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Патент USA US3031977

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May 1, 1962
J. R. JASSE
3,031,967
FIN ARRANGEMENT FOR PROJECTILES
Filed Feb. 2, 1959
Ni“
3 Sheets-Sheet 1
L1
May -1, 1962
J. R. JASSE
3,031,967
FIN ARRANGEMENT FOR PROJECTILES
Filed Feb. 2, 1959
3 Sheets-Sheet 2
him.
May 1, 1962
J. R. JASSE
3,031,967
FIN ARRANGEMENT FOR PROJECTILES
Filed Feb. 2, 1959
3 Sheets-Sheet 3
sparse?
United States Patent
Patented May 1, 1%62
2
1
FIG. 2 is a cross~sectional view taken along line 2-2
3,031,967
of FIG. 1;
FIN ARRANGEMENT FOR PROJECTILES
Joseph R. Jasse, Paris, Ih'ance, assignor to Hotchkiss
3 Claims.
(Cl. 102-50)
.
projectile as it leaves the launching tube or barrel;
FIG. 4 is a rear view of the ?n arrangement, the ?ns’
Brandt, Paris (Seine), France, a French body corporate
Filed Feb. 2, 1959, Ser. No. 790,407
Claims priority, application France Feb. 13, 1958
‘
'
FIG. 3 is partial view similar to FIG. 1, showing the
being in their opened out position;
FIG. 5 is a corresponding side elevational view of the
W
?n arrangement shown in FIG. 4;
FIG. 6 is a diagram showing how the locking means
The present invention relatesto ?n arrangements, the
?n of which are adapted to open out for artillery projec 10 vfor one of the ?ns is determined when the ?n is in its
opened position-and the corresponding portionof the
tiles launched by means‘ of a, launching powder charge,
heel of this fin, and
and more particularly projectilesj?red .by means ‘of'a
FIG. 7 is a partial cross-sectional View of a ?n and a ’
mortar with high pressure launching gases at the nozzle
modi?cation of locking meanstherefor.
of the gun barrel or tube and at high initial speed. .
In the embodiment shown in FIGS. 1 to 6, the ?n ar
The opening out of the ?ns by a pivotal movement 15
rangement A according to the invention is shown to‘be
about axes parallel with the longitudinal axis of the ?n
applied, by way of example, to a projectile B of known
arrangement is generally caused by springs which, how
type, which is selfapropelling after having been initially
ever, complicate the assembly and increase the cost.
' launched.
‘ Further, in the aforementioned ?ring conditions, the
gases of the launching charge exerton the ?ns of the ?n 20 This projectile comprises (FIG. 1) a body a having
a longitudinal axis XX within which a tubular sheath
arrangement large forces which could result, at the end
b forms an annular compartment in which is disposed
of the opening of the ?ns, in violent shocks liable to
the useful charge 0, and an axial compartment in which
deform the ?ns and impair the locking thereof in the
is disposed the self-propelling charge .d adapted to be
Owing to the high launching velocity the ?ns are, 25 ignited by the launching charge.
Screw-threadedly engaged in the rear of the body a, is
moreover, subjected to large aerodynamic forces, which
a nozzle e for ejectionof the self-propelling gases. This
require the provision of locking means for the ?ns in
nozzle is obturated before ?ring by an obturatin-g and
their openposition which are particularly strong and
?ring device 7‘ held in position by a shearable ring g,
capable of ensuring a locking without play, which is
which allows ejection of this device after ignition of the
essential to accurate ?ring.
30 self-propelling charge.
The object of the invention is to provide a simpler con- ,
Screw-‘threadedly engaged at 2 on the bodyof the
struction in eliminating the usual ?n opening springs
nozzle e, is the annular ?n-carrying body 1 for the ?n
and to remedy the aforementioned disadvantages due to
arrangement according to the invention. The body 1 car
the forces of the launching gases and the large aerody
ries a number of ?ns 3, in'the presently-described em
.namic forces.
bodiment four?nsf. Each .?n is pivotably mounted be
The invention provides an improved ?n arrangement
tween two bosses 4 and 5 forming a fork ‘and protruding
for an artillery projectile and more ‘particularly ‘for
from the periphery of the body 1, vby means of a shaft 6.
projectiles ?red by a mortar in which arrangement each
opened out position.
Each shaft 6 is constituted by a screw which extends
?n is disposed in such manner that in its folded position
it forms wtih the fin-carrying body a cavity which is 40 through the‘ boss'S and is screw-threadly engaged in a
tapped hole in the boss 4,
.
widely open toward the rear to ensure an automatic open
The axis'YY of the shaft 6 is disposed in such manner
ing of the ?n as soon as it issues from the muzzle of ‘
thatit makes a very slight angle x (FIG. 5) with a
the gun barrel or tube ‘under the effect of‘the expansion
radial axial plane, such as theplane XZ (FIG. 4), so
of a fraction of the gases under pressure which emanate
that when the ?n is opened out it has a positive incidence
from the launching charge and are trapped in said cavity.
' According to another feature of the invention, each ?n 45 ‘substantially equal to x with respect to the relative wind,
that is, facing the forward end of the projectile B. Fur
is pivoted to the ?n carrying body on a shaft which is in
ther, the axis YY is such that the projection Y’Y’ of this
clined at a certain angle relative to the longitudinal axis
axis YY on said axial radial plane, is slightly oblique rela
of said body, toward which it is inclined in the rearward
direction, so that the outer face of the closed ?n has a > tive to the axis XX toward which it converges rearward:
slight incidence toward the rear.
50 1y; said projection makes with the axis XX an angle y so
'
‘that when'the ?n is’ in its closed position against the body
,1, its outer face 7 is also slightly oblique relative to the
axis X—X toward which it converges rearwardly forming
with said axis an angle substantially equal to y.
centripetal component, in acting in opposition to the ex
pansion of the gases in the chambers formed under the 55
For example, the angles x and y could advantageously
?ns, damps the suddenness of the opening out of said
have the following values:.
Thus, a part of the gases ‘from the launching charge
which escape from the gun'barrel or tube creates on
the outer faces of the ?ns an aerodynamic thrust whose
x: 1 ° to 8°
y=l° to 10°
Another object of the invention is to provide a pro
jectile provided with the improved ?n arrangement de
?ned hereinbefore.
'
'
60
Further features and advantages of the invention will 7
be apparent from the ensuing description, with reference '
to the accompanying drawings, to which the invention
is inno way limited.
In the drawings:
’
,
.
,
,
.
65
_
The ‘arrangement is such that in the closed positions
of the ?ns 3 (FIGS.- 1 to 3), each ?n forms with the
body 1 a cavity 8 which is widely open at the rearat 9.
Each ‘?n 3 andthe body 1 are arrangedvto ensure a
practical resilient locking without play of the ?n in its
opened position.
-
-
FIG. 1 is an axial sectional view of the rear part of
To this end, the body 1 comprises, for example extend
a self-propelled projectile provided with a ?n arrange
ing the full distance between the two bosses 4 and 5, a
,lug whose bearing face 10 (FIGS. 4 and 5) is‘parallel
ment according to the invention, the ?ns beingshown in
their folded or closed position ‘and this ?n arrangement .70 ‘with, the corresponding longitudinal radial plane XZ.
being extended by the conventional detachabletaillunit _ _ The ?n 3 comprises a portion 11 de?ned by two ?at faces
which are perpendicular to 'one another and form a
adapted to receive the launching charge;
8,031,967
3
4
common edge 14 constituting a heel, a concave part-cylin
The end of the spring describes at the moment of lock
drical locking face 15, and 'a projection 16 constituting
a safety abutment.
The bearing face 12 is such that it is parallel with the
face 10 against which it abuts when the ?n is opened out.
The concave face 15 co-operates with a resilient lock
ing strip 17 which is ?xed with ‘a reinforcing plate 18 by
screws 19 to a cylindrical portion 20 of the outer wall of
the body 1 (FIG. 6).
7
ing the ?n the involute map of a circle (FIG. 6), and as
the shape of the face 15 is given by the same involute
which has been swung round through the angle z about
the point 11 situated about midway along said face, in
rising ‘after passage of the heel 14, the end of the spring
thus becomes wedged against said face 15 at n and main
tains the ?n in the opened position, the face 12 being
urged resiliently against the face 10 of the ?n-carrying
It will be understood that if the strip 17 is bent against 10 body.
or away from the face 20, its free end would describe an
Owing to this wedging effect, the ?n is maintained in
involute of a circle mnp. The directrix qnr of the face
15 of the ?n is an are having said involute map which
has been swung through a certain ‘angle 2 about an inter
its opened position without play.
ceive the launching powder charge 26. The plug 22 is
provided with passageways 27 for ignition of the self
The latter member is ?xed in the same manner as the
If it is desired to ?re the projectile with launching
charges which vary within wide limits, it could occur
mediate point, the angle is for example equal to about 15 that when using a low launching charge the spring se
10°.
lected for withstanding the maximum launching charge
The body 1 of the ?n arrangement comprises in its
would be too strong to permit the heel 14 to pass by the
bore coaxial with the axis XX (FIG. 1) a shoulder 21
end of the spring in the course of the opening of the ?n.
for centering a plug 22, held in position by one or two
When using a low launching charge, to remedy this
shearable pins 23. Screw-threadedly engaged at 24 on 20 disadvantage there could be provided according to the
this plug, which extends rearwardly beyond the body 1,
invention the locking element shown in FIG. 7 which
is the conventional perforated tail unit 25 adapted to re
comprises a rigid member 28 and a resilient member 29.
spring 17 described in the last'embodiment but its func
propelling charge by way of the obturating ‘and ?ring 25 tion is restricted to the shifting of the rigid locking mem
device f.
'
The tail unit carries externally and toward its forward
end a retaining member 28 which has as many cranked
arms as there are ?ns to be held in their closed position.
ber 28 in the course of the opening of the ?n, the abutting
locking means being constituted by the rigid member 28
riveted at 30 to the spring 29. In the opened position,
the ?n is locked by the plate 28 which is urged against
The ?n arrangement operates in the following manner: 30 the face 15 at n by the spring 29. The rear end 31 of
Before use, the ?ns 3 are held in their folded positions
the plate 28 is then substantially forced or wedged against
by the retaining member 28 (FIGS. 1 and 2) which is
the adjacent edge 32 of the ?xing plate 18. The end 31
connected to the tail unit 25 which is held in position in
and said adjacent edge 32 are charnfered so as to prevent
the body 1 by the pin or pins 23.
escape of the plate 28.
When the projectile is ?red and before it has left the 35 Although speci?c embodiments of the invention have
launching tube C (FIG. 3), the tail unit 25 separates
been described, many modi?cations and changes may be
from the projectile under the effect of its inertia by shear
made therein without departing from the scope of the
ing the shear pin or pins, so that when the projectile ?nal
invention as de?ned in the appended claims.
ly issues from the tub C (FIG. 3), the ?ns are no longer
The projectile can be of the self-propelled type or
40 otherwise, and in the case of a self-propelled projectile,
held in position by the retaining member 28.
At this moment, the gases which emanate from the
the obturating and ?ring device f could comprise an ad
launching powder and ?ll the cavities 8 open at 9 and
justable obturator disposed behind the device 1‘ which
whose pressure is equal to that prevailing in the muzzle
allows or prevents, depending on its position, ignition
of the tube, have a tendency to expand, and, owing to
of the self-propelling charge through the device 1‘.
their centrifugal pressure on the ?ns, they cause the latter 45
Having now described my invention what I claim as
to open out.
The suddenness of the opening, particularly with heavy
new and desire to secure by Letters Patent is: '
1. In a ?n arrangement for an artillery projectile
launching charges, that is, when the pressure at the muz
adapted to be ?red in a tube, a body having a longitudinal
zle of the launching tube is high, is damped owing to the
axis, a launching charge at the rear of said body, ?ns
fact that the ?ns 3 (FIGS. 1 and 3) have in their closed 50 pivoted to the body so that each ?n is capable of oc
position a certain inclination substantially equal to y
cupying successively a closed position against the body
relative to the axis XX of the projectile. Indeed, the gas
and an operative opened position in which latter position
stream of the launching powder acting in the direction of
the ?n is substantially in an axial radial plane of the
arrows f1 (FIG. 3) on the outer faces of the ?ns exerts
body; and a locking device for each ?n in the opened
on the latter an aerodynamic pressure having a centri 55 position, said device comprising, on the one hand, two
petal component which partly compensates the pressure
conjugate abutment faces provided respectively by the
exerted on the inner face of the ?n by the expansion of
?n and the body, and, on the other hand, a resilient means
the gases contained in the cavity '8. By suitably selecting
having one end ?xed to the body and another end which
the angle of inclination y of the‘ pivot axis of the ?ns,
is free to move to describe a ?rst involute of a circle and
-a rather gentle opening of the ?ns can be obtained which 60 co-operates with a wedging face which is provided on the
avoids their deformation or damage at high pressures.
?n and has the shape of a second involute of a circle
'It will be understood that in the opened position, the
which is identical to the ?rst involute, said ‘?rst involute
median plane of the ?n is inclined at the angle x (FIG.
forming an angle with and intersecting said second in
5) relative to the corresponding plane XZ containing the
volute toward the mid-point of its length so that, when
axis of the ?n arrangement.
65 the ?ns are in the operative opened position, said resilient
This inclination x causes a rotation of the projectile on
means is jammed against said wedging face to lock the
its trajectory, which rotation improves the ?ring accuracy,
?ns in said opened vposition with said abutment faces
since it compensates for the irregularities in construction
maintained in mutual contact.
and the reaction of the jet in the case of a self-propelled
2. A ?n arrangement as claimed in claim 1, wherein
projectile, such as that illustrated.
70 said resilient means is in the form of a single ?exible
In the course of opening out of the ?n, the heel 14
resilient strip one end of which is rigidly ?xed to said
(FIGS. 4 and 6) of the portion 11 of each ?n 3 puts
body the other end being free to describe the ?rst in
the spring 17 under stress, and the free end of this spring
volute of a circle.
after the heel 14, has travelled past this end, ?nally comes
3. A ?n arrangement as claimed in claim 1, wherein
into contact with the concave face 15.
75 said resilient means comprises in combination a ?exible
3,031,967
5
6
V
resilient strip rigidly secured by one end to said body, a
rigid element ?xed rigidly to said strip so that one of its
ends is adapted to form said free end of the resilient
means, and a reinforcing member reinforcing the attach
ment of the strip to the body, the rigid element and the
reinforcing member being so shaped and placed that, in
the position for locking the ?n in its open position, the
rigid element is wedged against the reinforcing member.
7
References Cited in the ?le of this patent .
UNITED STATES PATENTS
27,145,508
2,465,401
‘
Denoix ______________ __ Ian._3l, 1939
Skinner _____________ __ Mar. 29, 1949
FOREIGN PATENTS
1,061,242
1,155,665
France _____________ __ Nov. 25, 1953
France _______________ __ Dec. 2, 1957
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