Wing lift line slope determination method

Abstract

The invention belongs to the technical field of aircraft control, and particularly relates to a wing lift line slope determination method, which comprises the following steps: step 1, calculating the characteristic thickness tclim of the wing lift line slope, and determining the thickness types of wings, including thin wings and thick wings; 2, calculating the characteristic Mach number of the wing lift line slope, wherein the characteristic Mach number comprises the characteristic Mach number Max of a thin wing, the first peak value characteristic Mach number Ma1 of a thick wing, the second peak value characteristic Mach number Ma3 of the thick wing and the minimum peak value characteristic Mach number Ma2 of the thick wing; step 3, calculating a body interference influence factor Kb; and step 4, calculating the lift line slope CL alpha w of the wing based on the characteristic Mach number of the wing and the fuselage interference influence factor Kb.

Description

Technical Field

[0001] The present application belongs to the field of aircraft control technology, and specifically relates to a method for determining the slope of a wing lift line. Background Art

[0002] The slope of the wing lift line is an important parameter that characterizes the lift characteristics of an aircraft. Accurately determining the slope of the wing lift line can provide support for the calculation and evaluation of the aircraft lift characteristics.

[0003] The slope of the wing lift line is a function of the wing configuration and airfoil parameters. Affected by the compressibility of air, there are great differences in the variation characteristics of the lift line slope of wings with different thicknesses in the high subsonic and transonic regions with speed. In addition, fuselage interference also has an important influence on the slope of the wing lift line.

[0004] At present, the engineering calculation method of the wing lift line slope does not fully consider the impact of air compressibility and fuselage interference on the wing lift line slope. The accuracy of the wing lift line slope calculated based on this method is low, and it is difficult to provide effective support for the calculation and evaluation of aircraft lift characteristics.

[0005] This application is proposed in view of the above-mentioned technical defects. Summary of the invention

[0006] The purpose of the present application is to provide a method for determining the slope of a wing lift line, so as to overcome or alleviate at least one of the known technical deficiencies.

[0007] The technical solution of this application is:

[0008] A method for determining a wing lift line slope, comprising:

[0009] Step 1: Calculate the characteristic thickness tc of the wing lift line slope lim , determine the thickness type of the wing, including thin wing and thick wing;

[0010] Step 2: Calculate the characteristic Mach number of the wing lift line slope, including the characteristic Mach number M of the thin wing ax , the first peak characteristic Mach number M of the thick wing a1 , the second peak characteristic Mach number M of the thick wing a3 , the minimum peak characteristic Mach number M of the thick wing a2 ;

[0011] Step 3: Calculate the interference factor K b ;

[0012] Step 4: Based on the characteristic Mach number of the wing and the fuselage interference factor K b , calculate the lift line slope C of the wing Lαw .

[0013] According to at least one embodiment of the present application, in the above-mentioned method for determining the slope of the wing lift line, in step 1, the characteristic thickness tc of the slope of the wing lift line is calculated. lim , specifically:

[0014]

[0015] in,

[0016] AR is the wing aspect ratio;

[0017] Λ 1 / 2 It is the 1 / 2 chord sweep angle of the wing.

[0018] According to at least one embodiment of the present application, in the above-mentioned method for determining the slope of the wing lift line, in step 1, the thickness is less than the characteristic thickness tc lim The wing is determined to be a thin wing, and the thickness is greater than the characteristic thickness tc lim The wing is determined to be a thick wing.

[0019] According to at least one embodiment of the present application, in the above-mentioned method for determining the slope of the wing lift line, in step 2, the characteristic Mach number M of the thin wing ax , calculated as:

[0020] M ax =M a0 +(1-M a0 )(1-cosΛ 1 / 2 ) 2 ;

[0021]

[0022] in,

[0023] M a0 is an intermediate calculated value of the characteristic Mach number for a thin wing.

[0024] According to at least one embodiment of the present application, in the above-mentioned method for determining the slope of the wing lift line, in step 2, for a non-supercritical wing, the first peak characteristic Mach number M of the thick wing a1 , the second peak characteristic Mach number M of the thick wing a3 , the minimum peak characteristic Mach number M of the thick wing a2 , calculated as:

[0025]

[0026] M a2 =M a1 +tc;

[0027] M a3 =1.0+tc;

[0028] in,

[0029] C LD Design lift coefficient for the wing;

[0030] tc is the thickness of the mean aerodynamic chord of the wing.

[0031] According to at least one embodiment of the present application, in the above-mentioned method for determining the slope of the wing lift line, in step 2, for a supercritical wing, the first peak characteristic Mach number M of the thick wing a1 , the second peak characteristic Mach number M of the thick wing a3 , the minimum peak characteristic Mach number M of the thick wing a2 , calculated as:

[0032]

[0033]

[0034] M a3 =1.0+tc.

[0035] According to at least one embodiment of the present application, in the above-mentioned method for determining the slope of the wing lift line, in step 3, the fuselage interference influence factor K is calculated. b , specifically:

[0036]

[0037]

[0038] in,

[0039] d is the equivalent diameter of the fuselage where the wing joins the fuselage;

[0040] b is the wing span;

[0041] f is the intermediate quantity for calculating the fuselage interference influence factor.

[0042] According to at least one embodiment of the present application, in the above-mentioned method for determining the slope of the wing lift line, in step 4, for a thin wing, the wing speed M a Less than the characteristic Mach number M of a thin wing ax When the lift line slope C Lαw , calculated as:

[0043]

[0044] a op =a o / (2π);

[0045] in,

[0046] S plant is the wing projected area;

[0047] a o is the slope of the two-dimensional theoretical lift line of the wing;

[0048] S ref is the wing reference area;

[0049] a op An intermediate quantity calculated for the slope of the wing's lift line.

[0050] According to at least one embodiment of the present application, in the above-mentioned method for determining the lift line slope of the wing, in step 4, for a non-supercritical airfoil, the two-dimensional theoretical lift line slope a of the wing is o = 2πrad -1 ;

[0051] For supercritical airfoils, the slope of the two-dimensional theoretical lift line of the wing is a o , calculated as:

[0052]

[0053] According to at least one embodiment of the present application, in the above-mentioned method for determining the slope of the wing lift line, in step 4, for a thin wing, the wing speed M a Greater than the characteristic Mach number M of a thin wing ax When the lift line slope C Lαw , calculated as:

[0054]

[0055]

[0056]

[0057]

[0058]

[0059] in,

[0060] C LαMx An intermediate quantity calculated for the slope of the wing's lift line;

[0061] Z is the intermediate quantity for calculating the slope of the wing's lift line;

[0062] betap is the intermediate quantity calculated for the slope of the wing's lift line;

[0063] Y is the intermediate quantity calculated for the slope of the wing's lift line;

[0064] λ is the wing's tip-to-root ratio.

[0065] According to at least one embodiment of the present application, in the above-mentioned method for determining the slope of the wing lift line, in step 4, for a thick wing, the wing speed M a Less than the first peak characteristic Mach number M of the thick wing a1 When the lift line slope C Lαw , calculated as:

[0066]

[0067] According to at least one embodiment of the present application, in the above-mentioned method for determining the slope of the wing lift line, in step 4, for a thick wing, the wing speed M a Greater than the first peak characteristic Mach number M of the thick wing a1 , which is less than the second peak characteristic Mach number M of the thick wing a3 When the lift line slope C Lαw , calculated as:

[0068]

[0069]

[0070] in,

[0071] C LαM1 An intermediate quantity calculated for the slope of the wing's lift line;

[0072] K t is the wing thickness factor.

[0073] According to at least one embodiment of the present application, in the above-mentioned method for determining the slope of the wing lift line, in step 4, for a thick wing, the wing speed M a Greater than the second peak characteristic Mach number M a3 When the lift line slope C Lαw , calculated as:

[0074]

[0075]

[0076]

[0077]

[0078]

[0079] in,

[0080] C LαMx An intermediate quantity calculated for the slope of the wing's lift line;

[0081] Z is the intermediate quantity for calculating the slope of the wing's lift line;

[0082] betap is the intermediate quantity calculated for the slope of the wing's lift line;

[0083] Y is the intermediate quantity calculated for the slope of the wing's lift line;

[0084] λ is the wing's tip-to-root ratio.

[0085] According to at least one embodiment of the present application, in the above-mentioned method for determining the slope of the wing lift line, in step 4, the wing thickness influence factor K t , calculated as:

[0086]

[0087]

[0088]

[0089]

[0090] Δtc=tc-tc lim ;

[0091] in,

[0092] γ is the intermediate quantity for calculating the influence factor of wing thickness;

[0093] σ1 is the intermediate quantity for calculating the influence factor of wing thickness;

[0094] σ2 is the intermediate quantity for calculating the influence factor of wing thickness;

[0095] Δtc is the intermediate quantity for calculating the influence factor of wing thickness;

[0096] tc is the wing thickness.

[0098] This application has at least the following beneficial technical effects: BRIEF DESCRIPTION OF THE DRAWINGS

[0099] Figure 1 is a schematic diagram of a method for determining a wing lift line slope provided in an embodiment of the present application;

[0100] Figure 2 It is a schematic diagram of a curve showing a change in the slope of the wing lift line and the random wing Mach number provided in an embodiment of the present application.

[0101] In order to better illustrate the present embodiment, some contents of the drawings may be omitted, which is only used for illustrative purposes and should not be construed as limiting the present application. DETAILED DESCRIPTION

[0102] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be described in further detail in detail and in detail with reference to the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design.

[0103] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application shall have the usual meanings understood by those of ordinary skill in the art to which this application belongs. The words used in the description of this application to indicate orientation are only used to indicate relative directions or positional relationships. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. The word "include" used in the description of this application indicates that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0104] In addition, it should be noted that, unless otherwise clearly specified and limited, the words "installation", "connection" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Technical personnel in the field can understand its specific meaning in this application according to the specific circumstances.

[0105] The present application embodiment provides a method for determining the slope of a wing lift line based on the basic theory of lift calculation and a large amount of wind tunnel test data, such as Figure 1 shown.

[0106] The shape of the curve of the slope of the wing lift line changing with speed is closely related to the wing thickness. When the wing thickness is less than the characteristic thickness tc lim The peak value of the slope of the wing lift line occurs at the Mach number M ax , is the characteristic Mach number of the thin wing; when the wing thickness is greater than the characteristic thickness tc lim The first peak of the slope of the wing lift line appears at Mach number M a1 , is the first peak characteristic Mach number of the thick wing, and the second peak occurs at Mach number M a3 , is the second peak characteristic Mach number of the thick wing, and the minimum value occurs at Mach number M a2 , is the minimum peak characteristic Mach number of the thick wing.

[0107] Step 1: Calculate the characteristic thickness tc of the wing lift line slope lim , determine the thickness type of the wing, including thin wing and thick wing.

[0108]

[0109] in,

[0110] AR is the wing aspect ratio;

[0111] Λ 1 / 2 It is the 1 / 2 chord sweep angle of the wing.

[0112] The thickness of the thin wing is less than the characteristic thickness tc lim , the thickness of the thick wing is greater than the characteristic thickness tc lim .

[0113] Step 2: Calculate the characteristic Mach number of the wing lift line slope, including the characteristic Mach number M of the thin wing ax , the first peak characteristic Mach number M of the thick wing a1 , the second peak characteristic Mach number M of the thick wing a3 , the minimum peak characteristic Mach number M of the thick wing a2 .

[0114] The characteristic Mach number M of a thin wing ax , calculated as follows:

[0115] M ax =M a0 +(1-M a0 )(1-cosΛ 1 / 2 ) 2 …………(2)

[0116]

[0117] in,

[0118] M a0 is an intermediate calculated value of the characteristic Mach number for a thin wing.

[0119] For a non-supercritical wing, the first peak characteristic Mach number M of the thick wing a1 , the second peak characteristic Mach number M of the thick wing a3 , the minimum peak characteristic Mach number M of the thick wing a2 , calculated as follows:

[0120]

[0121] M a2 =M a1 +tc…………(5)

[0122] M a3 =1.0+tc…………(6)

[0123] in,

[0124] C LD Design lift coefficient for the wing;

[0125] tc is the thickness of the mean aerodynamic chord of the wing.

[0126] For a supercritical wing, the first peak characteristic Mach number M of a thick wing a1 , the second peak characteristic Mach number M of the thick wing a3 , the minimum peak characteristic Mach number M of the thick wing a2 , calculated as follows:

[0127]

[0128]

[0129] M a3 =1.0+tc…………(9)

[0130] Step 3: Calculate the interference factor K b .

[0131]

[0132]

[0133] in,

[0134] d is the equivalent diameter of the fuselage where the wing joins the fuselage;

[0135] b is the wing span;

[0136] f is the intermediate quantity for calculating the fuselage interference influence factor.

[0137] Step 4: Based on the characteristic Mach number of the wing and the fuselage interference factor K b , calculate the lift line slope C of the wing Lαw .

[0138] (a) For a thin wing, the wing speed M a Less than the characteristic Mach number M of a thin wing ax When the lift line slope C Lαw , calculated as follows:

[0139]

[0140] a op =a o / (2π);

[0141] in,

[0142] S plant is the wing projected area;

[0143] a o is the slope of the two-dimensional theoretical lift line of the wing;

[0144] S ref is the wing reference area;

[0145] a op An intermediate quantity calculated for the slope of the wing's lift line.

[0146] For a non-supercritical airfoil, the slope of the two-dimensional theoretical lift line of the wing is a o = 2πrad -1 .

[0147] For supercritical airfoils, the slope of the two-dimensional theoretical lift line of the wing is a o , calculated as follows:

[0148]

[0149] For a thin wing, the wing speed M a Greater than the characteristic Mach number M of a thin wing ax When the lift line slope C Lαw , calculated as follows:

[0150]

[0151]

[0152]

[0153]

[0154]

[0155] in,

[0156] C LαMx An intermediate quantity calculated for the slope of the wing's lift line;

[0157] Z is the intermediate quantity for calculating the slope of the wing's lift line;

[0158] betap is the intermediate quantity calculated for the slope of the wing's lift line;

[0159] Y is the intermediate quantity calculated for the slope of the wing's lift line;

[0160] λ is the wing's tip-to-root ratio.

[0161] (ii) For thick wings, the wing speed M a Less than the first peak characteristic Mach number M of the thick wing a1 When the lift line slope C Lαw , calculated as follows:

[0162]

[0163] For a thick wing, the wing speed M a Greater than the first peak characteristic Mach number M of the thick wing a1 , which is less than the second peak characteristic Mach number M of the thick wing a3 When the lift line slope C Lαw , calculated as follows:

[0164]

[0165]

[0166] in,

[0167] C LαM1 An intermediate quantity calculated for the slope of the wing's lift line;

[0168] K t is the wing thickness factor.

[0169] For a thick wing, the wing speed M a Greater than the second peak characteristic Mach number M a3 When the lift line slope C Lαw , calculated as follows:

[0170]

[0171]

[0172]

[0173]

[0174]

[0175] in,

[0176] C LαMx An intermediate quantity calculated for the slope of the wing's lift line;

[0177] Z is the intermediate quantity for calculating the slope of the wing's lift line;

[0178] betap is the intermediate quantity calculated for the slope of the wing's lift line;

[0179] Y is the intermediate quantity calculated for the slope of the wing's lift line;

[0180] λ is the wing's tip-to-root ratio.

[0181] Wing thickness influence factor K t , calculated as follows:

[0182]

[0183]

[0184]

[0185]

[0186] Δtc=tc-tc lim …………(31)

[0187] in,

[0188] γ is the intermediate quantity for calculating the influence factor of wing thickness;

[0189] σ1 is the intermediate quantity for calculating the influence factor of wing thickness;

[0190] σ2 is the intermediate quantity for calculating the influence factor of wing thickness;

[0191] Δtc is the intermediate quantity for calculating the influence factor of wing thickness;

[0192] tc is the wing thickness.

[0193] In the method for determining the wing lift line slope disclosed in the above embodiment, the wing thickness influence factor can accurately display the variation characteristics of the wing lift line slope with speed in the high subsonic region and the transonic region, the fuselage interference influence factor can reflect the influence of the fuselage diameter and the wing span, the characteristic thickness calculation of the wing lift line slope can divide the wing into a thin wing and a thick wing for accurate calculation, and the characteristic Mach number calculation can be divided into different speed regions for accurate calculation.

[0194] In the method for determining the wing lift line slope disclosed in the above embodiment, the influence of the wing configuration parameters and airfoil parameters on the lift line slope is fully considered, as well as the influence of air compressibility and fuselage interference on the wing lift line slope. The calculated wing lift line slope has high accuracy, which can provide effective support for the calculation and evaluation of aircraft lift characteristics, and can provide effective support for the design of wing, airfoil and fuselage configuration parameters.

[0195] In a specific example, the wing reference area is 300m2, the wing projected area is 300m2, the wingspan is 50m, the aspect ratio is 8, the wing 1 / 2 chord line sweep angle is 25°, the tip-to-root ratio is 0.3, the laminar airfoil, the average thickness is 0.11, and the fuselage equivalent diameter at the connection between the wing and the fuselage is 5.5m. The lift line slope of the wing is calculated using the method for determining the lift line slope of the wing disclosed in the above embodiment, as follows:

[0196] Calculate the characteristic thickness tc of the wing lift line slopelim :

[0197]

[0198] Characteristic thickness tc lim If the average thickness is greater than 0.11, it is a thick wing. The following calculation of the slope of the wing lift line adopts the thick wing related calculation model.

[0199] Calculate the characteristic Mach number of the wing's lift line slope:

[0200]

[0201] M ax =0.9117+(1-0.9117)(1-cos25) 2 =0.9125;

[0202]

[0203] M a2 =0.7026+0.11=0.8126;

[0204] M a3 =1.0+0.11=1.11.

[0205] Calculate the impact factor K b :

[0206]

[0207]

[0208] Thickness influence factor K for wing speed 0.2M~1.2M t , lift line slope C Lαw The calculation is as follows: Ma K CLaw / ° 0 1 0.0818 0.2 1 0.0823 0.4 1 0.085 0.6 1 0.0925 0.7 1 0.1001 0.76 0.725 0.0728 0.82 0.583 0.0585 0.93 0.709 0.0711 1.03 0.868 0.0871 1.1 0.899 0.0903 1.2 1 0.088

[0209] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the scope of protection of the present application.

Claims

1. A method for determining the slope of a wing lift line, characterized in that: include: Step 1: Calculate the characteristic thickness tc of the wing lift line slope lim , determine the thickness type of the wing, including thin wing and thick wing; Step 2: Calculate the characteristic Mach number of the wing lift line slope, including the characteristic Mach number M of the thin wing ax , the first peak characteristic Mach number M of the thick wing a1 , the second peak characteristic Mach number M of the thick wing a3 , the minimum peak characteristic Mach number M of the thick wing a2 ; Step 3: Calculate the interference factor K b ; Step 4: Based on the characteristic Mach number of the wing and the fuselage interference factor K b , calculate the lift line slope C of the wing Lαw .

2. The method for determining the slope of a wing lift line according to claim 1, characterized in that: In step 1, calculate the characteristic thickness tc of the wing lift line slope lim , specifically: in, AR is the wing aspect ratio; Λ 1 / 2 It is the 1 / 2 chord sweep angle of the wing.

3. The method for determining the slope of a wing lift line according to claim 2, characterized in that: In step 1, the thickness is less than the characteristic thickness tc lim The wing is determined to be a thin wing, and the thickness is greater than the characteristic thickness tc lim The wing is determined to be a thick wing.

4. The method for determining the slope of a wing lift line according to claim 3, characterized in that: In step 2, the characteristic Mach number M of the thin wing is ax , calculated as: M ax =M a0 +(1-M a0 )(1-cosΛ 1 / 2 ) 2 ; in, M a0 is an intermediate calculated value of the characteristic Mach number for a thin wing.

5. The method for determining the slope of a wing lift line according to claim 4, characterized in that: In step 2, for a non-supercritical wing, the first peak characteristic Mach number M of the thick wing is a1 , the second peak characteristic Mach number M of the thick wing a3 , the minimum peak characteristic Mach number M of the thick wing a2 , calculated as: M a2 =M a1 +tc; M a3 =1.0+tc; in, C LD Design lift coefficient for the wing; tc is the thickness of the mean aerodynamic chord of the wing.

6. The method for determining the slope of a wing lift line according to claim 5, characterized in that: In step 2, for a supercritical wing, the first peak characteristic Mach number M of the thick wing is a1 , the second peak characteristic Mach number M of the thick wing a3 , the minimum peak characteristic Mach number M of the thick wing a2 , calculated as: M a3 =1.0+tc。 7. The method for determining the slope of a wing lift line according to claim 6, characterized in that: In step 3, calculate the interference factor K b , specifically: in, d is the equivalent diameter of the fuselage where the wing joins the fuselage; b is the wing span; f is the intermediate quantity for calculating the fuselage interference influence factor.

8. The method for determining the slope of a wing lift line according to claim 6, characterized in that: In step 4, for thin wings, the wing speed M a Less than the characteristic Mach number M of a thin wing ax When the lift line slope C Lαw , calculated as: a op =a o / (2π); in, S plant is the wing projected area; a o is the slope of the two-dimensional theoretical lift line of the wing; S ref is the wing reference area; a op An intermediate quantity calculated for the slope of the wing's lift line.

9. The method for determining the slope of a wing lift line according to claim 8, characterized in that: In step 4, for non-supercritical airfoils, the slope of the two-dimensional theoretical lift line of the wing is o = 2π rad -1 ; For supercritical airfoils, the slope of the two-dimensional theoretical lift line of the wing is a o , calculated as:

10. The method for determining the slope of a wing lift line according to claim 9, characterized in that: In step 4, for thin wings, the wing speed M a Greater than the characteristic Mach number M of a thin wing ax When the lift line slope C Lαw , calculated as: in, C LαMx An intermediate quantity calculated for the slope of the wing's lift line; Z is the intermediate quantity for calculating the slope of the wing's lift line; betap is the intermediate quantity calculated for the slope of the wing's lift line; Y is the intermediate quantity calculated for the slope of the wing's lift line; λ is the wing's tip-to-root ratio.

11. The method for determining the slope of a wing lift line according to claim 10, characterized in that: In step 4, for thick wings, the wing velocity M a Less than the first peak characteristic Mach number M of the thick wing a1 When the lift line slope C Lαw , calculated as:

12. The method for determining the slope of a wing lift line according to claim 11, characterized in that: In step 4, for thick wings, the wing velocity M a Greater than the first peak characteristic Mach number M of the thick wing a1 , which is less than the second peak characteristic Mach number M of the thick wing a3 When the lift line slope C Lαw , calculated as: in, C LαM1 An intermediate quantity calculated for the slope of the wing's lift line; K t is the wing thickness factor.

13. The method for determining the slope of a wing lift line according to claim 12, characterized in that: In step 4, for thick wings, the wing velocity M a Greater than the second peak characteristic Mach number M a3 When the lift line slope C Lαw , calculated as: in, C LαMx An intermediate quantity calculated for the slope of the wing's lift line; Z is the intermediate quantity for calculating the slope of the wing's lift line; betap is the intermediate quantity calculated for the slope of the wing's lift line; Y is the intermediate quantity calculated for the slope of the wing's lift line; λ is the wing's tip-to-root ratio.

14. The method for determining the slope of a wing lift line according to claim 13, characterized in that: In step 4, the wing thickness influence factor K t , calculated as: K t =1-γ[4σ1(1-σ1)] 3 M a1 ≤M a <M a2 K t =0.9-0.53γ[4σ2(1-σ2)] 3 M a2 ≤M a <M a3 ; Δtc=tc-tc lim ; in, γ is the intermediate quantity for calculating the influence factor of wing thickness; σ1 is the intermediate quantity for calculating the influence factor of wing thickness; σ2 is the intermediate quantity for calculating the influence factor of wing thickness; Δtc is the intermediate quantity for calculating the influence factor of wing thickness; tc is the wing thickness.

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