KR20140101556A - Structural spring landing gears for aircraft without wheels, determination method of shape thereof, and program storage media - Google Patents

Abstract

According to the present invention, regarding landing gears fixated to one bottom side of an airplane, the landing gears include a plurality of landing members. The landing members is formed by a shape in which a first quadrant circle and a second quadrant circle, having the respective centers of circles placed opposite to each other based on the landing members, are combined.

Description

TECHNICAL FIELD [0001] The present invention relates to a non-sliding aircraft landing apparatus, a method for determining a shape of a non-sliding aircraft landing apparatus, and a program recording medium.

The present invention relates to a non-sliding aircraft landing apparatus, a method of determining the shape of a non-sliding aircraft landing apparatus, and a program recording medium. More particularly, the present invention overcomes the disadvantages of the prior art ring structure and beam structure, And more particularly, to a non-sliding aircraft landing apparatus, a method of determining a shape of a non-sliding aircraft landing apparatus, and a program recording medium having a new shape structure having load bearing capacity and flexibility.

Figure 1 shows a landing gear in the form of a fixed, two-legged. As shown in FIG. 1, landing gears of a fixed type are often applied to light aircraft or helicopters because the folds are very simple and light in weight compared to the system. However, since it is vulnerable to shock absorption, a device such as a spring damper is attached separately to prevent shock absorption and structural damage when applied to aircraft class of two or more passengers.

Fixed type landing gears have a ring structure with a beam or curvature under a small load depending on the load characteristics of the aircraft. The beam structure is simpler than the ring structure and more deformed than the ring structure, so that the energy absorbing ability is better, but the energy loss due to the frictional force is small and the recoil phenomenon occurs due to the recoil energy. On the other hand, the ring structure is less deformed than the beam structure and is vulnerable to the impact load, but has a merit of stabilizing immediately after the landing since the energy loss due to the friction is large.

Korean Patent Registration No. 602708 (2006.07.11) relates to an ultra light landing device for a vertical take-off and landing device. In order to provide a landing device capable of stable landing while minimizing weight and easy to produce and assemble, In a landing gear of a take-off and landing device, two or more arch-shaped bodies are coupled to intersect with a central portion coupled to and fixed to the main body of the vertical take-off and landing device, and the main body of the vertical take- A seat portion that is seated, a bent portion that is bent downward at a predetermined angle, and a landing portion that is in contact with the ground. However, this patent does not properly define the shape correctly.

Korean Patent No. 602708 (2006.07.11), an ultra-light landing apparatus for a VTOL aerial vehicle,

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to overcome the disadvantages of the conventional ring structure and beam structure, A method for determining a shape of an aircraft landing gear for non-sliding use, and a program recording medium.

It is another object of the present invention to provide a non-sliding aircraft landing apparatus, a method of determining the shape of an un-sliding aircraft landing apparatus, and a program recording medium having a harmful shape structure, For other purposes.

In order to achieve the above object, according to the present invention, there is provided a landing gear fixed to a lower side of an aircraft, the landing gear including a plurality of landing members, The first quadrant and the second quadrant being coupled to each other with the centers of the circles of the circles being opposite to each other with respect to the landing member.

Here, when the first quadrant is closer to the aircraft, and the second quadrant is closer to the ground, the landing member is positioned so that the center of the circle of the first quadrant exists in the opposite direction to the ground, And the center of the circle of the second quadrant exists in the paper surface direction.

At this time, it is preferable that the plurality of landing members are mounted on the aircraft in separated form, or applied to the front landing apparatus in the form of an outer leg.

Alternatively, if the first quadrant is closer to the aircraft and the second quadrant is closer to the ground, the landing member is positioned such that the center of the circle of the first quadrant exists in the ground direction , The center of the circle of the second quadrant may exist in the direction opposite to the ground.

In this case, it is preferable that the plurality of landing members are in the form of a two-legged landing gear structure.

In the case where the first radius R ₁ and the quadrant circle, and the radius of the second circle four minutes _{R 2, R 1 + R 2} = R, R 2 may be a 0.62R≤R ₂ ≤0.72R .

Also, when the radius of the first quadrant is R ₁ , the radius of the second quadrant is R ₂ , and R ₁ + R ₂ = R, R ₁ : R ₂ = 1: 2.

Also, when the radius of the first quadrant is R ₁ , the radius of the second quadrant is R ₂ , and R ₁ + R ₂ = R, R ₁ : R ₂ = 3: 7.

On the other hand, it is possible to extend the end of the landing member and adhere or fit the rubber flow having a high friction coefficient to the underside of the extended end.

Further, it is also possible to extend the end of the landing member to a minimum size of 0.1R, and to attach the rubber stream having a high friction coefficient to the bottom surface at a minimum size of 0.2R or to attach the rubber stream to the bottom surface.

According to another aspect of the present invention, there is provided a method of determining the shape of a non-sliding aircraft landing gear, the method comprising: determining a shape of a landing gear fixed to a lower side of an aircraft, And combining the first quadrant and the second quadrant, wherein the centers of the respective circles are opposite to each other with reference to the landing member.

A program recording medium according to another embodiment of the present invention records a program for causing a computer to execute all or a part of each step of the method for determining the shape of a non-sliding aircraft landing gear described above.

According to the non-sliding aircraft landing apparatus, the method of determining the shape of the non-sliding aircraft landing apparatus, and the program recording medium according to the present invention,

First, it is possible to overcome the disadvantages of the conventional ring structure and beam structure, and thus it is possible to provide a non-sliding aircraft landing apparatus having a new shape structure having load bearing capacity and flexibility.

Second, since the shape definition is clear in the present invention, it is possible for a person skilled in the art to easily produce it repeatedly.

Third, easy repetitive production is possible, and economical effect is also expected.

Figure 1 shows a landing gear in the form of a fixed, two-legged.
Fig. 2 shows the load acting on the landing gear obtained by using the energy equation in the absence of? E.
3 is a view showing a relationship between a beam structure and a ring structure displacement with reference to a friction coefficient μ = 0.55.
Fig. 4 is a view showing ring A type, ring B type, and beam type.
5 is a view showing a bending moment relationship.
Fig. 6 is a view showing a combination of a rigid type A type and a soft type B type.
7 is a view showing a displacement relationship of a double ring structure.
Fig. 8 shows shapes having different widths and heights.
Figure 9 is a plot of displacement versus b / a (height / width ratio) versus radius R ₂ .
10 is a diagram for an optimum split ratio of a double ring structure.
11 is a diagram comparing landing load ratios of the landing gear according to the present invention.
Fig. 12 shows an example of the shape of the fixed landing gear for non-sliding.
Figs. 13 and 14 are diagrams showing the moment distribution when the frictional force acts inward from the outside (mu = + 0.55) to the landing gear configuration of Fig. 12 (mu = -0.55).
Fig. 15 shows a displacement distribution in each cross section when the moment of Fig. 13 is applied.
16 is a diagram showing a linear EI change distribution.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately The present invention should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

Fig. 2 shows the load acting on the landing gear obtained by using the energy equation under the absence of DELTA E, Fig. 3 is a view showing the relationship between the beam structure and the ring structure displacement at the time of mu = 0.55, Ring type A, ring B type and beam type, FIG. 5 is a view showing a bending moment relationship, FIG. 6 is a view showing a combination of an A type, which is a rigid structure, and a B type, , Figure 7 is a view showing a displacement relation between the ring structure of 2, Fig. 8 is an exemplary width and height shown another shape, Figure 9 is a displacement with respect to b / a (height / width ratio) for R _2, the radius Fig. 11 is a view for comparing the landing load ratios of the landing gear according to the present invention, Fig. 12 is a diagram showing the shape of the fixed landing gear for non- 13 and Fig. 14 are views showing the landing gear shape of Fig. 12 FIG. 15 is a view showing a moment distribution when the frictional force works in the inward direction (μ = + 0.55) and the opposite direction (μ = -0.55), and FIG. 15 is a diagram showing the displacement distribution in each cross section when the moment in FIG. And Fig. 16 is a diagram showing a linear EI change distribution.

Conventional airplane landing gear absorbs impacts and design technology that emits its own energy is very important, so most of the aircraft that are subjected to large load have Oleo form.

Since the damper discharges energy and removes the repulsive force after landing, it is necessary for aircraft subjected to large load, but a lightweight aircraft of less than two persons under a relatively small load has a damper or skid form I am taking landing gear.

In this structure, the larger the amount of deformation is for energy equal to E α F δ, the smaller the load acting on the gas. Where E is the energy, F is the load acting on the gas, and δ is the deformation.

It is stated in the regulations that landing gear should withstand at least 8 to 10 ft / sec drop rate, although it is desirable to land at as low a speed as landing energy is proportional to the square of the drop rate.

Fig. 2 shows the load acting on the landing gear obtained by using the energy equation in the absence of? E.

Where v _s is the velocity of fall, L is lift, δ _v and δ _t are the vertical displacement and total displacement of the landing gear, K _eff is the stiffness of the landing gear, ΔE is the loss energy, m is the mass of the mass, .

As shown in Fig. 2, at the same dropping rate, the displacement of the landing gear is large, so that the landing load is reduced. Since the deformation of the landing gear is related to the frictional force, deformation due to frictional force should also be considered. The frictional force absorbs the energy, which reduces the recoil energy, which is a weak point of the elastomeric landing gear, but it can increase the impact load because it suppresses the deformation of the elastic landing gear.

Therefore, it is necessary to reduce the impact load by controlling the displacement by the frictional force, and reduce the recoil energy by inducing energy loss.

The coefficient of friction (μ) recommended in the design rules for the landing gear is μ = 0.55 at landing, and μ = 0.55 is applied for ground operation at maximum μ = 0.8 depending on the condition of the road surface.

In order to investigate the relation between the vertical load and the friction force, the displacement characteristics of the beam structure and the ring structure applied at present are analyzed and shown in FIG.

In the case of the beam structure, a substantially constant displacement (including frictional force) is generated irrespective of the width-to-height ratio (b / a). The displacement due to the frictional force component increases with the increase of b / a, but it is more than 0.5 times that of the case without friction at b / a> 0.9. That is, it means that the energy loss due to the frictional force is 50% or more when b / a> 0.9.

On the other hand, the ring structure has a small deformation due to the large displacement component due to the frictional force, and has a stiffness property compared with the beam structure although it is 0.5 times or more as compared with the case without friction at b / a> 0.57.

In the shape with b / a> 0.9, the beam structure can mitigate the impact load much more than the ring structure, and the recoil energy also has a loss of more than 50%. At b / a < 0.9, the impact load can be reduced. However, since the rebound energy of 50% or more is generated and may be vulnerable to vibration, it may be said that attachment of a damper capable of absorbing energy is required.

The ring structure is considered to be effective in the vicinity of b / a = 0.6. However, when 0.6 <b / a <0.9, it is not easy to meet the conditions of impact load and reaction energy in both beam structure and ring structure. do.

In order to understand the advantages and disadvantages of the beam structure and the ring structure, the displacement characteristics are analyzed for the ring structure and the beam structure as shown in FIG. The relationship between the displacement δ = c ₁ (PR ³ ) / EI and the displacement δ = c ₂ (HR ³ ) / EI due to frictional force is shown in Table 1 below. Where c ₁ and c ₂ are specific constants, P is the vertical load, H is the horizontal load, R is the radius, and EI is the flexural stiffness.

Vertical displacement Horizontal displacement c ₁ c ₂ c ₁ c ₂ Type A 0.356 -0.5 0.5 -0.785 B type 0.785 -0.5 0.5 -0.356 Beam type 0.471 -0.471 0.471 -0.471

The A type has a smaller deformation in the vertical direction than the B type and is highly effective as a load supporting structure due to a large deformation due to frictional force, but is unsuitable as a shock absorbing structure. The bending moment diagram of Fig. 5 when frictional force (mu = 0.55) acts on the three structural shapes can be seen more clearly. B type is excellent as an energy absorbing structure, but it is required as a structural reinforcement because there is a substantial portion of a cross section that acts more than moment acting on root. Although the shape of the beam structure seems appropriate as an impact relaxation structure, there is a disadvantage that the recoil energy is not largely lost according to the geometrical characteristics as shown in FIG.

Therefore, in the present invention, as shown in Fig. 6, two types of shapes (one quarter of a circle and hereinafter referred to as "quadrant") combined with the rigid structure A type and the soft structure B type The displacement was analyzed. R ₁ + R ₂ = R so as to have the same length (πR / 2) as the single ring structure of radius R.

The landing gear includes a plurality of landing members. The landing member includes a plurality of landing members each having a center of each circle, Can be defined as a combination of a first quadrant and a second quadrant that are opposite to each other with reference to the landing member. In this case, the "a" form indicates that the first quadrant is close to the aircraft And the second quadrant is closer to the ground, the landing member is positioned such that the center of the circle of the first quadrant exists in the ground direction, the center of the circle of the second quadrant is in the opposite direction of the ground, The "b" shape is such that when the first quadrant is close to the aircraft and the second quadrant is near the ground, the landing member is in the opposite direction when the center of the circle of the first quadrant is opposite , The center of the circle of the second quadrant exists in the paper surface direction.

And the displacement value of the &quot; a &quot; shape and the &quot; b &quot; shape is obtained according to the change ratio (R2 / R) of the outer radius of curvature. 7 is a diagram showing a displacement relationship of a double ring structure. The &quot; a &quot; shape is a rigid structure shape, and the &quot; b &quot; shape is a soft structure shape. The shape of "a" gradually becomes more flexible as R2 becomes larger, while the shape of "b" gradually becomes more rigid.

The "I" shape has a disadvantage in that it is bent at a right angle at the fixing part when the left and right are not fixed to the gas in a separated form. Particularly, since the fixing portion is vulnerable to stress concentration and fatigue load, there should be no sudden change of shape in the vicinity thereof, and the bending load should be small. Therefore, the "I" shape is not suitable for landing gear in the form of a double leg. However, it may be applied to a separate form or to a forward landing gear of a leg type.

Therefore, the two-legged landing gear structure is suitable for the "a" shape, and the method for deriving the shape is to reduce the displacement due to the frictional force at the point where the rigid structure of the "a" It is appropriate for the design to be set in the range up to 50%.

The landing gear should have a small impact load and a small rebound load. Since these conditions are incompatible with each other, it is very difficult to satisfy all at the same time. Therefore, we want to derive the optimal shape by defining quantitative criteria that satisfy both conditions simultaneously.

The impact load condition is defined as the point where the energy loss rate due to friction is at least 50% and the recoil load condition is defined as the point where the "b" type soft structure intersects with the "a" type stiffness structure. It is preferable to use the upper boundary line for aircraft subjected to a relatively large load and the lower boundary line for a small load, but two integer ratios are proposed as a golden division ratio.

- optimum shape: 0.62R≤R ₂ ≤0.72R

The golden split ratio is R ₁ : R ₂ = 1: 2 or R ₁ : R ₂ = 3: 7.

As shown in FIG. 8, the beam structure is effective in the shape of b / a> 0.9 and the ring structure is in the shape of the minimum b / a> 0.57 in the general case where the width (a) and the height The loss can be expected to be 50% or more, and the displacement is analyzed in order to examine the change of the optimum shape of the double ring structure in the shape of b / a = 0.6, 0.7, 0.8, 0.9 and 1.0, . For reference, FIG. 8 shows shapes having different widths and heights, and FIG. 9 shows displacements relative to b 2 / a (height / width ratio) versus radius R ₂ .

As the height decreases, the moment due to frictional force decreases. Therefore, the displacement due to frictional force decreases. Based on the point at which each friction force displacement line meets, the dividing line as shown in FIG. 10 is finally obtained. relative to the case of _{b / a> 0.8 R 1:} R 2 = 3: 7 , or _{R 1: R 2 = 1:} 2 and, in the case of b / a <0.8 is chosen to the nearest whole number ratio from FIG. 10 is a diagram for an optimum split ratio of a double ring structure.

The landing load ratio for the shape of the present invention was compared to the beam structure at b / a? 0.9, and to the ring structure at b / a < 0.9. In case of b / a = 0.9, the beam structure is compared with the beam structure because the impact load and the reaction load are very small compared with the ring structure. It can be seen that the impact load can be reduced by about 11% compared to the beam structure, while for the ring structure, the load decreases from b / a = 0.8 up to 40%.

The beam structure is effective when b / a is large. However, since the shape changes suddenly at the fixed portion, reinforcement should be performed considering stress concentration and fatigue characteristics. If the height of the landing gear is not sufficient, It has already been mentioned in FIG. If 0.6 <b / a <0.8, the ring structure is applied. Because of the high impact load, the application range is very limited.

However, the present invention has no geometric limitation, can significantly reduce the impact load and the reaction load, and also has the advantage that stress concentration does not occur because the shape change gradually changes along the curvature of the elliptical structure. 11 is a diagram comparing the landing load ratios of the landing gear according to the present invention.

12, b / a = 1, R ₁ : R ₂ = 1: 2, the end is extended to a minimum size of 0.1R, and a rubber having a high coefficient of friction is cut to a minimum size of 0.2R In the lower surface or in the form of fitting. For reference, Fig. 12 shows an example of the shape of a fixed landing gear for non-sliding.

13 and 14 show the moment distribution when the frictional force acts inward from the outside (μ = + 0.55) (μ = -0.55) against the landing gear configuration of FIG. 12. Here, + means that the frictional force acts from the outside to the inside, and - means to work in the opposite direction. It can be confirmed that the structure proposed in the present invention is advantageous both in terms of strength and flexibility of displacement. For reference, FIG. 13 shows a comparison of bending moment distributions when μ = + 0.55, and FIG. 14 shows a comparison of bending moment distributions when μ = -0.55.

Fig. 15 shows a displacement distribution in each cross section when the moment of Fig. 13 is applied. There is no change in the vicinity of the inflection point, but the deformation gradually increases. The damping material or the viscoelastic material may be added to the area where the moment decreases and the damping material or the viscoelastic material is adhered thereto. In this case, a plasticity effect such as a hysteresis phenomenon can be expected. Further, It is expected to be possible.

In order to increase the weight loss and flexibility, the displacement when the section ratio is reduced constantly as shown in FIG. 16 is increased by 12%, and the results are shown in Table 2. The weight is reduced by 18.7% and the displacement is increased by 10.4% compared to a certain cross section. The landing load at this time is relaxed up to 15% with reference to 0.125m displacement of a section, and the results are shown in Table 3. 16 is a diagram showing a linear EI variation distribution.

Comparison of displacement according to section ratio Section Linear change section End One 0.3 1/3 point One 0.86 [0035] One One EIδ / PR ³ 0.363 0.401 Displacement increase rate 0 10.4% Weight reduction rate 0 18.7%

Comparison of landing load according to section ratio Vs (m / sec) Landing load factor (g) Reduction rate Section Change section 0.00 1.00 1.00 0% 0.50 1.14 1.11 2% 1.00 1.56 1.46 7% 1.50 2.27 2.03 10% 2.00 3.25 2.84 13% 2.45 4.37 3.74 14% 3.00 6.07 5.13 15%

A method of determining the shape of a non-sliding aircraft landing gear according to the present invention is a method of determining the shape of a landing gear fixed to a lower side of an aircraft, comprising: a plurality of landing members constituting the landing apparatus; And a step of forming a first quadrant and a second quadrant having centers of respective circles opposite to each other based on the combination of the first quadrant and the second quadrant, and the detailed contents thereof have already been described above, and thus the description thereof will be omitted.

A program recording medium according to still another embodiment of the present invention records a program for causing a computer to execute all or a part of each step of the method for determining the shape of a non-sliding aircraft landing gear described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It is to be understood that various modifications and changes may be made without departing from the scope of the appended claims.

Claims (21)

A landing apparatus fixed to a lower side of an aircraft,
The landing gear includes a plurality of landing members,
Wherein the landing member has a shape in which a first quadrant and a second quadrant are coupled to each other, the centers of the respective circles being opposite to each other with respect to the landing member,
Non - sliding aircraft landing gear.
The method according to claim 1,
When the first quadrant is closer to the aircraft and the second quadrant is closer to the ground,
Wherein the landing member is such that the center of the circle of the first quadrant exists in the opposite direction of the ground and the center of the circle of the second quadrant exists in the direction of the ground.
3. The method of claim 2,
Wherein the plurality of landing members are each mounted on the aircraft in a separate form, or applied to the front landing gear in the form of a leg.
The method according to claim 1,
When the first quadrant is closer to the aircraft and the second quadrant is closer to the ground,
Wherein the landing member is such that the center of the circle of the first quadrant exists in the direction of the ground and the center of the circle of the second quadrant exists in the opposite direction of the ground.
5. The method of claim 4,
Wherein the plurality of landing members are in the form of a two-legged landing gear structure.
5. The method of claim 4,
If the first four minutes and one radius of the circle is R _1, the second radius R ₂ and quadrant circle, of _{R 1 + R 2 = R,} R 2 is ₂ ≤0.72R 0.62R≤R for the rain slide Aircraft landing gear.
5. The method of claim 4,
Wherein when the radius of the first quadrant is R ₁ , the radius of the second quadrant is R ₂ , and R ₁ + R ₂ = R, R ₁ : R ₂ = 1: 2, Device.
5. The method of claim 4,
The non-sliding aircraft landing with R ₁ : R ₂ = 3: 7 when the radius of the first quadrant is R ₁ , the radius of the second quadrant is R ₂ , and R ₁ + R ₂ = Device.
9. The method according to any one of claims 4 to 8,
Wherein an end of the landing member is extended and a rubber flow of a high coefficient of friction is attached to or fitted to the underside of the extended end.
9. The method according to any one of claims 6 to 8,
Wherein the end of the landing member is extended to a minimum size of 0.1R and a rubber having a high coefficient of friction is attached to or fitted to the bottom of the end at a minimum size of 0.2R.
A method of determining a shape of a landing gear fixed to a lower side of an aircraft,
And forming a plurality of landing members constituting the landing gear by combining a first quadrant and a second quadrant having centers of respective circles opposite to each other with reference to the landing member,
A method for determining the shape of a non - sliding aircraft landing gear.
12. The method of claim 11,
When the first quadrant is closer to the aircraft and the second quadrant is closer to the ground,
Wherein the landing member is positioned such that a center of a circle of the first quadrant exists in the opposite direction of the ground and a center of a circle of the second quadrant exists in the direction of the ground. .
13. The method of claim 12,
Wherein the plurality of landing members are each mounted on the aircraft in a separate form, or applied to the front landing gear in the form of an overhang.
12. The method of claim 11,
When the first quadrant is closer to the aircraft and the second quadrant is closer to the ground,
Wherein the landing member is positioned such that a center of a circle of the first quadrant exists in the direction of the ground and a center of a circle of the second quadrant exists in the opposite direction of the ground. .
15. The method of claim 14,
Wherein the plurality of landing members are in the form of a two-legged landing gear structure.
15. The method of claim 14,
If the first four minutes and one radius of the circle is R _1, the second radius R ₂ and quadrant circle, of _{R 1 + R 2 = R,} R 2 is ₂ ≤0.72R 0.62R≤R for the rain slide A method for determining the shape of an aircraft landing gear.
15. The method of claim 14,
Wherein when the radius of the first quadrant is R ₁ , the radius of the second quadrant is R ₂ , and R ₁ + R ₂ = R, R ₁ : R ₂ = 1: 2, A method for determining the shape of a device.
15. The method of claim 14,
The non-sliding aircraft landing with R ₁ : R ₂ = 3: 7 when the radius of the first quadrant is R ₁ , the radius of the second quadrant is R ₂ , and R ₁ + R ₂ = A method for determining the shape of a device.
19. The method according to any one of claims 14 to 18,
Wherein a rubber flow having a high friction coefficient is attached to or fitted to the underside of the extended end by extending the end of the landing member.
19. The method according to any one of claims 16 to 18,
Wherein the end of the landing member is extended to a minimum size of 0.1R and a rubber having a high coefficient of friction is attached or fitted to the bottom surface at a minimum size of 0.2R.
A program recording medium recording a program for causing a computer to execute all or a part of each step of a shape determination method of a non-sliding aircraft landing apparatus according to any one of claims 11 to 18.

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