Civil helicopter instrument longitudinal static stability verification flight test method

Abstract

The invention belongs to the technical field of airworthiness verification of aircrafts, and particularly relates to a test flight method for verifying longitudinal static stability of a civil helicopter instrument. Comprising the following steps: S1, determining a relation between a longitudinal control lever force and a longitudinal control position of a control lever; s2, verifying the longitudinal joystick force gradient of the acceleration section of the helicopter through a flight test; s3, verifying the longitudinal joystick force gradient of the helicopter deceleration section through a flight test; s4, verifying the balancing speed recovery characteristic of the acceleration section of the helicopter through a flight test; and S5, verifying the balancing speed recovery characteristic of the deceleration section of the helicopter through a flight test.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft airworthiness verification, and in particular relates to a civil helicopter instrument longitudinal static stability verification flight test method. Background Art

[0002] During the flight of a helicopter, there will be various short-term disturbances, such as gust disturbances, accidental shaking of the joystick, etc., which will destroy the balanced flight state of the helicopter. The movement trend of the helicopter at the moment when the balanced state is destroyed is called the static stability of the helicopter. The static stability of a helicopter is usually divided into longitudinal static stability, lateral static stability and heading static stability. The longitudinal static stability of a helicopter means that after being disturbed, the longitudinal balance is destroyed, and the flight speed and angle of attack of the helicopter change. If a new additional torque appears to automatically restore the original flight speed, the helicopter is statically stable, otherwise it is statically unstable. Good longitudinal static stability is a key requirement of instrument flight rules. It can ensure automatic correction of flight speed response and enable the pilot to be aware of any actual flight speed changes. In other words, the flight speed change must enable the pilot to clearly perceive the stick force (that is, a force gradient that can be felt and quantified). Summary of the invention

[0003] The present invention patent proposes a civil helicopter instrument longitudinal static stability verification test flight method, which verifies the longitudinal joystick force gradient and the balancing speed recovery characteristics separately, eliminates the influence between the longitudinal joystick force gradient verification and the balancing speed recovery characteristics in the combined verification method, thereby achieving speed recovery to within 10% of the balancing speed, meeting the requirements of airworthiness regulations.

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

[0005] A civil helicopter instrument longitudinal static stability verification flight method, the method comprising:

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

[0007] S2, verify the longitudinal joystick force gradient during the helicopter acceleration phase through flight tests;

[0008] S3, verify the longitudinal joystick force gradient during the helicopter deceleration phase through flight tests;

[0009] S4, verify the trim speed recovery characteristics of the helicopter during acceleration phase through flight tests;

[0010] S5, verify the trim speed recovery characteristics of the helicopter deceleration phase through flight tests.

[0011] Further, S1 is specifically:

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

[0013] Y=a1*X+b1

[0014] Further, S2 is specifically:

[0015] At the specified flight speed Z 0 Trim the helicopter with the specified helicopter power and record the trim longitudinal control position Y of the joystick 0 , keep the total pitch at the trim position, push the joystick forward, and gradually increase the longitudinal joystick force to stabilize the flight speed to Z 0 +10kt, Z 0 +20kt, record the corresponding longitudinal control position Y +10kt , Y +20kt , Z1 represents the flight speed, Y represents the longitudinal control position corresponding to the flight speed, and (Y 0 , Z 0 )、(Y +10kt , Z 0 +10kt) and (Y +20kt , Z 0 +20kt) three-point fitting results in the following relationship between the longitudinal control position and the flight speed:

[0016] Z1=a2*Y+b2.

[0017] Furthermore, S2 also includes:

[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 calculated:

[0019] Z1×a1*a2*X+a2*b1+b2

[0020] The longitudinal static stability of the instrument is determined based on the gradient relationship between the flight speed and the longitudinal joystick force. If a1*a2>0, the static stability is positive.

[0021] Further, S3 is specifically:

[0022] At the specified flight speed Z 0 Trim with the specified helicopter power and record the trim longitudinal control position Y of the joystick 0 , keep the total pitch at the trim position, pull the joystick back, and gradually increase the longitudinal joystick force to stabilize the flight speed to Z0 -10kt, Z 0 -20kt, record the corresponding longitudinal control position Y -10kt , Y -20kt , Z2 represents the flight speed, Y represents the longitudinal control position corresponding to the speed, and (Y 0 , Z 0 )、(Y -10kt , Z 0 -10kt) and (Y -20kt , Z 0 -20kt) three-point fitting results in the following relationship between longitudinal control position and flight speed:

[0023] Z2=a3*Y+b3.

[0024] Furthermore, S3 also includes:

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

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

[0027] The longitudinal static stability of the instrument is determined based on the gradient relationship between the flight speed and the longitudinal joystick force. If a1*a3>0, the static stability is positive.

[0028] Furthermore, at a specified speed Z 0 Trim with the specified power state, keep the total distance at the trim value, push the joystick forward, increase the longitudinal joystick force, and stabilize the speed to Z 0 +20kt, then slowly release the lever force. When the lever force has been removed and the speed has stabilized, record the speed Z3 at this time to determine whether it has recovered to within 10% of the trim speed, that is, Z3≤Z 0 +0.1*Z 0 .

[0029] Furthermore, at a specified speed Z 0 Trim with the specified power state, keep the total distance at the trim value, pull the control stick back, increase the longitudinal control stick force, and stabilize the speed to Z 0 -20kt, then slowly release the lever force. When the lever force has been removed and the speed has stabilized, record the speed Z4 at this time to determine whether it has recovered to within 10% of the trim speed, that is, Z4 ≥ Z 0 -0.1*Z 0 .

[0030] The invention proposes a civil helicopter instrument longitudinal static stability verification flight test method, which verifies the longitudinal joystick force gradient and the trim speed recovery characteristic separately, eliminates the mutual interference between the longitudinal joystick force gradient verification and the trim speed recovery characteristic verification, and provides a specific verification method. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of verifying the longitudinal joystick force gradient in the acceleration section provided by an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of verifying the longitudinal joystick force gradient in the deceleration section provided by an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of verifying the trim speed recovery characteristic of the acceleration section provided by an embodiment of the present invention;

[0034] Figure 4 A schematic diagram of verifying the trim speed recovery characteristics of the deceleration section 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] A civil helicopter instrument longitudinal static stability verification flight test method comprises the following steps:

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

[0038] The relationship between the longitudinal control lever force and the longitudinal control position is measured on the ground. Usually, the longitudinal control lever force increases linearly 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: Verify the longitudinal stick force gradient during acceleration through flight tests

[0041] In the specified automatic flight control system mode, at the specified speed Z 0 Trim with the specified power state and record the trim longitudinal control position Y 0 , keep the total distance at the trim value, push the joystick forward, and gradually increase the longitudinal joystick force to stabilize the speed to Z 0 +10kt, Z 0 +20kt, record the corresponding longitudinal control position Y +10kt , Y +20kt, usually the speed increases linearly with the increase of the longitudinal control position, Z represents the speed (unit kt), Y represents the longitudinal control position corresponding to the speed (unit %), through (Y 0 , Z 0 )、(Y +10kt , Z 0 +10kt) and (Y +20kt , Z 0 +20kt) three-point fitting results in the following relationship between longitudinal control position and speed:

[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 calculated:

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

[0045] The static stability is determined based on the gradient relationship between the speed and the longitudinal joystick force, that is, 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 control stick force gradient during deceleration through flight tests

[0047] In the specified automatic flight control system mode, at the specified speed Z 0 Trim with the specified power state and record the trim longitudinal control position Y 0 , keep the total distance at the trim value, pull the joystick back, and gradually increase the longitudinal joystick force to stabilize the speed to Z 0 -10kt, Z 0 -20kt, record the corresponding longitudinal control position Y -10kt , Y -20kt , usually the speed increases linearly with the increase of the longitudinal control position, Z represents the speed (unit kt), Y represents the longitudinal control position corresponding to the speed (unit %), through (Y 0 , Z 0 )、(Y -10kt , Z 0 -10kt) and (Y -20kt , Z 0 -20kt) three-point fitting results in the following relationship between longitudinal control position and speed:

[0048] Z2=a3*Y+b3

[0049] 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 calculated:

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

[0051] The static stability is determined based on the gradient relationship between the speed and the longitudinal joystick force, that is, if a1*a3>0, the static stability is positive, if a1*a3=0, the static stability is neutral, and if a1*a3<0, the static stability is negative.

[0052] Step 4: Verify the trim speed recovery characteristics during the acceleration phase through flight tests

[0053] In the specified automatic flight control system mode, at the specified speed Z 0 Trim with the specified power state, keep the total distance at the trim value, push the joystick forward, increase the longitudinal joystick force, and stabilize the speed to Z 0 +20kt, then slowly release the lever force. When the lever force has been removed and the speed has stabilized, record the speed Z3 at this time to determine whether it has recovered to within 10% of the trim speed, that is, Z3≤Z 0 +0.1*Z 0 ;

[0054] Step 5: Verify the trim speed recovery characteristics of the deceleration phase through flight tests

[0055] In the specified automatic flight control system mode, at the specified speed Z 0 Trim with the specified power state, keep the total distance at the trim value, pull the control stick back, increase the longitudinal control stick force, and stabilize the speed to Z 0 -20kt, then slowly release the lever force. When the lever force has been removed and the speed has stabilized, record the speed Z4 at this time to determine whether it has recovered to within 10% of the trim speed, that is, Z4 ≥ Z 0 -0.1*Z 0 .

[0056] The helicopter instrument longitudinal static stability verification flight test can be divided into longitudinal joystick force gradient verification and trim speed recovery characteristic verification. The present invention discloses a civil helicopter instrument longitudinal static stability verification flight test method, comprising the following steps:

[0057] Verification of longitudinal joystick force gradient during acceleration (see Figure 1 ): In the specified automatic flight control system mode, at the specified speed Z 0 Trim with the specified power state and record the trim longitudinal control position Y 0 , keep the total distance at the trim value, push the joystick forward, and gradually increase the longitudinal joystick force to stabilize the speed to Z 0 +10kt, Z 0 +20kt, record the corresponding longitudinal control position Y +10kt , Y+20kt ;

[0058] Verification of longitudinal joystick force gradient during deceleration (see Figure 2 ): In the specified automatic flight control system mode, at the specified speed z 0 Trim with the specified power state and record the trim longitudinal control position Y 0 , keep the total distance at the trim value, pull the joystick back, and gradually increase the longitudinal joystick force to stabilize the speed to Z 0 -10kt, Z 0 -20kt, record the corresponding longitudinal control position Y -10kt , Y -20kt ;

[0059] Verification of trim speed recovery characteristics during acceleration (see Figure 3 ): In the specified automatic flight control system mode, at the specified speed Z 0 Trim with the specified power state, keep the total distance at the trim value, push the joystick forward, increase the longitudinal joystick force, and stabilize the speed to Z 0 +20kt, then slowly release the stick force, when the stick force has been removed and the speed has stabilized, record the speed Z3 at this time to determine whether it has recovered to within 10% of the trim speed;

[0060] Verification of trim speed recovery characteristics in the deceleration section (see Figure 4 ): In the specified automatic flight control system mode, at the specified speed Z 0 Trim with the specified power state, keep the total distance at the trim value, pull the control stick back, increase the longitudinal control stick force, and stabilize the speed to Z 0 -20kt, then slowly release the lever force. When the lever force has been removed and the speed has stabilized, record the speed Z4 at this time to determine whether it has recovered to within 10% of the trim speed.

[0061] The key points of this method are: first, the longitudinal joystick force gradient and the trim speed recovery characteristic are verified separately to eliminate the mutual interference between the longitudinal joystick force gradient verification and the trim speed recovery characteristic verification, and a verification method is given; second, the relationship between the longitudinal joystick force and the longitudinal control position is measured through ground tests, and the relationship between the control position and the speed measured in the flight test is converted into the relationship between the longitudinal joystick force and the speed to determine the longitudinal joystick force gradient; third, the longitudinal joystick force gradient verification and the trim speed recovery characteristic verification are divided into acceleration section and deceleration section, and specific test steps are given.

[0062] The present invention proposes an airworthiness compliance verification flight test method for verifying the airworthiness regulations CCAR-29-R2 Appendix B.IV instrument longitudinal static stability. According to the method, the mutual interference between the joystick force gradient verification and the trim speed recovery characteristic verification can be eliminated, which is convenient for carrying out the test verification of the instrument longitudinal static stability and improving the success rate of the instrument longitudinal static stability verification flight test subject.

Claims

1. A civil helicopter instrument longitudinal static stability verification flight test method, characterized in that: The method comprises: S1, determining the relationship between the longitudinal control lever force and the longitudinal control position of the control column; S2, verify the longitudinal joystick force gradient during the helicopter acceleration phase through flight tests; S3, verify the longitudinal joystick force gradient during the helicopter deceleration phase through flight tests; S4, verify the trim speed recovery characteristics of the helicopter during acceleration phase through flight tests; S5, verify the trim speed recovery characteristics of the helicopter deceleration phase through flight tests.

2. A civil helicopter instrument longitudinal static stability verification flight test method according to claim 1, characterized in that: S1, specifically: The relationship between the longitudinal control lever force and the longitudinal control position is measured on the ground. Usually, the longitudinal control lever force increases linearly with the increase of the longitudinal control position. Y represents the longitudinal control position, and X represents the longitudinal control lever force corresponding to Y. The conversion relationship between the longitudinal control position and the longitudinal control lever force is as follows: Y=a1*X+b1.

3. A civil helicopter instrument longitudinal static stability verification flight test method according to claim 2, characterized in that: S2, specifically: Trim the helicopter at the specified flight speed Z0 and the specified helicopter power, record the trimmed longitudinal control position Y0 of the joystick, keep the collective distance at the trimmed position, push the joystick forward, gradually increase the longitudinal joystick force, make the flight speed stably reach Z0+10kt and Z0+20kt respectively, record the corresponding longitudinal control position Y +10kt , Y +20kt , Z1 represents the flight speed, Y represents the longitudinal control position corresponding to the flight speed, through (Y0, Z0), (Y +10kt , Z0+10kt) and (Y +20kt The relationship between the longitudinal control position and the flight speed is obtained by fitting the three points of Z0+20kt as follows: Z1=a2*Y+b2.

4. A civil helicopter instrument longitudinal static stability verification flight test method according to claim 3, characterized in that: S2, also includes: 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 calculated: Z1=a1*a2*X+a2*b1+b2 The longitudinal static stability of the instrument is determined based on the gradient relationship between the flight speed and the longitudinal joystick force. If a1*a2>0, the static stability is positive.

5. A civil helicopter instrument longitudinal static stability verification flight test method according to claim 2, characterized in that: S3, specifically: Trim at the specified flight speed Z0 and the specified helicopter power, record the trimmed longitudinal control position Y0 of the joystick, keep the collective distance at the trimmed position, pull the joystick back, gradually increase the longitudinal joystick force, make the flight speed stabilize to Z0-10kt and Z0-20kt respectively, record the corresponding longitudinal control position Y -10kt , Y -20kt , Z2 represents the flight speed, Y represents the longitudinal control position corresponding to the speed, through (Y0, Z0), (Y -10kt , Z0-10kt) and (Y -20kt The relationship between the longitudinal control position and the flight speed is obtained by three-point fitting: Z2=a3*Y+b3.

6. A civil helicopter instrument longitudinal static stability verification flight test method according to claim 5, characterized in that: S3, also includes: According to the conversion relationship between the longitudinal control position and the longitudinal control stick force, the relationship between the flight speed and the longitudinal control stick force is calculated: Z2=a1*a3*X+a3*b1+b3 The longitudinal static stability of the instrument is determined based on the gradient relationship between the flight speed and the longitudinal joystick force. If a1*a3>0, the static stability is positive.

7. A civil helicopter instrument longitudinal static stability verification flight test method according to claim 6, characterized in that: Trim at the specified speed Z0 and specified power state, keep the collective pitch at the trim value, push the joystick forward, increase the longitudinal joystick force, stabilize the speed to Z0+20kt, then slowly release the joystick force. When the joystick force has been removed and the speed has stabilized, record the speed Z3 at this time to determine whether it has recovered to within 10% of the trim speed, that is, Z3≤Z0+0.1*Z0.

8. A civil helicopter instrument longitudinal static stability verification flight test method according to claim 6, characterized in that: Trim at the specified speed Z0 and specified power state, keep the collective pitch at the trim value, pull back the joystick, increase the longitudinal joystick force, stabilize the speed to Z0-20kt, then slowly release the joystick force. When the joystick force has been removed and the speed has stabilized, record the speed Z4 at this time to determine whether it has recovered to within 10% of the trim speed, that is, Z4≥Z0-0.1*Z0.

Images