Technical Field
[0001] The present invention relates to vane structures for guiding the flight of projectiles,
and more particularly to fletchings for guiding and stabilizing the flight of arrows
when projected through the air by a bow.
Background of the Invention
[0002] Arrows and similar free flying projectiles are guided in flight by the action of
vanes or "fletchings" adjacent to the rear end thereof which usually has a nock with
a slot for engaging the string of a bow. It has long been known in both target and
hunting archery that the guiding vane or "fletching" is of great importance in establishing
the ballistic characteristics of arrow type projectiles. These ballistics include
a first phase when the arrow passes the handle of the bow which may include both an
arrow rest for supporting the underside of the arrow shaft and a sight window framed
by a portion of the handle that may contact one side or the other of the arrow shaft
depending on whether the archer is right or left handed. The second ballistic phase
is the flight of the arrow through the air after it leaves the bow and the third ballistic
phase is the entrance of the arrow into the target. When a plurality of arrows are
aimed at the same point on a target, the third ballistic phase is reflected by the
"grouping" of these arrows in the target.
[0003] During the first ballistic phase, one or more of the fletchings may hit the arrow
rest or the sight window frame portions of the bow handle because of various errors
in the shooting of the arrow. Such errors may occur during the return of the string
to its rest position as the arrow is shot by releasing the string while engaged by
the nock. The arrow at the moment of the shooting receives its energy from the limbs
of the bow as transmitted by the bow string and this causes the arrow shaft to bend
slightly. After rolling over the fingertips of the archer during the release, the
string returns to its rest position in an S-shaped curve. As the slightly bent arrow
passes above the arrow rest and through the sight window, it often happens that an
arrow fletching hits the arrow rest and/or the frame portion of the bow handle forming
the sight window. This contact causes a deviation of the rear or nock end of the arrow
shaft and may cause the arrow to wobble during its flight. An incorrect nock position
at the time of arrow release may also cause or contribute to arrow wobble during flight.
A wobble in the plane of the bow is known as "porpoising" and a wobble transverse
to the plane of the bow is known as "fishtailing". The mechanical qualities of arrow
fletchings are of vital importance in determining how quickly arrow wobble is dampened
and how large will be the final deviation of the arrow tip from the point of aim when
the arrow enters the target.
[0004] Arrow fletchings presently exist in many different forms. During the early development
of archery, mainly bird feathers were used, although leaves, fibers and other kinds
of natural materials were utilized. During the last 30 to 40 years, various kinds
of synthetic materials such as plastics have come into use for the production of a
wide variety of arrow fletchings. These synthetic fletchings can be divided into two
main groups. The first group comprises stiff, thin vanes made from hard, rigid plastics
or the like. The second group comprises pliable, usually slightly thicker vanes made
from relatively soft, flexible plastics or the like with good recovery characteristics.
[0005] The thin, stiff vanes tend to have less air resistance and give the arrow a relatively
flat trajectory which is advantageous when shooting at long distances. However, arrows
with these fletchings have greater wobble in flight and larger deviations in grouping
when they hit the arrow rest or the sight window frame of the bow handle.
[0006] On the other hand, arrows with fletchings made from pliable plastic materials have
less wobble and less deviation in grouping upon interference between a fletching and
the arrow rest or sight window frame. However, because they may be somewhat thicker,
these vanes tend to have a somewhat greater air resistance. The transverse cross-section
of pliable plastic vanes may be tapered so as to converge outwardly in order to reduce
air resistance during flight and also to reduce the flight deviations produced when
a fletching hits the arrow rest or the sight window frame.
[0007] Another problem that may occur with pliable plastic fletchings is that they may develop
vibrations known as "flutter" along the outer border of the vane during flight of
the arrow. Flutter along outer portions of the fletchings may cause the arrow to fall
short or otherwise increase grouping deviations.
[0008] Outdoor target archery is usually practiced at distances between 30 and 90 meters.
The corresponding distances for indoor target archery vary between 18 and 50 meters.
In order to stabilize the arrow flight more quickly at the relatively short indoor
distances, target arrows are often fletched with either larger plastic vanes or larger
natural feathers, such as turkey feathers, than can be used at longer distances. The
distance required for stabilization of the arrow after it leaves the bow, namely,
the distance traveled before wobble or oscillations of the arrow shaft can be dampened
out, may be 50 meters or more with conventional fletchings.
[0009] Fletchings made from natural feathers are believed to give quicker arrow stabilization
because of their larger friction against the air, and also are regarded as being more
"forgiving" in that they cause less flight deviations upon contact with the arrow
rest or the sight window frame than either rigid or pliable types of conventional
plastic fletchings. On the other hand, natural feathers vary considerably in thickness
and stiffness and do not have the uniformity of plastic fletchings in this regard.
Another problem with arrow fletchings made from natural feathers is that they lack
the resistance of plastic fletchings to the deteriorating effects of humidity.
[0010] For target archery or hunting archery at longer distances (greater than about 50
meters), arrows are often fletched with smaller plastic vanes having relatively little
air resistance. These small size plastic vanes also reduce flight deviations caused
by side winds, which is an essential consideration at long distance shooting.
Disclosure of the Invention
[0011] The invention provides a new structure for an arrow fletching, which may be made
either from plastic or some other kind of suitable material whether natural or synthetic.
The material may be either rigid or pliable, a pliable plastic such as polyurethane
or cellulose acetate-butyrate (CAB) being preferred: At least three, and sometimes
four or more, fletchings are mounted on the arrow shaft adjacent to a nock which the
bow string engages at one end of the arrow shaft. The tip or penetrating point of
the arrow is at the end of the shaft opposite to its nock end.
[0012] The new fletching has an elongated, relatively thin and substantially planar body
with an inner edge portion, an inner vane portion, and an outer vane portion. The
outer vane portion is shaped to provide a means for causing a turbulent flow of air
over this outermost vane section of the fletching at flight velocity. This shaped
portion is connected to the inner edge portion by the inner vane portion which is
unperforated and has continuous, substantially smooth side surfaces for providing
a laminar flow of air over this innermost vane section of the fletching at flight
velocity. The smooth vane portion of the fletching provides a moment arm for transmitting
to the arrow shaft the effects of the turbulence caused by the shaped outer portion.
The amount of the turbulence and the length of the moment arm are selected such that
the effects of the turbulence reaching the arrow shaft are sufficient to quickly stabilize
the flight of the arrow after it leaves the bow. The inner edge portion has a transverse
width sufficient to provide a base for mounting the fletching on an arrow shaft so
that its elongated body extends longitudinally in the axial direction of the shaft.
[0013] The outer vane portion of the fletching may have a variety of shapes for causing
turbulent air flow over this section of the fletching at flight velocity. One preferred
embodiment is shaped to provide a wavy outer edge contour comprising a series of slightly
rounded "saw-teeth" having peaks and valleys in the plane of the elongated fletching
body. Other fletching embodiments include outer vane portions with a series of ribs,
nodules, knobs or other protrusions projecting laterally from one or both sides of
the outer vane body; or a series of holes projecting through the outer vane body from
one side to the other; or a series of grooves or other indentations within one or
both sides of the outer vane body. Where ribs or grooves or similarly elongated elements
are provided as the turbulence generating means, these elements preferably extend
transversely across the outer vane portion and are spaced apart one after the other
in the longitudinal direction of the outer vane body, preferably at relatively close
intervals.
[0014] The new fletchings stabilize an arrow within a substantially shorter distance from
the bow than conventional fletchings of the same size class by quickly dampening oscillations
of the arrow shaft after its release from the bow. The new fletchings also reduce
the magnitude of the oscillations caused by contacts between a fletching and the arrow
rest or the sight window frame. The flight of an arrow fletched with the vanes of
the present invention is thus stabilized in a minimum period of time after the arrow
leaves the bow. These arrow fletchings thus improve the guiding effect throughout
the flight of the arrow from bow to target, especially where the fletchings are made
of a soft, pliable material such as polyurethane.
[0015] Practical shooting tests to compare arrows fletched with conventional vanes with
those fletched with vanes of the invention show that the invention stabilizes arrows
more quickly and reduces the magnitude of oscillations and other flight deviations
caused by contact between the fletching and the arrow rest or the sight window frame.
The latter improvement is enhanced where the outer shape includes a planar "saw-tooth"
projection or a lateral projection since contact may occur with only one of these
projections. In other words, contact with only one such projection may deflect the
nock end of the arrow so as to avoid further contact, while upon contact of a conventional
fletching with the bow, the moment affecting the arrow is generated along almost the
entire length of the vane. A similar improvement may be realized with the fletchings
having holes or indentations along a path adjacent to their outer borders since these
increase the flexibility of the outer vane portion so that contact generates less
moment.
[0016] The improved stabilizing effects of the invention are provided by the turbulence
producing shapes along or adjacent to the outer border of the vane. These cause a
turbulent air stream which is oriented towards the outer portion of the vane. At the
same time, the low surface friction of the smooth inner portion of the vane intermediate
between the shaped outer portion and the base adjacent to the arrow shaft causes a
laminar air stream which is oriented towards the portions of the fletching inwardly
of the shaped outer portion. As a result of this combination, the smooth inner portion
of the vane provides a moment arm for transmitting the effect of the outer turbulence
to the shaft of the arrow. This moment effect is believed to provide the stabilizing
qualities of the fletching of the present invention. The principal object of the invention
therefore is to create a turbulent air stream which is oriented towards the outer
portion of the fletching while minimizing the surface friction of those portions of
the fletching between the turbulent air stream and the arrow shaft.
[0017] Another advantage of the fletching of the invention is that it reduces the effects
of side winds which can cause the arrow to drift toward one side or the other during
its flight from the bow to the target. For a given size arrow shaft, the fletchings
made according to the present invention can be considerably smaller than conventional
fletchings. In addition, the surface area of the side profile of the fletching may
be reduced by removing those portions represented by the valleys of the "saw-tooth"
embodiments of the fletching. Both of these factors reduce the projecting area of
the fletching exposed to side winds so that such winds will produce less deviation
of the arrow away from its intended flight path.
Brief Description of the Drawings
[0018] The invention may be further understood from the description below of specific embodiments
taken in conjunction with the accompanying drawings in which:
Fig. 1 is a perspective fragmentary view of an arrow shaft having fletchings according
to the invention mounted adjacent to the nock end of the shaft.
Fig. 2 is a sectional view along lines 2-2 of Fig. 1.
Fig. 3 is a side elevational view of one of the fletchings of Fig. 1.
Fig. 4 is a side elevational view of another fletching embodiment according to the
invention.
Fig. 5 is a sectional view along lines 5-5 of Fig. 4.
Fig. 6 is a perspective fragmentary view of an arrow shaft with another fletching
embodiment according to the invention.
Fig. 7 is a side elevational view of one of the fletchings of Fig. 6.
Fig. 8 is a sectional view along lines 8-8 of Fig. 7.
Fig.9 is a perspective fragmentary view of an arrow shaft with another fletching embodiment
according to the invention.
Fig. 10 is a side elevational view of one of the fletchings of Fig. 9.
Fig. 11 is a sectional view along lines 11-11 of Fig. 10.
Fig. 12 is a sectional view similar to Fig. 11 but illustrating indentations along
the left side of the fletching instead of apertures through the fletching.
Fig. 13 is a sectional view similar to Fig. 11 but illustrating indentations along
the right side of the fletching instead of apertures through the fletching.
Fig. 14 is a sectional view similar to Fig. 11 but illustrating indentations along
both sides of the fletching instead of apertures through the fletching.
Fig. 15 is a perspective fragmentary view of an arrow shaft having another fletching
embodiment according to the invention.
Fig. 16 is a side elevational view of one of the fletchings of Fig. 15.
Fig. 17 is a sectional view along lines 17-17 of Fig. 16.
Fig. 18 is a sectional view similar to Fig. 17 illustrating ribs along the left side
of the fletching instead of along both sides of the fletching.
Fig. 19 is a sectional view similar to Fig. 17 illustrating ribs along the right side
of the fletching instead of along both sides of the fletching.
Description of Best Mode and Other Embodiments
[0019] Referring to Figs. 1, 2 and 3 of the drawing, there is shown a fletching having a
body, generally designated 10, mounted on the shaft 12 of an arrow adjacent to a nock
14 having a slot 15. The bottom of slot 15 is engaged by the bow string when the arrow
is shot into the air by a bow. Preferably three fletchings 10, 10ʹ and 10ʺ are mounted
on arrow shaft 12 as shown in Fig. 2, although four or more fletchings may be used
if desired.
[0020] Fletching 10 preferably comprises an outer contoured vane portion 20, an inner vane
portion 22, and an inner edge portion forming a base 24 having a greater transverse
width than vane portion 22. The contoured portion 20 creates turbulent airflow over
this portion of the fletching at flight velocity. The inner vane portion 22 is unperforated
and has continuous and sufficiently smooth side surfaces to provide laminar airflow
over this portion of the fletching at flight velocity. The flight velocity at which
these aerodynamic characteristics of the fletching portions 20 and 22 are realized
is preferably in the range of about 50 to about 60 meters per second.
[0021] Fletchings 10, 10ʹ and 10ʺ are of identical construction so that only fletching 10
will be described in detail. Referring to Fig. 3, contoured portion 20 has a plurality
of teeth 25 formed by a series of six rounded peaks 26 with five rounded valleys 27
interspersed therebetween. Each tooth 25 has a forward edge 28 and a rearward edge
29 inclined at different angles relative to the longitudinal axis 30 of arrow shaft
12. Except for the first and last teeth in the series, the forward edge 28 of one
tooth joins the rearward edge 29 of the adjacent preceding tooth at the bottom of
valley 27.
[0022] In the preferred fletching embodiment, the rearward edge of the majority of the teeth,
namely all but the most rearward tooth, passes forwardly through an imaginary plane
represented by broken line 32 which is perpendicular to the axis of the arrow shaft
so that valley 27 undercuts peak 26 as best shown in Fig. 3. Portions of both the
forward edge 28 and the rearward edge 29 preferably are inclined in the same direction
relative to the axis of the arrow shaft and the maximum inclination of this portion
of the forward edge is less than the maximum inclination of this portion of the rearward
edge except for the most rearward tooth.
[0023] As measured from the top of peak 26 to the bottom of the underlying valley, the depth
D of each valley is at least 1/4, preferably 1/3 to 2/3, and more preferably about
40%, the total height H of the fletching vane above its base 24. The depths of the
valleys are preferably substantially uniform and are critical to the invention in
a number of respects. The valley depth D determines the amount of turbulent airflow
along the contoured outer portion of the fletching. The depth D relative to the overall
height H of the fletching also determines the length of the moment arm M provided
by the smooth inner portion 22 of the vane between the valley bottoms 27 and fletching
base 24. The depth D and also the tooth shape are both preferably chosen so that if
the fletching contacts the arrow rest or the sight window frame, contact with only
a single fletching "tooth" will position the arrow shaft so as to prevent further
contact between the fletching and the bow. This also prevents contact between the
bow and the continuous, unperforated inner vane portion 22 of the fletching.
[0024] Referring to Figs. 4 and 5, the outer contoured portion of the fletching may have
different "saw-tooth" shapes as illustrated by the periodic wave-form of contoured
portion 42 of an alternative fletching 40. In this modified fletching, each tooth
41 has a convex forward edge 43 and a concave rearward edge 44 which intersect with
the corresponding edges of adjacent teeth at a relatively sharp peak 45 and a relatively
sharp valley bottom 46. The inclination of the rearward edge 44 relative to the axis
30 of the arrow shaft is in a direction opposite to the inclination of the forward
edge 43 relative to the axis 30 of the arrow shaft.
[0025] As seen in Fig. 4, the rearward edge 44 does not undercut peak 45 and therefore fletching
40 differs in this respect from fletching 10 of which rearward edge 29 undercuts peak
26. Another difference between fletching 40 and fletching 10 is that the elongated
opposing sides 48 and 49 of fletching 40 taper toward each other from base 50 to peak
45 as illustrated in Fig. 5. This inward aerodynamic taper of the transverse cross-section
of the fletching body may be used with any of the fletching embodiments to increase
the flexibility of the fletching body so as to further reduce arrow deviations caused
by contact between a part of the fletching and the arrow rest or sight window frame
of the bow.
[0026] The elongated sides of either fletching 10 or fletching 40 therefore may be either
transversely tapered outwardly toward each other, or at substantially an equal transverse
distance apart from each other (parallel) from the base outwardly to the outer contoured
edge. As a further alternative, the sides of the fletching may be tapered over only
an upper portion of their overall height (not shown). The degree of aerodynamic taper
chosen may depend upon the degree of pliability of the material from which the fletching
is made. Thus, no aerodynamic taper may be desirable where the fletching is made from
a highly pliable material such as polyurethane. On the other hand, some relatively
small degree of taper may be desirable where the fletching is made from a stiffer
material such as cellulose acetate-butyrate. A greater amount of taper may be appropriate
where harder plastics are used for the fletching.
[0027] Figs. 6, 7 and 8 illustrate another periodic wave-form for a "saw-tooth" contoured
portion 62 of an alternative fletching 60. Contoured outer vane portion 62 is connected
to base 63 by inner vane portion 64. A broken line 66 indicates generally the dividing
line between the outer vane portion 62 and the smooth inner vane portion 64. In this
embodiment, the peaks and valleys are both rounded and the valleys do not undercut
the peaks. This embodiment also illustrates that the bottoms of the valleys may be
of different heights above base 63, such as valleys 88 and 88ʹ. For this reason, the
height of moment arm Mʹ is taken as the distance between the base and the lowest valley,
namely valley 88ʺ. In this embodiment, the fletching body is tapered from base to
peak as illustrated by the transverse cross-section of Fig. 8.
[0028] Referring to Figs. 9, 10 and 11, the turbulence producing function of the saw-tooth
contours of Figs. 1-8 is provided by a series of apertures 70 spaced at intervals
along a longitudinal path within the outer vane portion 71 of an alternative fletching
72. Outer vane portion 71 is con nected to a base 73 by a smooth and continuous inner
vane portion 74. The transition between outer portion 71 and inner portion 74 of the
vane is represented by a broken line 75. As illustrated by the cross-section of Fig.
11, the body of fletching 72 has substantially no taper from base 73 to outer periphery
76.
[0029] As illustrated in Figs. 12-14, respectively, the turbulence provided by apertures
70 may instead be provided by a series of indentations or pockets 78 along the left
side, or a series of indentations or pockets 79 along the right side, or a series
of indentations or pockets 78ʹ and 79ʹ along both sides of the fletching body.
[0030] In the embodiments of Figs. 15-17, the turbulence producing function of the saw-tooth
contours of Figs. 1-8 is provided by a series of laterally projecting ribs 80 and
81 at closely, spaced intervals 82 along opposite sides 83 and 84, respectively, of
a fletching 85. The ribs 80 and 81 provide a rough outer vane portion 86 connected
to a base 87 by a smooth inner vane portion 88.
[0031] As illustrated in Figs. 18 and 19, respectively, a stabilizing turbulence may be
provided by a series of ribs 80ʹ on the left side of a tapered fletching body 90 or
a series of ribs 81ʹ on the right side of a tapered fletching body 92. Although the
turbulence provided by ribs on only one side of the fletching body may be less than
the turbulence provided by ribs on both sides of the fletching body, the amount of
turbulence produced by ribs on only one side is sufficient to provide the advantages
of the invention. In addition, turbulence on only one side of the vane may cause rotation
of the arrow shaft which may provide additional in-flight stability.
[0032] The ribs shown in Figs. 15-19, have a relatively narrow elongated shape and extend
longitudinally in a direction transverse to the elongated body of the fletching. As
shown in Figs. 15 and 16, these elongated ribs are preferably sloped at an angle to
the axis of the arrow shaft. However, the invention may be practiced using protuberances
having other shapes extending laterally from the fletching body, such as rounded bumps,
knobs, nodules and the like.
1. A fletching for guiding and stabilizing the flight of an arrow projected through
the air by a bow having a string which engages a nock at one end of the arrow shaft,
said fletching having an elongated, relatively thin and substantially planar body
comprising:
an inner edge portion of sufficient transverse width to provide a base for mounting
the fletching on said arrow shaft so that said elongated body extends longitudinally
in the axial direction of the shaft;
an outer vane portion extending radially in the plane of said elongated fletching
body to an outer edge and having a plurality of turbulence means extending along said
outer vane portion for providing a turbulent flow of air oriented substantially over
said outer vane portion at flight velocity, the radial extent of said outer vane portion
defining a width that is substantially uniform for a major proportion of the length
of said elongated fletching body and is at least 1/4 the height of said fletching
body as measured from said base; and,
an inner vane portion extending radially between said outer vane portion and said
base for a predetermined height in the plane of said elongated fletching body, said
predetermined height being at least 1/3 the height of said fletching body as measured
from said base;
said inner vane portion having substantially flat side surfaces and said base and
said inner vane portion having continuous and substantially smooth side surfaces for
providing a laminar flow of air oriented substantially over said inner vane portion
at flight velocity;
the radial extent of said inner vane portion defining a width that is substantially
uniform for a major proportion of the length of said elongated fletching body;
said width of said smooth inner vane portion providing a moment arm for transmitting
the effects of said turbulence to said arrow shaft;
and the amount of said turbulence and the length of said moment arm being sufficient
to quickly stabilize the flight of said arrow after it leaves the bow when at least
three of said fletchings are mounted on said shaft adjacent its nock end.
2. The fletching of claim 1 in which said fletching body has opposing elongated sides
that are at substantially an equal transverse distance from each other outwardly from
said base to the outer edge of said outer vane portion.
3. The fletching of claim 1 in which said turbulence means comprises a series of apertures
extending through and spaced at longitudinal intervals along said outer vane portion.
4. A fletching for guiding and stabilizing the flight of an arrow projected through
the air by a bow having a string which engages a nock at one end of the arrow shaft,
said fletching having an elongated, relatively thin and substantially planar body
comprising:
an inner edge portion of sufficient transverse width to provide a base for mounting
the fletching on said arrow shaft so that said elongated body extends longitudinally
in the axial direction of the shaft;
an outer vane portion having turbulence means for providing a turbulent flow of
air over said outer vane portion at flight velocity, said turbulence means comprising
a contoured outer edge forming a plurality of saw-teeth providing a series of peaks
and valleys in the plane of said fletching body, and said valleys having a depth of
at least 1/4 the height of said fletching body as measured from said base; and
an inner vane portion extending between said outer vane portion and said base for
a predetermined height, and having continuous and substantially smooth side surfaces
for providing a laminar flow of air over said inner vane portion at flight velocity,
the height of said smooth inner vane portion providing a moment arm for transmitting
the effects of said turbulence to said arrow shaft, and the amount of said turbulence
and the length of said moment arm being sufficient to quickly stabilize the flight
of said arrow after it leaves the bow when at least three of said fletchings are mounted
on said shaft ajdacent its nock end.
5. The fletching of claim 4 in which said contoured outer edge includes rearward edges
extending between said peaks and said valleys, and in which at least a majority of
said rearward edges extend forwardly through a plane perpendicular to the axis of
said arrow shaft such that valleys corresponding to said forwardly extending rearward
edges undercut corresponding peaks.
6. The fletching of claim 5 in which each of said undercut peaks has a forward edge
and a rearward edge each inclined relative to the axis of said arrow shaft and the
maximum inclination of said forward edge is less than the maximum inclination of
said rearward edge for at least a majority of said peaks.
7. A fletching according to claim 4 in which each of said peaks has a forward edge
and a rearward edge each inclined relative to the axis of said shaft, and in which
for at least a majority of said peaks the inclination of said rearward edge is in
the same direction as the inclination of said forward edge.
8. A fletching according to claim 4 in which each of said peaks has a forward edge
and a rearward edge each inclined relative to the axis of said shaft, and in which
for a majority of said peaks the inclination of said rearward edge is in a direction
opposite to the inclination of said forward edge.
9. The fletching of claim 4 in which the depths of said valleys is substantially uniform.
10. A fletching for guiding and stabilizing the flight of an arrow projected through
the air by a bow having a string which engages a nock at one end of the arrow shaft,
said fletching having an elongated, relatively thin and substantially planar body
comprising:
an inner edge portion of sufficient transverse width to provide a base for mounting
the fletching on said arrow shaft so that said elongated body extends longitudinally
in the axial direction of the shaft;
an outer vane portion having turbulence means for providing a turbulent flow of
air over said outer vane portion at flight velocity, said turbulence means comprising
a series of indentations spaced at longitudinal intervals along at least one side
of said outer vane portion; and
an inner vane portion extending between said outer vane portion and said base for
a predetermined height which is at least 50% of the height of said fletching body
as measured from said base, and having continuous and substantially smooth side surfaces
for providing a laminar flow of air over said inner vane portion at flight velocity,
the height of said smooth inner vane portion providing a moment arm for transmitting
the effects of said turbulence to said arrow shaft, and the amount of said turbulence
and the length of said moment arm being sufficient to quickly stabilize the flight
of said arrow after it leaves the bow when at least three of said fletchings are mounted
on said shaft adjacent its nock end.
11. The fletching of claim 10 in which said indentations are spaced longitudinally
along both sides of said outer vane portion.
12. The fletching of claim 11 in which said indentations on one side are aligned with
said indentations on the other side and are connected so as to provide a series of
apertures extending through and spaced at longitudinal intervals along said outer
vane portion.
13. A fletching for guiding and stabilizing the flight of an arrow projected through
the air by a bow having a string which engages a nock at one end of the arrow shaft,
said fletching having an elongated, relatively thin and substantially planar body
comprising:
an inner edge portion of sufficient transverse width to provide a base for mounting
the fletching on said arrow shaft so that said elongated body extends longitudinally
in the axial direction of the shaft;
an outer vane portion having turbulence means for providing a turbulent flow of
air over said outer vane portion at flight velocity, said turbulence means comprising
a series of protuberances spaced at longitudinal intervals along at least one side
of said outer vane portion; and,
an inner portion vane portion extending between said outer vane portion and said
base for a predetermined height which is at least 50% of the height of said fletching
body as measured from said base, and having continuous and substantially smooth side
surfaces for providing a laminar flow of air over said inner vane portion at flight
velocity, the height of said smooth inner vane portion providing a moment arm for
transmitting the effects of said turbulence to said arrow shaft, and the amount of
said turbulence and the length of said moment arm being sufficient to quickly stabilize
the flight of said arrow after it leaves the bow when at least three of said fletchings
are mounted on said shaft adjacent its nock end.
14. The fletching of claim 13 in which said protuberances are spaced longitudinally
along both sides of said outer vane portion.
15. A fletching for guiding and stabilizing the flight of an arrow projected through
the air by a bow having a string which engages a nock at one end of the arrow shaft,
said fletching having an elongated, relatively thin and substantially planar body
comprising:
an inner edge portion of sufficient transverse width to provide a base for mounting
the fletching on said arrow shaft so that said elongated body extends longitudinally
in the axial direction of the shaft;
an outer vane portion having turbulence means for providing a turbulent flow of
air over said outer vane portion at flight velocity, said turbulence means comprising
a series of apertures extending through and spaced at longitudinal intervals along
said outer vane portion; and,
an inner vane portion extending between said outer vane portion and said base for
a predetermined height which is at least 50% of the height of said fletching body
as measured from said base, and having continuous and substantially smooth side surfaces
for providing a laminar flow of air over said inner van portion at flight velocity,
the height of said smooth inner vane portion providing a moment arm for transmitting
the effects of said turbulence to said arrow shaft, and the amount of said turbulence
and the length of said moment arm being sufficient to quickly stabilize the flight
of said arrow after it leaves the bow when at least three of said fletchings are mounted
on said shaft adjacent its nock end.