Method for evaluating maximum take-off and landing weight of class-A barrier-free airport of civil helicopter

Abstract

The invention belongs to the technical field of aerodynamic design and verification of helicopters, 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. Comprising the following steps: selecting airports with different target heights and flight weights for takeoff and landing of a class-A barrier-free airport; obtaining the maximum weight GW1 of the takeoff and landing flight verification of the A-type barrier-free airports of the airports with different target heights; calculating the maximum takeoff weight Gw2 along with the change of the atmospheric temperature and the atmospheric pressure height within the A-type takeoff landing height and temperature envelope range after the takeoff acceleration torque increment is considered; obtaining the flight maximum weight GW3 equal to the test residual power Pw; taking off and landing in an A-class barrier-free airport within the range of atmospheric temperature and atmospheric pressure height; within the takeoff and landing atmospheric temperature and air pressure height range of the class-A barrier-free airport, the maximum flight weight GW5 corresponding to the remaining climb rate of 150 ft / min at the non-working power OEICT of one engine within 30 minutes and the selected speed VY of 1000 ft away from the ground is calculated; and comparing the maximum weight and taking a small value to obtain the maximum take-off and landing weight of the class-A barrier-free airport.

Description

Technical Field

[0001] The invention belongs to the technical field of helicopter aerodynamic design and verification, and in particular relates to a method for evaluating the maximum take-off and landing weight of a civil helicopter of Class A barrier-free airport. Background Art

[0002] Class A transport rotorcraft refers to a multi-engine rotorcraft whose engines and systems have isolation design characteristics in accordance with the provisions of CCAR-29, and can perform scheduled takeoff and landing operations in the event of a critical engine failure, that is, if an engine failure occurs, it can ensure a sufficient specified altitude range and sufficient performance to continue safe flight. Therefore, Class A transport rotorcraft require specific takeoff and landing trajectories, and need to determine the maximum weight to ensure the ability to continue safe flight after an engine failure, that is, the Class A maximum takeoff weight and landing maximum weight. According to the type of Class A takeoff site, it is usually divided into barrier-free airports, small-area airports, elevated helicopter airports, etc. This invention mainly focuses on the use of barrier-free airports and proposes a method for evaluating the maximum takeoff and landing weight of civil helicopters at Class A barrier-free airports. Summary of the invention

[0003] In view of the fact that the maximum takeoff and landing weight in the above-mentioned Class A takeoff and landing test flight must meet the profile requirements, the patent of this invention proposes a method for evaluating the maximum takeoff and landing weight of a civil helicopter at a Class A barrier-free airport, so as to meet the Class A flight capability of the helicopter within the takeoff and landing envelope of an barrier-free airport.

[0004] In order to achieve the above object, the present invention adopts the following technical solution to achieve it.

[0005] A method for evaluating the maximum takeoff and landing weight of a civil helicopter at a Category A barrier-free airport, the method comprising:

[0006] Step 1: Select different target altitude airports and flight weights for takeoff and landing at Class A barrier-free airports;

[0007] Step 2: Based on the test conditions in step 1, obtain the maximum weight GW1 for Class A barrier-free airport takeoff and landing flight verification at airports with different target altitudes, and the atmospheric temperature, pressure altitude, and density altitude corresponding to GW1;

[0008] Step 3: Calculate the maximum takeoff weight Gw2 as it changes with atmospheric temperature and pressure altitude within the range of Category A takeoff and landing altitude and temperature envelope after taking into account the takeoff acceleration torque increment;

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

[0010] Step 5: Calculate the maximum weight GW4 for the flight with a residual climb rate of 100 ft / min at 200 ft above the ground, 30 seconds / 2 minutes with one engine inoperative power OEI LO and the selected takeoff safety speed VTOSS within the range of takeoff and landing atmospheric temperature and pressure altitude at a Class A barrier-free airport;

[0011] Step 6: Calculate the maximum weight GW5 for a flight with a residual climb rate of 150 ft / min at 1000 ft above the ground, one engine inoperative power OEI CT and a selected speed VY within the range of takeoff and landing atmospheric temperature and pressure altitude at a Class A barrier-free airport;

[0012] Step 7: Compare the maximum weights in steps 2 to 6 and take the smaller value to get the maximum weight for takeoff and landing at a Class A barrier-free airport.

[0013] Furthermore, step 1 is specifically as follows:

[0014] Select the target airport altitude for the flight test, calculate the maximum weight of hovering in ground effect at the current airport altitude based on the selected airport altitude and temperature conditions, and use this as the preliminary selected test flight weight. During the test, ensure that the test flight weight is within the range of -1% to +3% of the preliminary selected test flight weight.

[0015] Furthermore, step 2 is specifically as follows:

[0016] According to step 1, obtain test results of no less than 5 valid Class A normal takeoff, rejected takeoff, continued takeoff, normal landing, continued landing, and rejected landing, respectively. Count the actual flight density altitude, atmospheric temperature, pressure altitude, and flight weight of the 6 flight subjects at different target altitude airports. Take the minimum value of the flight weight at the airport at the same altitude as the maximum weight GW1 for Class A barrier-free airport takeoff and landing flight verification at the airport at that altitude, as well as the atmospheric temperature, pressure altitude, and density altitude corresponding to GW1.

[0017] Furthermore, before step 3, the method further includes:

[0018] The torque required during normal takeoff acceleration and takeoff hovering in Class A at all altitude airports is 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 at different altitude airports.

[0019] Furthermore, step 3 is specifically as follows:

[0020] The torque increment Q1 required for takeoff is added to the torque required for hovering, and the maximum takeoff weight Gw2 that changes with atmospheric temperature and pressure altitude within the range of Class A takeoff and landing altitude and temperature envelope is calculated after considering the takeoff acceleration torque increment.

[0021] Furthermore, before step 4, the method further includes:

[0022] According to the statistics of airports at different altitudes, the power required for interrupted takeoff and continued takeoff during takeoff and hovering at Class A barrier-free airports and the maximum emergency available power of the helicopter after one engine fails are calculated, and the difference between the two, i.e. the residual power, is calculated. The minimum residual power is selected as the test residual power Pw for airports at different altitudes.

[0023] Furthermore, step 4 is specifically as follows:

[0024] Calculate the theoretical residual power of the helicopter at different flight weights within the range of atmospheric temperature and pressure altitude for takeoff and landing at a Class A barrier-free airport, and compare it with the test residual power Pw to obtain the maximum flight weight GW3 equal to the test residual power Pw.

[0025] Furthermore, before step 7, the method further includes:

[0026] The test flight results of near-ground handling characteristics at airports at different altitudes were statistically analyzed to obtain the helicopter's required torque at different wind speeds and directions. The torque was compared with the torque during takeoff and hovering, and the increment of torque Q2 required for takeoff and landing with a tailwind was obtained. Within the range of atmospheric temperature and pressure altitude for takeoff and landing at Class A barrier-free airports, the influence of the increment of torque Q2 on the takeoff and landing weight △GW at Class A barrier-free airports was calculated.

[0027] Furthermore, step 7 is specifically as follows:

[0028] By comparing the maximum weights of steps 2 to 6, taking the smaller value, the maximum weight for takeoff and landing at a Class A barrier-free airport is obtained. The maximum weight for takeoff and landing at a Class A barrier-free airport is subtracted from ΔGW to obtain the maximum weight for takeoff and landing at a Class A barrier-free airport under a tailwind condition.

[0029] The present invention proposes a method for evaluating the maximum takeoff and landing weight of a Class A barrier-free airport. The method itself takes into account the Class A takeoff and landing profile requirements of the airworthiness regulations, combines experiments and calculation analysis, and adopts the residual power method to demonstrate compliance with the airworthiness provisions. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of a normal takeoff profile at a Class A barrier-free airport provided by an embodiment of the present invention;

[0031] Figure 2 A schematic cross-sectional diagram of continued takeoff and rejected takeoff at a Class A barrier-free airport provided by an embodiment of the present invention;

[0032] Figure 3 A schematic diagram of a normal landing profile at a Class A barrier-free airport provided by an embodiment of the present invention;

[0033] Figure 4 A schematic diagram of a continued landing profile at a Class A barrier-free airport provided by an embodiment of the present invention;

[0034] Figure 5 A schematic diagram of an aborted landing profile at a Class A barrier-free airport provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0036] Category A takeoffs include normal takeoffs, interrupted takeoffs, and continued takeoffs. Figure 1 ), the helicopter starts to climb from hovering with its head down, and continues to climb after passing the takeoff decision point until it reaches VY and climbs to an altitude of 1000ft. If an engine failure occurs during a normal takeoff, continuing the takeoff requires the helicopter to have the ability to make a go-around, and aborting the takeoff requires the helicopter to have the ability to land safely. Figure 2 ), the helicopter needs to accelerate from the engine failure point to VTOSS and establish a positive climb rate, then start the first stage of the climb at VTOSS speed, climb to 60m (200ft) above the ground, then accelerate horizontally to VY, and finally start the second stage of the climb at VY speed, climb to 300m (1000ft) above the ground; Category A barrier-free airport aborted takeoff profile (see attached) Figure 2 ), the helicopter needs to descend and slow down from the point where the engine fails, and control the speed and descent rate within the limit before touching down to complete the safe touchdown and landing of the helicopter.

[0037] Category A takeoffs include normal landing, interrupted landing, and continued landing. Figure 3 ), the helicopter starts from the approach state, continues to approach after passing the landing decision point, flattens and slows down when approaching the ground, hovers above the landing point, and completes the landing. If an engine failure occurs during a normal landing, the helicopter needs to have the ability to take off to interrupt the landing, and the helicopter needs to have the ability to land safely to continue the landing. Figure 4 ), the helicopter needs to continue approaching from the engine failure point, control the speed and descent rate within the limit before touching down, and complete the safe touchdown and landing of the helicopter. Figure 5), the helicopter needs to adjust the speed to VTOSS from the engine failure point and establish a positive climb rate, then start the first stage climb at VTOSS speed, climb to an altitude of 60m (200ft) above the ground, then accelerate horizontally to VY, and finally start the second stage climb at VY speed, climb to an altitude of 300m (1000ft) above the ground.

[0038] According to the above description, the procedures for continued takeoff and interrupted landing at Class A barrier-free airports are similar. The maximum weight for Class A takeoff and the maximum weight for Class A landing are usually set to the same weight for ease of use. The maximum weight for takeoff and landing at Class A barrier-free airports must meet all the above takeoff and landing profile requirements at the same time, which is usually obtained based on flight test verification combined with calculation analysis. The present invention proposes an evaluation method for the maximum weight that meets the above Class A takeoff and landing requirements.

[0039] The method for evaluating the maximum takeoff and landing weight of a helicopter at a Class A obstacle-free airport provided by an embodiment of the present invention is obtained through flight tests and calculations, and the specific steps are as follows:

[0040] Step 1: Select different target altitude airports and flight weights for takeoff and landing at Class A barrier-free airports

[0041] According to the requirement of AC29.59 that the take-off weight of a Class A barrier-free airport cannot be extrapolated, the target altitude airport for the flight test is selected in combination with the verification target altitude. The maximum weight of hovering in ground effect at the current altitude airport is calculated based on the selected altitude airport and temperature conditions as the preliminary selected test flight weight. During the test, ensure that the test flight weight does not exceed the maximum weight range of hovering in ground effect of -1% to +3%;

[0042] Step 2: According to step 1, obtain test results of no less than 5 valid Class A normal takeoff, rejected takeoff, continued takeoff, normal landing, continued landing, and rejected landing, respectively. Count the actual flight density altitude, atmospheric temperature, pressure altitude, and flight weight of the 6 flight subjects at different target altitude airports. Take the minimum value of the flight weight at the airport at the same altitude as the maximum weight GW1 for Class A barrier-free airport takeoff and landing flight verification at the airport at that altitude, as well as the atmospheric temperature, pressure altitude, and density altitude corresponding to GW1.

[0043] The torque required during normal takeoff acceleration and takeoff hovering in Class A at all altitude airports is 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 at different altitude airports.

[0044] According to the statistics of airports at different altitudes, the power required for interrupted takeoff and continued takeoff during takeoff and hovering at Class A barrier-free airports and the maximum emergency available power of the helicopter after one engine fails are calculated, and the difference between the two, i.e. the residual power, is calculated. The minimum residual power is selected as the test residual power Pw for airports at different altitudes.

[0045] Step 3: Add the takeoff torque increment Q1 obtained in step 2 to the hovering torque, and calculate the maximum takeoff weight Gw2 that varies with atmospheric temperature and pressure altitude within the takeoff and landing altitude and temperature envelope of Class A after considering the takeoff acceleration torque increment.

[0046] Step 4:

[0047] Calculate the theoretical residual power of the helicopter at different flight weights within the range of atmospheric temperature and pressure altitude for takeoff and landing at a Class A barrier-free airport, and compare it with the test residual power Pw to obtain the maximum flight weight GW3 that is equal to the test residual power Pw;

[0048] Step 5: Calculate the maximum flight weight GW4 corresponding to a residual climb rate of 100 ft / min at 200 ft above the ground with one engine inoperative power OEI LO for 30 seconds / 2 minutes and the selected takeoff safety speed VTOSS within the range of takeoff and landing atmospheric temperature and pressure altitude at a Class A barrier-free airport;

[0049] Step 6: Calculate the maximum flight weight GW5 corresponding to a residual climb rate of 150 ft / min at 1000 ft above the ground with one engine inoperative power OEI CT for 30 minutes and the selected speed VY within the range of takeoff and landing atmospheric temperature and pressure altitude at a Class A barrier-free airport;

[0050] Step 7: Consider the effect of wind speed on takeoff weight, collect statistics on the test flight results of near-ground handling characteristics at airports at different altitudes, obtain the torque required for the helicopter at different wind speeds and directions, and compare it with the torque during takeoff and hovering, obtain the increment of torque required for takeoff and landing with a tailwind, Q2, and calculate the effect of the increment of torque required Q2 on the takeoff and landing weight at Class A barrier-free airports within the range of atmospheric temperature and pressure altitude for takeoff and landing at Class A barrier-free airports, GW6.

[0051] Step 8: By comparing the maximum weights of steps 2 to 6, taking the smaller value, we get the maximum weight for takeoff and landing at a Class A barrier-free airport, and adding the effect of wind speed on the weight for takeoff and landing at a Class A barrier-free airport in step 7, we get the maximum weight for takeoff and landing at a Class A barrier-free airport under a tailwind condition.

Claims

1. A method for evaluating the maximum takeoff and landing weight of a civil helicopter at a Class A barrier-free airport, characterized in that: The method comprises: Step 1: Select different target altitude airports and flight weights for takeoff and landing at Class A barrier-free airports; Step 2: Based on the test conditions in step 1, obtain the maximum weight GW1 for Class A barrier-free airport takeoff and landing flight verification at airports with different target altitudes, and the atmospheric temperature, pressure altitude, and density altitude corresponding to GW1; Step 3: Calculate the maximum takeoff weight Gw2 as it changes with atmospheric temperature and pressure altitude within the range of Category A takeoff and landing altitude and temperature envelope after taking into account the takeoff acceleration torque increment; Step 4: Calculate the theoretical residual power of the helicopter at different flight weights within the range of atmospheric temperature and pressure altitude for takeoff and landing at a Class A barrier-free airport, and compare it with the test residual power Pw to obtain the maximum flight weight GW3 equal to the test residual power Pw; Step 5: Calculate the maximum weight GW4 for the flight with a residual climb rate of 100 ft / min at 200 ft above the ground, 30 seconds / 2 minutes with one engine inoperative power OEI LO and the selected takeoff safety speed VTOSS within the range of takeoff and landing atmospheric temperature and pressure altitude at a Class A barrier-free airport; Step 6: Calculate the maximum weight GW5 for a flight with a residual climb rate of 150 ft / min at 1000 ft above the ground, one engine inoperative power OEI CT and a selected speed VY within the range of takeoff and landing atmospheric temperature and pressure altitude at a Class A barrier-free airport; Step 7: Compare the maximum weights in steps 2 to 6 and take the smaller value to get the maximum weight for takeoff and landing at a Class A barrier-free airport.

2. A method for evaluating the maximum takeoff and landing weight of a civil helicopter at a Class A barrier-free airport according to claim 1, characterized in that: Step 1 is as follows: Select the target airport altitude for the flight test, calculate the maximum weight of hovering in ground effect at the current airport altitude based on the selected airport altitude and temperature conditions, and use this as the preliminary selected test flight weight. During the test, ensure that the test flight weight is within the range of -1% to +3% of the preliminary selected test flight weight.

3. A method for evaluating the maximum takeoff and landing weight of a civil helicopter at a Class A barrier-free airport according to claim 2, characterized in that: Step 2 is as follows: According to step 1, obtain test results of no less than 5 valid Class A normal takeoff, rejected takeoff, continued takeoff, normal landing, continued landing, and rejected landing, respectively. Count the actual flight density altitude, atmospheric temperature, pressure altitude, and flight weight of the 6 flight subjects at different target altitude airports. Take the minimum value of the flight weight at the airport at the same altitude as the maximum weight GW1 for Class A barrier-free airport takeoff and landing flight verification at the airport at that altitude, as well as the atmospheric temperature, pressure altitude, and density altitude corresponding to GW1.

4. A method for evaluating the maximum takeoff and landing weight of a civil helicopter at a Class A barrier-free airport according to claim 3, characterized in that: Before step 3, the method further comprises: The torque required during normal takeoff acceleration and takeoff hovering in Class A at all altitude airports is 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 at different altitude airports.

5. A method for evaluating the maximum takeoff and landing weight of a civil helicopter at a Class A barrier-free airport according to claim 4, characterized in that: Step 3 is as follows: The torque increment Q1 required for takeoff is added to the torque required for hovering, and the maximum takeoff weight Gw2 that changes with atmospheric temperature and pressure altitude within the takeoff and landing altitude and temperature envelope of Class A is calculated after considering the takeoff acceleration torque increment.

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

7. A method for evaluating the maximum takeoff and landing weight of a civil helicopter at a Class A barrier-free airport according to claim 6, characterized in that: Step 4 is as follows: Calculate the theoretical residual power of the helicopter at different flight weights within the range of atmospheric temperature and pressure altitude for takeoff and landing at a Class A barrier-free airport, and compare it with the test residual power Pw to obtain the maximum flight weight GW3 equal to the test residual power Pw.

8. A method for evaluating the maximum takeoff and landing weight of a civil helicopter at a Class A barrier-free airport according to claim 7, characterized in that: Before step 7, the method further includes: The test flight results of near-ground handling characteristics at airports at different altitudes were statistically analyzed to obtain the helicopter's required torque at different wind speeds and directions. The torque was compared with the torque during takeoff and hovering, and the increment of torque Q2 required for takeoff and landing with a tailwind was obtained. Within the range of atmospheric temperature and pressure altitude for takeoff and landing at Class A barrier-free airports, the influence of the increment of torque Q2 on the takeoff and landing weight △GW at Class A barrier-free airports was calculated.

9. A method for evaluating the maximum takeoff and landing weight of a civil helicopter at a Class A barrier-free airport according to claim 8, characterized in that: Step 7 is as follows: By comparing the maximum weights of steps 2 to 6, taking the smaller value, the maximum weight for takeoff and landing at a Class A barrier-free airport is obtained. The maximum weight for takeoff and landing at a Class A barrier-free airport is subtracted from ΔGW to obtain the maximum weight for takeoff and landing at a Class A barrier-free airport under a tailwind condition.

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