JPH09211017A - Pitot static pressure tube and method of manufacturing the same - Google Patents

Abstract

(57) [PROBLEMS] To provide a Pitot static pressure tube which is easy to manufacture and has a small static pressure error, and a manufacturing method thereof. SOLUTION: A Pitot static pressure pipe 1 is composed of a spindle-shaped tip portion for aerodynamic compensation and a conduit portion having a double pipe structure. Inside the Pitot static pressure pipe 1, there is a dynamic pressure pipe 4 along the central axis.
Is arranged. On the outer peripheral surface of the Pitot static pressure pipe 1, a plurality of static pressure holes 3 are formed at the same position in the axial direction and at predetermined intervals in the circumferential direction. The cross-sectional shape of the entire outer peripheral surface along the tube axis direction is formed to be a spindle shape having a radius of curvature R1. On the other hand, the outer peripheral surface near the static pressure hole 3 has a radius of curvature R1.
It is formed with a larger radius of curvature R2 and is formed, for example, in a plane.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a Pitot static pressure tube applied to an aircraft or the like.

[0002]

2. Description of the Related Art A Pitot static pressure tube is often used when measuring the speed and altitude of an aircraft or the like. At that time, the Pitot static pressure pipe was installed so as to project forward from the fuselage, main wing, and tail, and the measurement was performed while avoiding the influence of the airframe as much as possible.

As an example of prior art, Japanese Patent Laid-Open No. 63-915.
There is a publication No. 10 in which a method for manufacturing a Pitot hydrostatic tube is proposed in which the pressure coefficient distribution in the outer peripheral surface region is obtained and then the positions of the hydrostatic holes are determined.

As another prior art, Japanese Patent Laid-Open No. 5-10
There is a Japanese Patent Publication No. 961 and there is proposed a Pitot static pressure pipe in which a cap for eliminating a static pressure error is provided in front of the static pressure hole.

[0005]

However, the static pressure indicated by the Pitot static pressure tube is sensitively affected by errors such as the shape and surface roughness of the outer peripheral surface. Therefore, it is necessary for a skilled worker to make each one by hand and fine-tune the error, which is not suitable for mass production and is an expensive product.

In particular, the aerodynamic compensation type Pitot static pressure tube which compensates for the influence of the airframe is mass-produced to some extent,
Since it has a spindle-shaped outer peripheral surface, it is practically impossible to modify it after cutting once.

An object of the present invention is to provide a Pitot static pressure tube which is easy to manufacture and has a small static pressure error, and a manufacturing method thereof.

[0008]

According to the present invention, in a pitot static pressure tube having a spindle-shaped outer circumferential surface having static pressure holes, the cross-sectional shape of the entire outer circumferential surface along the tube axis direction has a first radius of curvature. The pitot static pressure tube is characterized in that the outer peripheral surface near the static pressure hole is formed with a second radius of curvature larger than the first radius of curvature. According to the present invention, the entire outer peripheral surface is first cut by a precision machining machine such as a numerically controlled lathe during trial manufacture. Further, the outer peripheral surface near the static pressure hole is formed with a second radius of curvature larger than the first radius of curvature by the same additional cutting work. By forming the outer peripheral surface shape with a plurality of radii of curvature in this manner, it is possible to easily manufacture a prototype with slightly different aerodynamic correction amounts without changing the overall shape of the Pitot hydrostatic tube. In other words, in order to improve accuracy, it is possible to measure the static pressure error one by one in a wind tunnel test or the like, and finely adjust the machining amount in the vicinity of the static pressure hole to compensate the error. By such correction work, static pressure error can be almost eliminated.
At that time, in order to keep the shape correction amount in the processing direction at all times, the first radius of curvature of the entire outer peripheral surface is made slightly smaller than the ideal radius of curvature, and it is overcompensated before correction.
It is preferable to use a method in which processing is performed at the stage of correction work.

According to the present invention, the outer peripheral surface near the static pressure hole is 1
It is characterized in that it is formed by a quadric surface.

Further, according to the present invention, the spindle-shaped outer peripheral surface is formed so that the cross-sectional shape of the entire outer peripheral surface along the pipe axis direction has a predetermined radius of curvature, and then the outer peripheral surface near the static pressure hole becomes a primary curved surface. A method for manufacturing a Pitot static pressure tube, which is characterized in that machining is performed so that According to the present invention, during mass production, the entire outer peripheral surface including the primary curved surface in the vicinity of the static pressure holes can be suppressed from being processed by a precision processing machine.

[0011]

1 is a cross-sectional view of a Pitot hydrostatic tube according to the present invention, taken along the tube axis direction. The Pitot static pressure pipe 1 is composed of a spindle-shaped tip portion for aerodynamic compensation and a conduit portion having a double pipe structure. Inside the pitot static pressure pipe 1, a dynamic pressure pipe 4 is arranged along the central axis, and the opening at the tip functions as a dynamic pressure hole. On the outer peripheral surface of the Pitot static pressure pipe 1, a plurality of static pressure holes 3 are formed at the same position in the axial direction and at predetermined intervals in the circumferential direction. The static pressure hole 3 is formed slightly toward the tip from the position where the spindle has the maximum diameter.

A static pressure chamber 5 for guiding the static pressure in the static pressure hole 3 is formed between the dynamic pressure pipe 4 and the outer pipe of the Pitot static pressure pipe 1. Static pressure sensor 6 installed
Is introduced to

FIG. 2 (a) is an external view showing an embodiment of the present invention, and FIG. 2 (b) is a sectional view in the vicinity of the static pressure hole 3 along the tube axis direction. In FIG. 2B, the radius of curvature is exaggerated for easy understanding.

The cross-sectional shape of the entire outer peripheral surface along the tube axis direction is formed into a spindle shape having a radius of curvature R1. On the other hand, the outer peripheral surface near the static pressure hole 3 is formed with a radius of curvature R2 larger than the radius of curvature R1, and FIG. 2B shows an example in which the radius of curvature R2 is formed as a plane corresponding to infinity. .

The radius of curvature R1 of the entire outer peripheral surface can be mass-produced by a precision processing machine. Further, the radius of curvature R2 near the static pressure hole 3 is formed by additional machining. At this time, the radius of curvature R1 of the entire outer peripheral surface is made slightly smaller than the ideal radius of curvature to make it aerodynamically over-compensated, and the compensation amount is adjusted by the machining work in the subsequent process.

When the entire outer peripheral surface is machined, the radius of curvature R1,
It is also possible to process R2 simultaneously.

Generally, the inner diameter of the static pressure hole 3 is 1 to 1.5 mm.
The processing correction amount Δt near the static pressure hole is 1 to 10 μm.
It will be the order quantity.

FIG. 3A is a graph showing the correction effect of the additional processing in the vicinity of the static pressure hole, and FIG. 3B is a sectional view showing the measurement conditions. Here, the correction width W is plotted on the horizontal axis, and the change ΔCp of the static pressure coefficient Cp is plotted on the vertical axis. In addition, when W = 2 mm, Δt = 2.4 μm, and when W = 4 mm, Δt = 9.5 μm.

Additional processing width W and processing amount Δt near the static pressure hole 3
The relationship of is uniquely obtained by the radii of curvature R1 and R2. By measuring ΔCp for some values of width W, the relationship between ΔCp and width W is derived.

Therefore, the processing amount Δt or the width W required to obtain the predetermined ΔCp can be easily determined.

FIG. 4 (a) is a graph showing an example of measurement results in the wind tunnel test. The horizontal axis shows the position X from the tip of the Pitot static pressure tube 1, and the vertical axis shows the pressure coefficient Cp of static pressure (the upper side is negative). A curve A is a graph which is entirely processed with a radius of curvature R1, and a curve B is a curve of desirable Cp. It is an object of the present invention to bring the point a at the static pressure hole position to the point b without affecting the aerodynamic characteristics of the entire Pitot static pressure tube.

Therefore, as shown in FIG. 4 (c), the pressure coefficient Cp of the static pressure at the position of the static pressure hole is obtained by processing the width W in the vicinity of the static pressure hole with the radius of curvature R2 (> R1). , As shown in FIG. 4B, the value at point a changes to the value at point b.

[0023]

As described in detail above, according to the present invention, the outer peripheral surface is formed with the radius of curvature R1 smaller than the desired radius of curvature, and then the vicinity of the static pressure hole is additionally processed with the radius of curvature R2 larger than R1. It is possible to easily manufacture a prototype that exhibits a predetermined static pressure coefficient without affecting the aerodynamic characteristics of the entire Pitot static pressure pipe. Further, by reproducing this result as it is in a precision processing machine such as a numerically controlled lathe during mass production, it is possible to provide a highly accurate Pitot static pressure pipe while reducing costs.

[Brief description of drawings]

FIG. 1 is a cross-sectional view along a pipe axis direction showing a Pitot static pressure pipe according to the present invention.

2 (a) is an external view showing an embodiment of the present invention, and FIG. 2 (b) is a cross-sectional view in the vicinity of the static pressure hole 3 along the tube axis direction.

FIG. 3 (a) is a graph showing a correction effect by a flat file, and FIG. 3 (b) is a sectional view showing measurement conditions.

FIG. 4 is a graph showing an example of measurement results in a wind tunnel test.

[Explanation of symbols]

 1 Pitot static pressure pipe 3 Static pressure hole 4 Dynamic pressure pipe 5 Static pressure chamber 6 Static pressure sensor

Claims (3)

[Claims] 1. A pitot static pressure tube having a spindle-shaped outer circumferential surface having static pressure holes, wherein the cross-sectional shape of the entire outer circumferential surface along the tube axis direction is formed to have a first radius of curvature. The neighboring outer peripheral surface has a second radius larger than the first radius of curvature.
A Pitot static pressure tube characterized by being formed with a radius of curvature of. 2. The Pitot static pressure tube according to claim 1, wherein an outer peripheral surface near the static pressure hole is formed by a primary curved surface. 3. A spindle-shaped outer peripheral surface is formed so that the cross-sectional shape of the entire outer peripheral surface along the pipe axis direction has a predetermined radius of curvature, and then the outer peripheral surface near the static pressure hole is a primary curved surface. A method for manufacturing a Pitot static pressure tube, characterized by performing machining.