A flight test method for water-dropping effect of fire-fighting aircraft

Abstract

The invention belongs to the aircraft flight test technology field in the aircraft test and test flight technology field, and relates to a fire-fighting aircraft water-dropping effect flight test method, which solves the technical problem of verifying the water-dropping effect flight test of the fire-fighting aircraft. The optimal water-dropping height, the optimal water-dropping speed, and the water-dropping correction amount under different wind directions and wind speeds obtained by the invention have high feasibility and high accuracy, and effectively improve the water-dropping fire-fighting efficiency of the fire-fighting aircraft.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft flight testing in the technical field of aircraft testing and flight testing, and in particular relates to a flight testing method for water dropping effect of a fire-fighting aircraft. Background Art

[0002] The United States and Canada are the main countries where aerial firefighting is widely used. The flight requirements for aircraft carrying out firefighting missions emphasize the qualifications of pilots such as training experience, licenses, operating experience, and aircraft type authorization. There are no standardized requirements for the technical requirements for water dropping and effect evaluation of firefighting aircraft from the perspective of conducting flight tests to guide flight verification.

[0003] At present, my country does not have a dedicated firefighting aircraft that meets the relevant mission requirements of the national emergency rescue system. The only large-scale firefighting / water rescue amphibious aircraft 1001 under development has the initial capability to perform firefighting missions and serves as a demonstration and verification platform for the firefighting mission system.

[0004] The flight test verification of the water-dropping effect of fire-fighting aircraft requires comprehensive consideration of multiple factors such as aircraft flight performance, water-dropping speed, water-dropping height, wind direction and speed. It is a typical multi-input and multi-output research with great uncertainty. There is no mature experience to draw on at home and abroad, and organizing verification test flights is difficult and risky.

[0005] What needs to be solved at this stage is how to overcome the multi-input and multi-output technical difficulties in the flight test verification of the water-dropping effect of fire-fighting aircraft, design a flight test method for the water-dropping effect of fire-fighting aircraft, and obtain the optimal water-dropping height, optimal water-dropping speed and water-dropping correction value under different wind directions and wind speeds with high credibility and high accuracy, so as to improve the water-dropping fire-fighting efficiency of fire-fighting aircraft. Summary of the invention

[0006] Purpose of the invention: The purpose of the invention is to solve the multi-input multi-output technical difficulties of the above-mentioned fire-fighting aircraft water-dropping effect flight test verification, and propose a fire-fighting aircraft water-dropping effect flight test method.

[0007] The technical solution of the present invention:

[0008] A method for flight testing the water-dropping effect of a fire-fighting aircraft comprises the following steps:

[0009] (1) Build a ground rectangular grid-type target water-dropping area test site;

[0010] (2) Under no wind or light wind conditions, the fire-fighting aircraft maintains a constant water-dropping speed and simultaneously uses radio altitude increments of equal distance to fly several times at several altitude points to drop water on the test site in step (1);

[0011] (3) measuring the amount of precipitation each time the water is poured in step (2), plotting a curve of effective utilization rate of water pouring and water pouring height, and obtaining an optimal water pouring height;

[0012] (4) Under no wind or light wind conditions, the fire-fighting aircraft maintains the optimal water-dropping altitude in step (3) and simultaneously drops water on the test field flight in step (1) at a number of speed points using water-dropping speed increments of equidistant steps;

[0013] (5) measuring the amount of water dropped each time in step (4), drawing a curve of effective utilization rate of water drop and water drop speed, and obtaining the optimal water drop speed;

[0014] (6) Under the conditions of fixed wind direction and different wind speeds, the fire-fighting aircraft uses the optimal water-dropping height in step (3) and the optimal water-dropping speed in step (5) to drop water in the test field;

[0015] (7) measuring the precipitation offset of each watering in step (6), plotting a precipitation offset and wind speed curve, and obtaining the watering correction under fixed wind direction and different wind speed conditions;

[0016] (8) Under the conditions of fixed wind speed and different wind directions, the fire-fighting aircraft uses the optimal water-dropping height in step (3) and the optimal water-dropping speed in step (5) to drop water in the test field;

[0017] (9) Measure the precipitation offset of each watering in step (8), draw a curve of precipitation offset and wind direction, obtain the watering correction under fixed wind speed and different wind directions, and complete the test.

[0018] Further, in step (1),

[0019] 1) The length and width of the ground rectangular grid target watering area shall not be less than 100m×50m;

[0020] 2) The rectangular target water-dropping area is marked with symmetrical axes along its length;

[0021] 3) The grid is symmetrically distributed along the axis and evenly divides the rectangular target water delivery area;

[0022] 4) The area of ​​a single grid is 1 / 500 of the rectangular target water injection area.

[0023] Further, in step (2):

[0024] 1) The wind speed in any wind direction shall not exceed 2m / s;

[0025] 2) The water dropping speed is fixed at 1.23V for this type of aircraft in the water dropping configuration SR ; V SR It is the reference stall speed of this type of aircraft in the water-dropping configuration;

[0026] 3) The initial value of radio altitude is 30m;

[0027] 4) The equidistant step increment of water injection height is +10m;

[0028] 5) There shall be no less than 5 water test height points.

[0029] Further, in step (3):

[0030] 1) The average precipitation in the watering coverage grid area is not less than 1.2 mm;

[0031] 2) The effective utilization rate of water injection in the test field of the target water injection area shall not be less than 55%.

[0032] Further, in step (4):

[0033] 1) The wind speed in any wind direction shall not exceed 2m / s;

[0034] 2) The initial value of the water-dropping speed is 1.23V in the water-dropping configuration of this type of aircraft. SR -20km / h;

[0035] 3) The equidistant step increment of water injection speed is +10km / h;

[0036] 4) There shall be no less than 5 water injection test speed points.

[0037] Further, in step (5):

[0038] 1) The average precipitation in the watering coverage grid area is not less than 1.2 mm;

[0039] 2) The effective utilization rate of water injection in the test field of the target water injection area is not less than 55%

[0040] Further, in step (6):

[0041] 1) Select a fixed wind direction that forms a 90° angle with the true heading of the symmetry axis of the rectangular target water-dropping area;

[0042] 2) Select different wind speeds of 2.0±0.5m / s, 5.0±1.0m / s, 7.5±1.0m / s, and 10±1.0m / s under a fixed wind direction to carry out water injection tests.

[0043] Further, in step (8):

[0044] 1) Select a fixed wind speed of 5.0±1.0m / s;

[0045] 2) Select different wind directions with angles of 0°, 45°, 90°, 135° and 180° to the true heading of the symmetry axis of the rectangular target water-dropping area to carry out water-dropping tests.

[0046] The beneficial effects of the invention are as follows: the invention is a flight test method for the water-dropping effect of a fire-fighting aircraft, which solves the technical difficulties in flight test verification of the water-dropping effect of a fire-fighting aircraft. The optimal water-dropping height, the optimal water-dropping speed, and the water-dropping correction amount under different wind directions and wind speeds obtained by the invention have high feasibility and high accuracy, and effectively improve the water-dropping fire-fighting efficiency of fire-fighting aircraft. DETAILED DESCRIPTION

[0047] The following is a further detailed description of the specific implementation of the present invention, such as the shape, structure, relative position and connection relationship between the various components involved, the function and working principle of each part, the manufacturing process and operation method, etc., through the description of the embodiments, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of the present invention:

[0048] The present invention provides a flight test method for water-dropping effect of a fire-fighting aircraft, which is used to obtain the optimal flight altitude, optimal flight speed and water-dropping correction amount for different wind speeds and wind directions of the water-dropping effect of the fire-fighting aircraft through a flight test. The present invention is further described below in conjunction with an embodiment.

[0049] In one embodiment of the present invention, a flight test method for the water-dropping effect of a fire-fighting aircraft proposed in the present invention is used for a certain type of amphibious fire-fighting aircraft to verify the water-dropping effect of the aircraft in a flight test, and the steps are as follows:

[0050] (1) Build a ground rectangular grid target water-dropping area test field for measuring the amount of water dropped by fire-fighting aircraft, with the following requirements: 1) The rectangular target water-dropping area is not less than 100m×50m (length×width); 2) The rectangular target water-dropping area is marked with symmetrical axes along the length direction; 3) The grids are symmetrically distributed along the axis and evenly divide the rectangular target water-dropping area; 4) The area of ​​a single grid is about 1 / 500 of the rectangular target water-dropping area. The reason for setting the water-dropping area to be not less than 100m×50m in this step is that the aircraft's water-dropping speed is fast, generally around 150km / h~250km / h (converted to 42m / s~69m / s), and the water-dropping time is 3s~5s. As large a test site as possible is needed to accommodate the water-dropping area, and the above site is close to the minimum requirement; the symmetrical distribution of the water-dropping area is conducive to the aircraft flying along the axis to drop water; and the evenly divided grid is conducive to the statistical calculation of the precipitation within a unit area.

[0051] (2) Under no wind or light wind conditions, the water-dropping speed is fixed and the water is dropped along the axis of the test field over the target water-dropping area using radio altitude increments of equal distance steps. The requirements are: 1) The wind speed in any wind direction is not greater than 2 m / s; 2) The water-dropping speed is fixed at 1.23 V under the water-dropping configuration of this type of aircraft. SR; 3) The initial value of the radio height is 30m; 4) The equidistant step increment of the watering height is +10m; 5) There are no less than 5 watering test height points. This step sets the wind speed below 2m / s as no wind to soft wind (wind force level in meteorology). The wind speed has no obvious effect on the rainfall trajectory after watering, eliminating factors that may affect the watering effect; 1.23V SR It is a fixed speed constant. In flight tests, the low-speed boundary of the test subject is generally set at 1.23V. SR (The airworthiness clauses have initial speed requirements for low-speed boundary test subjects, and this speed can be gradually lowered after safety verification); 30m is the treetop height, which is the minimum height for dropping water for firefighting, ensuring the safe height of the aircraft for firefighting flight; the water dropping height increment and the number of test points are set because there are differences in rainfall coverage area and rainfall amount after water dropping at different heights, and the optimal water dropping height for firefighting is found through the test data curve.

[0052] (3) Measure the precipitation of each water drop in the test field of the target water drop area, draw the curve of water drop effective utilization rate and water drop height, and obtain the optimal water drop height data, with the following requirements: 1) The average precipitation in the water drop coverage grid area is not less than 1.2 mm; 2) The effective utilization rate of water drop in the test field of the target water drop area is not less than 55% (that is, the proportion of grids that meet requirement 1) is not less than 55% of the total grids). Because the rainfall of medium to heavy rain is 17mm to 38mm within 24 hours, the precipitation of 1.2mm per flight is converted into the precipitation of single aircraft multiple flights of fire fighting as medium to heavy rain (10 hours of daytime, 2 fire fightings per hour, 20 fire fightings per day by a single aircraft, and rainfall of 24mm), which can effectively extinguish fires; 55% utilization rate is the threshold for measuring the accuracy of aircraft water drop fire fighting, and determines the efficiency and economic value of aircraft water drop fire fighting.

[0053] (4) In the absence of wind or with light wind, water shall be dropped by flying over the test field in the target water-dropping area along the axis of the test field using the optimal water-dropping height and water-dropping speed increments of equal distance steps. The requirements are as follows: 1) The wind speed in any wind direction shall not exceed 2 m / s; 2) The initial value of the water-dropping speed is 1.23 V under the water-dropping configuration of this type of aircraft. SR -20km / h; 3) The equidistant step increment of water throwing speed is +10km / h; 4) There are no less than 5 water throwing test speed points. This step sets the wind speed below 2m / s as no wind to soft wind (wind force level in meteorology). The wind speed has no obvious effect on the rainfall trajectory after water throwing, eliminating factors that may affect the effect of water throwing; the water throwing speed increment and the number of test points are set because there are differences in the rainfall coverage area and rainfall after water throwing at different speeds, and the optimal water throwing fire extinguishing speed is found through the test data curve.

[0054] (5) Measure the precipitation of each watering in the test field of the target watering area, draw the curve of watering effective utilization rate and watering speed, and obtain the optimal watering speed data, with the following requirements: 1) The average precipitation in the grid area covered by watering is not less than 1.2 mm; 2) The effective utilization rate of watering in the test field of the target watering area is not less than 55% (that is, the proportion of grids that meet requirement 1) is not less than 55% of the total grids). In this step, the rainfall from heavy rain is 17 mm to 38 mm within 24 hours. The precipitation of 1.2 mm per flight is converted into the rainfall of single aircraft multiple flights for firefighting as medium to heavy rain (10 hours in daytime, 2 firefighting per hour, 20 firefighting per day by a single aircraft, and rainfall of 24 mm), which can effectively extinguish fires; 55% utilization rate is the threshold for measuring the accuracy of aircraft watering firefighting, and determines the efficiency and economic value of aircraft watering firefighting.

[0055] (6) Under the conditions of fixed wind direction and different wind speeds, use the optimal water dropping height and speed to fly over the test site of the target water dropping area along the axis of the test site to drop water. The requirements are: 1) Select a fixed wind direction that is at a 90° angle to the true heading of the symmetry axis of the rectangular target water dropping area; 2) Select different wind speeds of 2.0 ±0.5m / s, 5.0±1.0m / s, 7.5±1.0m / s, and 10±1.0m / s under a fixed wind direction to carry out water dropping tests. The purpose of setting a fixed wind direction in this step is to eliminate the influence of different wind directions on the water dropping effect and turn the wind direction into a constant; the wind speed increment and the number of test points are set because different wind speeds have an impact on the rainfall coverage area and rainfall after water dropping, and the optimal water dropping wind speed is found through the test data curve)

[0056] (7) Measure the precipitation offset of each watering in the test field of the target watering area, draw the precipitation offset and wind speed curve, and obtain the watering correction under fixed wind direction and different wind speed conditions. Different wind speeds have a great influence on the rainfall coverage area and rainfall after watering. The data curve obtained by the test in step 6) can be used by the flight crew to correct the watering parameters according to the wind speed data of the meteorological radar when performing firefighting tasks, so as to obtain better firefighting effects.

[0057] (8) Under the conditions of fixed wind speed and different wind directions, the optimal water-dropping height and speed are used to drop water over the test field of the target water-dropping area along the axis of the test field. The requirements are as follows: 1) Select a fixed wind speed of 5.0±1.0m / s; 2) Select different wind directions to be at angles of 0°, 45°, 90°, 135°, and 180° with the true heading of the symmetric axis of the rectangular target water-dropping area to carry out water-dropping tests. The purpose of setting a fixed wind speed in this step is to eliminate the influence of different wind speeds on the water-dropping effect and turn the wind speed into a constant; the wind direction increment and the number of test points are set because different wind directions have an influence on the rainfall coverage area and rainfall after water-dropping. The optimal water-dropping wind direction is found through the test data curve, and the wind direction is 360 degrees symmetrical, and only 180 degrees is needed to symmetrically obtain the data of the other half.

[0058] (9) Measure the precipitation offset of each watering in the test field of the target watering area, draw the precipitation offset and wind speed curve, and obtain the watering correction under fixed wind direction and different wind speed conditions. Different wind directions have a great influence on the rainfall coverage area and rainfall after watering. The data curve obtained by the test in step 8) can be used by the flight crew to correct the watering parameters according to the wind direction data of the meteorological radar when performing firefighting tasks, so as to obtain better firefighting effects.

[0059] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for testing the water-dropping effect of a fire-fighting aircraft, characterized in that: The following steps are involved: (1) Build a ground rectangular grid-type target water-dropping area test site; (2) Under no wind or light wind conditions, the fire-fighting aircraft maintains a constant water-dropping speed and simultaneously uses radio altitude increments of equal distance to fly several times at several altitude points to drop water on the test site in step (1); (3) measuring the amount of precipitation each time the water is poured in step (2), plotting a curve of effective utilization rate of water pouring and water pouring height, and obtaining an optimal water pouring height; (4) Under no wind or light wind conditions, the fire-fighting aircraft maintains the optimal water-dropping altitude in step (3) and simultaneously drops water on the test field flight in step (1) at a number of speed points using water-dropping speed increments of equidistant steps; (5) measuring the amount of water dropped each time in step (4), drawing a curve of effective utilization rate of water drop and water drop speed, and obtaining the optimal water drop speed; (6) Under the conditions of fixed wind direction and different wind speeds, the fire-fighting aircraft uses the optimal water-dropping height in step (3) and the optimal water-dropping speed in step (5) to drop water in the test field; (7) measuring the precipitation offset of each watering in step (6), plotting a precipitation offset and wind speed curve, and obtaining the watering correction under fixed wind direction and different wind speed conditions; (8) Under the conditions of fixed wind speed and different wind directions, the fire-fighting aircraft uses the optimal water-dropping height in step (3) and the optimal water-dropping speed in step (5) to drop water in the test field; (9) Measure the precipitation offset of each watering in step (8), draw a curve of precipitation offset and wind direction, obtain the watering correction under fixed wind speed and different wind directions, and complete the test.

2. A fire-fighting aircraft water-dropping effect flight test method according to claim 1, characterized in that: In step (1), 1) The length and width of the ground rectangular grid target watering area shall not be less than 100m×50m; 2) The rectangular target water-dropping area is marked with symmetrical axes along its length; 3) The grid is symmetrically distributed along the axis and evenly divides the rectangular target water delivery area; 4) The area of ​​a single grid is 1 / 500 of the rectangular target water injection area.

3. A fire-fighting aircraft water-dropping effect flight test method according to claim 1, characterized in that: In step (2): 1) The wind speed in any wind direction shall not exceed 2m / s; 2) The water dropping speed is fixed at 1.23V for this type of aircraft in the water dropping configuration SR , V SR It is the reference stall speed of this type of aircraft in the water-dropping configuration; 3) The initial value of radio altitude is 30m; 4) The equidistant step increment of water injection height is +10m; 5) There shall be no less than 5 water test height points.

4. A fire-fighting aircraft water-dropping effect flight test method according to claim 3, characterized in that: In step (3): 1) The average precipitation in the watering coverage grid area is not less than 1.2 mm; 2) The effective utilization rate of water injection in the test field of the target water injection area shall not be less than 55%.

5. A fire-fighting aircraft water-dropping effect flight test method according to claim 1, characterized in that: In step (4): 1) The wind speed in any wind direction shall not exceed 2m / s; 2) The initial value of the water-dropping speed is 1.23V in the water-dropping configuration of this type of aircraft. SR -20km / h; 3) The equidistant step increment of water injection speed is +10km / h; 4) There shall be no less than 5 water injection test speed points.

6. A fire-fighting aircraft water-dropping effect flight test method according to claim 5, characterized in that: In step (5): 1) The average precipitation in the watering coverage grid area is not less than 1.2 mm; 2) The effective utilization rate of water injection in the test field of the target water injection area shall not be less than 55%.

7. A fire-fighting aircraft water-dropping effect flight test method according to claim 1, characterized in that: In step (6): 1) Select a fixed wind direction that forms a 90° angle with the true heading of the symmetry axis of the rectangular target water-dropping area; 2) Select different wind speeds of 2.0±0.5m / s, 5.0±1.0m / s, 7.5±1.0m / s, and 10±1.0m / s under a fixed wind direction to carry out water dropping tests.

8. A fire-fighting aircraft water-dropping effect flight test method according to claim 1, characterized in that: In step (8): 1) Select a fixed wind speed of 5.0±1.0m / s; 2) Select different wind directions with angles of 0°, 45°, 90°, 135°, and 180° to the true heading of the symmetry axis of the rectangular target water-dropping area to carry out water-dropping tests.