the technical field of helicopter snowfield flight and evaluation of the severity of the visual obstruction caused by snow blindness in the cockpit has not carried out relevant research, the present application provides a method for measuring the visual distance of passengers in the cockpit of a helicopter during the take-off and landing in a snowy area.

[0006] The technical scheme of the present application is a method for measuring the visual distance of passengers in the cockpit of a helicopter during the take-off and landing in a snowy area, which specifically comprises the following steps:

[0007] S1. Selecting a test environment and a test site that meet the test conditions;

[0008] S2. Determining a safe flight condition for the test according to the performance of the helicopter and the limitations of the test environment and the test site;

[0009] S3. The helicopter pilot determined in S2 first conducts simulation training on the simulator, and then conducts flight training on the snow-free ground; it is judged whether the existing snow on the test site meets the test requirements that can be blown up by the airflow under the rotor to form a snow blindness scene, and if the snow state meets the test requirements, S4 is directly performed; if the existing natural snow does not meet the test requirements, measures need to be taken to make the snow on the ground meet the test requirements;

[0010] S4. After confirming the helicopter test position on the test site, the equipment used for the test is installed;

[0011] S5. Set up the identification target on the test site;

[0012] S6. Paste the graphic identification paper and the E-shaped visual chart identification paper on the helicopter body;

[0013] S7. Measure the physical properties of the snow on the test site;

[0014] S8. Perform pre-flight checks to ensure that each system and component is functioning properly; the helmet-mounted camera is installed on the side of the helmet worn by the pilot in the cockpit;

[0015] S9. Perform the test according to the determined flight conditions;

[0016] S10. After the single vehicle test is completed, ensure that the helicopter stops power output and check the status of the helicopter;

[0017] S11. Measure the parameters of the test snow again, and record the influence of the helicopter flight on the snow changes;

[0018] S12. Confirm whether there is any remaining test for the day; if there is any remaining test for the day, go to S7, or continue the test after changing the snow state; if the test for the day is completed, all the measurement equipment used for the test is collected and stored indoors;

[0019] S13. Analyze the test data and evaluate the influence of different test conditions on the severity of snow blindness.

[0020] Further, the flight conditions described in S2 include the takeoff weight of the helicopter, the height of the helicopter as a function of time, the hovering height, and the hovering time.

[0021] Further, when the existing natural snow on the test site described in S3 cannot meet the requirements of the snow blindness test, measures need to be taken, and the specific method is:

[0022] Physical method to loosen the snow layer: use mechanical equipment to directly act on the snow layer, and make the snow layer become loose by physical means.

[0023] Further, the equipment used in the test of S4 includes a mobile weather station, a visibility meter, and a camera.

[0024] Further, the identification target of S5 is a printed identification target and an LED light-emitting identification target; and at least three identification targets are arranged at different distances and different directions with the ground projection of the center of the main rotor hub of the helicopter as the reference.

[0025] Further, the helicopter is a full-size manned helicopter, which needs to be equipped with standard helicopter flight instruments.

[0026] Further, the standard helicopter flight instruments include a flight data recording device and a weather sensor.

[0027] Further, the printed identification target has a length of 1.5 m and a width of 1 m, and the printed pattern is selected from an E chart or graphics of different sizes, and the color of the printed pattern is black.

[0028] Further, the LED light-emitting identification target has a length of 1 m and a width of 1 m, and different colors and patterns can be displayed on the LED light-emitting identification target.

[0029] Further, the graphic identification sticker and the E chart identification sticker have a length of 1 m and a width of 1 m; and the graphic identification sticker has a circular, square, or cross-shaped pattern.

[0030] Further, the method for measuring the physical properties of the snow on the test site of S7 specifically includes:

[0031] The method for measuring the temperature of the snow is to insert a probe-type temperature sensor into the snow to be measured to obtain the snow temperature data at different depths;

[0032] The method for measuring the depth and density of the snow is to vertically insert a transparent snow density sampler from above into the snow to be measured until the sampler contacts the ground, at which time the sampler has completed the snow sampling, the bottom of the sampler is sealed with a cover plate, the snow is removed, the snow depth is read through the scale line on the transparent sampler, and the weight of the snow in the container is measured, so that the overall density of the snow is obtained;

[0033] The method for measuring the shape and size of the snow particles is to use a calibrated electron microscope to measure the shape and size of the snow particles in the snow to be measured, and the specific steps are as follows: place the electron microscope outdoors, keep the snow particles in their original shape, turn on the power of the equipment, turn on the CCD camera and the display screen, sample the snow particles to be measured with a snow sample collection plate and place them in the observation area of the electron microscope, adjust the brightness of the LED source, adjust the position of the lens, make the snow crystal image on the display screen clear, collect multiple image information, and analyze the shape and size data of the snow particles.

[0034] Further, the height of the camera lens of the helmet needs to be consistent with the height of the eyes of the crew in the cockpit.

[0035] The present application has the following beneficial effects relative to the prior art:

[0036] 1. The present application uses a full-size manned helicopter equipped with standard flight instruments to simulate snow blindness phenomenon based on outdoor cold environment and snow-covered area, and can accurately quantify the visual range of the helicopter during the landing stage in the snowfield environment by formulating a standardized cabin occupant visual distance measurement test method, and provides operational flight safety evaluation data.

[0037] 2. The present application provides technical support for safe flight of helicopters in polar and other special scenarios and all-weather environments, and provides operational and followable flight test methods and requirements for subsequent domestic helicopter snowfield flight and snow blindness research, and has important engineering application and guiding value. BRIEF DESCRIPTION OF DRAWINGS

[0038] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The illustrative embodiments of the present application and their descriptions serve to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0039] Figure 1 A flowchart of a method for measuring the visual distance of a helicopter cabin occupant during the landing stage in the snowfield;

[0040] Figure 2 A bird's eye view of the layout of the test site equipment;

[0041] Figure 3 A schematic diagram of the ground marker target;

[0042] Figure 4 A schematic diagram of the helicopter with the marker pasted;

[0043] Figure 5 A schematic diagram of the equipment worn by the cabin occupant.

[0044] In the drawings: 1-helicopter, 2-mobile weather station, 3-visibility meter, 4-marker target, 5-ground personnel, 6-camera, 7-printed marker target, 8-LED light-emitting marker target, 9-graphic marker sticker, 10-E visual acuity chart marker sticker, 11-cabin occupant, 12-helmet, 13-helmet camera. DETAILED DESCRIPTION

[0045] In order to make the technical solutions and advantages in the embodiments of the present application clearer and more apparent, the following further describes the exemplary embodiments of the present application in conjunction with the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than an exhaustive enumeration of all embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0046] Embodiment 1, Reference Figures 1-5 In this embodiment, a method for measuring the visual distance of a helicopter cabin occupant during the takeoff and landing stage in a snowy area is described, which specifically includes the following steps:

[0047] S1. Select a test environment and test site that meets the test conditions:

[0048] Select a cold outdoor natural environment as the test environment, and select an area with flat terrain and away from the crowd as the test site to avoid large undulations or obstacles; according to the size and flight characteristics of the helicopter 1, the test site needs to have enough space;

[0049] S2. Determine the test-safe flight conditions according to the performance of the helicopter 1 and the limitations of the test environment and test site;

[0050] S3. The helicopter 1 pilot first performs simulation training on the simulator according to the flight conditions determined in S2, and then performs test flight on the ground without snow; determine whether the existing snow in the test site meets the test requirements that the rotor downwash airflow can blow up to form a snow blindness scene, if the snow state meets the test requirements, directly proceed to S4; if the existing natural snow does not meet the test requirements, measures need to be taken to make the ground snow reach the state that meets the test requirements;

[0051] S4. After confirming the test position of the helicopter 1 in the test site, install the test equipment:

[0052] After confirming the test position of the helicopter 1, install the mobile weather station 2 and the visibility meter 3 in a safe position; arrange the cameras 6 at different distances on the front side, left and right sides of the helicopter 1 body center ground projection of the main rotor hub as the reference;

[0053] S5. Set the identification target 4 in the test site;

[0054] S6. Paste the graphic identification sticker 9 and the E-shaped visual acuity chart identification sticker 10 on the helicopter 1 body;

[0055] S7. Measure the physical properties of the snow in the test site;

[0056] S8. Perform pre-flight check of the helicopter 1 to ensure the normal operation of each system and component; the helicopter 1 cabin occupant 11 needs to wear a helmet 12, and the helmet 12 side is installed with a helmet camera 13;

[0057] S9. Perform the test according to the determined flight conditions:

[0058] The laser range finder is used to measure the distance between the identification target 4 and the helicopter; the cabin occupant 11 identifies the printed identification target 7 at different distances and different orientations under the guidance of the ground personnel 5, and records the size of the letters that can be clearly identified on the printed identification target 7; the LED light-emitting identification target 8 displays different colors and patterns, and gradually reduces the size of the patterns, and records the size of the patterns that can be clearly identified at different colors;

[0059] The LED light-emitting identification target 8 is randomly changed to different images for the cabin occupant 11 to identify, and the identification reaction time of the cabin occupant 11 to the ground object under the influence of snow blindness is tested; at the same time, the ground personnel 5 observe the graphic identification sticker 9 and the E-shaped visual chart identification sticker 10 on the fuselage of the helicopter 1 at the position of the camera 6, and record the size of the letters and patterns that can be clearly identified;

[0060] Since the pattern recognition behavior of a person is subjective, multiple tests need to be performed by changing the personnel to obtain the average value of the visual distance, and the information recorded by the helmet camera 13 and the camera 6 is also used for objective evaluation of the influence of snow blindness on the visibility of the cabin in the later stage;

[0061] S10. After the single-trip test is completed, ensure that the helicopter 1 stops power output, and check the state of the helicopter 1;

[0062] S11. The parameters of the test snowfield are measured again, and the influence of the flight of the helicopter 1 on the change of the snow is recorded;

[0063] S12. Confirm whether there is remaining test for the day; if there is remaining test for the day, go to S7, or go to S7 to continue the test after changing the snow state; if the test for the day is completed, all the measuring devices used in the test are collected and stored indoors;

[0064] S13. Analyze the test data to evaluate the influence of different test conditions on the severity of snow blindness:

[0065] The visual distance data of the cabin occupant 11 during the test is processed, the collected image information can objectively verify the rules, and the influence of different environments, different snow parameters, different total weights of the aircraft, and different flight conditions on the snow blindness of the helicopter 1 and the field of view of the cabin occupant 11 is analyzed;

[0066] According to the test results, the visibility and safety of the helicopter during the take-off and landing stage in the snow environment are evaluated, and optimization suggestions for the visual distance of the cabin occupant 11 are proposed.

[0067] Further, the flight condition described in S2 includes the take-off weight of the helicopter 1, the height of the helicopter 1 as a function of time, the hovering height, and the hovering time.

[0068] Further, when the existing natural snow on the test site of S3 cannot meet the requirements of the snow blindness test, measures need to be taken. The specific method is:

[0069] Physical method to loosen the snow layer: use mechanical equipment to directly act on the snow layer, and make the snow layer loose through physical means; or, artificial snow: use a snow maker to make artificial snow, and then use a snow plow or snow shovel to evenly distribute the snow generated by the snow maker on the test site, thereby forming the loose snow conditions required for the test.

[0070] Further, the test equipment of S4 includes a mobile weather station 2, a visibility meter 3, and a camera 6.

[0071] Further, the identification target 4 of S5 is divided into a printed identification target 7 and an LED light-emitting identification target 8; with the ground projection of the main rotor hub of the helicopter 1 as the reference, at least three identification targets 4 are arranged at different distances and different directions.

[0072] Further, the helicopter 1 is a full-size manned helicopter, which needs to be equipped with standard helicopter flight instruments.

[0073] Further, the standard flight instruments of the helicopter 1 include a flight data recording device and a weather sensor.

[0074] Further, the printed identification target 7 has a length and width of 1.5m*1m, and the printed pattern is selected from an E chart or graphics of different sizes, and the printed pattern color can be black or other bright colors.

[0075] Further, the LED light-emitting identification target 8 has a length and width of 1m*1m, and different colors and patterns can be displayed on the LED light-emitting identification target 8.

[0076] Further, the graphic identification sticker 9 and the E chart identification sticker 10 have a length and width of 1m*1m; the pattern of the graphic identification sticker 9 is a circle, a square, or a cross.

[0077] Further, the method for measuring the physical properties of the snow on the test site of S7 specifically includes:

[0078] Snow temperature measurement method: use a probe-type temperature sensor to insert into the snow area to be measured, and obtain snow temperature data at different depths;

[0079] Snow depth and density measurement method: use a transparent snow density sampler to vertically insert into the snow area to be measured from above until it touches the ground, at which time the sampler has completed snow sampling, and the bottom of the sampler is sealed with a cover plate. The snow is removed, the snow depth is read through the scale line on the transparent sampler, and the weight of the snow in the container is measured, so that the overall density of the snow can be obtained;

[0080] Snow particle shape and particle size measurement method: a calibrated electron microscope is used to measure the shape and particle size of snow particles in the snow area to be measured, and the specific steps are as follows: the electron microscope is placed outdoors, the snow particles are kept in their original shape, the power supply is turned on, the CCD camera and display screen are turned on, the snow sample collection plate is used to sample the snow particles to be measured and placed in the electron microscope observation area, the LED source brightness is adjusted, the lens position is adjusted, the snow crystal picture in the image on the display screen is clear, multiple groups of image information are collected and measured, and the snow particle shape and particle size data are analyzed.

[0081] Further, the helmet camera 13 lens height needs to be consistent with the eye height of the cockpit occupant 11.

[0082] By the present application, the snow blindness phenomenon can be simulated based on the outdoor cold environment and the covered snow area by using a full-size manned helicopter equipped with standard flight instruments, and the visual distance of the helicopter during the landing stage in the snow environment can be accurately quantified by formulating a standardized cockpit occupant visual distance measurement test method, thereby providing operational flight safety evaluation data.

[0083] By the present application, technical support is provided for the safe flight of helicopters in polar and other special scenarios and all-weather environments, and an operational and followable flight test method and requirement are provided for subsequent domestic helicopter snowfield flight and snow blindness research, which has important engineering application and guiding value.

[0084] Although the present application has been described in terms of limited embodiments, those skilled in the art, with the benefit of the above description, will appreciate that other embodiments are possible within the scope of the application described herein. Furthermore, it should be noted that the language used in the specification has primarily been chosen for readability and instructional purposes and can not have been chosen to convey an exclusive or exhaustive description of the subject matter of the application. Therefore, many modifications and variations of the application are possible in light of the above teachings without departing from the scope and spirit of the appended claims. The disclosure of the application is illustrative only and not limiting of the scope of the application, which is defined by the appended claims.

Claims

1. A method for measuring the visual distance of cockpit occupants during helicopter takeoff and landing in snowy areas, characterized in that: The specific steps include: S1. Select a test environment and test site that meets the test conditions; S2. Determine the flight conditions for safe testing based on the performance of the helicopter (1) and the limitations of the test environment and test site; S3. According to the flight conditions determined in S2, the helicopter pilot (1) first conducts simulation training on the simulator, and then conducts a test flight on a snow-free ground; determines whether the existing snow at the test site meets the test requirements of being blown away by the rotor downwash to form a snow blindness scenario. If the snow condition meets the test requirements, proceed directly to step S4; The existing natural snow cover does not meet the test requirements, and measures must be taken to ensure that the snow cover on the ground meets the test requirements; S4. After confirming the test position of the helicopter (1) at the test site, install the equipment used for the test; S5. Set up identification targets (4) at the test site; S6. Paste graphic identification stickers (9) and E-shaped eye chart identification stickers (10) on the helicopter (1) fuselage; S7. Measure the physical properties of snow at the test site; S8. Conduct a pre-flight inspection of the helicopter (1) to ensure that all systems and components are functioning properly; the helicopter (1) cockpit occupant (11) must wear a helmet (12) with a helmet camera (13) mounted on the side of the helmet (12); S9. Conduct tests according to the determined flight conditions; S10. After the single vehicle test is completed, ensure that the helicopter (1) stops power output and check the status of the helicopter (1); S11. Measure the parameters of the test snow field again and record the effect of the helicopter (1) flight on the snow cover. S12. Confirm whether there are any remaining tests for the day. If so, proceed to S7, or continue testing after the snow cover condition has changed. If the full day's testing is complete, collect all test equipment and store it indoors. S13. Analyze the test data and evaluate the effects of different test conditions on the severity of snow blindness.

2. The method for measuring the visual distance of cockpit occupants during helicopter takeoff and landing in snowy areas according to claim 1, characterized in that: The flight conditions in S2 include the take-off weight of the helicopter (1), a function of the change in the height of the helicopter (1) over time, the hovering height, and the hovering time.

3. The method for measuring the visual distance of cockpit occupants during helicopter takeoff and landing in snowy areas according to claim 1, characterized in that: When the existing natural snow cover at the test site described in S3 cannot meet the requirements of the snow blindness test, the following measures shall be taken: Physical method to loosen the snow layer: Use mechanical equipment to directly act on the snow layer to loosen the snow layer through physical means.

4. The method for measuring the visual distance of cockpit occupants during helicopter takeoff and landing in snowy areas according to claim 1, characterized in that: The equipment used in the experiment of S4 includes a mobile weather station (2), a visibility meter (3) and a camera (6).

5. The method for measuring the visual distance of cockpit occupants during helicopter takeoff and landing in snowy areas according to claim 1, characterized in that: The identification targets (4) described in S5 are divided into printed identification targets (7) and LED luminous identification targets (8); with the ground projection of the center of the main rotor hub of the helicopter (1) as a reference, no less than three identification targets (4) are arranged at different distances and different orientations.

6. The method for measuring the visual distance of cockpit occupants during helicopter takeoff and landing in snowy areas according to claim 1, characterized in that: The helicopter (1) is a full-size manned helicopter and needs to be equipped with standard helicopter flight instruments.

7. The method for measuring the visual distance of cockpit occupants during helicopter takeoff and landing in snowy areas according to claim 6, characterized in that: The standard flight instruments of the helicopter (1) include flight data recording equipment and meteorological sensors.

8. The method for measuring the visual distance of cockpit occupants during helicopter takeoff and landing in snowy areas according to claim 5, characterized in that: The printing plate marking target (7) has a length and width of 1.5m*1m, and the printing pattern is selected from an E-shaped eye chart or graphics of different sizes, and the color of the printing pattern is black.

9. The method for measuring the visual distance of cockpit occupants during helicopter takeoff and landing in snowy areas according to claim 5, characterized in that: The LED light-emitting identification target (8) has a length and width of 1m*1m, and can display different colors and patterns.

10. The method for measuring the visual distance of cockpit occupants during helicopter takeoff and landing in snowy areas according to claim 1, characterized in that: The graphic identification sticker (9) and the E-shaped eye chart identification sticker (10) have length and width dimensions of 1m*1m; the pattern of the graphic identification sticker (9) is circular, square, or cross-shaped.

11. The method for measuring the visual distance of cockpit occupants during helicopter takeoff and landing in snowy areas according to claim 1, characterized in that: The method for measuring the physical properties of snow at the test site described in S7 specifically includes: Snow temperature measurement method: Use a probe-type temperature sensor to insert into the snow test area to obtain snow temperature data at different depths; Snow depth and density measurement method: Use a transparent snow density sampling meter to insert it vertically downward from the top into the snow area to be measured until it touches the ground. At this time, the meter has completed snow sampling. Seal the bottom of the meter with a cover plate, remove the snow, read the snow depth according to the scale line on the transparent meter, and measure the weight of the snow in the container at the same time to obtain the overall density of the snow. Snow particle shape and particle size measurement method: Use an electron microscope with a scale to measure the shape and particle size of snow particles in the snow test area. The specific steps are as follows: Place the electron microscope outdoors so that the snow particles maintain their original shape, turn on the power of the equipment, turn on the CCD camera and display screen, use the snow sample collection plate to sample the snow particles to be measured and place them in the electron microscope observation area, adjust the LED source brightness, adjust the lens position so that the snow crystal image on the display screen is clear, collect and measure multiple sets of image information, and analyze the snow particle shape and particle size data.

12. The method for measuring the visual distance of cockpit occupants during helicopter takeoff and landing in snowy areas according to claim 1, characterized in that: The height of the lens of the helmet camera (13) must be consistent with the eye height of the cockpit occupant (11).

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