Patent Application
20080067291
Further features and advantages will become apparent from the following and more particular description of the preferred embodiments of the invention, as illustrated in the accompanying drawings, and in which like referenced characters generally refer to the same parts or elements throughout the views, and in which:
Before describing the present invention in detail, it is to be understood that this invention is not limited to particularly exemplified materials, methods or structures as such may, of course, vary. Thus, although a number of materials and methods similar or equivalent to those described herein can be used in the practice of the present invention, the preferred materials and methods are described herein.
It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only and is not intended to be limiting.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one having ordinary skill in the art to which the invention pertains.
Further, all publications, patents and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety.
Finally, as used in this specification and the appended claims, the singular forms “a, “an” and “the” include plural referents unless the content clearly dictates otherwise.
The present invention is an aerodynamic wing having a lifting surface with a leading edge, a trailing edge, and a flexible canopy that substantially forms a lifting surface. In a presently preferred embodiment, the wing is a power or traction kite having an inflatable leading edge design. Also preferably, the kite is controlled by two steering lines and two front lines in conjunction with a trim line. As will be described in detail, the trim line has a variable length that is adjustable and can be mechanically fixed by the user while the kite is in flight.
Turning to
As shown in
The chicken loop line 28 configuration and depower adjustment 32 are used in a conventional manner to control the angle of attack of kite 10. Depower adjustment 32 establishes the sheeting range available to the user when moving the control bar up and down the chicken loop line 28. Generally, a user employs the depower adjustment 32 to adapt kite 10 to the prevailing wind conditions and moves the control bar 26 up and down chicken loop line 28 to provide immediate control over the kite's angle of attack, allowing the user to spontaneously generate more or less power in the kite as desired. Typically, a control bar is tuned so that maximum power is developed in kite 10 when depower adjustment 32 is set to provide the greatest extension of front lines 22 and when control bar 26 is fully sheeted in to maximize the length of front lines 22 relative to steering lines 18 and 20.
In addition to the conventional sheeting mechanisms described above, the present invention provides enhanced control over the aerodynamic profile of kite 10. Referring again to
As shown in
As shown, chicken loop line 28 terminates in a chicken loop 42, which is configured to allow ready engagement and disengagement with a harness hook 44 worn by the user. Preferably, chicken loop 42 is attached to chicken loop line 28 by a swivel attachment 45, such as a ball bearing race or other similar mechanism, and is conventionally formed by a tubing reinforced section of line, which will tend to hold the loop in an open position to allow ready engagement with hook 44. Chicken loop 42 has a quick release safety 46 that allows the user to open loop 42, releasing chicken loop line from hook 44 without unhooking. Chicken loop 42 can also have a length of tubing 47 that may be engaged with hook 44 to prevent chicken loop 42 from detaching from hook 44 unintentionally. Alternative configurations can also be employed, such as by terminating chicken loop line 28 with a rigid ring adapted to be retained by a shackle worn by the user, or other suitable methods.
The proximal location of user adjustable length device 40 allows convenient operation by the user and easy incorporation into a safety system, wherein the trim line 24 is restrained when the control bar 26 is dropped and the chicken loop line 28 is disengaged from the user. As shown in
As can be appreciated, the coaxial relation between trim line 24 and chicken loop line 28 together with the central routing of both lines through aperture 30 minimizes the potential for tangles and twists to develop in the control lines of the kite, even when the control bar and kite are rotated. Although the coaxial routing of trim line 24 is preferred, the trim line could also run adjacent chicken loop line through aperture 30. Further, the trim line 24 could also run directly to a user adjustable length device 40 located proximal to control bar 26 without passing through an aperture, although this can increase the risk of tangles and complicate the use of trim line 24 in a safety system.
For example, users of a kite may wish to perform spins, rotations or loops while flying the kite and may wish to loop the kite itself. All of these maneuvers will impart one or more twists in the control lines. Although such twists can be undone by performing the opposite maneuver, it is often more convenient to simply spin the control bar 26 in the appropriate direction, while maintaining the attachment of chicken loop line 28 to the user. In prior art systems, the safety line or one or more of the other control lines will develop twists or tangles when the control bar is spun on an axis about the chicken loop line. In the present invention, the control bar 26 can be freely spun around chicken loop line 28 without imparting twists between front lines 22 and trim line 24. In turn, this allows the user to quickly untwist the control lines following a sequence of maneuvers without creating additional twists or tangles. Further, the coaxial routing of trim line 24 within chicken loop line 28 presents the user with a clean and uncluttered control bar 26 set up. By minimizing the number of loose and exposed lines, the potential for snags and other interference is reduced.
The adjustment offered by the user adjustable trim line length of the present invention adds a substantial degree of control over the kite's performance characteristics when used in conjunction with the conventional depower adjustment 32 and chicken loop line 28 configuration described above. Specifically, adjusting the trim line length in conjunction with the conventional adjustments of the relative line lengths between the steering lines 18 and 20 and the front lines 22 allows the user to exert precise control over the angle of attack of kite 10 as well as effecting changes in the projected area.
Angle of attack is a critical parameter that effects almost all aspects of a given aerodynamic profile's performance characteristic. For example, angle of attack has a direct correlation to the amount of lifting force generated by the wing. The angle of attack also effects other aspects of the wing's flight such as the relative position of the wing in the wind window. As those having skill in the art appreciate, a kite can occupy a range of positions from forward in the window, that is, in a direction more aligned with the traveling direction of the user, to back in the window, that is, in a direction more perpendicular to the direction of travel. In general, a kite that is positioned further back in the window tends to generate more raw power. However, because of the kite location, that power is developed in a direction more perpendicular to the direction of travel. Some situations, such as accelerating from non-planing speeds and performing certain maneuvers, benefit from a kite that develops more power. Other situations, such as traveling upwind, benefit from a kite that is positioned forward in the window. Even though such a positioning may generate less overall power, the power is delivered in a direction more aligned with the direction of travel and results in a net improvement. Therefore, the ability of the user to adjust the positioning of the kite within the wind window represents a significant performance advantage.
Conventional control systems offer little or no control over the position of the kite within the wind window. Instead, prior art systems substantially rely upon the kite design to govern where the kite will sit in the window. Generally, kites that have been designed with a medium aspect ratio sit further back in the window and develop more power at slower speeds. Such designs can lose some efficiency at higher speeds and may have less upwind ability. Similarly, kites that are designed with a high aspect ratio often exhibit enhanced efficiency at speed and can improve upwind performance. However, high aspect ratio kites can suffer from a lack of power at lower speeds and may be more sensitive to variations in wind velocity. Therefore, users of prior art kites are typically confronted with a choice among competing characteristics and must sacrifice performance in certain areas to gain advantages in others.
In contrast, the present invention provides a control system wherein the position of kite 40 can be precisely controlled by varying the length of trim line 24 and fixing the tension at user adjustable length device 40. Specifically, decreasing the length of trim line 24 causes kite 10 to rotate forward, on a pivot approximately extending through the attachment point of front lines 22 adjacent the leading edge. The noted rotation forward generally makes the kite perform more like a high aspect ratio kite. In this mode, kite 10 sits further forward in the wind window, offering improved upwind ability and greater efficiency at speed. Similarly, increasing the relative length of trim line 24 causes kite 10 to rotate backward, making it perform more like a moderate aspect ratio kite. In this configuration, kite 10 sits further back in the wind window and generates more consistent, low end power. As one having skill in the art will appreciate, this allows a user to modify the characteristics of kite 10 to match changing conditions and demands. For example, it may be desirable to trim kite 10 to fly further back in the wind window to develop sufficient power at lower speeds. Once at speed, kite 10 can be trimmed to fly further forward in the window, to improve upwind ability or further back in the window, to develop consistent pull for maneuvers and tricks.
Another aspect of a kite's aerodynamic performance is its projected area. Given a conventional LEI kites curved profile, the projected area refers to the portion of the kite that is capable of generating lift parallel to the flying lines. Since this area is what represents the pull of the kite, the power of a kite is directly correlated to its projected area. While the projected area can be increased simply by making the kite larger, other design parameters can affect the projected area. For example, given kites having equivalent total area, a kite with a shallower angle of curvature will exhibit more projected area and will develop more power.
Conventional kites and control systems do not generally offer a means for controlling the projected area of a kite, particularly while the kite is in flight. Indeed, since conventional systems do not provide control over this characteristic, most designs attempt to restrain the kite shape to prevent changes in projected area. Although such stability offers more predictable handling characteristics, the range of suitable wind conditions for a given kite are limited.
The present invention, on the other hand, also provides a system and method for controlling the projected area of kite 10 to increase or decrease the overall power generated as desired. Accordingly, kites employing the invention can be used in a wider range of conditions and are suitable for a wider range of users. Specifically, reducing the length of trim line 24 with respect to front lines 22 and steering lines 18 and 20 allows the wingtips to spread, thus increasing the projected area of kite 10. Similarly, increasing the length of trim line 24 with respect to front lines 22 and steering lines 18 and 20 transfers more load to the wingtip lines, effectively drawing them together and decreasing the projected area of kite 10. Thus, adjusting the length of trim line 24 also controls the projected area of kite 10 and the power it can develop. A complementary benefit associated with the ability to modify the profile of the leading edge of kite 10 is that trim line 24 helps stabilize the shape in its modified configuration.
As discussed above, adjusting the length of trim line 24 imparts significant control over the aerodynamic performance of kite 10. By combining the control over the angle of attack and projected area with the conventional sheeting and depowering mechanisms, any number of performance enhancements can be gained in a wide variety of conditions.
For example, in one mode the user adjustable length device is engaged to shorten trim line 24 and depower adjustment 32 is set to provide the greatest extension of front lines 22. When control bar 26 is positioned from about the middle of its throw and inward on chicken loop line 28, kite 10 exhibits additional low end power because the projected area is increased. In this configuration, the kite also flies relatively further forward in the wind window. As with conventional systems, sheeting control bar 26 in further increases the power of kite 10. However, sheeting control bar 26 out in this mode effectively increases the aspect ratio of kite 10. Thus, providing kite 10 is moving at sufficient speed, enhanced upwind performance can be obtained by sheeting control bar 26 out. Engaging depower adjustment 32 substantially maintains these performance attributes, but attenuates the power of the kite in order to compensate for increased wind velocity or overpowered conditions.
As one of skill in the art will appreciate, various combinations of the controls can be selected to accommodate specific situations. For example, maximum low end power at minimal kite speed can be developed by fully sheeting in control bar 26 and shortening trim line 24 a moderate amount to increase the projected area of kite 10. Once kite 10 has reached flying speed, the aspect ratio of kite 10 can effectively be increased by further shortening trim line 24, providing improved upwind ability and enhanced efficiency at speed. Once at speed, sheeting control bar 26 fully out and returning trim line 24 to a moderate length provides maximum upwind performance by increasing the projected area and maintaining an effective high aspect ratio. Maximum speed can be obtained by fully engaging the user adjustable length device to minimize the length of trim line 24 while sheeting control bar 26 half way and engaging depower adjustment 32 at about half the available range. Finally, when optimum steering control is desired, depower adjustment 32 and user adjustable length device 40 should be fully disengaged to provide maximum extension of front lines 22 and maximum length of trim line 24.
Turning now to
As discussed above, the control systems of the invention couple improved aerodynamic performance with enhanced safety. Specifically, shortening the length of trim line 24 relative to the other flying lines offers the option of fully depowering the kite. This can be achieved either by manually pulling on handle 50 while the user remains secured to chicken loop line 28 or by attaching safety line 48 to trim line 24, thus allowing the user to disengage from chicken loop line 28 and drop control bar 26.
Trim line 24 also facilitates the relaunch of kite 10, allowing kite 10 to be rolled onto its back from a face down position, and relaunched with controlled power by adjusting tension on trim line 24.
Control systems embodying adjustable trim lines according to the invention also allow the user to adjust the handling characteristics as desired. For example, it is recognized that conventional four line kites exhibit a characteristic feel when steering the kite in flight. Certain kites tend to balance more force on the front lines, and thus little force is transmitted through the steering lines, generating relatively light bar pressure. On the other hand, other kite designs transmit more pull to the steering lines. Thus, in use, the user has to overcome greater resistance when sheeting in the control bar, creating relatively heavier bar pressure. Each design offers various advantages and drawbacks, depending on the wind conditions and the preferences of the user. By employing user adjustable length device 40 to change the length of trim line 24, a user can adjust the feel of the kite between light and heavy bar pressure.
An alternate embodiment of the invention is shown in
Chicken loop line 78 extends through aperture 86 in control bar 62 and terminates in chicken loop 88. Preferably, chicken loop 88 is attached to chicken loop line 78 by a swivel attachment 90, such as a ball bearing race or other similar mechanism. Also preferably, chicken loop 88 has a quick release safety 92 that allows the user to open loop 88, releasing chicken loop line 78 without unhooking. Chicken loop 88 can also have a length of tubing 94 to help prevent unintentional detachment.
Positioning user adjustable length device 72 distal to control bar 62 still allows ready access to all the length adjustments and benefits associated with having increased control over the trim of the kite. This configuration is not as preferred for attaching a safety line to trim line 70, however. The position of user adjustable length device 72 allows twists to develop in a safety line secured to trim line 70 when the bar is rotated or the kite is looped. Nevertheless, this configuration is still suitable, particularly in situations where other safety provisions have been made or when rotations of the kite or control bar are unlikely.
Described herein is a preferred embodiment, however, one skilled in the art that pertains to the present invention will understand that there are equivalent alternative embodiments. In particular, the preferred embodiments described involve a four line control system with a trim line, wherein the trim line and chicken loop line are routed through the control bar and wherein the user adjustable length device is located proximal to the control bar. Nevertheless, other embodiments are suitable for the practice of the invention including systems wherein the user adjustable length device is located distal to the control bar or systems utilizing only two steering lines and the trim line. As such, these changes and modifications are properly, equitably, and intended to be, within the full range of equivalence of the following claims.
