JP4241328B2 - Air pressure barometric altimeter and its error correction method - Google Patents

Description

  The present invention relates to an air pressure altimeter for detecting the altitude of a flying object and an error correction method thereof.

Sensors for detecting the altitude of flying objects such as rockets include radio wave altimeters and GPS, but these are generally expensive. On the other hand, an altimeter using a barometric sensor (hereinafter referred to as a barometric altimeter) is characterized in that it can be reduced in cost.
The barometric altimeter detects the atmospheric pressure difference corresponding to the target altitude difference from the atmospheric pressure at the launch point (reference atmospheric pressure) acquired before the launch of a flying object such as a rocket bullet and the atmospheric pressure sensor through the static pressure hole provided on the aircraft surface. To do.

  Patent Document 1 is disclosed as an example of a flying object such as a rocket bullet. Further, Patent Literature 2 is disclosed as an altimeter test device using air pressure. Further, Patent Document 3 and Non-Patent Document 1 disclose means for correcting an air pressure altimeter of an aircraft.

  The “flying object” of Patent Document 1 is capable of dealing with all directions in a flying object that is launched from an aircraft toward a forward or backward target object, and the target object is used when attacking a backward target object. The flying object is provided behind the fuselage 57 of the launch tube 52 as shown in FIG. 9 so that the flying body can obtain a large turning load multiple at the time of meeting even when it is far away. The steering wing 59 that glides and raises the altitude of the launcher, the altitude estimation means 51 for estimating the altitude of the launcher provided at a predetermined portion of the launcher, and the rear end of the launcher It is provided with altitude reduction suppression means 56 that suppresses a reduction in altitude of the launcher when the launcher reaches a predetermined altitude. In the embodiment of Patent Document 1, the altitude estimating means 51 is a barometer provided on the side surface of the body 57, and the altitude reduction suppressing means 56 is a parachute.

  The “altitude / speed tester” of Patent Document 2 performs an altimeter and speedometer test using air pressure by accurately generating air pressure corresponding to a set value on the ground.

  Patent Document 3 “Position Error Calibration Apparatus and Method” describes the true air speed necessary for position error calibration of an air pressure altimeter and an air speed meter, and the wind direction and wind speed at the test execution altitude at the time of test flight. The purpose is to measure on the plane of the airplane performing the test flight, and input and record it for calibration of the instrument. As shown in FIG. 10, the heading from the attitude angle meter 62, the ground speed, and the A calculation unit 66 for calculating the true airspeed, wind direction, and wind speed from the air speed, a recorder 68 for recording the output value from the calculation unit, and the heading and instructing the heading with the output value from the calculation unit The attitude indicating device and attitude holding device 67 to be held, the speed indicating device and speed holding device 63 for instructing and holding the airspeed by the airspeed and the output value from the calculating unit, and the pressure altitude and the output value from the calculating unit Indicating and maintaining the atmospheric pressure altitude with A pointing device and a pressure altitude holding device 64, is made of high holding device 65 for holding the high output value from the relative value highly and barometric altitude holding device. In the embodiment of Patent Document 3, the barometric altimeter 61 calculates the altitude from the output of the static pressure port 60.

  As shown in FIG. 11, the rocket bullet of Non-Patent Document 1 is a timed method in order to avoid the fact that the static pressure (atmospheric pressure) cannot be measured correctly and the altitude error becomes very large due to the influence of the flow velocity during flight. By separating the payload once and decelerating with a parachute, the altitude is measured with a barometric altimeter, thereby reducing the influence of the flow velocity and reducing the static pressure error.

JP 2003-156300 A, “Flying object” Japanese Patent Laid-Open No. 5-87832 “Altitude / Speed Tester” JP 2001-91295 A, “Position error calibration apparatus and method”

Catalog of "PW216, 130mm Advanced RF Distribution Decay Round", Chemring Countermeasures, England

  As described above, the conventional barometric altimeter detects a barometric pressure difference corresponding to a target altitude difference from a barometric pressure at the launch point (reference barometric pressure) by a barometric pressure sensor through a static pressure hole provided on the surface of the aircraft. There is a problem that the influence of the pressure difference (static pressure error) from the static pressure (atmospheric pressure) generated by the flow velocity during flight is large.

  For this reason, in large aircraft, etc., the static pressure hole position where this effect is small is carefully selected by wind tunnel tests, flight tests, etc., and air data is based on information such as aircraft attitude and speed from other sensors. Although correction is performed by a computer (ADC), in the case of a small flying object such as a small rocket with a limited outer shape, there are restrictions on the selection of static pressure hole positions, and pressure errors such as attitude information are corrected. The application of sensors for this purpose has a problem that is not practical in terms of cost for inexpensive rockets.

  Further, as in Non-Patent Document 1, when using a speed reducer such as a separation device or a parachute, the mechanism becomes complicated and the cost increases, and the time lag (operation delay) increases due to the speed reduction. is there.

  The present invention has been developed to solve the above-described problems. That is, the object of the present invention is to detect a flying object's altitude accurately by only pressure measurement without using information such as airframe attitude and speed and without using a speed reducer. It is to provide an altimeter and its error correction method.

According to the present invention, a flying object pressure altimeter for detecting the height of a flying object having a cylindrical outer surface with a flying direction as a central axis,
A plurality of static pressure holes provided at equal positions from the flying direction tip of the cylindrical outer surface, an average static pressure detector for detecting an average static pressure of the plurality of static pressure holes, and provided at the tip of the flying direction. A total pressure detector that detects the total pressure through the total pressure hole, and an altitude calculation device that calculates the altitude by correcting the average static pressure during flight from the detected average static pressure and total pressure. A flying air pressure altimeter is provided.

  Further, according to the present invention, a plurality of static pressure holes are provided on the cylindrical outer surface at the same position from the front end in the flight direction of the flying object having a cylindrical outer surface with the flight direction as the central axis, and the plurality of static pressure holes Detecting the average static pressure P of the flight, and simultaneously detecting the total pressure P1 acting on the tip in the flight direction, correcting the average static pressure during the flight from the detected average static pressure and the total pressure, and calculating the altitude. A characteristic error correction method for a flying object barometric altimeter is provided.

According to the above-described apparatus and method of the present invention, since the plurality of static pressure holes are provided at the same position from the front end of the cylindrical outer surface in the flight direction, the position (phase) of the static pressure holes is varied even when the angle of attack varies. ) Can be detected.
Therefore, by correcting the average static pressure during flight from the average static pressure and total pressure detected by the altitude calculation device, the altitude error factor generated by the influence of the flow velocity can be greatly reduced, without a separation mechanism or deceleration mechanism, Altitude can be accurately detected during normal flight.

  According to a preferred embodiment of the present invention, the plurality of static pressure holes have a small variation due to the angle of attack of the pressure coefficient Cp, and the pressure coefficient Cp when the flow velocity direction due to flight coincides with the central axis of the cylindrical outer surface. Is provided at a position where the value becomes zero or a value close to zero.

  With this configuration, the pressure coefficient Cp is almost zero when the flow velocity direction due to flight coincides with the central axis of the cylindrical outer surface, and the variation due to the angle of attack is small. Therefore, even when the angle of attack with respect to the flight direction varies, the static pressure The average static pressure can be detected while greatly reducing the influence of the hole position (phase) and maintaining the pressure coefficient Cp at a value close to zero.

  The flying object is a rocket or a rocket bullet having an elongated cylindrical body and a tail at its end, and the plurality of static pressure holes are sufficiently separated from the tail and the tail at the end and the pressure coefficient Cp is close to zero. Six or more positions are provided at the same phase angle in the plane perpendicular to the central axis and around the central axis.

  With this configuration, even when the angle of attack varies, the influence of dynamic pressure can be reduced and the pressure coefficient Cp can be maintained at a value close to zero.

An estimated dynamic pressure value q0 during flight is calculated from the average static pressure P and the total pressure P1 as a differential pressure q0 = P1-P between the total pressures P1 and P, and an average value Cp ′ of pressure coefficients at each static pressure hole position. Is set in advance by a wind tunnel test, CFD analysis, etc., and the static pressure P ′ for altitude calculation is calculated by correcting the average static pressure P by the following (Equation 1).
Static pressure correction value P ′ = P−Cp ′ × q0 (Expression 1)
It is preferable.

  It was confirmed by an example described later that the altitude error detection accuracy is greatly improved by this correction method.

  As described above, the air pressure altimeter and its error correction method of the present invention can be used only for pressure measurement without using information such as the attitude and speed of the airframe and without decelerating using the speed reducer. It has excellent effects such as being able to accurately detect altitude.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a configuration diagram of a flying object equipped with a flying object barometric altimeter according to the present invention. In this figure, (A) is a side view of the flying object, and (B) is an end view as seen from the rear of the flying object. In this example, the flying object 1 is a rocket or a rocket having an elongated cylindrical body 2 and a tail 3 at its end, but the present invention is not limited to this, and all flying objects including an aircraft are also included. Can be applied.

  Hereinafter, in this application, the trunk | drum 2 is hemispherical at the front-end | tip (left end in a figure), the whole is a cylindrical shape which has the fixed diameter d, and makes the full length including the tail 3 be L. Further, with the tip of the body 2 as the origin, as shown in the figure, an xyz orthogonal coordinate system, an angle of attack α, and a phase angle θ are defined. That is, the x-axis is a cylindrical central axis, the angle of attack α is an angle formed by the x-axis and the flow velocity direction generated by flight, and the phase angle θ is an angle around the x-axis with respect to the upper side.

  The flying object barometric altimeter 10 of the present invention detects the altitude of the flying object 1 described above. As shown in FIG. 1, a plurality of static pressure holes 12, an average static pressure detector 14, a total pressure detector. 16 and an advanced arithmetic unit 18.

The plurality of static pressure holes 12 are provided at equal positions from the front end of the flying body of the cylindrical outer surface 2 a of the flying body 1. This position can significantly reduce the influence of the position (phase) of the static pressure hole even when the angle of attack with respect to the flight direction fluctuates, and can detect the average static pressure while maintaining the pressure coefficient Cp at a value close to zero. It is preferable that the pressure coefficient Cp is provided at a position where the fluctuation due to the angle of attack of the pressure coefficient Cp is small and the pressure coefficient Cp becomes zero or a value close to zero when the flow velocity direction coincides with the central axis of the cylindrical outer surface.
The plurality of static pressure holes 12 are sufficiently separated from the tip and tail tails so that the influence of dynamic pressure can be reduced and the pressure coefficient Cp can be maintained at a value close to zero even when the angle of attack varies. It is preferable to provide 6 or more at a position where the pressure coefficient Cp is close to zero, with a phase angle equal to the circumference of the central axis in a plane orthogonal to the central axis.

  The average static pressure detector 14 is, for example, a single pressure transducer provided on the x-axis of the flying object 1 and communicates with each static pressure hole 12 via a plurality of conduits (not shown). The average static pressure of the hole 12 is detected. Instead of a single pressure transducer, a pressure transducer may be provided in each static pressure hole 12, and the output may be averaged. The detected average static pressure P is input to the advanced arithmetic unit 18 as an analog or digital electrical signal.

  The total pressure detector 16 is a pressure transducer provided at the tip of the flying object 1 in the flight direction, and detects the total pressure P1 through a total pressure hole provided at the tip of the flying direction. The total pressure detector 16 may be single or plural. The detected total pressure P1 is input to the advanced arithmetic unit 18 as an analog or digital electrical signal.

The altitude calculation device 18 is a computer or a microcomputer, and calculates the altitude by correcting the average static pressure during flight from the detected average static pressure P and the total pressure P1.
The calculation by the altitude calculation unit 18 obtains the estimated dynamic pressure q0 during flight from the average static pressure P and the total pressure P1 as a differential pressure q0 = P1-P between the total pressures P1 and P, and at each static pressure hole position. An average value Cp ′ of the pressure coefficient is set in advance by a wind tunnel test, CFD analysis, or the like, and the average static pressure P is corrected by the following (Equation 1) to calculate the static pressure P ′ for altitude calculation.
Static pressure correction value P ′ = P−Cp ′ × q0 (Expression 1)
By this correction method, the altitude error detection accuracy can be greatly improved.

Examples of the present invention will be specifically described below.
1. In a non-guided rocket, a timed method is generally used as a method for determining the timing of an event during flight (for example, separation, payload release, etc.). The altitude detection method has little range error for rockets flying ballistically, so there are few examples of its application. However, there is a need to prioritize event operation at a predetermined altitude over range error in operations where the altitude variation increases due to variations in the angle of incidence, etc. In this case, the altitude detection method is effective.
Sensors for detecting altitude include a radio altimeter, GPS, and the like, but these are generally expensive. An altimeter using a barometric sensor is capable of reducing the cost, although there are restrictions on flight speed and applicable altitude, and an altitude detection method can be applied to rockets at low cost.
As an altitude detection method using an atmospheric pressure sensor, the atmospheric pressure sensor detects the atmospheric pressure difference corresponding to the target altitude difference from the atmospheric pressure (reference atmospheric pressure) of the launch point acquired before launching through the static pressure hole provided on the aircraft surface. Think about it. At this time, factors of altitude error due to the atmospheric pressure sensor include EN (temperature characteristics, responsiveness, etc.) of the sensor alone, fluctuations in atmospheric pressure and air density due to weather phenomena, etc., but it becomes the most problematic when applied to rockets. This is the influence of the pressure difference (static pressure error) from the static pressure (atmospheric pressure) generated by the flow velocity during flight.
For large aircraft, etc., the static pressure hole position with a small influence is selected carefully by wind tunnel tests, flight tests, etc., and an air data computer (based on information such as aircraft attitude and speed from other sensors) ADC).
In the case of a small rocket with a limited outer shape, there are restrictions on selecting the static pressure hole position. Also, the application of sensors for correcting pressure errors such as attitude information is not practical in terms of cost for inexpensive rockets.
In the present invention, a method for reducing the altitude error due to the static pressure error will be described as a specific application example to a rocket.

2. Relation between atmospheric pressure and altitude and static pressure error in rocket bullet The relation between atmospheric pressure P (hPa) and altitude H (m) in the standard atmosphere is given by (3.1) in (Equation 1).

The static pressure error of a flying rocket fluctuates depending on the angle of attack, dynamic pressure, and the installation position of the static pressure hole (axis direction distance and phase angle from the tip), and is expressed by (3.2) in (Equation 2). expressed.

ここで、Ｐ：機体表面圧力、Ｐ∞：静圧、Ｃｐ（Ｌ１，θ，α）：機体表面の圧力係数、Ｌ１：先端からの機軸方向距離、θ：位相角、α：迎角、ｑ：動圧（＝１／２・ρ・Ｖ²、ρ：空気密度、Ｖ：流速）である。

Here, P: Aircraft surface pressure, P∞: Static pressure, Cp (L1, θ, α): Aircraft surface pressure coefficient, L1: Axial direction distance from tip, θ: Phase angle, α: Angle of attack, q : Dynamic pressure (= 1/2 · ρ · V ² , ρ: air density, V: flow velocity).

3. Rocket bullets to which the altitude detection method is applied In the present invention, the rocket ammunition to which the altitude detection method is applied is as shown in FIG. 1, FIG. 2 shows its flight sequence, and FIG. 3 shows the flight under ideal conditions. It is a profile.
In the present invention, it is assumed that the external dimensions and the like cannot be changed as a constraint when applying the atmospheric pressure sensor (that is, the pressure detectors 14 and 16). In order to reduce costs, expensive sensors such as detecting the posture and speed are not applied.

4). Method for reducing altitude error due to static pressure error A method for reducing altitude error due to static pressure error when the altitude detection method is applied to the rocket bullets described above is shown below.

(1) Grasp of rocket bullet surface Cp distribution and selection of appropriate static pressure hole position Fig. 4 shows the results of calculating the rocket bullet surface Cp distribution by CFD analysis. In this figure, (a) shows the case where the angle of attack α = 5 °, and (b) shows the case where the angle of attack α = 10 °.
From this figure, in the vicinity of the tip where the flow accelerates from the stagnation point (tip of the body portion 2), the pressure fluctuation due to the axial direction distance and the phase angle θ from the tip is large, and the absolute value of Cp decreases as the distance from the tip increases. Although it approaches the static pressure, it can be seen that the absolute value of Cp increases conversely due to the effect near the tail.
Further, in order to improve the estimation accuracy of Cp, it is necessary to install a static pressure hole at a position that is close to the static pressure and has a small fluctuation due to the phase angle and the angle of attack. Therefore, the installation position of the static pressure hole is selected in the vicinity of L1 = 0.6 L where the absolute value of Cp is almost minimum.

(2) Reduction of pressure variation by averaging of multiple phases and estimation of Cp of static pressure hole position Static pressure holes are provided at the selected position of L1 = 0.6L, and Cp measurement for each phase angle is performed by a wind tunnel test. The results and the corresponding CFD analysis results are shown in FIG. Note that the CFD analysis and the wind tunnel test results almost coincided.
From this figure, it can be seen that when the angle of attack is large, Cp varies greatly depending on the phase angle. Therefore, in the case of a roll-free rocket, the phase angle during flight fluctuates and cannot be specified. Therefore, in order to increase the Cp estimation accuracy, it is necessary to suppress this variation.

In FIG. 6, when the static pressure holes are provided at equal intervals in a plurality of phases and the average value of the pressure is taken (average number of static pressure holes), the variation width (half width) of Cp depending on the phase, and the corresponding altitude error (ideal (Value at a flight altitude of 200 m at the time). When the pressure average is not taken, the Cp variation is ± 0.06 (corresponding to an altitude error of ± 40 m) at an angle of attack of 10 °, but when taking an average of 6 phases or more, it is ± 0.002 or less (altitude It was found that the error can be suppressed to ± 1 m or less.
In the present invention, static pressure holes are provided in 8 phases and averaged. The variation (upper limit and lower limit value) due to Cp and phase with respect to the angle of attack at this time is shown in FIG. It can be seen that the Cp fluctuation due to the phase angle and the angle of attack is suppressed smaller than before the averaging shown in FIG.

(3) Estimation of dynamic pressure and correction of static pressure error In order to reduce the altitude error due to static pressure error, the static pressure error is estimated from Cp and dynamic pressure of the static pressure hole position during flight. What is necessary is just to correct | amend the pressure input into an atmospheric pressure sensor from a static pressure hole. The dynamic pressure during flight can be estimated by taking the difference between the total pressure obtained through the pressure hole installed at the tip of the aircraft and the average pressure of 8 phases. The error in the estimated dynamic pressure value increases according to the angle of attack, but the error is sufficiently smaller than the fluctuation of Cp, and it can be said that there is no problem in correction.
Using this estimated dynamic pressure value and the 8-phase Cp average value, the equation (3.3) in (Equation 3) is applied to the 8-phase average pressure input to the atmospheric pressure sensor from the static pressure hole. The altitude error was reduced by performing the correction shown.

ここで、Ｐ₈（ｔ）：飛翔中の各時刻ｔにおいて、静圧孔から気圧センサに入力される
８位相の平均圧力計測値、Ｃｐ０：迎角０°時のＣｐの８位相平均値、（静圧孔位置により一意に決まる補正用設定値）、ｑ０（ｔ）：飛翔中の各時刻ｔにおける、機体先端圧力と８位相平均圧力Ｐ₈（ｔ）との差圧計測値である。

Here, P ₈ (t): an 8-phase average pressure measurement value input from the static pressure hole to the atmospheric pressure sensor at each time t during flight, Cp0: an 8-phase average value of Cp at an angle of attack of 0 °, (Correction set value uniquely determined by static pressure hole position), q0 (t): a differential pressure measurement value between the fuselage tip pressure and the 8-phase average pressure P ₈ (t) at each time t during flight.

5. Verification by simulation The simulation of the pressure input to the atmospheric pressure sensor during flight was performed, and the effect of reducing the altitude error by the correction method described above was verified. FIG. 8 shows altitude error calculation results by simulation under the following two flight conditions. In this simulation, it is assumed that the relationship between the atmospheric pressure and the altitude follows the standard atmosphere, and there is no error in the atmospheric pressure sensor alone.

Flying condition 1: In case of ideal condition (launch angle 45 °, wind speed 0m / s) Flying condition 2: An example of conditions in which altitude error becomes large (launch angle 60 °, tail wind 20m / s) And attenuating the attack angle vibration to reduce aerodynamic stability)

In FIG. 7A, the altitude error is 18 m without correction for the target detection altitude difference of 200 m, whereas the altitude error is reduced to 0.4 m with correction according to the present invention. . Similarly, in FIG. 7B, the altitude error is 19 m without correction for the target detection altitude difference of 200 m, whereas the altitude error is 0.3 m with correction according to the present invention. It has been reduced to.
Therefore, it can be seen from these results that the altitude error can be greatly reduced by performing the correction of the present invention under both conditions.

6). As described above, the present invention has shown that the altitude error due to the static pressure error can be reduced by the following correction method for the target rocket.
(1) Grasping airframe surface Cp distribution by CFD analysis and wind tunnel test and selection of appropriate static pressure hole position (2) Reduction of pressure variation by averaging multiple phases and estimation of estimated dynamic pressure of Cp at static pressure hole position This makes it possible to accurately detect the altitude of the flying object only by pressure measurement without using information such as the attitude and speed of the aircraft and without decelerating using the reduction device. confirmed.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.

It is a block diagram of a flying object provided with the atmospheric pressure altimeter for flying objects of this invention. This is a flight sequence of a flying object to be applied. It is a flight profile at the ideal condition of the flying object to be applied. It is the result of having calculated the airframe surface Cp distribution of the flying object made into an application object by CFD analysis. It is a CFD analysis result of Cp change by the angle of attack for each phase angle. It is a relationship diagram of the pressure average number and the dispersion | variation in Cp. It is a figure which shows the 8-phase average value of Cp with respect to each angle of attack. It is a figure which shows the height error calculation result by simulation. 2 is a schematic diagram of a “flying object” of Patent Document 1. FIG. 10 is a schematic diagram of “Position error calibration apparatus and method” in Patent Document 3. FIG. It is explanatory drawing of the rocket bullet of a nonpatent literature 1.

Explanation of symbols

1 flying body, 2 trunk, 2a outer surface, 3 tail wings,
10 Air pressure altimeter, 12 static pressure holes, 14 average static pressure detector,
16 Total pressure detector, 18 Advanced arithmetic unit

Claims (7)

A pressure altimeter for a flying object for detecting the height of a flying object having a cylindrical outer surface with a flying direction as a central axis,
A plurality of static pressure holes provided at equal positions from the flying direction tip of the cylindrical outer surface, an average static pressure detector for detecting an average static pressure of the plurality of static pressure holes, and provided at the tip of the flying direction. A total pressure detector that detects the total pressure through the total pressure hole, and an altitude calculation device that calculates the altitude by correcting the average static pressure during flight from the detected average static pressure and total pressure. Air pressure altimeter for flying objects. The plurality of static pressure holes have a small fluctuation due to the angle of attack of the pressure coefficient Cp, and the position where the pressure coefficient Cp becomes zero or a value close to zero when the flow velocity direction due to flight coincides with the central axis of the cylindrical outer surface. The air pressure altimeter for a flying object according to claim 1, wherein the air pressure altimeter is provided for the flying object. The flying object is a rocket or a rocket bullet having an elongated cylindrical body and a tail at its end, and the plurality of static pressure holes are sufficiently separated from the tail and the tail at the end and the pressure coefficient Cp is close to zero. The air pressure altimeter for a flying object according to claim 1, wherein six or more are provided at a position in a plane perpendicular to the central axis and at a phase angle equal to the central axis. A plurality of static pressure holes are provided on the cylindrical outer surface at the same position from the tip of the flying direction of the flying object having the cylindrical outer surface with the flight direction as the central axis, and the average static pressure P of the plurality of static pressure holes is detected. Simultaneously detecting the total pressure P1 acting on the tip in the flight direction, calculating the altitude by correcting the average static pressure during the flight from the detected average static pressure and total pressure, and calculating the altitude for the flying object Error correction method. A position where the variation of the pressure coefficient Cp due to the angle of attack is small and the pressure coefficient Cp becomes zero or a value close to zero when the flow velocity direction due to flight coincides with the central axis of the cylindrical outer surface. The error correction method according to claim 4, wherein the error correction method is provided. The flying object is a rocket or a rocket having an elongated cylindrical body and a tail at the end thereof, and the plurality of static pressure holes are sufficiently separated from the tail and the tail of the tip and the pressure coefficient Cp is close to zero. The error correction method according to claim 4, wherein six or more positions are provided at a position in a plane orthogonal to the central axis and at a phase angle equal to the central axis. An estimated dynamic pressure value q0 during flight is calculated from the average static pressure P and the total pressure P1 as a differential pressure q0 = P1-P between the total pressures P1 and P, and an average value Cp ′ of pressure coefficients at each static pressure hole position. Is set in advance by a wind tunnel test, CFD analysis, etc., and the static pressure P ′ for altitude calculation is calculated by correcting the average static pressure P by the following (Equation 1).
Static pressure correction value P ′ = P−Cp ′ × q0 (Expression 1)
The error correction method according to claim 4.

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