NL2019116B1 - Improverd dart - Google Patents

Abstract

Darts is a famous throwing sport in which small missiles or arrows are thrown at a circular dartboard fixed to a wall. A conventional dart comprises a point, a barrel, a shaft and a flight. A disadvantage of the conventional dart is that the dart frequently wobbles while completing a trajectory between a hand releasing the dart and a board acting as target. The current invention provides a tail assembly improving the stability of the dart. The tail assembly (300) for a dart (100) comprising a front assembly (200) and describing a trajectory after release, comprises: - an elongated flight holder (310) comprising a coupling (311) arranged for coupling the tail assembly to the front assembly forming the dart and wherein the elongated flight holder has a longitudinal axis (A); and - a flight (320) connected to the elongated flight holder and arranged for radially extending discrete rotational symmetric relative to the longitudinal axis beyond the elongated flight holder and shaped for continuously generating drag while the dart describes the trajectory.

Description

FIELD OF THE INVENTION

The invention relates to the field of darts, specifically to darts for the game of darts, flights for darts, tail assemblies for darts, front assemblies for darts and pumping stations cooperating with the darts.

BACKGROUND OF THE INVENTION

Darts is a form of a throwing sport in which small missiles or arrows are thrown at a circular dartboard fixed to a wall. Though various boards and rules have been used in the past, the term darts now usually refers to a standardised game involving a specific board design and set of rules. As well as being a professional competitive sport, darts is a traditional pub game, commonly played in Britain and Ireland, across the Commonwealth, the Netherlands, Germany, the Scandinavian countries, the United States, and elsewhere.

A conventional dart comprises a point, a barrel, a shaft and a flight. The point is the part of the dart hitting and partly penetrating the board. The barrel, typically securely attached to the point, provides a grip for gripping the dart when throwing the dart and weight. The shaft is connected to the barrel at one end and at the other end has a cross-shaped notch for receiving a flight.

A disadvantage of the conventional dart is that the dart frequently wobbles while completing a trajectory between a hand releasing the dart and a board acting as target.

SUMMARY OF THE INVENTION

An object of the invention is to provide a dart with improved stability.

According to a first aspect of the invention, a tail assembly for a dart comprising a front assembly and describing a trajectory after release, comprising: an elongated flight holder comprising a coupling arranged for coupling the tail assembly to the front assembly forming the dart and wherein the elongated flight holder has a longitudinal axis; and a flight connected to the elongated flight holder and arranged for radially extending discrete rotational symmetric relative to the longitudinal axis beyond the elongated flight holder and shaped for continuously generating drag while the dart describes the trajectory.

The typical way of a dart to fly through the air is with the point upfront, followed by the barrel providing weight, followed by the elongated flight holder coupling the trailing flight to the barrel. A dart may be partitioned in a front assembly and a tail assembly, typically connected together with a screw connection. The front assembly may comprise the point and barrel, the tail assembly may comprise an elongated flight holder and a flight.

The longitudinal axes of the point, barrel and elongated flight holder are typically aligned to each other forming a longitudinal axis of the dart. After the dart has been thrown, the dart traverses a trajectory and the longitudinal axis has substantially the same direction as the flight direction. If the longitudinal axis of the dart deviates too much from the flight direction, more air will impinge on the surface area of the known flight, thereby developing a drag force after a while, which drag force pushes the longitudinal axis back in line with the flight direction.

Rotational symmetry around an axis is defined as that the shape of the object does not change if rotated around the axis. Discrete rotational symmetry around an axis is defined as that the shape of the object does not change if rotated a particular angle around the axis. For example, a typical prior art flight is discreetly rotational symmetric when rotated over 90 degrees. This may also be described as that the flight is rotational symmetric or discreetly rotational symmetric of order 4.

The flight according to the current invention extends discrete rotational symmetric relative to the longitudinal axis beyond the elongated flight holder. Further, the flight according to the current invention is shaped for continuously generating drag while the dart describes the trajectory. The flight will therefore continuously push air away, thereby continuously generating a drag force opposite to the flight direction.

As the longitudinal axis of the dart may deviate from the flight direction, the already present drag force may directly exert a pulling force pulling the longitudinal axis back in line with the direction of flight. This already present pulling may act instantly. This in contrast to the known flight, which drag force has to build up first before exerting this pushing force upon the flight. The effect of the already present drag force is that the drag force acts quicker upon the flight, thus bringing the longitudinal axis quicker in line with the flight direction. Hence, the dart becomes more stable.

Typically, the elongated flight holder has a diameter of less than 20 mm, preferably less than 10 mm, more preferably less than 7 mm, most preferably less than 5 mm. Typically, the flight has a diameter of more than 10 mm, preferably more than 15 mm, more preferably more than 17 mm, most preferably more than 20 mm.

In an embodiment of the tail assembly, the flight is discrete rotational symmetrically shaped relative to the longitudinal axis of an order of 2, 3, 4 or higher than 4, such as 6, 8 or 10. The dart may deviate from the trajectory in any radial direction. This provides the advantage that the drag force is more symmetrically spread out over all angles relative to the longitudinal axis of the elongated flight holder improving the stability.

In an embodiment of the tail assembly, the flight is rotational symmetrically shaped relative to the longitudinal axis. The dart may deviate from the trajectory in any radial direction. This provides the advantage that the drag force is evenly spread out over all angles relative to the longitudinal axis of the elongated flight holder improving the stability for deviations with an angle in any direction relative to the longitudinal axis.

In an embodiment of the tail assembly, the elongated flight holder and the flight are integrated. The front assembly may have a relative high weight compared to the flight. The inertia moment of the front assembly exerts a force of inertia on the front assembly and via the coupling on the elongated flight holder opposite to any force exerted on the front assembly causing it to deviate from a linear trajectory with a constant velocity. While the dart is traversing the trajectory, the continuously present drag force will continuously decelerate the flight. The connection of the front assembly and the tail assembly of the dart therefore has to withstand the separating forces comprising the force of inertia in one direction and the drag force in the other direction, preventing the flight from separating from the elongated flight holder during flight. The effect of integrating the elongated flight holder and the flight is that the elongated flight holder and the flight will not separate as the integration withstands the separation forces.

In an embodiment of the tail assembly, the tail assembly comprises a releasable connection for connecting the flight and the elongated flight holder, wherein releasing the releasable connection at least comprises a rotation of the flight relative to the elongated flight holder. As described for the previous embodiment, the connection between the flight and elongated flight holder has to withstand the separation forces separating the flight and elongated flight holder during that the dart traverses the trajectory. These separation forces are substantially in the direction of the longitudinal axis of the elongated flight holder. The effect of the step of releasing comprises a rotation is that the separation forces are under an angle of 90 degrees with this rotation and thus should not be able to induce the rotation for releasing. Thus, this embodiment provides an advantageous solution for a connection between an elongated flight holder and a flight.

In an embodiment of the tail assembly, the flight is expendable and/or contractible. This provides the advantage that the flight is adaptable to the required drag force for improving the stability. This also provides the advantage that the flight may be adapted to the condition of the dart, such as being transported, just thrown or when present in the target. Further, the flight may be contracted after the dart hits the target, providing the advantage of not obstructing any other darts thrown by a person to the same target or not obstructing the view of the person throwing the dart on the target.

In a further embodiment of the tail assembly, the flight is retractable. The elongated flight holder may be hollow and the flight may be retracted in the elongated flight holder when not used providing improved safety against damage to the flight. The flight may also be retracted after the dart hits the target, providing the advantage of not obstructing any other darts thrown by a person to the same target or not obstructing the view of the person throwing the dart on the target.

In a further embodiment, the tail assembly comprises a cap covering the opening in the elongated flight holder through which the flight was retracted. This provides the advantage of protecting the flight in retracted position from damage to the flight.

In a further embodiment of the tail assembly, expendable is inflatable and/or contractible is deflatable. This provides the advantage of using flexible materials for simplifying manufacturing of the flight. In a further embodiment of the tail assembly, the flight is repeatable inflatable and deflatable. This provides the advantage of providing a reusable flight. In a further embodiment of the tail assembly, the flight is a balloon. This provides the advantage of using a readily available embodiment of the flight as part of the current invention.

In an embodiment of the tail assembly, the flight is arranged for being shaped at a distal end for creating additional drag during that the dart describes the trajectory. The distal end is distal to the elongated flight holder. The distal end of the flight is the rear part of the dart while the dart traverses a trajectory. The rear part may be shaped to generate an additional drag force. The additional drag force generated by the shape depends on the amount of deviation of the preferable laminar airflow at the rear of the flight. Generating an additional continuous drag force with the distal end of the flight provides the advantage that the flight has to extend less from the longitudinal axis of the elongated flight holder for generating a larger continuous drag force.

In a further embodiment of the tail assembly, the flight comprises a cavity and the tail assembly comprises a string arranged in the cavity and is arranged for pulling on the distal end of the flight for shaping the distal end of the flight. This may provide a distal end with the shape of a flattened projection or even depression. This feature may specifically be combined with that the flight may be expendable and/or contractible, preferably inflatable and/or deflatable.

According to another aspect of the invention, a front assembly for a dart comprising: an elongated body; and control means for controlling expanding and/or contracting of a flight of a tail assembly according to an embodiment of the tail assembly. The tail assembly used for this aspect of the invention is an embodiment wherein the tail assembly the flight is expendable and/or contractible, preferably inflatable and/or deflatable. This provides the advantage that the flight may be adapted to the condition of the dart, such as being transported, just thrown or when present in the target. Further, the flight may be contracted after the dart hits the target, providing the advantage of not obstructing any other darts thrown by a person to the same target or not obstructing the view of the person throwing the dart on the target.

In an embodiment of the front assembly, the control means comprise a valve and wherein expanding is inflating and/or contracting is deflating. Inflating and deflating a flight is typically done by inserting or releasing air from inside the flight. Introducing a valve in the front assembly provides the advantage of a simple means of controlling the inserting and releasing as well as that the introduction of the valve in the front assembly provides a balance point to the dart, which is advantageous during a flight of the dart. An example of a suitable valve is a spring-loaded ball valve.

In a further embodiment of the front assembly, the control means comprise trigger means arranged for triggering the valve to deflate the flight after the dart hits a target. This provides the advantage that the flight may provide improved stability, while the flight may be deflated after the dart hits the target, providing the advantage of not obstructing any other darts thrown by a person to the same target or not obstructing the view of the person throwing the dart on the target.

In an embodiment, the front assembly comprises a point longitudinally moveable attached to the elongated body for triggering the deflating valve.

The elongated body has a weight. As the point hits a target, the point rapidly decelerates. The deceleration may be dampened as the point may partly penetrate the target. The inertia moment of the longitudinal body may exceed a retaining force retaining the point fixated relative to the longitudinal body. As the point is moved relative to the elongated body, this movement may trigger the control means. For example, the control means may be a spring-loaded ball valve. And the movement of the point moves the ball opposite to the force of the spring for opening the valve. The retaining force in this example may be the force the spring is exerting on the ball and thereby closing the valve.

In a further embodiment, the front assembly comprises a retaining index for retaining the point in position and providing an additional retaining force additional to the spring of the spring-loaded ball valve. This provides the advantage of allowing a weaker spring to be used in the front assembly. The retaining index may comprise a circumferential groove and an O-ring arranged in the groove. The circumferential groove may be arranged in the point and the O-ring may be arranged in a fixed position on the inside of the longitudinal body. The O-ring may be positioned in the groove for exerting an additional retaining force holding the point relative to the elongated body. This embodiment of the index provides the advantage of a simple retaining mechanism.

In an embodiment, the front assembly comprises a deflating index for holding the spring-loaded ball valve in an open position. When the valve is in an open position, the flight may deflate. Further, in the open position the spring exerts a force on the ball for moving the valve to the closed position. The deflating index typically has a holding force large than the spring force. Thereby, the deflating index asserts that the flight deflates. The valve is typically brought in the open position after the dart hits a target. The advantage may be that the flight is not obstruction any later dart aimed at the same target or view on the target. Furthermore, an advantage may be that the flight may be covered when deflated to prevent damages by any later dart.

In a further embodiment, the deflating index is provided by arranging a groove and O-ring as described above for the retaining index.

In an embodiment, the front assembly comprises a retaining index and a deflating index. This provides the advantage of a practical combination of indexes for using the dart.

In an embodiment of the front assembly, the valve is discretely rotationally symmetrically arranged to a longitudinal axis of the elongated body. The weight of the valve is equally distributed the over the radius of the longitudinal axis. This provides the advantage that it is indifferent how the dart is rotated while traversing the trajectory.

According to another aspect of the current invention, a dart comprising: a tail assembly according to any of the embodiments according to the current invention described throughout this application; and/or a front assembly according to any of the embodiments according to the current invention described throughout this application. This provides the advantage of having a dart combining the advantages of the front and tail assembly according to the current invention.

According to another aspect of the current invention, a pumping station comprising: an inflate coupling for coupling with a dart comprising a tail assembly according to any of the embodiments described in this application able to inflate; and a pump arranged for inflating the flight through the inflate coupling. This provides the advantage of enabling the use of the dart according to the current invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be apparent from and elucidated further with reference to the embodiments described byway of example in the following description and with reference to the accompanying drawings, in which:

Figure 1 schematically shows a perspective view of a dart according to an embodiment of the current invention with the flight in an inflated condition;

Figure 2 schematically shows a perspective view of a dart according to an embodiment of the current invention with the flight in a deflated condition;

Figure 3 schematically shows a cross-section of a dart according to an embodiment of the current invention;

Figure 4 schematically shows an exploded view of a dart according to an embodiment of the current invention;

Figure 5a schematically shows a perspective view of a tail assembly according to a second embodiment of the current invention;

Figure 5b schematically shows a perspective view of a tail assembly according to a second embodiment of the current invention;

Figure 6a schematically shows a perspective view of a tail assembly according to a first embodiment of the current invention;

Figure 6b schematically shows a perspective view of a tail assembly according to a third embodiment of the current invention; and

Figure 7 schematically shows a cross-section of the first embodiment of the tail assembly according to the current invention.

The figures are purely diagrammatic and not drawn to scale. In the figures, elements which correspond to elements already described may have the same reference numerals.

LIST OF REFERENCE NUMERALS

100	dart
200	front assembly
210	point
211	tip
212	proximal end point
220	housing / barrel / elongated body
221	grip
225	guide
226	abutment
230	valve
231	ball
232	spring
233	spring holder
240	retaining means
241	retaining O-ring
250	deflating means
251	deflating O-ring
260	index bush
261	support ring
270	channel
271	channel guide section
272	channel abutment section
273	channel index bush section
300	tail assembly
310	elongated flight holder
311	coupling (to front assembly, threaded coupling)
312	elongated shaft

313	elongated flight holder cavity
314	flight holder aperture
320	flight
321	balloon
322	balloon rim
323	balloon notch
324	balloon distal end
325, 326, 327, 328	flaps
335, 336, 337, 338	frontal surfaces
340	cap
341	rim
344	releasable connection
345	holder ring
346	string
347	clamp ball
351, 352, 353, 354	ribs
A	longitudinal axis of elongated flight holder

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following figures may detail different embodiments.

Figure 1 schematically shows a perspective view of a dart 100 according to an embodiment of the current invention. The dart comprises a front assembly 200 and a tail assembly 300.

The front assembly comprises a point 210 and an elongated body 220. The point is attached with a proximal end to the elongated body. The distal end of the point is labelled tip 211. When the dart hits a target, such as a board, the tip is normally hitting the target first and may at least partly penetrate the target.

The elongated body, also called housing or barrel, comprises a grip 221.

The grip provides a surface of increased friction for gripping the dart. The improved grip on the dart allows the dart to be accelerated for throwing the dart.

The tail assembly comprises an elongated flight holder 310, a flight 320 and 15 a cap 340. The elongated flight holder defines a longitudinal axis A and comprises an elongated shaft 312. The longitudinal axis is an axis of symmetry for the tail assembly. The front assembly and tail assembly typically share the longitudinal axis A as axis of symmetry.

The flight may comprise a balloon 321. The flight is shown in an inflated condition. The elongated flight holder couples to the front assembly at one end. The flight holder has the flight extending from another end. The flight further defines a distal end 324, distal to the elongated flight holder. The cap is arranged to the distal end of the flight for shaping the distal end of the flight.

The drag equation in fluid dynamics is defined as: Fd = ^pu²C_DB wherein:

Fd is the drag force, which is by definition the force component in the direction of the flow velocity;

p is the mass density of the fluid;

u is the flow velocity relative to the object;

B is the reference area; and

Cd is the drag coefficient.

Cd is a dimensionless coefficient related to the object's geometry and taking into account both skin friction and form drag, in general Cd depends on the Reynolds number. The reference area B is typically defined as the area of the orthographic projection of the object on a plane perpendicular to the direction of motion.

The flight in inflated condition radially extends relative to the longitudinal axis beyond the elongated flight holder. As the elongated flight holder is relatively long, the laminar flow of air will be along the elongated flight holder. Therefore, the inflated flight will contribute to the reference area B and thus to the drag force Fd. Typical lengths of the elongated flight holder are at least longer than 10 mm, preferably longer than 20 mm, more preferably longer than 25 mm, most preferably longer than 30 mm.

The flight typically also radially extends beyond the elongated body or barrel of a front assembly coupled to the tail assembly. As the flight extends beyond the elongated flight holder and the elongated body, the inflated flight will contribute to the reference area B and thus to the drag force Fd.

As the drag force is continuously present while the dart traverses a trajectory, the drag force will continually create a force generally opposite to the direction of travel of the dart. The direction of travel of the dart is typically parallel to the longitudinal axis A.

In case the longitudinal axis starts to deviate from the direction of travel of the dart, the drag force will immediately counteract this deviation as the continuously present drag force opposite to the direction of travel pulls the flight back to a status wherein the longitudinal axis is predominantly parallel to or the same as the direction of travel of the dart.

Furthermore, in case the longitudinal axis starts to deviate from the direction of travel of the dart, the reference area B is also increased, as with the conventional flight, thus adding up to the force aligning the longitudinal axis of the dart with the direction of travel of the dart. Additionally, as this flight is rotationally symmetric relative to the longitudinal axis, the radial direction of deviation does not change the pulling force correcting for the deviation. This, while the conventional flight has a directional dependency. Hence, the advantage of radial indifferent pulling the longitudinal axis inline with the direction of flight of the dart.

Figure 2 schematically shows a perspective view of a dart 100 according to an embodiment of the current invention. The dart comprises a front assembly 200 and a tail assembly 300.

The front assembly comprises a point 210 and an elongated body 220. The point is attached with a proximal end to the elongated body. The distal end of the point is labelled tip 211. The elongated body comprises a grip 221.

The tail assembly comprises an elongated flight holder 310, a flight 320 -not shown-, an elongated flight holder cavity 313 -not shown- and a cap 340. The elongated flight holder comprises an elongated shaft 312.

The flight is in a deflated condition. In the deflated condition, the flight is retracted into the elongated flight holder cavity. Furthermore, the opening, through which the retracted flight is pulled into the flight holder cavity is covered by the cap. This provides the advantage of protecting the flight from any damages. For example, a further dart may not damage the inflatable flight. A further advantage is, that a further dart may be directed to a target without being obstructed by the flight of the dart.

Figure 3 schematically shows a cross-section of a dart 100 according to an embodiment of the current invention. The dart comprises a front assembly 200 and a tail assembly 300.

The tail assembly comprises an elongated flight holder 310, a flight 320, an elongated flight holder cavity 313 and a cap 340. The elongated flight holder comprises an elongated shaft 312. The flight is in a deflated condition and may be a balloon 321. The flight is arranged to the elongated flight holder cavity.

Further, the tail assembly comprises shaping means for shaping a distal end 324 of the balloon. The shaping means comprise a string 346, a clamp ball 347 and a holder ring 345. A side of the balloon at the distal end of the balloon is arranged between the cap and the clamp ball. The cap clamps the clamp ball for fixating the side of the balloon in between. The string is with one side attached to the clamp ball and with the other side to the holder ring. The holder ring is held at one end of the elongated flight holder. The string may be flexible. When the balloon is inflated, the string will exert a pulling force on the clamp ball thereby deforming the distal end of the balloon.

The front assembly comprises a point 210 and an elongated body 220. The point is attached with a proximal end to the elongated body. The distal end of the point is labelled tip 211.

The elongated body comprises a guide 225 for longitudinal movable arranging the point to the elongated body. The elongated body further comprises an abutment for abutting the longitudinal movable point.

The elongated body further comprises a valve 230. Further, the elongated body comprises a communication channel 270. The valve is via the communication channel with one side in fluid communication with the inflatable flight and with another side with the outside air. The valve and the channels for communication may be arranged discrete rotational symmetrical relative to the longitudinal axis, preferable rotational symmetrical relative to the longitudinal axis, providing the advantage of an even mass distribution relative to the longitudinal axis, providing the further advantage that the dart with traverse the trajectory more stable.

The valve may be a spring-loaded valve, as shown in this embodiment. The valve comprises a ball 231, a spring 232 and a spring holder. Further, the elongated body comprises deflating means 250, such as a deflating O-ring 251. The spring presses the ball onto the deflating O-ring for closing the at least one communication channel thereby preventing a coupled tail assembly with inflated flight from deflating. The spring holder holds the spring in place.

The elongated body further comprises retaining means 240 for retaining the point relative to the elongated body. The retaining means comprise a retaining O-ring 241 and a circumferential retaining groove in the point cooperating with the retaining O-ring. As the point is in an extended position, the retaining O-ring is arranged in the retaining groove for providing a retaining force. Only when this retaining force is overcome, the point will move relative to the elongated body. This retaining force may be overcome when the point hits a target. When the point hits a target, the point will suddenly decelerate to a standstill, while the elongated body having a particular mass will encounter an inertia force. The retaining means are configured such that the inertia force typically overcomes the retaining force.

The elongated body further comprises an abutment 226 for abutting the movement of the point inside the elongated body. If the retaining force and the spring force of the valve are overcome, the point will be pushed into the elongated body. This movement will be abutted on the abutment. If the point is in contact with the abutment, a proximal end 212 of the point pushes the ball of the valve away from the deflating 0ring for joining the communication channels for allowing a flight of a coupled tail assembly to deflate.

The deflating means further comprise a circumferential deflating groove in the point. A second function of the deflating O-ring is to cooperate with the circumferential deflating groove for retaining the point in a deflating position. As the point pushes the ball of the valve aside, this push is based on the inertia developed by the deceleration of the elongated body relative to the point. This deceleration may end before the flight had the opportunity to fully deflate. Therefore, the point is held in the deflating position by the deflating means. The deflating means hold the point relative to the elongated body if the deflating O-ring is arranged in the circumferential deflating groove. The deflating means are configured such that the spring of the valve does not overcome the holding force of the deflating means.

The holding force of the deflating means is typically overcome by manually pulling the point outward from the elongated body. Alternatively, this may be done by a method for inflating the flight as part of an inflate method of the flight. This method may be performed by a pumping station for inflating the flight.

The circumferential grooves may alternatively be labelled indexes. Further, the elongated body comprises an index bush 260 for creating a distance between the retaining O-ring and the deflating O-ring. Further, the elongated body comprises a support ring 261 for keeping the index bush in place. The index bush and holder ring together define the distance between the respective O-rings.

The tail assembly further comprises a coupling 311 for coupling the tail assembly to the front assembly. The coupling may comprise threads for forming a screw joint with the front assembly. When the front assembly is screwed into the tail assembly forming the coupling, the front assembly also contacts the holder ring for applying a holding pressure onto the ring for holding a balloon rim 322 of the balloon in place. The holding force therefore fixates the balloon relative to the elongated flight holder. The holder ring also provides for an air tight seal between the front assembly and the tail assembly when coupled.

Figure 4 schematically shows an exploded view of a dart 100 according to an embodiment of the current invention. A part with a number equal to a number of a part as mentioned in figure 3 is the same part.

The exploded view shows each part individually. The exploded view therefore shows that the elongated body 220 comprises a channel 270 for fluid communication between the fluid trapped inside the inflatable flight and the outside of the dart. The fluid is typically air. The channel is interrupted by the valve. The channel comprises a channel guide section 271 arranged in the guide, a channel abutment section 272 arranged in the abutment and a channel index bush section 273 together forming the part of the channel between the valve and the outside of the dart.

Figure 5a schematically shows a perspective view of a dart 100 according to a second embodiment of the current invention. The dart comprises a front assembly 200 and a tail assembly 300. The tail assembly is further detailed in figure 5b.

Figure 5b schematically shows a perspective view of a tail assembly 300 according to a second embodiment of the current invention. The tail assembly comprises an elongated flight holder 310 and a flight 320. The elongated flight holder comprises an elongated shaft 312. The elongated flight holder and/or the elongated shaft define a longitudinal axis A.

The flight comprises four flaps 325, 326, 327, 328. The flaps have respective frontal surfaces 335, 336, 337, 338. The frontal surfaces are arranged to attribute to the reference surface B, as defined above. The flaps are arranged discrete rotational symmetric relative to the longitudinal axis. Furthermore, the frontal surfaces radially extend beyond the elongated flight holder relative to the longitudinal axis. Therefore, the flaps have the effect of continuously generating drag while the dart describes the trajectory. Hence, this embodiment provides the same advantages as described above.

The flaps may be retractable into the elongated flight holder. The retraction may be triggered when the point of a front assembly coupled to the tail assembly hits a target. The front assembly may comprise a trigger mechanism to trigger the retraction. Alternatively, the retraction may be triggered before transportation providing the advantage of preventing damage to the flaps during transportation.

Figure 6a schematically shows a perspective view of a tail assembly 300 according to a first embodiment of the current invention. The tail assembly is similar to the tail assemblies shown in figures 1,2, 3, 4 and 7.

The tail assembly comprises an elongated flight holder 310 and a flight 320. The elongated flight holder comprises an elongated shaft 312. The elongated flight holder and/or the elongated shaft define a longitudinal axis A.

The flight may be inflatable. The flight may be retractable inside the elongated flight holder. Further, the flight may comprise a balloon 321. The balloon comprises a distal end 324, which is shaped to provide an additional drag force.

Figure 6b schematically shows a perspective view of a tail assembly according to a third embodiment of the current invention. The tail assembly comprises an elongated flight holder 310 and a flight 320. The elongated flight holder comprises an elongated shaft 312. The elongated flight holder and/or the elongated shaft define a longitudinal axis A.

The flight may comprise a balloon 321 and ribs 351, 352, 353, 354, 355, 356. The ribs are arranged to an outer surface of the balloon for reinforcing the balloon. The ribs may provide the advantage of minimizing or even preventing deformation of the balloon due to the drag force while the dart traverses the trajectory. The ribs may provide the advantage of minimizing or even preventing flapping of the balloon due to the drag force while the dart traverses the trajectory. The flight is, due to the ribs, discrete rotational symmetric relative to the longitudinal axis. The flight may be deflatable and/or retractable.

Figure 7 schematically shows a cross-section of the first embodiment of the tail assembly 300 according to the current invention. Although details are shown in the figure, the parts are described above.

A dart may alternatively be called a small missile, a slender missile or an arrow.

In the foregoing specification, the invention has been described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein without departing from the scope of the invention as set forth in the appended claims. For example, the shapes may be any type of shape suitable to achieve the desired effect. Devices functionally forming separate devices may be integrated in a single physical device.

However, other modifications, variations and alternatives are also possible. The specifications and drawings are, accordingly, to be regarded in an illustrative rather than in a restrictive sense.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word ‘comprising’ or ‘including’ does not exclude the presence of other elements or steps than those listed in a claim. Furthermore, the terms “a” or “an,” as used herein, are defined as one or as more than one. Also, the use of introductory phrases such as “at least one” and “one or more” in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles a or an limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases one or more or at least one and indefinite articles such as a or an. The same holds true for the use of definite articles. Unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

Claims (15)

Embodiments: 1. Tail assembly (300) for a dart (100) including a front assembly (200) and describing a trajectory after release, including: - an elongated flight holder (310) including a coupling (311) arranged for coupling the tail assembly to the front assembly forming the dart and the elongated flight holder has a longitudinal axis (A); and - a flight (320) connected to the elongated flight holder and arranged for radially extending discrete rotational symmetric relative to the longitudinal axis beyond the elongated flight holder and shaped for continuously generating drag while the dart described the trajectory. 2. Tail assembly according to embodiment 1, where the flight is discrete rotational symmetrically shaped relative to the longitudinal axis or an order higher than 4. 3. Tail assembly according to embodiment 1 or 2, where the flight is rotational symmetrically shaped relative to the longitudinal axis. 4. Tail assembly according to any of the 1 to 3, the elongated flight holder and the flight are integrated, or the tail assembly comprises a releasable connection (344) for connecting the flight and the elongated flight holder, releasing the releasable connection at least comprises a rotation of the flight relative to the elongated flight holder. 5. Tail assembly according to any of the 1-4, the flight is expendable and / or contractible. 6. Tail assembly according to edition 5, where expendable is inflatable and / or contractible is deflatable. 7. Tail assembly according to embodiment 5 or 6, the flight is arranged for being shaped at a distal end (324) for creating additional drag during the dart described the trajectory. 8. Tail assembly according to the preceding embodiment, the flight comprising a cavity (313) and following the tail assembly comprising a string (346) arranged in the cavity and arranged for pulling on the distal end of the flight for shaping the distal end of the flight. 9. Front assembly (200) for a dart (100) including: - an elongated body (220); and - control means for controlling expanding and / or contracting or a flight (320) or a tail assembly (300) according to embodiment 5. 10. Front assembly according to embodiment 9, where the control means include a valve (230) and expending is inflation and / or contracting is deflating. 11. Front assembly according to edition 10, where the control means include trigger means arranged for triggering the valve to deflate the flight after the dart hits a target. 12. Front assembly according to embodiment 10 or 11, including a point (210) longitudinally moveable attached to the elongated body for triggering the deflating valve. 13. Front assembly according to any of the 12-12, the valve is discretely rotated symmetrically arranged on a longitudinal axis (A) or the elongated body. 14. Dart (100) including: - a tail assembly (300) according to any of the 1-8; and / or - a front assembly (200) according to any of the 9-13. 15. Pumping station including: - an inflation coupling for coupling with a dart (100) including a tail assembly (300) according to embodiment 5; and - a pump arranged for inflating the flight (320) through the inflate coupling. CONCLUSIONS An arrow assembly (300) for an arrow (100) comprising a front assembly (200) and describing a web after release, comprising: - an elongated flight holder (312) comprising a coupling (311) which is adapted for coupling the tail structure to the front assembly for forming the arrow and wherein the elongated flight holder has a longitudinal axis; and - a flight (320) connected to the elongated flight holder and adapted to radially discretely rotate symmetrically with respect to the longitudinal axis beyond the elongated flight holder and formed to continuously generate resistance while the arrow describes the trajectory. 2. Tail assembly as claimed in claim 1, wherein the flight is discretely shaped rotationally symmetrically with respect to the longitudinal axis with an order higher than 4. 3. Tail assembly as claimed in claim 1 or 2, wherein the flight is shaped rotationally symmetrically with respect to the longitudinal axis. The tail assembly according to any of claims 1-3, wherein the elongated flight holder and the flight are integrated, or wherein the tail assembly comprises a releasable connection (344) for connecting the flight and the elongated flight holder, wherein releasing the releasable connection comprises at least one rotation of the flight relative to the elongated flight holder. The tail assembly of any one of claims 1 to 4, wherein the flight is extensible and / or contractible. 6. Tail assembly according to claim 5, wherein expandable is inflatable and / or contractible is deflatable. The tail assembly of claim 5 or 6, wherein the flight is adapted to be formed on a distal end (324) to create additional resistance while the arrow describes the trajectory. The tail assembly of the preceding claim, wherein the flight comprises a cavity (313) and wherein the tail structure comprises a cord (346) arranged in the cavity and adapted to pull the distal end of the flight to form the distal end of the flight. A front assembly (200) for an arrow (100) comprising: - an elongated body (220); and - control means for controlling the expansion and / or contraction of a flight (320) of a tail assembly (300) according to claim 5. The front assembly of claim 9, wherein the control means comprises a valve (230) and wherein expansion is inflating and / or contraction is deflated. 11. Pre-assembly as claimed in claim 10, wherein the control means comprise trigger means which are adapted to trigger the valve to deflate the flight after the arrow has hit a target. A front assembly according to claim 10 or 11, comprising a point (210) movably mounted along a longitudinal axis to the elongate body for activating the deflation valve. A front assembly according to any of embodiments 10-12, wherein the valve is discretely arranged rotationally symmetrically on a longitudinal axis of the elongate body. An arrow (100) comprising: - a tail assembly (300) according to any of claims 1-8; and / or - a front assembly (200) according to any of claims 9-13. 15. Pumping station comprising: - an inflation coupling for coupling with an arrow (100) comprising a tail assembly (300) according to claim 5; and - a pump adapted to inflate the flight (320) by the inflation coupling. 2.0 ^ ⁹ 3 or 9 "Π 4 or 9 5 or 9 6 or 9> 7 or 9 8 or 9 9 or 9