NL2034567B1 - A throwing dart and a flight assembly for a throwing dart - Google Patents

Abstract

A dart having a flight assembly and a flight assembly are disclosed. The flight assembly of the present invention may include a wing comprising a frontal section connected to a rear end of a tem, having a first leading edge forming a first sweep angle; and a rear section connected to the frontal section, having a second leading edge forming a second sweep angle wherein the first sweep angle is larger than the second sweep angle.

Description

A THROWING DART AND A FLIGHT ASSEMBLY FOR A THROWING DART

TECHNICAL FIELD

[0001] The present invention relates generally to a throwing dart and a flight assembly for a throwing dart. More particularly, but not exclusively, the present invention relates to a flight assembly that stabilizes the dart quickly when thrown through the air and preferably enhances the probability of stacking.

BACKGROUND

[0002] Darts is a sport in which players throw projectiles called darts at a circular target board called dartboard. The dartboard is divided into 62 sections with different point values and is installed vertically. The players take turns throwing three darts each, from a certain distance away from the dartboard. The points are added up based on where the darts land on the dartboard.

[0003] A dart is a projectile comprising, from the front to the back, a point (also known as tip’), a barrel, a stem (also known as ‘shaft’) and a flight. The direction (front and back) is normally defined by the travelling direction of the dart when thrown in air. In other words, location of the tip is at the front, or a leading side, of the dart and the location of the flight is in the rear, or a trailing side, of the dart. The point, barrel, and the stem normally are in the form of an elongated body which may define a longitudinal axis also referred as a nominal centerline. A flight also has a longitudinal axis where the flat wings are disposed about the longitudinal axis forming a rotational symmetry such as three-fold, four-fold, or higher-fold rotational symmetry. In other words, the flat wings are disposed in an angular distribution with a discrete rotational symmetry about the longitudinal axis. When the dart is assembled, or integrally put together, the longitudinal axes of different parts (point, barrel, stem, and flight) are aligned to form a centrally disposed longitudinal axis of the entire dart. The longitudinal axis is normally a centrally disposed axis connecting the elements from the tip to the flight. The longitudinal axis is also referred to as ‘tip-to-flight axis’.

[0004] The barrel is an elongated body that serves as the main body of the dart. It also serves as the primary gripping point or surface for a user. Therefore, the barrel is typically designed to provide the user with the desired level of comfort, grip, and control. The barrel may be made of various materials including metals, metal alloys, plastic, composite materials and more. The choice of the material may affect the weight, balance, and overall feel of the dart depending on the user’s preference. The barrel can be designed to provide a desired weight, balance, and texture for a user. For example, a typical material used for the barrel is a tungsten alloy having a high mass density, which allows for barrels with smaller diameters to achieve the desired given weight. The barrel typically has a gripping pattern such as grooves to provide a good grip.

[0005] The point, or the tip, of the dart is located at the front end of the dart and is connected to a front end of the barrel, in a direction that the dart is designed to fly. The point can be made from a variety of materials including steel, tungsten, brass, nickel-silver, plastic or any other suitable materials. The choice of material can be tailored to desired weight, balance, and durability of the point. The point can be coated for enhancing durability or texture. The point can be a magnetic point or a suction-cup point.

[0006] The shaft (also known as ‘stem’) connects the barrel to a flight. A stem can be fixed to the barrel or releasably connected to the barrel. Various mechanical fastening means can be used for connecting the stem to the barrel and/or the flight. The stem may be connected to the barrel with a pair of internal and external threads. A stem may be made from different materials including nylon, aluminum, carbon fiber, composite materials and any other materials that are suitable for connecting the barrel and the flight. The length of the stem may vary, hence varying the total length of the dart along its longitudinal axis. Longer stems provide greater stability and accuracy, while shorter stems allow for faster, more agile play.

The cross-section of the stem may vary along the longitudinal axis connecting the tip and the flight. A stem may be fixed rotatably to the barrel and the flight using for example a thread.

[0007] The flight, also known as the fin, is a thin, flat material that is located at the rear/back of the dart, at the opposite side of the tip with respect to the barrel. The flight can be seen as forming a tail of the dart. The flight may be connected to the stem if a dart includes a stem.

The flight is designed to stabilize the dart during its flight by producing lift and drag at a position downstream of the center of mass. The downstream means the tip-to-flight direction and the center of mass is normally within the barrel which is usually the heaviest component of a dart. The flight may have at least two wings forming the outermost edges of the flight when seen from the longitudinal axis (or from the back of the dart). The number of wings is not limited to two. A dart may have three, four, or even more wings. The wings stabilize the dart by providing a stabilizing moment around the center of mass when thrown in air which aligns the longitudinal axis with the direction of travel. The thickness of the wing of the flight is typically small with the goal of reducing weight and the thickness may be lower than 0.5 millimeters or even lower than 0.1 millimeters such as 70 microns. In this document, the term “flight” will be mostly used for indicating the flight element at the rear portion of a dart.

[0008] Deflection is a common challenge that a dart player or a user faces during game. The deflection occurs when a dart is pushed off course by hitting another dart or the wires of the dartboard during flight. This may cause the dart to miss the intended target. The likelihood of deflection may be affected by various factors including shape and weight of the dart. A dart with low probability of deflecting is hence desired. One solution to the challenge is to make the flight portion less firm, for example, by rotatably fixing the flight to the stem such that, when a second dart contacts the flight of a first dart, the rotatable flight of the first dart may absorb the impact of the collision with rotation and leave the second dart’s intended trajectory less altered. However, having a less rigid flight portion may reduce the overall stability and accuracy of the dart. It is hence desirable to have a dart that can avoid deflection while having a stable structure.

[0009] Stacking is a technique where a player throws three darts in close proximity to each other, resulting in a grouping or cluster of darts on an intended section of the dartboard. This technique is desired by dart players as it is necessary to achieve the highest scores, particularly by repeatedly hitting sections such as the triple twenty or bullseye. Typically, a good dart player is able to land a first dart on an intended high-point section. Although the skills of the player mainly determine the chance of successful stacking, the shape of the dart affects how the trajectories may change when a dart collides with a previous dart on the board. Because the flight of the dart occupies the largest area in the cross-section of the darts (when seen from the longitudinal axis}, it is common that the flights of a second and a third dart will touch the flight, particularly from the trailing edge of the flight, of a previous dart landed in the intended section. Therefore, it is desired to have a flight that is designed to facilitate the stacking effect while avoiding deflection. In other words, it is desired to design a dart that can effectively draw the following darts toward a first dart.

[0010] US patent US5,388,840 discloses a dart with a dart flight the has a stepped configuration on its leading and trailing edges. The stepped configuration allows for the flight of a second or a third dart to easily be ejected from the shaft by the impact of collision created with the trailing edge of the first dart. However, this type of dart requires reinstallation of flights if they are ejected in a previous round. This may cause the flights being mounted differently in different rounds, negatively affecting the player's performance as well as distracting the player from his game.

[0011] UK patent application GB2133997A discloses flights of a dart that are mounted on a spindle which is freely rotatable about a longitudinal axis of the dart. The rotatable flight may lower the probability of deflection. However, the rotatability inherently imparts low stability when the dart is thrown in air. In addition, drag will be increased by the rotational motion during travelling in air.

[0012] Therefore, it is desired to have a dart that can quickly stabilize mid-air upon release, preferably with a design that may also facilitate stacking.

[0013] The Background section of this document is provided to place embodiments of the present invention in technological and operational context to assist those skilled in the art understanding the scope and utility of the present invention. Unless explicitly identified as such, no statement herein is admitted being prior art merely by its inclusion in the

Background section.

SUMMARY

[0014] It is an object of the present invention to provide a flight assembly and a throwing dart that can provide improved stability when a dart is thrown in air.

[0015] The first aspect of the present invention relates to a flight assembly, for a throwing dart, having a centrally disposed longitudinal axis, wherein the flight assembly comprises, from front to back: - a stem comprising a barrel connection portion at a front end of the stem and a rear end connected to a main flight unit; and - the main flight unit, having at least two wings symmetrically disposed at spaced intervals about the longitudinal axis, wherein the wing comprises: - a frontal section connected to the rear end of the stem, having a first leading edge forming a first sweep angle; and - arear section connected to the frontal section, having a second leading edge forming a second sweep angle and having a trailing edge forming a third sweep angle, wherein the first sweep angle is larger than the second sweep angle.

[0016] As a skilled person will appreciate, a dart typically contains, from front to back, a point, a barrel, a stem, and a flight (also referred as flight assembly). Each element typically has an elongated shape defining a centrally disposed longitudinal axis. The centrally disposed longitudinal axes of the elements can be mutually aligned when they are assembled as a dart. The aligned longitudinal axes then collectively define a centrally disposed longitudinal axis of the entire dart. Typically, a dart is thrown while the point is in the front and the flight is in the back. In this document, the term ‘front’ refers to the direction that is facing the dartboard when the dart is thrown in air. The term ‘back/rear’ hence refers to the direction that is opposite to the ‘front’ and facing the player that has thrown the dart.

[0017] In conventional darts, a stem is mainly used for elongating the overall length of the dart to a desired length without additional aerodynamic functionality. In other words, the length of a stem generally defines a non-zero distance between the barrel and a lift generating element — such as a flight. In embodiments of the present invention, the stem is included in the flight assembly and may be significantly shorter than that of the conventional dart. This is because the frontal section of the wing can act as an elongating element. The frontal section of the wing of the present invention effectively brings aerodynamic structure closer to the barrel than conventional darts, hence generating lift early on, close to the barrel, when thrown in air.

[0018] In embodiments, when seen from the centrally disposed longitudinal axis, the rear section of the wing defines the outermost edges of the flight assembly. In other words, in the 5 cross-section viewed from the longitudinal axis, the frontal section occupies less space than the rear section. This allows the flight assembly to bring aerodynamic structure closer to a barrel with the frontal section with a smaller cross-section, while keeping the overall space occupied by the flight assembly small.

[0019] In embodiments, the barrel connection portion of the stem may be a thread. An internal thread may be used when connecting to a barrel that has an external thread at the rear end of the barrel. Alternatively, an external thread may be used when connecting to a barrel that has an internal thread at the rear end of the barrel. In embodiments, the barrel connection portion of the stem may be a hollow tube which may be fitted to a rearward protrusion at a rear end of the barrel. In embodiments, the barrel connection portion of the stem may have grip elements on the laterally (also can be seen as radially when seen from the axis) outermost surface. These grip elements may be grooves or a pattern of protrusions. The grip elements may enhance the grip of a player when throwing a dart containing the flight assembly. Additionally, the grip elements may generate vortices closer to the barrel when thrown in air. By promoting the transition from laminar flow to turbulent flow, the generation of lift by the flight is improved when the angle of attack is large.

[0020] In embodiments, the main flight unit may have more than two wings such as three- or four-wings extending radially {also referred as ‘laterally’) from the centrally disposed longitudinal axis. The wing may be a flat, planar surface extending perpendicularly from the longitudinal axis. The surface of the wing is desired to be designed to enhance lift and to reduce drag when thrown in air.

[0021] The wings are symmetrically disposed at angularly spaced intervals about the longitudinal axis. In other words, when seen from the back of the dart, the wings are extending from the center with a radially equal distance from each other. When four wings are used, a cross-hair shape will be seen from the back of the dart wherein each pair of angularly adjacent wings are at a 90 degree angle. When three wings are used, the radially equal distance will be 120 degrees.

[0022] The frontal section of the wing is connected to the rear end of the stem having a first leading edge forming a first sweep angle. A leading edge is used to indicate a foremost edge of a wing or a lifting surface that meets the airflow first in the air. On the contrary, a trailing edge is a rear edge of a lifting surface. In embodiments, the rear section of the wing may further comprise a longitudinal edge between the second leading edge and the trailing edge.

[0023] A “sweep angle”, or an “edge-sweep”, of an edge is defined as an acute angle between the edge and a transverse axis perpendicular to the longitudinal axis. The transverse axis is perpendicular to the centrally disposed longitudinal axis and in the same plane with the longitudinal axis and the edge. When the radial distance of the edge with respect to the longitudinal axis increases in a backward direction (also referred as downstream direction, tip-to-flight direction, point-to-flight direction), the edge is considered as swept backward. A swept-back edge has a positive sweep angle that is an acute angle measured from the transverse axis. On the contrary, when the radial distance of an edge with respect to the longitudinal axis decreases in a backward direction, the edge is considered as swept forward. A swept-forward edge has a negative sweep angle that is an acute angle measured from the transverse axis. When a sweep angle is positive, the larger the sweep angle, the more swept back the edge is.

[0024] In embodiments, the first, second, and third sweep angles are all positive sweep angles.

When the first leading edge of the frontal section has a larger sweep angle than the second leading edge of the rear section, the first leading edge is more swept back than the second leading edge, resulting in that the frontal section has a smaller lifting surface than the rear section and occupies less space. In a preferred embodiment, a positive first sweep angle is larger than a positive second sweep angle. In a more preferred embodiment, a positive first sweep angle is larger than a positive second sweep angle, and the positive second sweep angle is larger than a positive third sweep angle.

[0025] In embodiments, the first sweep angle may be at least 10 degrees larger than the second sweep angle. Preferably, the first sweep angle may be at least 20 degrees larger than the second sweep angle. More preferably, the first sweep angle may be at least 30 degrees larger than the second sweep angle.

[0026] In embodiments, the second sweep angle is larger than the third sweep angle of the trailing edge. In conventional darts, the trailing edge of wings normally forms a negative sweep angle. By having a trailing edge with a positive sweep angle, the present invention may enhance stacking effect. When a player lands a first dart in a region and intends to land a second dart in the same region, he or she would intend to throw an almost identical trajectory as the first one. When a second dart arrives close to the first dart, it is likely that the two darts will make contact. Therefore, it is desired to have a trailing edge that can draw the second dart toward the first dart. A trailing edge with a negative sweep angle may achieve such effect by guiding any part of the second dart (point, barrel, flight) toward the longitudinal axis of the first dart when contacting the trailing edge of the first dart.

[0027] In embodiments, the frontal section may have a length of at least 1 centimeter along the longitudinal axis. In a preferred embodiment, the frontal section has a length of between 2-4 centimeters. In a more preferred embodiment, the frontal section has a length of around 3 centimeters. The frontal section forms a straked section which brings the lift-generation element upstream while avoiding making the entire flight overly large. A frontal section of a first dart may also serve as a supporting structure for a second dart. When the point or a barrel of the second dart makes contact on a frontal section of the first dart, the second dart may deviate from original trajectory and tilt toward the longitudinal axis of the first dart.

[0028] In embodiments, the leading edges and the trailing edges may not be straight edges but curved edges having major edge axes. A sweep angle may be defined based on an average sweep angle that a curved edge is forming with respect to the lateral axis along the edge.

The connecting regions between the edges may be smoothly connected round edges or corners.

[0029] In embodiments, the main flight unit may further comprise a central stem that is centered at the longitudinal axis. The central stem may be hollow or filled depending on a desired weight distribution.

[0030] In embodiments, the trailing edge may include a negative sweep angle region near the longitudinal axis. The negative sweep angle region is kept small such that the average sweep angle of the entire trailing edge is positive. The negative sweep angle region may have a maximal lateral length of 7 mm, preferably 5 mm, more preferably 3 mm. The negative sweep angle region may be formed such that it does not extend rearward beyond an outermost edge of the trailing edge. This negative sweep angle may prevent jamming of following darts in the trailing edge region.

[0031] In embodiments, the flight assembly may be formed integrally using the same or different material.

[0032] In embodiments, the frontal section of the wing is a strake. A “strake” is a protruding surface in addition to and upstream of a main aerodynamic structure of a flying object, such as a wing. An angle of attack is defined by an angle between a reference line of a body and the vector representing the relative motion between the body and the air which the body is moving in. In the case of darts, the reference line is the longitudinal axis. Having zero angle of attack for a dart means the longitudinal axis is aligned with the relative motion of the airflow that the dart is travelling in. The strake creates a vortex of air during flight at non-zero angles of attack and generates lift and reduces drag, particularly at very large angles of attack common in the trajectory of a dart, when a thin wing no longer produces substantial lift.

[0033] In embodiments, the stem is an internal thread configured to mechanically engage with an external thread of a barrel of the dart. The stem may use any other mechanical or chemical connection mechanism that is suitable for connecting to a barrel. In an alternative embodiment, the connecting member may have an external thread and the barrel has an internal thread.

[0034] In embodiments, the stem may be configured to engage with or connect to the barrel or the shaft using different mechanisms including threaded connection, push-in connection, slot-lock connection, shell-lock connection, or magnetic connection. A skilled person will appreciate that any plausible connecting mechanism can be used for such connection.

[0035] A second aspect of the present invention relates to a method for manufacturing the flight assembly of the first aspect. The manufacturing technique may include 3D-printing, injection molding, casting, die-cutting, screen printing, or laser cutting.

[0036] A third aspect of the present invention relates to a throwing dart having a centrally disposed longitudinal axis, wherein the throwing dart comprises, from front to back: - a point disposed at a front end of the throwing dart; - a barrel having an elongated barrel body; and - a flight assembly of the first aspect of the present invention, wherein the flight assembly is connected to a rear end of the elongated barrel body.

[0037] In embodiments, the point is made from any material consisting essentially of steel, tungsten, brass, nickel-silver, or plastic material.

[0038] In embodiments, the point may be a magnetic or a suction-cup.

[0039] A throwing dart typically has a longitudinal profile that is pointy at the front (i.e. a point, tip) and more voluminous at the back (i.e. a flight), along a longitudinal axis. This longitudinal profile allows for defining a cone which represents a conic volume that a dart or a part of the dart occupies. The cone may have an apex at a front end of the point of the dart and have a height along the longitudinal axis of the dart. The height can be the length of the entire dart or a partial length of the dart that a cone is designated to represent. The angle of the cone, or a cone angle, can be defined by the angle between the longitudinal axis and a tangential line stemming from the apex and tangential to the dart or a part of the dart that the cone is designated to represent. For example, a cone can be defined to represent a volume that an entire dart occupies. In this case, the tangential line is likely to be touching a part of the flight. When a cone is defined to represent a minimal cone that the point and the barrel (without flight) are occupying, the tangential line is likely to be touching a part of the barrel.

[0040] In embodiments, a first cone angle may be defined by an angle between the longitudinal axis and a first tangential line, from a front end of the point, that is tangential to the throwing dart, and wherein a second cone angle is defined by an angle between the longitudinal axis and a second tangential line that is tangential to the barrel of the throwing dart, and wherein the second cone angle is less than 50% of the first cone angle, preferably less than 60% of the first cone angle, more preferably less than 70% of the first cone angle. By having a second cone angle that is smaller than a first cone angle, it is possible to allow the points of a first dart and a second dart to be aligned as close as possible without being limited by the position of the laterally outermost point of the entire dart. This allows for an efficient use of space for enhancing stacking of darts.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG. 1 illustrates a conventional throwing dart.

[0042] FIG. 2 illustrates a flight of the conventional throwing dart of FIG. 1.

[0043] FIG. 3A illustrates a throwing dart of the present invention having a flight assembly of the first aspect.

[0044] FIG. 3B illustrates an embodiment of the flight assembly of the first aspect.

[0045] FIG. 3C illustrates another embodiment of the flight assembly of the first aspect.

[0046] FIG. 3D illustrates yet another embodiment of the flight assembly of the first aspect.

[0047] FIGS. 4A-4B illustrate a first exemplary stacking scenario of the present invention.

[0048] FIGS. 5A-5D illustrate a second exemplary stacking scenario of the present invention.

[0049] FIGS. 6A-6C illustrate a top view of the second exemplary stacking scenario of the present invention.

[0050] FIGS. 7A-7C illustrate a prior art counterpart of the top view of the second exemplary stacking scenario of FIGS. 6A-6C.

[0051] FIGS. 8A-8D illustrate a prior art counterpart of the second exemplary stacking scenario of FIGS. 5A-5D.

[0052] FIG. 9 illustrates a throwing dart having a shape that can facilitate efficient stacking.

DETAILED DESCRIPTION

[0053] The following description describes embodiments illustrated in the drawings.

[0054] FIG. 1 illustrates a conventional throwing dart that is not included in the present invention. A dart 100 comprises a point 102, a barrel 104, a stem 106, and a flight 108. The components are aligned along a centrally disposed longitudinal axis 110. The flight 108 has one leading edge and a trailing edge. The trailing edge has a negative sweep angle.

[0055] FIG. 2 illustrates a zoomed-in view of the flight 108 of FIG. 1. The leading edge 204 of the flight 108 defines a first sweep angle A1 that is defined with respect to a lateral axis 202.

The first sweep angle A1 is positive since it is swept backward. The trailing edge 206 of the flight defines a second sweep angle A2 which is negative (swept frontward). The trailing edge 206 with a negative angle does not confer any stacking effect because the angle of the trailing edge will push any contacting object away from the centrally disposed longitudinal axis 110.

[0056] Now follows a description of certain embodiments of the invention, given by way of example only and with reference to the figures.

[0057] FIG.3A illustrates an exemplary embodiment of a throwing dart 300 having a flight assembly 308 according to the third aspect of the invention, wherein the flight assembly 308 is an exemplary embodiment of the first aspect of the present invention. The throwing dart 300 has a centrally disposed longitudinal axis 310. From front to back along the centrally disposed longitudinal axis 310, a point 302, a barrel 304, and a flight assembly 308 are connected to form the entire throwing dart 308.

[0058] FIG. 3B illustrates an exemplary embodiment of flight assembly 308 of the first aspect of the present invention. Flight assembly 308 comprises a stem 312 comprising a barrel connection portion at a front end of the stem 312 and a rear end connected to a main flight unit 314. The main flight unit 314 comprises at least two wings 314 symmetrically disposed at spaced intervals about the longitudinal axis 310. The wing 314 comprises a frontal section 316 connected to the rear end of the stem 312. The wing 314 has a first leading edge 316 forming a first sweep angle A1. The wing 314 further comprises a rear section 320 connected to the frontal section 316. The rear section 320 comprises a second leading edge 322 forming a second sweep angle A2 and a trailing edge 324 forming a third sweep angle

A3. The first sweep angle A1 is larger than the second sweep angle A2. The second sweep angle A2 may be larger than the third sweep angle A3.

[0059] FIG. 3C illustrates another embodiment of the first aspect of the present invention. In addition to the features illustrated in FIG.3B, the flight assembly 308 of this embodiment further comprises a negative sweep angle region 326 centered on the longitudinal axis 310.

The negative sweep angle region 326 may be connected to the main portion of the trailing edge 322 with a curved surface. On the longitudinal axis 310, the sweep angle may be zero, forming a flat surface perpendicular to the longitudinal axis 310.

[0060] FIG. 3D illustrates yet another embodiment of the first aspect of the present invention. In addition to the features illustrated in FIG. 3B or FIG 3C, the flight assembly 308 of this embodiment further comprises a trailing edge that has a rounded corner connected to a longitudinal edge. The rounded corner may be directly connected to the first leading edge of the frontal section. The sweep angles A1, A2, A3 can be defined by major edge axes of the edges that occupy majority of the lengths of the edges. The edges shown in FIG. 3D are mostly linear. However, the edges may be non-linear. When the edges are non-linear, a sweep angle of a non-linear edge can be defined by an average sweep angle that the non- linear edge is forming along its length.

[0061] FIGS. 4A-4C illustrate a first exemplary stacking scenario of the present invention. In

FIG. 4A shows a first dart 420 landed in a target region 410. A second dart 430 is following the same trajectory of the first dart 420. The first and second darts 420,430 may be any embodiment of the present invention. A trajectory is defined by a trajectory of a center-of- mass of a dart. FIG 4B shows that the second dart 430 is making contact with the first dart 420 at the leading edge of the rear section of the second dart 430. The trailing edge of the first dart 420 guides the second dart 430 toward the first dart 420 using the positive sweep angle. At the same time, the contact generates a forward rotation of the second dart 430 around a center-of-mass of the second dart 430 which is located in the barrel. The rotational motion results in alignment of the point of the second dart 430 toward the location of the point of the first dart 420 as shown in FIG. 4C.

[0062] FIGS. 5A-5D illustrate a second exemplary stacking scenario of the present invention.

The second dart 430 is shown to have a trajectory that is lower than that of the first dart 420.

FIG. 5B shows a moment that the first and second darts 420, 430 are making contact.

Thanks to the frontal section of the wing, the first and second darts 420, 430 are making contact at multiple locations along the wing. This stable contact guides the second dart 430 to travel along a surface of the wing of the first dart 420 and toward the longitudinal axis of the first dart 420 due to the positive sweep angle of the trailing edge of the first dart 420.

Similarly, as in the first exemplary stacking scenario, FIG. 5C shows that when the rear section of the wing of the second dart 430 touching the trailing edge of the first dart 420, the second dart 430 rotates forward resulting in point alignment as in the first scenario. FIG. 5D shows the aligned point locations resulted from this scenario.

[0063] FIGS. 6A-6C illustrate a top view of the second exemplary stacking scenario of FIGS. 5A-5D. FIG. 8A shows a moment that a front end of the barrel of the second dart 430 is making contact with the trailing edge of the first dart 420. Due to the positive sweep angle of the trailing edge of the first dart 420, the second dart 430 rotates toward the longitudinal axis of the first dart 420. FIG 6.B shows that the second dart 430 is guided toward the first dart 420 along a surface of a wing of the first dart 420 close to the back of the barrel. At the same time, the leading edge of the rear section of the second dart 430 is making contact with the trailing edge of the first dart 420, creating extra rotational movement rotating the point of the second dart 430 toward the point of the first dart 420. FIG. 6C shows that the two points of the two darts 420, 430 are put close to each other as a result of this exemplary scenario.

[0064] FIGS. 7A-7C illustrate a prior art counterpart of the top view of the second exemplary stacking scenario of FIGS. 6A-6C. FIG. 7A shows that when the barrel of the second dart 730 makes contact with the trailing edge of the first dart 720, the point of the second dart 730 rotates away from the first dart 720 due to the negative sweep angle of the trailing edge.

FIG. 7B shows that the rotational movement is further intensified when the leading edge of the second dart 730 is making contact with the trailing edge of the first dart 720. FIG 7C shows that this prior art scenario results in a deflection of the second dart 730 away from the first dart 720, deviating from its original trajectory.

[0065] FIGS. 8A-8D illustrates a prior art counterpart of the second exemplary stacking scenario of FIG. 5A-5D. When the second dart 730 makes contact with a surface of a flight of the first dart 720, the contacting surface of this case is significantly smaller than the scenario of FIG. 5A-5D due to the lack of frontal section, or a strake section, of the flight.

FIG. 8C shows that shortly after the contact, the second dart 730 rotates forward where the point of the second dart 730 is rotating away from the point of the first dart 720. FIG. 8D shows that this prior art scenario results in a poor point alignment compared to FIG. 5D.

[0066] FIG. 9 illustrates another embodiment of a throwing dart according to the third aspect of the present invention. Features in the dart that have already been described above with reference to the darts and flight assemblies in figures 3A-3D may also be present in the dart shown in figure 9 and will not all be discussed here again. A first cone angle 930 can be defined by the longitudinal axis 310 of the throwing dart 300 and a first tangential line 910 starting from a front end 950 of the point of the throwing dart 300 and tangential to the entire throwing dart at a tangential point 960. A second cone angle 940 is defined by the longitudinal axis 310 and a second tangential line 920 connecting the front end 950 of the throwing dart 300 and tangential to the barrel 970. The first cone angle 930 may represent a minimal conic volume that the entire dart can occupy, whereas the second cone angle 940 may represent a minimal conic volume that the point and the barrel 970 can occupy. The cone angles of the entire dart and the barrel part of the dart are important factors to consider in designing. The interplay between the cone angles may affect how efficient the space can be used when two or more throwing darts are stacked closely on the dartboard. The second cone angle 940 may be less than 50% of the first cone angle 930. In a preferred embodiment, the second cone angle 940 is less than 60% of the first cone angle 930. In a more preferred embodiment, the second cone angle 940 may be less than 70% of the first cone angle 930.

[0067] The present invention may, of course, be carried out in other ways than those specifically set forth herein without departing from essential characteristics of the invention.

The present embodiments are to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

Claims (18)

Conclusions 1. A flight assembly (308) for a dart having a central longitudinal axis (310), the flight assembly (308) comprising: a. a stem (312) having a barrel connecting portion at a forward end of the stem (312) and having a rear end adapted to connect to a flight unit (314); and b. a flight unit (314) having at least two symmetrically disposed wings at regular intervals about the longitudinal axis (310), the wing comprising: i. a front portion (316) connected to the rear end of the stem (312), having a first leading edge (316) disposed at a first arrow angle (A1); and ii. a rear portion (320) connected to the front portion (316), having a second leading edge (322) disposed at a second arrow angle (A2) and having a rear edge (324) disposed at a third arrow angle (A3), the first arrow angle (A1) being greater than the second arrow angle (A2). 2. The flight assembly of claim 1, wherein the first, second and third arrow angles are positive angles. 3. The flight assembly of claim 2, wherein the second arrow angle is greater than the third arrow angle. 4. The flight assembly of any preceding claim, wherein the first arrow angle is at least 10 degrees greater than the second arrow angle, or preferably at least 20 degrees greater than the second arrow angle, or even more preferably at least 30 degrees greater than the second arrow angle. 5. The flight assembly of any preceding claim, wherein the first and second leading edges, and the trailing edge are non-linear and wherein the arrow angle is defined based on average arrow angles of the first and second leading edges, and the trailing edge. 6. The flight assembly of any preceding claim, wherein the barrel connecting portion of the stem further comprises grip elements on a lateral outer surface. 7. The flight assembly of claim 6, wherein the grip elements are grooves or protruding patterns. 8. The flight assembly of any of claims 6 to 7, wherein the grip elements are designed to generate air vortices when thrown through the air. 9. The flight assembly of any preceding claim, wherein the trailing edge includes a negative arrow angle region adjacent the longitudinal axis. 10. The flight assembly of claim 9, wherein the negative arrow angle region does not extend rearward beyond the outer edge of the trailing edge. 11. The flight assembly of any preceding claim, wherein the forward portion of the wing is a fin. 12. The flight assembly according to any of the preceding claims, wherein the flight unit comprises at least three wings, preferably at least four wings. 13. The flight assembly of any preceding claim, wherein the flight assembly is integrally formed with the same material. 14. The flight assembly of any preceding claim, wherein the stem has an internal thread adapted to mechanically engage an external thread of a barrel of the dart. 15. A method of manufacturing a wing assembly according to any one of the preceding claims. 16. The method of claim 13, wherein the flight assembly is manufactured using 3D printing or injection molding. 17. A dart with a centrally placed longitudinal axis (310), the dart comprising, in sequence from a front side: a. a point placed at the front end of the dart; b. a barrel having an elongated barrel body; and c. a flight assembly according to any one of claims 1 to 14, connected to the rear end of the elongated barrel body. 18. The dart of claim 17, wherein a first cone angle is defined by an angle between the longitudinal axis and a first tangent, from the forward end of the point, tangent to the dart, and wherein a second cone angle is defined by an angle between the longitudinal axis and a second tangent tangent to the barrel of the dart, and wherein the second cone angle is less than 50% of the first cone angle, preferably less than 60% of the first cone angle, even more preferably less than 70% of the first cone angle.