A method for evaluating the maximum takeoff and landing weight of a civil helicopter at a class a unobstructed airport

Abstract

The present application belongs to the technical field of helicopter aerodynamic design and verification, and particularly relates to a method for evaluating the maximum takeoff and landing weight of a civil helicopter in a class A barrier-free airport. The method comprises the following steps: selecting different target height airports and flight weights for takeoff and landing in a class A barrier-free airport; obtaining the maximum weight GW1 for flight verification of takeoff and landing in a class A barrier-free airport at different target height airports; calculating the maximum takeoff weight Gw2 that changes with atmospheric temperature and barometric height within the range of takeoff height and temperature envelope of a class A, considering the takeoff acceleration torque increment; obtaining the maximum flight weight GW3 that is equal to the remaining power Pw; calculating the maximum weight GW5 for flight with a 30-minute one-engine inoperative (OEI) power OEICT and a selected speed VY with a 150ft / min remaining climb rate at 1000ft from the ground within the range of atmospheric temperature and barometric height for takeoff and landing in a class A barrier-free airport; and obtaining the maximum weight for takeoff and landing in a class A barrier-free airport by comparing the maximum weights and taking the smaller one.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of helicopter aerodynamic design and verification, and particularly relates to a method for evaluating the maximum take-off and landing weight of a civil helicopter in a class A barrier-free airport. BACKGROUND

[0002] For a class A transport type rotorcraft, it refers to a multi-rotor aircraft with isolation design characteristics of engines and systems according to the provisions of CCAR-29, and can perform scheduled take-off and landing operation in the case of key engine failure, that is, if one engine fails, it can ensure a sufficient specified height range and sufficient performance to continue safe flight. Therefore, the class A transport type rotorcraft needs a specific take-off and landing trajectory, and needs to determine the maximum weight that can ensure the ability to continue safe flight after one engine fails, that is, the class A take-off maximum weight and landing maximum weight. According to the type of class A take-off site, it is usually divided into barrier-free airport, small area airport, elevated helicopter airport, etc. The present application mainly aims at the use of barrier-free airport, and proposes a method for evaluating the maximum take-off and landing weight of a civil helicopter in a class A barrier-free airport. SUMMARY

[0003] In view of the fact that the maximum take-off and landing weight in the class A take-off and landing flight test needs to meet the profile requirements, the present application proposes a method for evaluating the maximum take-off and landing weight of a civil helicopter in a class A barrier-free airport, so as to meet the class A flight capability of the helicopter within the take-off and landing envelope range of the barrier-free airport.

[0004] To achieve the above purpose, the present application adopts the following technical scheme.

[0005] A method for evaluating the maximum take-off and landing weight of a civil helicopter in a class A barrier-free airport, the method comprising:

[0006] Step 1: selecting different target height airports and flight weights for class A barrier-free airport take-off and landing;

[0007] Step 2: obtaining the maximum weight GW1 of class A barrier-free airport take-off and landing flight verification of different target height airports and the atmospheric temperature, air pressure height and density height corresponding to GW1 according to the test conditions of step 1;

[0008] Step 3: calculating the take-off maximum weight Gw2 that changes with atmospheric temperature and air pressure height within the class A take-off and landing height and temperature envelope range after considering the take-off acceleration torque increment;

[0009] Step 4: Calculate the theoretical residual power of the helicopter in different flight weights in the range of atmospheric temperature and barometric altitude of the A-class barrier-free airport takeoff and landing, and compare it with the test residual power Pw to obtain the maximum weight GW3 corresponding to the flight equal to the test residual power Pw;

[0010] Step 5: Calculate the maximum weight GW4 corresponding to the flight with 100ft / min residual climb rate at the selected takeoff safety speed VTOSS in the range of atmospheric temperature and barometric altitude of the A-class barrier-free airport takeoff and landing, with one engine not working power OEI LO at 200ft off the ground and 30 seconds / 2 minutes.

[0011] Step 6: Calculate the maximum weight GW5 corresponding to the flight with 150ft / min residual climb rate at the selected speed VY in the range of atmospheric temperature and barometric altitude of the A-class barrier-free airport takeoff and landing, with one engine not working power OEI CT at 1000ft off the ground and 30 minutes.

[0012] Step 7: Take the smaller value by comparing the maximum weights of steps 2-6 to obtain the maximum weight of the A-class barrier-free airport takeoff and landing.

[0013] Further, step 1 is specifically:

[0014] Select the target height airport for flight test, calculate the maximum weight with ground effect hovering at the current height airport according to the selected height airport and temperature conditions, and take the preliminary selected test flight weight, which ensures that the test flight weight is within the range of -1% to +3% of the preliminary selected test flight weight during the test process.

[0015] Further, step 2 is specifically:

[0016] According to step 1, obtain not less than 5 times of effective test results of A-class normal takeoff, interrupted takeoff, continued takeoff, normal landing, continued landing, and interrupted landing, respectively, according to different target height airports, and take the minimum value of the flight weight at the same height airport as the maximum weight GW1 of the A-class barrier-free airport takeoff and landing flight verification at that height airport, and the atmospheric temperature, barometric altitude and density altitude corresponding to GW1.

[0017] Further, before step 3, the method further comprises:

[0018] Statistically, the required torque during the A-class normal takeoff acceleration process and the required torque during the takeoff hovering process at all height airports are calculated, and the difference between the two is calculated as the takeoff required torque increment, and the maximum value of the takeoff required torque increment is selected as the takeoff required torque increment Q1 at different height airports.

[0019] Further, step 3 is specifically:

[0020] On the basis of hovering required torque, the take-off required torque increment Q1 is added, and the take-off maximum weight Gw2 considering the take-off acceleration torque increment is calculated to change with the atmospheric temperature and pressure height in the A-class take-off and landing height and temperature envelope.

[0021] Further, before step 4, the method further comprises:

[0022] According to the different height airport, the required power of the A-class unobstructed airport interruption take-off, the required power of the A-class unobstructed airport continuous take-off, the required power at the take-off hovering time and the maximum emergency available power of the helicopter after the failure of one engine are calculated, the difference between the two, that is, the residual power, is selected as the minimum value of the residual power at different height airports, as the test residual power Pw.

[0023] Further, step 4 is specifically:

[0024] The theoretical residual power of the helicopter at different flight weights in the atmospheric temperature and pressure height range of the A-class unobstructed airport take-off and landing is calculated, and compared with the test residual power Pw, to obtain the maximum flight weight GW3 equal to the test residual power Pw.

[0025] Further, before step 7, the method further comprises:

[0026] The near-ground maneuvering characteristic test flight results of different height airports are counted, the required torque of the helicopter at different wind speed and direction is obtained, and compared with the torque at the take-off hovering time, the increment Q2 of the required torque at the upwind hovering take-off and landing is obtained, and the influence △GW of the required torque increment Q2 on the A-class unobstructed airport take-off and landing weight is calculated in the atmospheric temperature and pressure height range of the A-class unobstructed airport take-off and landing.

[0027] Further, step 7 is specifically:

[0028] By comparing the maximum weights of steps 2-6, the minimum value is obtained as the maximum weight of the A-class unobstructed airport take-off and landing, and the maximum weight of the A-class unobstructed airport take-off and landing is obtained under the upwind state.

[0029] The present application provides a method for evaluating the maximum take-off and landing weight of the A-class unobstructed airport, which considers the airworthiness regulations A-class take-off and landing profile requirements, combines test and calculation analysis, and uses the residual power method to show the compliance of the airworthiness provisions. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The A-class unobstructed airport normal take-off profile diagram provided for the embodiments of the present application;

[0031] Figure 2 A class of barrier-free airport take-off and interrupted take-off profile schematic diagram provided for the embodiment of the present application;

[0032] Figure 3 A class of barrier-free airport normal landing profile schematic diagram provided for the embodiment of the present application;

[0033] Figure 4 A class of barrier-free airport continued landing profile schematic diagram provided for the embodiment of the present application;

[0034] Figure 5 A class of barrier-free airport interrupted landing profile schematic diagram provided for the embodiment of the present application. DETAILED DESCRIPTION

[0035] The technical solutions of the present application will be described in detail below with reference to the accompanying drawings.

[0036] A class of take-off includes normal take-off, interrupted take-off, and continued take-off. A class of barrier-free airport normal take-off profile (see attached Figure 1 ), the helicopter starts from hovering, heads down and accelerates to climb, continues to accelerate to climb after passing the take-off decision point, and reaches VY and climbs to 1000ft. If engine failure occurs during normal take-off, continued take-off requires the helicopter to have the ability to fly again, and interrupted take-off requires the helicopter to have the ability to land safely. A class of barrier-free airport continued take-off profile (see attached Figure 2 ), the helicopter needs to accelerate from the engine failure point to VTOSS and establish a positive climb rate, then starts the first stage of climb at VTOSS speed, climbs to 60m (200ft) above ground level, accelerates horizontally to VY, and finally starts the second stage of climb at VY speed, climbs to 300m (1000ft) above ground level; A class of barrier-free airport interrupted take-off profile (see attached Figure 2 ), the helicopter needs to descend in height and speed from the engine failure point, and control the speed and descent rate within the limit before landing, to complete the safe landing and landing of the helicopter.

[0037] A class of take-off includes normal landing, interrupted landing, and continued landing. A class of barrier-free airport normal landing profile (see attached Figure 3 ), the helicopter starts from the approach state, continues to approach after passing the landing decision point, and lands at the landing point after hovering and decelerating near the ground. If engine failure occurs during normal landing, interrupted landing requires the helicopter to have the ability to fly again, and continued landing requires the helicopter to have the ability to land safely. A class of barrier-free airport continued landing profile (see attached Figure 4 ), the helicopter needs to continue to approach from the engine failure point, and control the speed and descent rate within the limit before landing, to complete the safe landing and landing of the helicopter. A class of barrier-free airport interrupted landing profile (see attached Figure 5), the helicopter needs to adjust the speed from the engine failure point to VTOSS and establish a positive climb rate, then starts the first stage climb at VTOSS speed, climbs to 60m (200ft) height, accelerates horizontally to VY, and finally starts the second stage climb at VY speed, climbs to 300m (1000ft) height.

[0038] According to the above description, the A-class barrier-free airport continues the takeoff and interrupted landing procedures, and the maximum weight of the A-class takeoff and the maximum weight of the A-class landing are usually set as the same weight for convenience. The maximum takeoff and landing weight of the A-class barrier-free airport needs to meet all the takeoff and landing profile requirements at the same time, which is usually obtained according to flight test verification and combined with calculation analysis. The present application provides an evaluation method for the maximum weight meeting the above A-class takeoff and landing requirements.

[0039] The method for evaluating the maximum takeoff and landing weight of the A-class barrier-free airport of the helicopter provided by the embodiment of the present application is obtained through flight test and calculation, and the specific steps are as follows:

[0040] Step 1: Selecting different target height airports for A-class barrier-free airport takeoff and landing and flight weight

[0041] According to the requirement that the A-class barrier-free airport takeoff weight cannot be extrapolated according to AC29.59, the target height airport for flight test is selected in combination with the verification target height. The maximum weight of ground effect hovering at the current height airport is calculated according to the selected height airport and temperature condition, which is used as the preliminary selected test flight weight. It is ensured that the test flight weight does not exceed the range of -1% to +3% of the maximum weight of ground effect hovering during the test.

[0042] Step 2: According to step 1, at least 5 effective test results of A-class normal takeoff, interrupted takeoff, continued takeoff, normal landing, continued landing, interrupted landing are obtained respectively, the actual flight density height, atmospheric temperature, pressure height and flight weight of the 6 flight subjects are counted according to different target height airports, the minimum value of the flight weight of the same height airport is taken as the maximum weight GW1 of the A-class barrier-free airport takeoff and landing flight verification of the height airport, and the atmospheric temperature, pressure height and density height corresponding to GW1.

[0043] The required torque during the A-class normal takeoff acceleration process and the required torque during the takeoff hovering at all height airports are counted, and the difference between the two is calculated as the takeoff required torque increment. The maximum value of the takeoff required torque increment is selected as the takeoff required torque increment Q1 of different height airports.

[0044] The difference between the two is the residual power, and the minimum value of the residual power is selected as the test residual power Pw of the airport at different altitudes.

[0045] Step 3: The take-off maximum weight Gw2 considering the take-off acceleration torque increment is calculated by adding the take-off torque increment Q1 obtained in step 2 to the hover required torque.

[0046] Step 4:

[0047] The theoretical residual power of the helicopter at different flight weights in the range of atmospheric temperature and barometric altitude for take-off and landing at Class A barrier-free airport is calculated and compared with the test residual power Pw to obtain the maximum flight weight GW3 equal to the test residual power Pw.

[0048] Step 5: In the range of atmospheric temperature and barometric altitude for take-off and landing at Class A barrier-free airport, the maximum flight weight GW4 corresponding to a 100ft / min residual climb rate with a 200ft off-ground at 30 seconds / 2 minutes and a selected take-off safety speed VTOSS is calculated.

[0049] Step 6: In the range of atmospheric temperature and barometric altitude for take-off and landing at Class A barrier-free airport, the maximum flight weight GW5 corresponding to a 150ft / min residual climb rate with a 1000ft off-ground at 30 minutes and a selected speed VY is calculated.

[0050] Step 7: Considering the effect of wind speed on take-off weight, the required torque of the helicopter at different wind speeds and directions is obtained by statistical analysis of the results of near-ground maneuvering characteristics test flights at different altitudes, and compared with the torque at take-off hover to obtain the increment Q2 of the required torque for take-off and landing in headwind hover. In the range of atmospheric temperature and barometric altitude for take-off and landing at Class A barrier-free airport, the effect of the increment Q2 of the required torque on the take-off and landing weight of Class A barrier-free airport GW6 is calculated.

[0051] Step 8: By comparing the maximum weights in steps 2-6, the minimum value is obtained as the maximum weight for take-off and landing at Class A barrier-free airport, and the effect of wind speed on the weight of take-off and landing at Class A barrier-free airport in step 7 is added to obtain the maximum weight for take-off and landing at Class A barrier-free airport in headwind state.

Claims

1. A method of assessing the maximum take-off and landing weight for a civil helicopter at a Class A unobstructed aerodrome, characterised in that, The method comprises: Step 1: selecting different target height airports and flight weights of A-class barrier-free airport takeoff and landing; Step 2: obtaining the maximum weight GW1 of A-class barrier-free airport takeoff and landing flight verification of different target height airports according to the test conditions of step 1, and the atmospheric temperature, air pressure height and density height corresponding to GW1; Step 3: calculating the maximum takeoff weight Gw2 considering the takeoff acceleration torque increment within the A-class takeoff and landing height and temperature envelope range varying with atmospheric temperature and air pressure height; Step 4: calculating the theoretical residual power of the helicopter at different flight weights within the atmospheric temperature and air pressure height range of A-class barrier-free airport takeoff and landing, and comparing it with the test residual power Pw to obtain the flight maximum weight GW3 equal to the test residual power Pw; Step 5: within the atmospheric temperature and air pressure height range of A-class barrier-free airport takeoff and landing, calculating the maximum weight GW4 corresponding to the flight with 100ft / min residual climb rate at the selected takeoff safety speed VTOSS with 30 seconds / 2 minutes of one-engine inoperative (OEI) LO at 200ft above ground level and 30 minutes of one-engine inoperative (OEI) CT at 1000ft above ground level and the selected speed VY; Step 6: within the atmospheric temperature and air pressure height range of A-class barrier-free airport takeoff and landing, calculating the maximum weight GW5 corresponding to the flight with 150ft / min residual climb rate at the selected speed VY with 30 minutes of one-engine inoperative (OEI) CT at 1000ft above ground level and the selected speed VY; Step 7: obtaining the maximum weight of A-class barrier-free airport takeoff and landing by comparing the maximum weights of steps 2-6 and taking the smaller value.

2. The method for evaluating the maximum takeoff and landing weight of a civil helicopter in a Class A unobstructed airport according to claim 1, characterized in that, Step 1 is specifically: Selecting a target height airport for flight test, calculating the maximum weight with ground effect hovering at the current height airport under the selected height airport and temperature conditions as the preliminary selected test flight weight, and ensuring that the test flight weight is within the range of -1% to +3% of the preliminary selected test flight weight during the test.

3. A method of evaluating the maximum take-off and landing weight of a civil helicopter at a Class A unobstructed aerodrome according to claim 2, characterized in that, Step 2 is specifically: According to step 1, obtaining not less than 5 times of effective test results of A-class normal takeoff, interrupted takeoff, continued takeoff, normal landing, continued landing, and interrupted landing, respectively, and calculating the density height, atmospheric temperature, air pressure height and flight weight of the actual flight of the six flight subjects according to different target height airports, taking the minimum value of the flight weight of the same height airport as the maximum weight GW1 of A-class barrier-free airport takeoff and landing flight verification of the height airport, and the atmospheric temperature, air pressure height and density height corresponding to GW1.

4. The method for evaluating the maximum takeoff and landing weight of a civil helicopter in a Class A unobstructed airport according to claim 3, characterized in that, Before step 3, the method further comprises: Statistically analyzing the required torque during A-class normal takeoff acceleration and the required torque during takeoff hovering at all height airports, and calculating the difference value as the takeoff required torque increment, and selecting the maximum value of the takeoff required torque increment as the takeoff required torque increment Q1 of different height airports.

5. The method for evaluating the maximum takeoff and landing weight of a civil helicopter in a Class A unobstructed aerodrome according to claim 4, characterized in that, Step 3 is specifically: Increasing the takeoff required torque increment Q1 based on the hovering required torque to obtain the maximum takeoff weight Gw2 considering the takeoff acceleration torque increment within the A-class takeoff and landing height and temperature envelope range varying with atmospheric temperature and air pressure height.

6. The method for evaluating the maximum takeoff and landing weight of a civil helicopter in a Class A unobstructed airport according to claim 5, characterized in that, Before step 4, the method further comprises: According to the airport statistics of different altitudes, the difference between the maximum emergency available power of the helicopter after one engine failure and the required power during take-off hovering in the take-off and the continued take-off in the A-class barrier-free airport is calculated, that is, the residual power, and the minimum value of the residual power is selected as the test residual power Pw of the airport of different altitudes.

7. The method of assessing the maximum take-off and landing weight of a civil helicopter at a Class A unobstructed aerodrome according to claim 6, characterized in that, Step 4 is specifically: The theoretical residual power of the helicopter at different flight weights in the atmospheric temperature and pressure altitude range of the take-off and landing in the A-class barrier-free airport is calculated, and compared with the test residual power Pw, to obtain the maximum flight weight GW3 equal to the test residual power Pw.

8. A method of evaluating the maximum take-off and landing weight of a civil helicopter at a Class A unobstructed aerodrome according to claim 7, characterized in that, Before step 7, the method further comprises: The test results of the near-ground maneuvering characteristics of the airport of different altitudes are counted, the required torque of the helicopter at different wind speeds and directions is obtained, and compared with the torque during take-off hovering, to obtain the increment Q2 of the required torque during upwind hovering take-off and landing, and the influence △GW of the increment Q2 of the required torque on the take-off and landing weight in the A-class barrier-free airport in the atmospheric temperature and pressure altitude range of the take-off and landing is calculated.

9. A method of evaluating the maximum take-off and landing weight of a civil helicopter at a Class A unobstructed aerodrome according to claim 8, characterized in that, Step 7 is specifically: By comparing the maximum weights of steps 2-6, the minimum value is obtained as the maximum weight of the take-off and landing in the A-class barrier-free airport, and the maximum weight of the take-off and landing in the A-class barrier-free airport under the upwind state is obtained by subtracting △GW from the maximum weight of the take-off and landing in the A-class barrier-free airport.

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