A method for verifying the longitudinal static stability of a civil helicopter instrument

Abstract

The present application belongs to the technical field of aircraft airworthiness verification, and particularly relates to a kind of civil helicopter instrument longitudinal static stability verification flight test method.The method comprises the following steps: S1, determining the relationship between the longitudinal control stick force and the longitudinal control position of the control stick;S2, verifying the longitudinal control stick force gradient of the helicopter acceleration section through flight test;S3, verifying the longitudinal control stick force gradient of the helicopter deceleration section through flight test;S4, verifying the trimming speed recovery characteristics of the helicopter acceleration section through flight test;S5, verifying the trimming speed recovery characteristics of the helicopter deceleration section through flight test.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of airworthiness verification of aircraft, and particularly relates to a method for verifying instrument longitudinal static stability of a civil helicopter. BACKGROUND

[0002] During the flight of a helicopter, various short-time disturbances such as wind gusts and accidental shaking of the control stick will destroy the balanced flight state of the helicopter. The movement tendency of the helicopter in the moment when the balanced state is destroyed is called the static stability of the helicopter. The static stability of the helicopter is generally divided into longitudinal static stability, lateral static stability and directional static stability. The longitudinal static stability of the helicopter refers to that, after being disturbed, the longitudinal balance is destroyed, the flight speed and the angle of attack of the helicopter change, and if a new additional moment appears to automatically restore the original flight speed, the helicopter is statically stable, and otherwise is statically unstable. Good longitudinal static stability is a key requirement of instrument flight rules, which can ensure automatic correction of the flight speed response and enable the pilot to be aware of any actual flight speed change, that is, the flight speed change must enable the pilot to clearly perceive the stick force (i.e. the force gradient that can be felt and quantified). SUMMARY

[0003] The present application proposes a method for verifying instrument longitudinal static stability of a civil helicopter, which verifies the longitudinal stick force gradient and the trim speed recovery characteristics separately, eliminates the influence between the verification of the longitudinal stick force gradient and the trim speed recovery characteristics in the combined verification method, and thus realizes that the speed is restored to within 10% of the trim speed, thereby meeting the requirements of airworthiness regulations.

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

[0005] A method for verifying instrument longitudinal static stability of a civil helicopter, the method comprising:

[0006] S1, determining the relationship between the longitudinal stick force of the control stick and the longitudinal control position;

[0007] S2, verifying the longitudinal stick force gradient of the helicopter in the acceleration section through flight test;

[0008] S3, verifying the longitudinal stick force gradient of the helicopter in the deceleration section through flight test;

[0009] S4, verifying the trim speed recovery characteristics of the helicopter in the acceleration section through flight test;

[0010] S5, verifying the trim speed recovery characteristics of the helicopter in the deceleration section through flight test.

[0011] Further, S1 specifically comprises:

[0012] The relationship between the longitudinal control stick force and the longitudinal control position is measured on the ground, and the longitudinal control stick force usually increases linearly with the increase of the longitudinal control position. Y represents the longitudinal control position, and X represents the longitudinal control stick force corresponding to Y. The conversion relationship between the longitudinal control position and the longitudinal control stick force is as follows:

[0013] Y=a1*X+b1

[0014] Further, S2, specifically:

[0015] The helicopter is trimmed at a specified flight speed Z0 and a specified helicopter power, and the trimming longitudinal control position Y0 of the control stick is recorded. The total distance is kept at the trimming position, the control stick is pushed forward, the longitudinal control stick force is gradually increased, and the flight speed is respectively stabilized to Z0+10kt, Z0+20kt, and the corresponding longitudinal control positions Y +10kt , Y +20kt are recorded. Z1 represents the flight speed, and Y represents the longitudinal control position corresponding to the flight speed. The relationship between the longitudinal control position and the flight speed is obtained by fitting the three points (Y0, Z0), (Y +10kt , Z0+10kt), and (Y +20kt , Z0+20kt) as follows:

[0016] Z1=a2*Y+b2.

[0017] Further, S2, further comprises:

[0018] According to the relationship between the longitudinal control stick force and the longitudinal control position, the relationship between the flight speed and the longitudinal control stick force is converted as follows:

[0019] Z1×a1*a2*X+a2*b1+b2

[0020] According to the gradient relationship between the flight speed and the longitudinal control stick force, the instrument longitudinal static stability is determined. If a1*a2>0, the static stability is positive.

[0021] Further, S3, specifically:

[0022] The helicopter is trimmed at a specified flight speed Z0 and a specified helicopter power, and the trimming longitudinal control position Y0 of the control stick is recorded. The total distance is kept at the trimming position, the control stick is pulled backward, the longitudinal control stick force is gradually increased, and the flight speed is respectively stabilized to Z0-10kt, Z0-20kt, and the corresponding longitudinal control positions Y -10kt , Y -20kt are recorded. Z2 represents the flight speed, and Y represents the longitudinal control position corresponding to the speed. The relationship between the longitudinal control position and the flight speed is obtained by fitting the three points (Y0, Z0), (Y -10kt , Z0-10kt), and (Y -20kt, Z0-20kt) three-point fitting obtains the relationship between the longitudinal control position and the flight speed as follows:

[0023] Z2=a3*Y+b3.

[0024] Further, S3 further comprises:

[0025] According to the conversion relationship between the longitudinal control position and the longitudinal control lever force, the relationship between the flight speed and the longitudinal control lever force is converted:

[0026] Z2=a1*a3*X+a3*b1+b3

[0027] According to the gradient relationship between the flight speed and the longitudinal control lever force, the instrument longitudinal static stability is determined, and a1*a3>0 is positive.

[0028] Further, with the specified speed Z0 and the specified power state trimming, the total distance is kept at the trimming value, the front push driving rod is increased, the longitudinal control lever force is increased, the speed is stabilized to Z0+20kt, and then the rod force is slowly released. When the rod force has been unloaded and the speed has been stabilized, the speed Z3 at this time is recorded, and it is determined whether it is restored to the 10% range of the trimming speed, that is, Z3≤Z0+0.1*Z0.

[0029] Further, with the specified speed Z0 and the specified power state trimming, the total distance is kept at the trimming value, the rear pull driving rod is increased, the longitudinal control lever force is increased, the speed is stabilized to Z0-20kt, and then the rod force is slowly released. When the rod force has been unloaded and the speed has been stabilized, the speed Z4 at this time is recorded, and it is determined whether it is restored to the 10% range of the trimming speed, that is, Z4≥Z0-0.1*Z0.

[0030] The present application proposes a civil helicopter instrument longitudinal static stability verification flight test method, which separates the longitudinal control lever force gradient and the trimming speed recovery characteristics, eliminates the mutual interference between the longitudinal control lever force gradient verification and the trimming speed recovery characteristics verification, and gives a specific verification method. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The longitudinal control lever force gradient verification schematic diagram of the acceleration section provided for the embodiment of the present application;

[0032] Figure 2 The longitudinal control lever force gradient verification schematic diagram of the deceleration section provided for the embodiment of the present application;

[0033] Figure 3 The trimming speed recovery characteristic verification schematic diagram of the acceleration section provided for the embodiment of the present application;

[0034] Figure 4The speed recovery characteristic verification schematic diagram of the trim speed of the deceleration section provided for the embodiment of the present application. DETAILED DESCRIPTION

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

[0036] A method for verifying the longitudinal static stability of a civil helicopter instrument, comprising the following steps:

[0037] Step 1: measuring the relationship between the longitudinal control lever force and the longitudinal control position through ground tests

[0038] The relationship between the longitudinal control lever force and the longitudinal control position is measured on the ground, and generally, the longitudinal control lever force linearly increases with the increase of the longitudinal control position. Y represents the longitudinal control position (unit %), and X represents the longitudinal control lever force corresponding to Y (unit N). The conversion relationship between the longitudinal control position and the longitudinal control lever force is as follows:

[0039] Y=a1*X+b1

[0040] Step 2: verifying the longitudinal control lever force gradient of the acceleration section through flight tests

[0041] In a specified automatic flight control system mode, trim at a specified speed Z0 and a specified power state, record the trim longitudinal control position Y0, keep the total distance at the trim value, push the control stick, gradually increase the longitudinal control lever force, and make the speed stable to reach Z0+10kt, Z0+20kt, and record the corresponding longitudinal control position Y +10kt , Y +20kt Generally, the speed linearly increases with the increase of the longitudinal control position. Z represents the speed (unit kt), and Y represents the longitudinal control position corresponding to the speed (unit %). The relationship between the longitudinal control position and the speed is obtained by fitting the three points (Y0, Z0), (Y +10kt , Z0+10kt) and (Y +20kt , Z0+20kt) as follows:

[0042] Z1=a2*Y+b2

[0043] According to the conversion relationship between the longitudinal control position and the longitudinal control lever force measured in step 1, the relationship between the speed and the longitudinal control lever force can be converted as follows:

[0044] Z1=a1*a2*X+a2*b1+b2

[0045] According to the gradient relationship between the speed and the longitudinal control lever force, the static stability is determined. If a1*a2>0, the static stability is positive, if a1*a2=0, the static stability is neutral, and if a1*a2<0, the static stability is negative.

[0046] Step 3: Verify the longitudinal stick force gradient of the deceleration segment by flight test

[0047] In the specified auto flight control system mode, trim at the specified speed Z0 and specified power state, record the trim longitudinal stick position Y0, keep the total distance at the trim value, pull back the stick, increase the longitudinal stick force gradually, and stabilize the speed to Z0-10kt, Z0-20kt, record the corresponding longitudinal stick position Y -10kt , Y -20kt , usually the speed increases linearly with the increase of the longitudinal stick position, Z represents the speed (unit: kt), Y represents the longitudinal stick position corresponding to the speed (unit: %), and the relationship between the longitudinal stick position and the speed is obtained by fitting the three points (Y0, Z0), (Y -10kt , Z0-10kt) and (Y -20kt , Z0-20kt) as follows:

[0048] Z2=a3*Y+b3

[0049] According to the conversion relationship between the longitudinal stick position and the longitudinal stick force measured in step 1, the relationship between the speed and the longitudinal stick force can be converted as follows:

[0050] Z2=a1*a3*X+a3*b1+b3

[0051] According to the gradient relationship between the speed and the longitudinal stick force, the static stability is determined, i.e. a1*a3>0, the static stability is positive, a1*a3=0, the static stability is neutral, and a1*a3<0, the static stability is negative.

[0052] Step 4: Verify the trim speed recovery characteristics of the acceleration segment by flight test

[0053] In the specified auto flight control system mode, trim at the specified speed Z0 and specified power state, keep the total distance at the trim value, push the stick, increase the longitudinal stick force, and stabilize the speed to Z0+20kt, then slowly release the stick force, when the stick force has been unloaded and the speed has stabilized, record the speed Z3 at this time, and determine whether it is within 10% of the trim speed, i.e. Z3≤Z0+0.1*Z0.

[0054] Step 5: Verify the trim speed recovery characteristics of the deceleration segment by flight test

[0055] In the specified auto flight control system mode, trim at the specified speed Z0 and specified power state, keep the total distance at the trim value, pull back the stick, increase the longitudinal stick force, and stabilize the speed to Z0-20kt, then slowly release the stick force, when the stick force has been unloaded and the speed has stabilized, record the speed Z4 at this time, and determine whether it is within 10% of the trim speed, i.e. Z4≥Z0-0.1*Z0.

[0056] For the helicopter instrument longitudinal static stability verification flight, it can be divided into longitudinal control stick force gradient verification and trim speed recovery characteristic verification. The application discloses a civil helicopter instrument longitudinal static stability verification flight method, which comprises the following steps:

[0057] Longitudinal control stick force gradient verification in the acceleration section (see Figure 1 ): in the specified automatic flight control system mode, trim at the specified speed Z0 and the specified power state, record the trim longitudinal control position Y0, keep the total distance at the trim value, push the stick forward, gradually increase the longitudinal control stick force, make the speed stabilize to Z0+10kt, Z0+20kt, and record the corresponding longitudinal control positions Y +10kt , Y +20kt .

[0058] Longitudinal control stick force gradient verification in the deceleration section (see Figure 2 ): in the specified automatic flight control system mode, trim at the specified speed Z0 and the specified power state, record the trim longitudinal control position Y0, keep the total distance at the trim value, pull the stick backward, gradually increase the longitudinal control stick force, make the speed stabilize to Z0-10kt, Z0-20kt, and record the corresponding longitudinal control positions Y -10kt , Y -20kt .

[0059] Trim speed recovery characteristic verification in the acceleration section (see Figure 3 ): in the specified automatic flight control system mode, trim at the specified speed Z0 and the specified power state, keep the total distance at the trim value, push the stick forward, increase the longitudinal control stick force, make the speed stabilize to Z0+20kt, then slowly release the stick force, when the stick force has been released and the speed has been stabilized, record the speed Z3 at this time, and judge whether the speed is recovered to the range of 10% of the trim speed.

[0060] Trim speed recovery characteristic verification in the deceleration section (see Figure 4 ): in the specified automatic flight control system mode, trim at the specified speed Z0 and the specified power state, keep the total distance at the trim value, pull the stick backward, increase the longitudinal control stick force, make the speed stabilize to Z0-20kt, then slowly release the stick force, when the stick force has been released and the speed has been stabilized, record the speed Z4 at this time, and judge whether the speed is recovered to the range of 10% of the trim speed.

[0061] The key points of the method are: 1. The longitudinal control lever force gradient and the trim speed recovery characteristic are verified separately, the mutual interference between the longitudinal control lever force gradient verification and the trim speed recovery characteristic verification is eliminated, and the verification method is given; 2. The relationship between the longitudinal control lever force and the longitudinal control position measured through the ground test is used to convert the relationship between the control position and the speed measured through the flight test into the relationship between the longitudinal control lever force and the speed, so as to determine the longitudinal control lever force gradient; 3. The longitudinal control lever force gradient verification and the trim speed recovery characteristic verification are carried out separately, and the specific test steps are given.

[0062] The present application provides a kind of for verifying the airworthiness compliance verification flight test method of airworthiness regulation CCAR-29-R2 appendix B. IV instrument longitudinal static stability, according to the method, the mutual interference between the control lever force gradient verification and the trim speed recovery characteristic verification can be eliminated, the test verification of instrument longitudinal static stability is facilitated, and the success rate of instrument longitudinal static stability verification flight test purpose is improved.

Claims

1. A method for verifying the longitudinal static stability of a civil helicopter instrument flight, characterized in that, The method comprises: S1, determining the relationship between the longitudinal control stick force and the longitudinal control position of the driving stick; S2, verifying the longitudinal control stick force gradient of the accelerating section of the helicopter through flight test; S3, verifying the longitudinal control stick force gradient of the decelerating section of the helicopter through flight test; S4, verifying the trimming speed recovery characteristic of the accelerating section of the helicopter through flight test; S5, verifying the trimming speed recovery characteristic of the decelerating section of the helicopter through flight test; S1, specifically: the relationship between the longitudinal control lever force and the longitudinal control position is obtained by ground measurement, usually the longitudinal control lever force increases linearly with the increase of the longitudinal control position, Y represents the longitudinal control position, X represents the longitudinal control lever force corresponding to Y, and the conversion relationship between the longitudinal control position and the longitudinal control lever force is as follows: ; S2, specifically: with the specified flight speed and the specified helicopter power to trim the helicopter, record the trim longitudinal control stick position , the total distance is kept at the trim position, the pilot stick is pushed forward, the longitudinal control stick force is gradually increased, and the flight speed is respectively stabilized to 、 , record the corresponding longitudinal control position 、 , let Z1 represent the flight speed, Y represent the longitudinal control position corresponding to the flight speed, and through 、 and three-point fitting, the relationship between the longitudinal control position and the flight speed is as follows: ; S2, further comprising: converting a relationship between the flight speed and the longitudinal control stick force according to a relationship between the longitudinal control stick force and the longitudinal control stick position: ; The instrument longitudinal static stability is determined according to the gradient relation between the flight speed and the longitudinal control lever force, The static stability is positive. S3, specifically: trim at specified flight speed and specified helicopter power, record the trim longitudinal control stick position , total distance is kept at trim position, pull back the control stick, gradually increase the longitudinal control stick force, make the flight speed respectively stabilize to 、 , record the corresponding longitudinal control position 、 , Z2 represents the flight speed, Y represents the longitudinal control position corresponding to the speed, through 、 and three-point fitting, the relationship between the longitudinal control position and the flight speed is as follows: ; S3, further comprising: according to a conversion relationship between the longitudinal manipulation position and the longitudinal manipulation lever force, converting a relationship between the flight speed and the longitudinal manipulation lever force: ; The instrument longitudinal static stability is determined according to the gradient relation between the flying speed and the longitudinal control lever force, The static stability is positive. S4, in particular: trim at specified speed and specified power state, total distance kept at trim value, push on stick, increase longitudinal stick force, speed stabilizes to , then slowly release stick force, when stick force has been released and speed has stabilized, record speed at that time , determine if back to within 10% of trim speed, i.e. ; S5, specifically: at a specified speed and specified power trim, total distance kept at trim value, pull back on stick, increase longitudinal stick force, speed stabilizes to , then slowly release stick force, when stick force has been released and speed has stabilized, record speed at this time , determine if back to within 10% of trim speed, i.e. .

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