DEVICE FOR SUPPRESSING PITCH ANGLE FLUCTUATION IN SEAPLANE

Abstract

Provided is a device for suppressing pitch angle fluctuation in the main body of a seaplane, and enabling operation in higher waves. A float (3) is divided in the length direction thereof into a base member (3a) linked at the center thereof to a seaplane main body (2), and a turning member (3b) located at the lengthwise end of the base member, the turning member being capable of turning between a normal position for being positioned along the length direction of the base member, and an active position for being positioned higher than the length direction of the base member, a linking means (K(6)) being provided between the base member and the turning member to link the two members together in a manner enabling the members to rotate relative to each other, the linking means urging the turning member toward the normal position.

Claims

1. A device for suppressing pitch angle fluctuations in a seaplane, the device being used for a seaplane having a float attached to a lower part of a seaplane main body to suppress pitching of the seaplane main body, the device comprising: a base member provided by dividing the float in its length direction, the base member being a central part of the float and linked to the seaplane main body; a turning member connected at a lengthwise end of the base member, the turning member being capable of turning between a normal position at which the turning member is positioned along a length direction of the base member and an active position at which the turning member is positioned higher than the length direction of the base member; and a linking means disposed between the base member and the turning member, the linking means linking the two members together in such a way as to allow them to rotate relative to each other and urging the turning member to toward the normal position, wherein the linking means forms a center of turn of the turning member on an upper part of the float.

2. The device for suppressing pitch angle fluctuations in a seaplane according to claim 1, wherein the turning member is provided at front of the base member.

3. The device for suppressing pitch angle fluctuations in a seaplane according to claim 1, wherein the turning member is provided at front of the base member and at rear of the same.

4. The device for suppressing pitch angle fluctuations in a seaplane according to claim 1, wherein the linking means is made of an elastic material linked to the base member and to the turning member.

5. The device for suppressing pitch angle fluctuations in a seaplane according to claim 1, wherein the linking means includes: a hinge mechanism linking the base member to the turning member in such a way as to allow them rotate freely; and a spring set straddling the hinge mechanism and interposed between the base member and the turning member.

6. The device for suppressing pitch angle fluctuations in a seaplane according to claim 5, wherein the linking means has an attenuating function of attenuating an urging force of the spring.

7. The device for suppressing pitch angle fluctuations in a seaplane according to claim 5, wherein a substantially spherical projection is formed on one of the base member and the turning member while a recession allowing the projection to be fitted therein is formed on the other of the same.

8. The device for suppressing pitch angle fluctuations in a seaplane according to claim 5, wherein a non-hydrous sealing material capable of elastic deformation is interposed between a counter face of the base member and a counter face of the turning member.

9. The device for suppressing pitch angle fluctuations in a seaplane according to claim 5, wherein a flexible waterproof sheet is provided such that it covers periphery of respective counter faces of the base member and the turning member to watertightly close up a space between the counter faces.

10. The device for suppressing pitch angle fluctuations in a seaplane according to claim 1, wherein a buffer having an elasticity function and an attenuating function is disposed between the seaplane main body and the base member of the float, the buffer linking the seaplane main body to the base member in such a way as to allow them to move relative to each other.

11. The device for suppressing pitch angle fluctuations in a seaplane according to claim 2, wherein a buffer having an elasticity function and an attenuating function is disposed between the seaplane main body and the base member of the float, the buffer linking the seaplane main body to the base member in such a way as to allow them to move relative to each other.

12. The device for suppressing pitch angle fluctuations in a seaplane according to claim 3, wherein a buffer having an elasticity function and an attenuating function is disposed between the seaplane main body and the base member of the float, the buffer linking the seaplane main body to the base member in such a way as to allow them to move relative to each other.

13. The device for suppressing pitch angle fluctuations in a seaplane according to claim 4, wherein a buffer having an elasticity function and an attenuating function is disposed between the seaplane main body and the base member of the float, the buffer linking the seaplane main body to the base member in such a way as to allow them to move relative to each other.

14. The device for suppressing pitch angle fluctuations in a seaplane according to claim 5, wherein a buffer having an elasticity function and an attenuating function is disposed between the seaplane main body and the base member of the float, the buffer linking the seaplane main body to the base member in such a way as to allow them to move relative to each other.

15. The device for suppressing pitch angle fluctuations in a seaplane according to claim 6, wherein a buffer having an elasticity function and an attenuating function is disposed between the seaplane main body and the base member of the float, the buffer linking the seaplane main body to the base member in such a way as to allow them to move relative to each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG. 1 is a side view of a seaplane to which a first embodiment of the present invention is applied;

[0041] FIG. 2 is a front view of the seaplane to which the first embodiment of the present invention is applied;

[0042] FIG. 3 is a side view of the seaplane for explaining an effect of the first embodiment of the present invention;

[0043] FIG. 4 is a chart showing the result of a simulation of the pitch angle fluctuations of the seaplane;

[0044] FIG. 5 is a side view of the seaplane to which a second embodiment of the present invention is applied;

[0045] FIG. 6 is a front view of the seaplane to which the second embodiment of the present invention is applied;

[0046] FIG. 7 is a side view of the float to which a third embodiment of the present invention is applied;

[0047] FIG. 8 is a plan view of the float to which the third embodiment of the present invention is applied;

[0048] FIG. 9 is aside view of the float for explaining an effect of the third embodiment of the present invention;

[0049] FIG. 10 is a side view of the float to which a fourth embodiment of the present invention is applied;

[0050] FIG. 11 is a side view of the float, the side view showing a modification of a fifth embodiment of the present invention;

[0051] FIG. 12 is a side view of the float, the side view showing a modification of a sixth embodiment of the present invention;

[0052] FIG. 13 is a perspective view of a seaplane according to a seventh embodiment of the present invention; and

[0053] FIG. 14 is a perspective view of a different seaplane to which the first embodiment of the present invention is applied

BEST MODE FOR CARRYING OUT THE INVENTION

[0054] A first embodiment of the present invention will hereinafter be described, referring to drawings.

[0055] In FIG. 1, reference numeral 1 denotes a seaplane to which this embodiment is applied. The seaplane 1 includes a seaplane main body 2 and floats 3 attached to the lower part of the seaplane main body 2. The floats 3 are each provided with a device S for suppressing pitch angle fluctuations according to this embodiment.

[0056] The seaplane main body 2 has a wing 2a disposed on top of the center of the seaplane main body 2, a vertical tail 2b disposed on top of the rear of the seaplane main body 2, horizontal tails 2c disposed on both side faces of the lower part of the vertical tail 2b, respectively, an engine 2d disposed above the rear of the wing 2a, and a propeller 2e for generating propelling power, which is attached to the engine 2d.

[0057] As shown in FIG. 2, the floats 3 are attached to both sides of the seaplane main body 2, respectively. Each float 3 is divided into two parts in its length direction such that a rear part serves as a base member 3a while a front part serves as a turning member 3b. The turning member 3b is allowed to turn in a range between a normal position, at which the turning member 3b is positioned in the length direction of the float, and an active position, at which the turning member 3b is positioned higher than the length direction of the float 3.

[0058] The float 3 has its base member 3a fixed integrally to the seaplane main body 2 via a plurality of leg members 4. Between the base member 3a and the turning member 3b, a linking means K is disposed for linking the base member 3a to the turning member 3b. This linking means K is made of an elastic material, of which the elastic deformation allows the turning member 3b to turn toward the active position, relative to the base member 3a. The elastic force of the linking means K urges the turning member 3b to return to the normal position. These base member 3a, turning member 3b, and linking means K make up the device S for suppressing pitch angle fluctuations according to this embodiment.

[0059] The linking means K has end faces whose shape is substantially identical with the shape of the front end face of the base member 3a and with the shape of the rear end face of the turning member 3b. The linking means K is provided as an anisotropic elastic material (e.g., elastic material whose elastic coefficients in the directions of three axes, X-axis, Y-axis, and Z-axis, are perpendicular to each other), which is made of a fiber-reinforced plastic using glass fibers, etc. The linking means K is bonded integrally to the base member 3a and to the turning member 3b, using an adhesive, etc.

[0060] When an external force, which causes the turning member 3b to turn upward, is applied to the turning member 3b, the linking means K deforms elastically to allow the turning member 3b to turn. As the external force diminishes, the linking means K applies an urging force to the turning member 3b, which urging force causes the turning member 3b to return to the position before its turning, i.e., to the above normal position.

[0061] According to this embodiment offering such a configuration, the effect of the device S for suppressing pitching fluctuations positions the base member 3a and turning member 3b of the float 3 on a straight line, that is, keeps them at the normal position, as shown in FIG. 1, in which state the seaplane floats on the water surface.

[0062] When the seaplane starts its flight operation on the calm water surface, the seaplane starts sliding over the water surface with the float 3 kept in its straight position, and continues to slide with less up-and-down movements.

[0063] As a result, pitch angle fluctuations caused at the seaplane main body 2 linked to the float 3 remain small, which gives the seaplane stable aerodynamic characteristics, allowing it to behave in a stable manner.

[0064] Higher waves lead to the larger up-and-down movement of the float 3. As a result, in the case of a conventional seaplane, the pitch angle fluctuations of the seaplane main body 2 grow larger.

[0065] When waves grow higher enough to cause pitch angle fluctuations that make it impossible for the seaplane to retain flight stability, the seaplane comes to have difficulty in operation.

[0066] According to this embodiment, when waves grow higher to a certain level and the upward pushing force of a wave W exceeds the urging force of the linking means K, the wave W pushes up the turning member 3b on the front part of the float 3, as shown in FIG. 3.

[0067] In this process, the turning member 3b is turned upward around the linking means K, which moves the front end of the turning member 3b upward. Meanwhile, the rear end of the turning member 3b is moved up to a smaller extent than the front end. The rear end of the turning member 3b thus stays at a lower position, and the front end of the base member 3a, which is linked to the turning member 3b, also stays at a lower position.

[0068] The base member 3a thus comes in contact with the wave while remaining at its lower position. This allows the base member 3a to climb past the wave at a lower level, which suppresses the up-and-down movement of the base member 3a.

[0069] The turning member 3b having climbed past the wave is caused to return to the normal position by the elastic force of the linking means K, quickly coming in contact with the water surface that follows the wave the turning member 3b having climbed past. This move suppresses the downward movement of the base member 3a.

[0070] Hence not only the upward movement of the base member 3a but also the downward movement of the same is suppressed. This achieves an overall effect that the up-and-down movement of the base member 3a is reduced, which means that the seaplane main body 1 is kept in a position closer to a horizontal position with less pitch angle fluctuations.

[0071] In this manner, the pitch angle fluctuations of the seaplane main body 2 linked to the base member 3a are suppressed and a change in the aerodynamic characteristics of the seaplane 1 is kept small.

[0072] This allows the seaplane to operate on the water surface with high waves, thus easing restrictions on weather conditions under which the seaplane can be operated.

[0073] A second embodiment of the present invention will then be described, referring to FIGS. 5 and 6.

[0074] In the following description, the same components as described in the above first embodiment will be denoted by the same reference numerals and will be omitted in further description.

[0075] This embodiment offers a configuration in which buffers 5 having an elastic function and an attenuating function are disposed between the base member 3a of the float 3 and the seaplane main body 2.

[0076] According to this configuration, the buffers 5 attenuate the up-and-down movement of the base member 3a and transmit the attenuated up-and-down movement to the seaplane main body 2.

[0077] This further enhances the effect achieved by the first embodiment, thus offering an effect of suppressing pitch angle fluctuations against higher waves.

[0078] FIG. 4 depicts the result of a simulation of the pitch angle fluctuations of the seaplane 1. A curve A represents pitch angle fluctuations in a conventional seaplane not having the device for suppressing pitch angle fluctuations. A curve B represents pitch angle fluctuations in the seaplane having the device for suppressing pitch angle fluctuations according to the first embodiment of the present invention. A curve C represents pitch angle fluctuations in a seaplane having a device for suppressing pitch angle fluctuations according to an invention filed by the applicant prior to the present invention. A curve D represents pitch angle fluctuations in a seaplane having a device for suppressing pitch angle fluctuations according to the second embodiment, which device is a combination of the device for suppressing pitch angle fluctuations according to the first embodiment of the present invention and the device for suppressing pitch angle fluctuations according to the invention filed prior to the present invention.

[0079] As it is clearly understood from the simulation result, the first embodiment of the present invention offers an effect of suppressing pitch angle fluctuations higher than an effect of suppressing pitch angle fluctuations offered by the conventional case. Combining the device for suppressing pitch angle fluctuations according to the first embodiment with the same according to the invention filed prior to the present invention achieves the effect of suppressing pitch angle fluctuations as an extremely high level of effect.

[0080] Observing this result in terms of comparison between the length of the seaplane 1 and the height of a wave leads to a conclusion that the height of a wave that allows the seaplane 1 to take off from or land on the water surface is 1/10 of the length of the seaplane 1.

[0081] In this manner, the effect of suppressing pitch angle fluctuations leads to stabilized flight and offers another effect of reducing impact at the seaplane's taking off from or landing on the water surface. The effect also suppresses porpoising, which refers to such destabilizing behavior of the seaplane 1 that it starts bouncing on the water surface and continues to bounce ceaselessly.

[0082] Such effects enable various activities including swift ferrying to isolated islands and medical services there, which are used to be unconceivable, making access to an area, to which land routes are closed due to a disaster, from the area's seashore, supplying medial goods, food, etc., maintain/checking off-shore wind power generation facilities and tidal current power generation facilities, fish-finding on the vast sea, quickly transporting catches from the deep sea, maintain/checking marine culture facilities, coastal guarding, and aerial fire fighting against bushfire carried out by scooping water/seawater from the sea/lake surface to spray water.

[0083] It is understood from the simulation result that the effect of suppressing pitch angle fluctuations according to the first embodiment is smaller than the effect of suppressing pitch angle fluctuations according to the invention filed prior to the present invention. According to the invention filed prior to the present invention, the device for suppressing pitch angle fluctuations is disposed between the seaplane main body 2 and the float 3, which limits types of seaplanes to which the device is applicable. In contrast, the device for suppressing pitch angle fluctuations according to the first embodiment is provided as the float 3 itself. This device, therefore, can be applied to a so-called flying boat whose float itself serves as the main body of the flying boat. The device thus offers an advantage that its range of applications is wider.

[0084] The shapes and sizes of components described in the above embodiments are examples and may be changed to various shapes and sizes according to design requirements, etc.

[0085] For example, the linking means K described in the above embodiments may be replaced with a linking means 6 shown in FIGS. 7 to 9.

[0086] The linking means 6 is structured in the following manner. A link piece 7 is fixed on top of the vicinity of the linking part linking the base member 3a to the turning member 3b and is connected rotatably to a bracket 8 disposed on top of the turning member 3b, via a pivot 9, to form a hinge mechanism. A bracket 10 is disposed at a position where is separated from the hinge mechanism of the turning member 3b, and a buffer 11 composed of a compression spring and an attenuator is connected rotatably to the bracket 10 and to the link piece 7.

[0087] The linking means 6 structured in this manner works in the following manner. In a normal situation, the compression spring of the buffer 11 causes the turning member 3b to stay at the normal position, thus keeping the turning member 3b straight relative to the base member 3a. When an upward pushing force acts on the turning member 3b, as shown in FIG. 9, the compression spring is compressed, allowing the turning member 3b to turn. As the upward pushing force on the turning member 3b diminishes, the compression spring allows the turning member 3b to return toward the normal position.

[0088] As the turning member 3b makes its turning motion, the elastic force of the compression spring is attenuated by the attenuator. This reduces the turning motion of the turning member 3b to zero, that is, causes the turning member 3b to stop turning.

[0089] The above embodiment indicates the example in which the float 3 is divided into two parts to form the turning member 3b on the front end part of the float 3. As shown in FIG. 10, the float 3 may be divided into three parts in its length direction such that the central part serves as the base member 3a and the other parts at the front and rear of the base member 3a serve as turning members 3b and 3c.

[0090] In FIG. 10, the linking means 6 are used to link the above members together. The above linking means K of the first embodiment, however, may be used in place of the linking means 6.

[0091] In this manner, in a case where the turning member 3c is provided at the rear of the base member 3a to make up the device S for suppressing pitch fluctuations, when the seaplane 1 is about to land on the water surface, the turning member 3c at the rear is allowed to land first on the water surface to actuate the device S for suppressing pitch fluctuations, in which case the up-and-down movement of the base member 3a is suppressed.

[0092] Hence the pitch angle fluctuations of the seaplane main body 2 at the seaplane's landing on the water surface can be suppressed effectively.

[0093] As shown in FIG. 11, the linking means 6 may be disposed between the counter face of the base member 3a and that of the turning member 3b.

[0094] When the buffer 11 is used as the linking means 6, the spring of the buffer 11 must be a tensile spring.

[0095] Use of the above linking means 6 may lead to an assumed case where gaps are formed between the base member 3a and the turning members 3b and 3c and when the turning members 3b and 3c are turned, the gaps are expanded, allowing water to flow therein to create resistance to the seaplane's sliding.

[0096] To solve this problem, as shown in FIG. 12, a substantially spherical projection 12 is formed on one of the base member 3a and the turning member 3b (formed on the base member 3a in FIG. 12) while a recession 13, in which the projection 11 is fitted, is formed on the other of the same. Fitting the projection 12 in the recession 13 reduces the gap between the base member 3a and the turning member 3b.

[0097] In another case, as shown in FIG. 13, a non-hydrous sealing material 14 capable of elastic deformation is interposed between the counter face of the base member 3a and that of the turning member 3b to fill the gap with the sealing material 14.

[0098] In still another case, a flexible waterproof sheet (not depicted) is provided such that it covers the periphery of the counter faces of the base member 3a and turning member 3b to watertightly close up the gap between the counter faces. This sheet covers up the gap tightly to prevent water from flowing into the gap.

[0099] In each of the above embodiments, examples of applying the device S to the seaplane 1 having a pair of the floats 3 are described. However, as described in FIG. 14, the device S may also be applied to a seaplane 21 having one float 3 attached to the lower part of a seaplane main body 20. As described above, the device S may also be applied to a flying boat structured such that the float itself serves as the main body of the flying boat.

EXPLANATION OF LETTERS AND NUMERALS

[0100] 1 Seaplane [0101] 2 Seaplane main body [0102] 2a Wing [0103] 2b Vertical tail [0104] 2c Horizontal tail [0105] 2d Engine [0106] 2e Propeller [0107] 3 Float [0108] 3a Base member [0109] 3b Turning member [0110] 3C Turning member [0111] 4 Leg member [0112] 5 Buffer [0113] 6 Linking means [0114] 7 Link piece [0115] 8 Bracket [0116] 9 Pivot [0117] 10 Bracket [0118] 11 Buffer [0119] 12 Projection [0120] 13 Recession [0121] 14 Sealing member [0122] 20 Seaplane main body [0123] 21 Seaplane [0124] K Linking means [0125] S Device for suppressing pitching fluctuations [0126] W wave