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Патент USA US3087437

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April 30, 1963
KARL-JOHN 'r. THORILDSSON
3,087,427.
POWER DRIVEN, MINE CLEARING EXPLOSIVE SNAKE
Filed Oct. 18, 1960
4/
INVENTOR.
KARL-JOHN THOR/L0 THOR/LDSSDN
BY
A T'T'ORNE rs
States
aten
1
"cc
3,987,427.
Patented Apr.- 30, v9&3
2
3,087,427
in the appended claims forming a part of the applica
tion.
In the accompanying drawing, several prefer-red em
Karl-John Thorild Thorildsson, Bofors, Sweden, assignor
to Aktiebolaget Bofors, Bofors, Sweden, a Swedish cor
poration
bodiments of the invention are shown by way of illustra
tion, and not byway of limitation.
in the drawing:
Filed Oct. 18, 1960, Ser. No. 63,437
Claims priority, application Sweden Oct. 30, 1959
6 Claims. (Cl. 102-34.!)
?ring a mine-clearing snake, the snake being shown in
the condition ready for ?ring;
POWER DREVEN, Mh‘gBACgEEARWG
EXPLOSIVE
S
I
The present invention relates to power driven explosive
snakes as are used for clearing a safe path through a
FIG. 1 is a diagrammatic view of an installation for
10
FIG. 2 is a graph showing the variations of the driving
force and the braking force acting upon the snake during
its trajectory;
FIG. 3 is a diagrammatic view of the stabilizing device
according to the invention;
mine ?eld.
Such snakes generally consist of a hose or tube made
of a pliable material and ?lled with an explosive mate 15
FIG. 4 is a similar view of a modi?cation of the sta
rial, such as TNT. The snake is usually about 100 to 200
bilizing device;
meters long. The driving power may be and is usually
.FIG. 5 is a similar view of another modi?cation of the
supplied by a rocket, and the snake is ?red with a tra
stabilizing device; and
>
jectory such that it will land across a mine ?eld. The
FIG. 6‘ is a similar view of still another modi?cation
shock waves generated by a detonation of the snake will
of the stabilizing device.
'
set oif all the land mines within the vicinity of the snake,
Referring ?rst to FIGS. 1 and 2 in detail, FIG. 1 shows
thus clearing a safe path for the advance of troops.
a coiled snake consisting of a hose or tube 1 made of
It is common practice to stabilize the trajectory of the
any suitable pliable material, such as a plastic, and ?lled
snake by attaching a brake parachute to the snake, for
with an explosive material. A folded or packed para
instance by fastening the canopy of the parachute to the 25 chute 4, including the stabilizing device according to the
rear end of the snake by means of guy ropes secured to
invention, is attached to the rear end of the snake, that
the canopy in circumferential spacing.
is, to the end which is rearward during the ?ight of the
The braking action of the parachute is intended to
snake. The parachute assembly will be more fully de
assure that the snake lands fully stretched out in a per
scribed hereinafter. The snake is ?red by means of a
pendicular plane to utilize fully the effective length of the 30 launching device '12, in which is inserted a rocket 3; at~
snake. As is ew'dent, the braking action of the parachute
tached to the forward end of the snake and supplying the
is a function of the wind pressure acting upon the para
driving force. The ?ring of the snake and the arrange
chute during the ?ight of the snake, and the wind pressure,
ment of the driving rocket do not constitute part of the
in turn, is a function of the ?ight velocity of the snake.
invention and should be visualized as being conven
As is also evident, the ?ight velocity of the snake de 35 tional. The parachute opens by being pulled out of its
clines during the last part of the trajectory and the thus
bag when the rear part of the snake has obtained a cer
correspondingly declining wind pressure may be balanced
tain predetermined velocity. The manner in which the
or even overcome by side winds. In consequence, the
parachute opens should also be visualized as being con
rear portion of the snake may drift laterally in reference
ventional.
to the true forward course of the snake still maintained
Turning now to FIG. 2, the graph, according to this
by the forward part of the snake in a perpendicular plane.
?gure, shows the driving force F as a function of the
Accordingly, the effective length of the snake when it
time t. The curve FD shows the driving force and, as is
lands is shortened, so that the depth of the mine ?eld may
apparent, the driving force ?rst increases rapidly and then
not be fully spanned and a safe passage is not clearly
remains substantiallyconstant until the rocket motor
de?ned. As a result, several snakes may have to be used 45 burns out and the driving force ceases. The braking
to clear a passageway which is often di?icult under con
power exerted by the parachute is shown by the curve
ditions of warfare.
FB. 7 As is seen, the opening of the parachute causes a
‘It is the broad object of the invention to provide a novel
sharp surge of the braking power. This surge is of very
and improved trajectory stabilizing device for an explo
short duration and, after it subsides, the braking power
sive mine-clearing snake of the kind above referred to 50 remains substantially constant and declines gradually
which assures that the snake will land substantially fully
during the terminal part of the ?ight until it finally
stretched out, thus clearing a path of a length correspond
reaches a zero value. It is desirable that the braking
ing to the full useful length of the snake through a mine
power should cease as abruptly as possible when it has
?eld.
declined to the value FBI, and it is the purpose of the
A more speci?c object of the present invention is to 55 present invention to obtain such abrupt termination of
provide a novel and improved trajectory stabilizing de
the braking force to avoid, or at least minimize, the
vice for an explosive mine-clearing snake which im~
aforedescribed tendency of lateral drifting of the rear part
pedes lateral drifting of the rear portion. of the snake
of the snake close to the end of the trajectory.
during the terminal part of the ?ight of the snake, thus
Referring now to FIG. 3, the stabilizing device accord
holding the snake in a substantially fully stretched out 60 ing to the invention comprises a parachute, the canopy
position until it lands.
4 of which is joined by circumferentially spaced shrouds
Another more speci?c object of the invention is to pro
or guy ropes 6 to a swivel joint 5 which, in turn, is at
vide a novel and improved trajectory stabilizing device
tached by means of connector 2 to the snake 1 proper.
for an explosive mine-clearing snake which compensates
'Swivel joint 5 permits spinning of the parachute during
for the declining stabilizing power of the parachute 65 the ?ight without twisting the snake. According to the
during the terminal part of the ?ight by causing a change
invention, an elastically stretchable means 7 extends be
in the con?guration of the parachute, such that the brak
tween swivel joint 5 and the center part of canopy 4. The
ing power of the parachute is reduced, for instance, by
causing a. partial collapse of the parachute.
elastically stretchable means is shown as a coiled tension
spring, but it may also be an elastic rope, such as a rope
Other and further objects, features and advantages of 70 consisting of a plurality of twisted rubber strands encased
the invention will be pointed out hereinafter and set forth
in a sheath.
3,087,427
4
3
chute to hold the canopy thereof in a partially collapsed
shape in a relaxed state of the compensating means and
to permit full opening of the canopy in a tensioned state
of the compensating means, said compensating means be
ing tensioned by the opening of the parachute and main
‘Spring 7 is relaxed prior to the opening of the para
chute‘and in that state, it~tends to hold the canopy in 'a
more or less collapsed shape and in any event in a shape
such thatthe canopy cannot assume the fully opened
shape in 'which it exerts~its~maxiinumbraking-power.
When the parachute opens during ?ight, spring is
tained tensioned by a wind pressure above a predeter
mined value, a decline of the wind pressure below said
‘tensioned and is so‘shown in FIG. 3. It is'held in its
tensioned state as longas the braking power‘Fj; is still
value releasing the compensating means for return into
the relaxed state thereof thereby e?fecting an at least par
approaches the value lFBl, or in other words’ as the wind 10 tial collapse of the canopy causing an abrupt decrease
appreciably above the ‘value FBI. As the braking power
of the braking power of the parachute below said pre
pressure acting upon'the parachute declines below a pre
determined value, the'tensional force'stored in the spring
determined wind pressure.
2. A snake according to claim 1 wherein shroud lines
attached to the rim of the canopy secure the parachute
to said rearward end of the ‘snake, and wherein said
begins to overcome the counteraction of the wind pres
sure and, as a result, spring 7 begins to contract towards
its relaxed state, thereby effecting an at least partial col
lapse of the canopy, thus spilling the air out of the canopy
yieldable compensating means comprise elastically stretch
able means extendingbetween said rearward end and the
center. part of the canopy, said elastically stretchable
and terminating abruptly‘ more or less completely the
Ibrakingpower of the parachute and, at the same time,
making the parachute ‘less susceptible to the action of
side winds.
means being tensioned by the opening of the canopy
whereby the tensioned elastically stretchable means exert
,
a force pulling said center part of the canopy toward said
rearward end of the snake to effect the at least partial
collapse of the canopy.
'8, attached’to the canopy 4 along the circumference there
3. A snake according to claim 2 wherein said elastical
of. The function of rope 8 is the same in principle as
that of spring 7. The rope, when in its relaxed state, 25 ly stretchable means comprise a coiled spring.
4. A snake according to claim 1 wherein shroud lines
more or less holds the canopy in a con?guration in which
attached to the rim of the canopy secure the parachute
the same cannot exert its maximum braking power. The
‘to said rearward end of the snake, and wherein said
‘rope is expanded when‘ and while the parachute has
yieldable means comprise elastically stretchable means at
‘opened and is exposed to a wind pressure above the
tached to the canopy along the rim thereof, said elastical
value FBI. FIG. 4 shows the rope in its expanded or
ly stretchable means when relaxed holding said canopy
tensioned state. As soon as-the braking‘power declines
According to FIG. 4,- the elastically strechable means
is shown in the form of an elastic ribbon, band or rope
in an at least partially collapsed con?guration and being
below the value FBI, the rope contracts thus effecting‘ a
stretched by an opening of the canopy in response to a
more or less complete collapse of the canopy.
wind pressure above said predetermined value, the ten
According to FIG. 5, the same result is obtained by
replacing one'of the guy ropes 6 by anelastic'ally stretch 35 sional force stored in the elastically stretchable means
constituting a force tending to elfect the partial collapse
able spring or rope 9. The function of the rope or spring
of the parachute when the wind pressure acting-upon the
"9'- is apparent from the previous description and is, in
parachute declines below said predetermined value.
effect, the same as that of spring 7 or rope 8.
5. A snake according to claim 1 wherein'shroud lines
Finally, ‘according to FIG. 6, the same effect -is ob
tained byattaching elastically stretchable ropes or springs 40 attached to the rim of the canopy secure the parachute
to said rearward end of the snake, and wherein said yield
.10‘ crosswise tofthe circumference of the canopy. Both
able means comprise elastically stretchable means consti
‘ropes or, springs 10 remain stretched as long as‘the ‘brak
ing force is above the value F131 and begin to‘contract
'when that‘value is approached, thus collapsing the canopy
more ‘or less andispilling the wind out'of the-parachute. .
tuting one of said shroud lines, said elastically stretchable
means when relaxed‘holding the canopy in an at least
45
While the invention has been described’in detail with
respect to certain-now preferred examples‘ and embodi
partially collapsed con?guration and being stretched by
an opening of the'canopy in response to a wind pressure
, above said predetermined value, the ltensional force stored
in the elastically ‘stretchable means effecting the partial
‘ments of the invention, it‘ will be understood by those
collapse of the parachute when the wind pressure declines
skilled in the art, after understanding the invention, that
various' changes and modi?cations may be made" without 50 below said predetermined value.
6. A snake according to claim! 1 wherein shroud lines
departing from the spirit and scope of the'irrvention, and
‘attached't'o the rim of the canopy secure the parachute to
‘it is intended, therefore, to cover all'such‘chan'ges and
said rearward end of the snake, and wherein said yield
‘modi?cations in the’ appended claims.
.
What'isclaimed as‘ new and desired to be secured'by 55 able means lcor‘nprise elastically stretchable means ex
tending across the canopy attached to the rim thereof, said
‘Letters Patent is:
elastically stretchable means when relaxed holding the
‘1. A power driven explosivesnake for clearing a path
canopy inan at least partially collapsed con?guration and
across‘a mine ?eldb'y ?ring the snake across the mine
being stretched .by an opening of the canopy in response
held in free-?ight and ma substantially stretched out
condition, said snake comprising a rollable ‘and 'pliable 60 to ‘a wind pressure above said predetermined value, the
tensional force stored in the elastically stretchable means
tube-?lled‘with an explosive materialand a's'tabilizing
meanslfor stabilizing the trajectory of the snake, said
stabilizing means being attached to the rearward end of
the tube and including a parachute having a canopy ar
ranged to be opened by the windpressure acting upon the
canopy due to the flight velocity of the snake, said para 65
chute exerting astabilizing braking force for holding the
snake on its trajectory, the strength of said braking force
effeoting'the partial collapse of the parachute when the
wind pressure acting upon the parachute declines below
said predetermined value.
References Cited in the ?le of this patent
UNITED STATES PATENTS
1,340,259
Taylor ______________ __ May 18, 11920
being a function of the effective area of the canopy and
11,519,857‘
said'effective area being a ‘function of the wind pressure, 70 1,978,641
and yieldable compensating means attached to the para
*2,77l1,‘841
Lucas ______________ .._ Dec. '16, 1924
Martin _______________ __ ,Oct. 30‘, 1934
De Finol _____________ __ Nov. 27, 1956
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