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Патент USA US2407846

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Sept. 17, 1946.
E. c. MoRlARTYl
2,407,844
BOMB FUSE
Filéd April 2, 19:52
4 Sheets-Sheet 1
32
dtâorrceg
*Sept 17, 1946.
E_ @_ M0R|ARTYI
2,407,844
BOMB FUSE
Filed April 2, 1932
_
4 Sheets-Sheet 2
Sept. 17, 1946.
- E. c. MoRlARTY
2,407,844
BOMB FUSE
Filed April 2, 1932
37
4 Sheets-Sheet 3
Sepi 17, 1946-
E. c. MoRlARTY
l
2,407,844
BOMB FUSE
Filed April 2, 1932
b4 Sheets-sheet 4
8
_573 @JL M ~
dâfarmey
Patented Sept. 17, 1946
SITES.
ÂTENT OFFKC
2,407,844
BOMB FUSE
Ernest C. Moriarty, Washington, D. C.
Application April 2, 1932, Serial No. 602,795
10 claims. (Cl. 102-812)
1
2
This invcntion relates to bomb fuses and more
particularly to fuses for bombs launched from
of a bomb by firing a detonating or an ignition
train of explosives that lead to the main explo
sive charge of the bomb.
aircraft.
The objects of this invention are:
During the World War, bombs designed to be
First, to provide a bomb fuse that is simple in 5 laimched from aircraft were used extensively,
construction and is made of few parts;
and it is Well-known that a large number of the
Second, to provide a bomb fuse Whose ñring
bombs so dropped failed to explode as intended.
mechanism may be removed from the body of “ The large number of such fail-ures has resulted in
the fuse in either the armed or unarmed condi
the practise, especially in the larger size of
tion, Without removing the body of the fuse from 10 bombs, of using two fuses in each bomb, one in
the bomb, and when so removed, all parts of
the nose and one in Vthe tail of the bomb. Fail
the ?ring mechanism are self-contained and
visible, and the mechanism may be operated by
ure of a bomb fuse to function as intended may
be due to defective elements in the detonating
hand;
or ignition train, a defective booster, or the de
Third, to provide a bomb fuse that has no 15 fects in the ?ring mechanism, Which may be due
loose part-s that might be lost and whose ?ring
to defects in design or to the condition of the
mechanism, Which includes the initiating explo
mechanism.
sive train, may be stoWed separately from the
A bomb fuse is usually attached to'a bomb in
body, Which may contain a booster charge;
an unarmed condition and remains so set until
Fourth, to provide a bomb fuse that may be 20 the bomb is launched on its flight. In its un
armed or unarmed by hand Without removing
armed condition a resistance is interposed to
any part from the fuse or the fuse from the
prevent the ?ring of the explosive train leading
bomb, and Without the use of tools or spare parts.
to the main charge of the bomb, this resistance
Also, fuses having been armed accidentally may
being sufiicient to prevent an accidental explo
be returned to the unarmed condition Without 25 sion or even permitting a heavy impact such as
the use of tools;
that caused by dropping the bomb on a hard
Fifth, to provide a fuse that can be readily
surface from any altitude less than that Which
checked as to completeness of assembly of its
Will cause the explosion of the main charge of
parts. their condition and ability to function;
the bomb Without fuse action. Until a bomb is
Sixth, to provide a bomb fuse that has great
launched, its fuse usually is constrained from
resistance to firing When in the unarmed condi
arming by a Wire or other suitable means. When
launching a bomb, the' constraining Wire is re
tion;
Seventh, to provide a bomb fuse that is more
moved and the fuse arms. As bombs are some
certain to ?re by utilizing a plurality of initiat
times accidentally dropped While the aircraft
ing explosive trains;
is taking off and also because it is safer to use
Eighth, to provide means for obtaining vari
fuses that do not arm until the bombs have
ous delays in arming of the fuse to suit the con
cleared the aircraft from Which they are
launched, a delay in arming, after the constrain
ditions under Which the bomb is to be launched;
Ninth, to provide a. bomb fuse that, if acci
ing device is removed, is desirable,
dentally armed While being carried by an air 40
A bomb fuse is in the armed condition When
craft at high speed, will be automatically un
the resistance to ?ring is such that the fuse Will
function to explode the bomb when it impacts
armed When the speed of the aircraft is vreduced
below a predetermined air speed;
on an object or at the end of a time interval.
Tenth, to provide a bomb fuse in Which the
The resistance to ?ring in the unarmed con
friction caused by the mass of the parts is de 45 dition' is usually obtained by the physical
creased as a function of the angle of inclination
strength of the parts of the mechanism, but it
may be increased by a discontinuity in the ?ring
of the axis of the fuse With the horizontal;
Eleventh, to provide a bomb fuse that is rela
train of' the fuse. Such a discontinuity is usually
tively inexpensive to manufacture and assemble.
referred 'to as “detonator out of line,” and is
With the above and other objects in view, this 50 accomplished by anl arrangement Where the ini
invention consists in the arrangement and con
ti'ating explosive train is out of line With the ?r
struction of parts as Will be hereinafter more
-i-ng pin and the lead to the booster and main ex
fully described.
plosive charge of the bomb When the fuse is un
A bomb fuse usually consists of a ?ring mech
armed. For a given initiating train of explo
anism that is designed to initiate the exp-losion 55 sives there is a minimum distance that must
2,407,844
3
separate it from the other explosives in order
to insure that its accidental ?ring will not cause
the detonation of the other explosives in the
bomb, the factor of safety increasing as the min
imum distance is exceeded.
Bomb fuse; are usually armed by the action of
air on a propeller, the time required to actuate
the propeller giving the desired delay. The size
of a bomb fuse propeller is limited by the clear
ance in the bomb racks. etc., and hence, the in
ternal work due to friction, springs, etc., that is,
to be overcome by the torque of the propeller is
also limited.
«
4
sition and retains it in this position until the end
of the delay. This is desirable as the resistance
to ?ring is not lessened progressively during the
arrning delay, the other parts of the fuse remain
ing in their unarmed position until the end of
the delay, Means are provided for obtaining any
length of delay that may be desired. In the case
of dive bombing, where bombs may be launched
from a plane traveling in a nearly vertical, verti
cal or beyond the vertical (plane on its back)
direction, and where the velocity of the plane
is practically equal to its terminal velocity, all
bomb fuses of the usual design arm too quickly.
To meet this condition, when there is a slow sepa
ration of the bomb and the plane (both falling
This invention is based in part on the above
consideration, and is applicable to bomb fuses of 15 practically in a vertical direction) , means are pro
the usual type of both nose and tail fuses, but is
vided for obtaining a suitable delay by a rela
not limited thereto.
tively large number of turns of a slow-revolving
The mechanism of my invention is simple in
propeller having a steep pitch or the equivalent
construction and contains but comparatively few
thereto.
parts. This is desirable. as it lessens the liability 20
In case a fuse should be accidentally armed
of malfunctioning due to the omission of parts or
when a bombl is carried by an aircraft traveling
the use of defective parts during the assembling
at a high speed, means are provided for unarm
of the fuse. The mechanism may be assembled
ing the fuse when the speed of the aircraft is
in two units; the fuse body, with or without a
reduced :below a given air speed. This is desir
booster, and the ?ring mechanism: The ?ring
able in case the aircraft is to land with bombs
mechanism may be removed from the fuse body
attached to it.
with the fuse in either the unarmed or armed
In the arming mechanisms of bomb fuses it is
condition, without removing the body of the fuse
the usual practise to mount the propellers so that
from the bomb, and when so removed, all parts
they turn parts of the mechanisms on a screw
of the mechanism are self-contained and visible 30 thread, Due to the small torque developed by
and the mechanism may be operated by hand.
the propellers, generally a fractional part of an
There are no loose parts that might be lost.
inch-pound at an air speed of 60 miles per hour,
Also, the ?ring mechanism which includes the
either the diameter of the screw threads or the
initiating explosive train may be sto-wed sepa
mass of the revolving parts must be relatively
rate from the body of the fuse which may oon
small. Bombs are generally carried in a position
tain a weaker charge, a separate stowage of det
practically parallel to the longitudinal axis of
onators being usually considered a safer practise.
the aircraft, and are launched from this position.
The fuses may be armed or unarmed by hand
At low air speeds when the aircraft is traveling in
without removing any part from the fuse or the
a, direction which is substantially horizontal, the
fuse from the bomb and without the use of tools ILO torque, due to friction that must be overcome
or snare parts. Fuses that have been armed ac
in order to turn a part of the fuse on a screw
cidentally may be returned to the armed condi
thread is practically proportional to the mass
tion without the use of tools. The ready means
of the part and there is little if any change in the
of checking the completness of the assembling
torque when the axis of the bomb is inclined to
of the parts of the fuse, their condition, and their
the horizontal. At high air speeds there may
ability to function, lessens the liability of mal
be a thrust on the part due to the action of the
functioning of the fuses when the bombs are
launched.
air, especially if the part is exposed to the air
and the fuse is designed to operate at a low
The resistance to ?ring when the fuses are in
the unarmed condition is accomplished by both 50 terminal velocity. The dif?culty experienced in
turning parts of a fuse on a screw thread by the
physical strength of the parts of the mechanism
action of an air propeller is Well known to those
and by the initiating ex'olosive trains being out
Skilled in the art, and their use in .bomb fuses has
of line with the ?ring pin and the lead to the
been limited. In order to overcome the di?iculty
booster charge. The construction and operation
of turning parts of considerable mass, I have
of the detonator holders is such that the detona
devised means whereby the torque due to the fric
tor may be separated from the booster lead by
tion caused by the mass of the parts is decreased
three or four times the distance usually found
as a function of the angle of inclination of the
in bomb fuses. In case of severe impact, a drop
axis of the fuse with the horizontal, so that these
on a hard surface from a high altitude, resulting
in crushing the parts of the fuse, an additional 00 parts may be operated by propellers of the usual
size.
safeguard is provided consistingr of means for
This invention may be best understood by ref
sealing the lead to the booster. and thus increas
erence to the accompanying drawings, in which:
ing the resistance to ?ring in excess of that due
Fig. 1 shows a fuse assembled in the nose of a
to the distance which separates the initiating ex
bomb;
plosive train from the lead to the lbooster charge.
Fig. 2 shows a fuse asseinbled in the tail of a
The construction of the detonator holder is
bomb;
such that two o-r more initiating explosive trains
Fig. 3 is a cross-section of the fuse in Fig. l
may be mounted therein, and the fuse set to ?re
showing the propeller after it reaches the limit of
either one, as may be desired, or all may be ?red
simultaneously. The liability of malfunctioning 70 its longitudinal travel and again after it has ro
tated the striker somewhat;
due to a defective element in either train is there
Fig. 4 is a cross-section of the fuse on line fl-ll
by reduced.
The delay in arming is accomplished by the
action of an air operated propeller, the shaft of
which looks the mechanism in the unarmed po
of Fig. 3;
Fig. 5 is a cross-section of the fuse on line 5-5
of Fig. 3;
2,407,844
5
Fig. 6 is a cross-section of the fuse on line 6-6
of Fig. 3;
Fig. 7 is a cross-section of the fuse on line 7-7
of Fig. 3;
Fig. 8 is a cross-section of Fig. 7 at 8-8;
Fig. 9 is a cross-section of the fuse on line 9--9
6
body. It does not rotate with the propeller shaft
but with the striker to which it is attached. The
clearance between the extension and cap must
permit su?icient longitudinal movement of the
striker relative to the fuse body for the fuse to
function.
of Fig. 3;
In Fig. 3, @9 is the remainder of the booster
charge assembled in the fuse body and held in
lši-lü of Fig. 3;
place by a thin disk 50. Detonator holder 5| is
Fig. 11 is a cross-section of the body of the 10 pivoted on a small bearing surface in the body
fuse with the ñring mechanism removed;
of the fuse by pivot 52 and has a cylindrical
Fig. 12 is a plan view of the fuse body;
stem 53 which projects through firing pin holder
Fig. 13 is a cross-section of the ?ring mecha
54 and is secured to striker 33 by a pin 55 that is
nism removed from the body of the fuse;
shearable on impact. Firing pin holder 54 car
Fig. 14 is a view of the ?ring mechanism from
ries the ñring pin, as will be described later, and
below;
is held in place -fby thumb nut 42. By unscrewing
Fig. 15 shows the fuse body 'in one piece;
thumb nut 42, the entire firing mechanism can
Fig. 16 is a plan view of the fuse body in one
be lifted out of the body of the fuse. The pro
piece;
peller shaft di) is threaded throughout its entire
Figs. 17 and 18 show the detonator holder with 20 length with the exception of the portion 56 which
and without a pivot, respectively;
stops the rotation of the shaft when it reaches
Fig. 19 is a view of the detonator holder from
bearing 57 which is internally threaded to coop
below;
erate with the threads on shaft 40, and the 'pro
Fig. 20 is a cross-section of a portion of the
peller then turns the striker 36 and detonator
fuse through vent, ?ring pin, detonator and 25 holder 5| to the armed position. Detonator hold
booster lead;
er 51 has a small bearing surface 58 touching the
Fig. 21 shows a detent for holding the fuse in
?ring pin holder 54. The real importance of this
the armed position;
will be explained later. The upper part of the
Fig. 22 is an elevation of the detonator holder
fuse body 55 may be formed from a separate
showing the cam slot;
30 piece and forced onto the body 55 as shown. Vent
Fig. 23 shows how the fuse may be armed in
50 assures the easy passage of stem 53 into cavity
three different positions;
6! by allowing the enclosed air to escape readily.
Fig. 24 shows the detonator holder with three
Fig. 4 is a cross-section of the fuse at ê-é,
detonators;
Fig. 3. This shows how pin 55 secures stem 53
Fig. 25 shows vthe ?ring pin holder with two
to the cylindrical portion of striker 35. Three
ñring pins;
projections 62 extend from the top of the body
Fig. 26 shows the detonator holder with two
of the fuse and have intervening spaces. The
detonators;
height of these projections must be slightly great
Fig. 27 shows the ?ring pin holder with a skirt
er than the full movement required of the striker
around the top;
40 relative to the body of the fuse in operation.
Fig. 28 is a plan view of Fig. 27;
Shaf-t ed passes through a slot that is partly in
Fig. 29 is a diagram of the propeller having
the striker and partly in the fuse body and thus
two vanes;
prevents rotation of the former relative to the
Fig. 30 shows a design with auxiliary vanes on
latter until the shaft is withdrawn during the
the striker;
arming of the fuse.
Fig. 31 shows a propeller with vanes set at two
Fig. 5 is a cross-section of the fuse at 5--5,
angles;
Fig. 3. This shows three projections 53 that ex
Figs. 32 and 33 show a spring _that may be used
tend from the lower` side of the striker 35, which
for arming or unarming;
I
has intervening spaces. In the unarmed condi
Fig. 34 shows a looking pin for the fuse without
tion of the fuse the projections 53 are in align
Fig. 10 is a cross-section of the fuse on line
a propeller;
merit with the projections 62, thereby prevent
Fig. 35 shows a striker with rollers to reduce
the friction.
Similar numerals refer to similar vparts
ing longitudinal movement of the striker relative
to the fuse body.
Fig. 6 is a cross-section of the fuse at 'e`-5,
Fig. 3, but which is reduced from the dimensions
of that ?gure. This shows the position of the
detonator 64 in the detonator holder in the un
armed condition. This is shown in cross-section
in Fig. 20.
Fig. 7 is a cross-section of the fuse at l_'.=',
Fig. 3, showing a vent hole 55 that in the un
armed condition of the bomb is directly over the
detonator or initiating explosive train. This vent
is for the escape of gas in case the detonator
should be fired accidentally when the fuse is un
armed. There is enough clearance around shaft
fiil and striker 35 for this gas to readily escape
to the atmosphere. Piece 55 is the ?ring pin
throughout the several views.
Reference numeral 59, Fig. 1, represents the
body of a bomb, 3! the main explosive charge of
a bomb, and 32 is a part of the booster charge
assembled in an adapter 33. Reference numeral
35 represents the body of the fuse, 36 a striker,
57 a propeller, 38 an arming wire that passes
through a hole in 35 and through one vane of
37, it being retained in position by a clip 39. Pro
peller 37 is secured to shaft 40 by nuts lil. The
axis of shaft 45 is not coincident with the axis r
of the body of the fuse. Thumb screw 42 holds
the ?ring mechanism in the fuse body 35.
In Fig. 2, 133 is the cone of the tail to which
the vanesI 44 are attached. The body of the fuse
whose position, as well as the location of the
is extended rearward and this extension, together 70 vent in firing pin holder 5=t, is shown more clear
with nut 45, serves as a means for holding the
ly in Figs. 8 and 20. This pin is located at the
cone in place on the bomb. The base of the cone
same radius from the axis of the fuse as the
43 is secured to the bomb 35 by studs 135, so that
opening 4? is opposite thumb nut yllii. rE'he -cap
48 covers the opening in the extension of the fuse
vent and diametrically opposite it, so that the
detonator, which is under the vent when ro
tated. through 180°, Will be under the ?ring pin.
_2,407,844
7
The method of supporting the ?ring pin by a
small shearable pin is shown in Fig. 20. The
end of thumb screw 42 enters a cavity in ?ring
pin holder 54 and holds it secure in relation to
the body of the fuse as the striker and detonator
holder rotate during the arming of the fuse.
Fig. 8 shows a portion of a cross-section of the
8
position until the bomb strikes its objective.
The plunger 15 projects into cam slot 19 due to
the action of spring 16. Thumb nut 18 is for
the purpose of withdrawing the plunger from the
cam slot in case it is desired to unarm the fuse
by hand. Spring 15 acts on bushing 11 and a
shoulder on plunger 15. The plunger does not
bear against the surface of the cam slot and
fuse at 8-8, Fig. '7. The ?ring pin does not
therefore offers no initial moment, due to fric
extend below the lower side, but does extend
above the upper side of ñring pin holder 54 and 10 tion, that opposes the turning of the detonator
holder in the fuse body. Such reduction of fric
to within a short distance from the cylindrical
tion is important, as will be explained more fully
projection of striker 36. This, during operation,
later. However, during the arming operation,
allows the ?ring pin su?icient movement relative
the cam slot has a large mechanical advantage
to the bearing 54 to insure explosion of the det
15 in compressing spring 16, and when the slot 80
onator.
is opposite the plunger, the compressed spring
Fig. 9 is a cross-section of the fuse at 9-6;
will force the plunger into the slot and lock the
Fig. 3, but which is reduced from the dimensions
fuse in the armed condition. It will be seen that
of that ñgure. This shows the position of the
this gives an 180° movement of the detonator
lead '61 from the cavity of the fuse body to part
of the booster charge 49. This lead 61 is in line 20 holder relative to the fuse body so that the ?ring
pin, detonator and booster lead will be in line.
with the ?ring pin as is shown in Fig. 20.
The detent may also be applied to the cylindrical
Fig. 10 is a cross-section of the fuse at i?-l?,
projection of the striker and have the same ac
Fig. 3. This shows the method of obtaining an
tion. Also, more than one detent may be used
exact rotation of 180° of the striker and detona
tor relative to the body of the fuse. Stop 68 is 25 when the fuse is designed to be ñred with the
detonator holder in several different positions,
shown in the unarmed condition resting against
as will be further explained later on.
one of the projections 62. During the arming op
Fig. 22 shows an elevation of a detonator hold
eration, stop 66 passes through arcuate slot 66
er showing the cam slot 19.
and comes to rest in cavity 16. Means for main
Fig. 23 shows a slight change in design over
taining the stop in this cavity while the armed 30
that shown in Fig. 10 whereby the fuse may be
condition prevails, will be described later.
armed in three diiferent positions. Slots 69 are
Fig. ll is a cross-section of the body of the
cut in two of the projections 62 and cavity'16 in
fuse with the ?ring mechanism removed. Two
the third one. The fuse may be armed by stop
of the projeotions 62 are shown here and the ar
cuate slot 69. Also, that part of the slot 86 35 68, coming to rest against either of stop pins 8|
or cavity 16. The stop pins 8| may be inserted
contained in the fuse body, into which shaft 69
or removed, as necessary. The amount of rota
?ts, is seen at the left of the cavity which hor
mally holds the ñring mechanism.
Fig. 13 shows the ?ring mechanism removed
from the body of the fuse. The ?ring pin 66 and cavity 'il are in front of the plane of the
section as shown in Figs. '7 and 9 respectively.
The cavity 1.2 receives the end of thumb screw 42.
Fig. 15 shows a fuse body of one piece, that is,
part 59 is made integral with the body of the
fuse instead of Sepa-rate as shown in Fig. 3.
Figs. 17 and 13 show detonator holders with and
tion of the ?ring mechanism relative to the fuse
body until the stop strikes the ?rst stop pin is
60°, the second stop pin 180° and the cavity 300”.
This fuse has been shown with three projec
tions 62, 63 on the body and the striker, but it is
evident that a fuse could be constructed with one
or two or more projections. If one projection on
each part is used, the arming requires a rotation
through an angle of 180'”, more or less, depending
upon .the angles subtended by the projections.
place by soft metal containers. Soft metal gasket
If two projections are used on each part, there
will be two positions, one 90° and one 270° from
the unarmed position, in which it. may be ar
ranged to have the fuse armed.
Fig. 24 shows the detonator holder with three
detonators so located that one will be under the
?ring pin after a rotation of the ?ring mecha
nism relative to the fuse body of 60°, 180° or 300°
respectively. Each detonator consists of a per
cussion cap, a delay pellet and a detonating ele
ment. The delay pellets have different time de
M is for the purpose of sealing lead 61 in case
lays so that a selection may be made of a delay
without pivot 52.
,
Fig. 20 is a cross-section of a portion of the
fuse through the vent, ?ring pin, detonator and
booster lead. This shows the location of vent
65 over the detonator 64 and ?ring pin 66 over
cavity 16 in the unarmed condition. She-arable
pin '53 supports the ?ring pin until the striker
shears it on impact. The lead 61, to part of the
booster charge, is shown in line with the ?ring
pin.
Detonator 613 and lead 6? are retained in
the bomb is accidentally dropped Without arming. 60 suitable to the particular use to which the bomb
If the impact is su?icient to shear projections
is to be put.
62 and 63, Fig. 3, the striker will move longi
Fig. 25 shows a ?ring pin holder 54 with two
tudinally relative to the fuse body and impinges
firing pins 66 and two vents 65 which in the un
upon ?ring pin 56, shearing supporting pin '23,
armed position are over the two detonators shown
moving the ?ring pin into cavity 'H and forcing 65 in Fig. 26. Such an arrangement is desirable in
order to decrease the probability of failures.
the detonator holder against gasket 'a'li whereby
the lead 61 to the booster charge is effectively
sealed.
It will thus be seen that there is a very
high resistance to ?ring the main charge of the
bomb by an impact on the striker when the fuse
is in the unarmed condition. In fact, it will
Fig. 26 shows a detonator holder with two det
onators 64. In the unarmed condition the cavi
ties 1| are under the respective ?ring pins 66 of
Fig. 25, but a rotation of 180° of .the detonator
holder relative to the fuse body will place the
detonators under the respective ?ring pins of
stand any impact short of that su?icient to fire
Fig. 25, so that on impact both detonators will
the main charge without fuse action.
be ñred simultaneously.
Fig. 21 shows a detent that, after the arming
Fig. 27 shows a ?ring pin holder 54 with a skirt
operation, will hold the fuse looked in the armed 75
2,407,844
10
82. Such an arrangement makes it possible to
set the fuse deeper into the bomb with the striker
tical will be less than the torque exerted by-the
propeller. Transferring the reaction due to the
projecting from the bomb by as small a distance
as may be desired. The skirt is engaged by thumb
screw 42 of Fig. 3 which, as is apparent, must be
mass of the parts to be turned from a bearing
of large diameter to a bearing of small diame
ter when the axis of the fuse is inclined, results
in a reduction of the moment due to friction,
and the reduction increases as the angle that
the axis of the fuse makes with the horizontal
increases.
outside the bomb. The cylindrical portion of the
striker Fig. 13 is designed to project into the skirt
of the ?ring pin holder to a point near the ?ring
pin, in the unarmed condition, and to move suf
?ciently far into the skirt to strike the ?ring pin 10
When the fuse is used as a tail fuse, the reac
and explode the fuse on impact.
tion due to the mass of the striker and detonator
The distance that the striker of a nose fuse
holder is on the pivot 52 of Fig. 3, the action
projects beyond the body of the fuse is largely
of this pivot being similar to the small bearing
determined by the angle from the vertical that it
58 in the case of a nose fuse.
is desired to have the striker impinge upon a 15
When the terminal velocity of the striker of a
horizontal surface, the angle increasing as the
nose fuse isl considerably less than the terminal
projection of the striker from the body of the
velocity of the bomb as a unit, the pivot 52 of Fig.
bomb is increased.
3 may be used to take the end thrust of the
Fig. 29 shows a diagram of a propeller having
striker due to the action of the air. When the
two vanes. If F represents the resultant force 20 terminal velocity of the striker is higher than
acting on each vane, the torque about an axis
that of the bomb, the pivot 52 may be omitted
perpendicular to the plane of the figure and pass
as the striker will always tend to fall out of
ing through its center will be 2TF, r being the
the bomb When its axis approaches the vertical.
radius from the center of .the ñgure to the center
In order to overcome the reaction of the shaft
of pressure of each vane. The torque about an 25 49, Fig. 3, on bearing 51 and the body of the
axis parallel to the above-mentioned axis but
fuse, a propeller having a maximum torque at
separated from it by a distance a: will be
(r-x)F+(r+x)F=2rF. Hence, it follows that
the torque about any axis parallel to the ?rst
mentioned axis will be 2rF.
`
Referring to Fig. 3, when the stop 56 of the pro
peller shaft reaches bearing 51, the torque of the
zero velocity of rotation is needed. Such pro
pellers arm the fuse too quickly. The propeller
shown in Fig. 31 has been arranged to overcome
30 this fault.
V
When an air propeller with flat vanes is re
volved by the action of the air, the resultant
propeller tends to turn the striker and detonator
direction of the air stream on the vanes changes
so that the angle of incidence is reduced. If
.the propeller is turning, it stores up momentum 35 the load on the propeller is small, the angle of
and the moment of this momentum about .the
incidence at the extreme radius of the vanes
axis of shaft 120 will be the same as that about
may be zero or less. In the latter case, the
holder about the axis of the fuse body. While
the axis of the fuse. This can be readily proved
by replacing the force in diagram of Fig. 29 by
momentum.
Fig. 30 shows a modification in arming pro
outward portion of the vanes acts as an air brake
and the torque of this portion is negative. When
40 the torque due to the load on the propeller and
the negative torque equals the positive torque
pellers that is desirable sometimes. Here aux
iliary vanes 83 have been secured to the head
of the striker. With this design propeller shaft
of the inner portion of the vanes, the correspond
ing velocity of rotation of the propeller will be
the maximum for that particular velocity and
Lif) may or may not have the stop 56 as shown 45 condition of the air.
in Fig. 8. If the stop is omitted, the propeller
In view of the above, vanes 84 of Fig. 31 are
screws the shaft out of the fuse and together they
set to give the maximum torque at zero velocity
fall away from it in space. The striker is then
of rotation and vanes 85 are set normal to the
rotated to the armed position by means of vanes
air stream and hence give zero torque at zero
83. If the stop 58 is used, the striker is rotated 50 velocity o_f rotation of the propeller. But as
by the combinedaction of the two propellers.
the propeller turns, vanes 85 exert a negative
One of the major problems in designing fuses
torque with the result that the maximum speed
for bombs to be launched from aircraft is the
of the propeller under any given conditions is
reduction of the internal friction of the fuse
equivalent to that of a propeller having a very
parts that must be overcome by the action of 55 steep pitch. Propellers made in this manner
the propeller. In the present fuse, when the
are very easy to adjust. The proper size and
axis of the fuse is horizontal, the reaction, due
shape of the positive vanes may be calculated
to mass of the striker on the body of the fuse,
and tested for torque in a wind tunnel sepa
acts on the cylindrical projection of the striker
rately from vane 85, and when assembled in a
which extends into the fuse body. The radius 60 propeller with vanes 85, the time for any number
of the projection of the striker is relatively large
of revolutions may be arrived at by adjust
and offers a correspondingly large torque due
ing the angle or size of the vanes 85, the time
to friction to be overcome by the action of the
being shortened if they are inclined slightly so
propeller. After the bomb has been launched,
as to exert a positive torque or being increased
the axis of the bomb and fuse turn towards 65 if they are inclined slightly in the opposite direc
the vertical. The reaction due to the mass of
tion. The two sets of vanes may be on one pro
the striker has two components, one acting on
peller or each set or combination thereof may
the projection of the striker and one on the small
be contained in separate propellers mounted on
saring surface 53 of Fig. 3 which is supported
one propeller shaft.
by ?ring pin holder 543. When the fuse is Ver 70 The operation of the propeller shafts is not
tical, the entire mass of the striker and detona
limited to any particular type of propeller, as
tor holder is supported by bearing 58. This bear
any type giving suf?cient torque and the desired
ing may be made as small as desired so that
delay may be used. The propeller shafts may
the torque necessary to turn striker and detona
be shorter than those shown if the bombs are
tor holder on this bearing when the fuse is Ver
to be launched at low air speeds, but the' length
,
11
12
_
.
parts may be made within the scope of the ap
pended claims without sacri?cing any of the ad
vantages of this invention.
I claim:
1. A bomb fuse comprising a fuse body having
?rst projections with intervening spaces thereon
must be suificient to engage the body of the
fuse. With any given length of propeller'shaft,
a preliminary adjustment may be made so that
the portion entering the fuse is such as to give
any desired delay less than the maximum delay
that may be obtained for a given air speed and
and provided with a cavity therein, a striker hav
condition of the air.
ing second projections with intervening spaces
Figs. 32 and 33 show a further modification of
thereon, a ?ring pin holder, a detonator holder,
the fuse. The spring 86 is mounted on the core
81, one end of the spring being attached to piece 10 the three latter parts having a common axis
with said cavity, said ?ring pin holder being se
88 which is soldered or otherwise secured to the
cured in the body of the f-use by means of a de
core and, also, attached to the body of the fuse
tent operated from without the body of the fuse,
said detonator holder being at the bottom of the
cavity and having a stem passing through the
?ring pin holder and attached at the mouth of
by pin 89. The other end of the spring is at
tached to a slider 98 which has a projection 95
that may be turned up or down. , When turned up
and inserted in a cavity in the striker, the spring
will be compressed by rotation of the striker rela
tive to the body of the fuse. The movement of
the slider is limited to 180° by the stop 93 which
is formed by an increase in diameter of the core.
As shown, the spring opposes the action of the
propeller to arm the fuse. The force exerted by
the spring may be adjusted so that the fuse will
not arm until a given air speed is' exceeded, and
if the fuse is accidentally armed when the carry
ing plane goes into a steep dive, where its air
speed is high, it will unarm when the plane as
sumes normal ?ight and the air speed of the fuse
is reduced below that for which the spring is ad
justed. It is evident that the spring may be so ar
a cavity in said striker by a shearable connec
tion, said striker being mounted in the fuse body
so that it may rotate between stops, said ?rst and
second projections being in alignment in the un
armed condition and being opposite correspond
ing spaces in the armed condition, a ?ring pin,
a detonator, a lead to an explosive charge, the
latter three elements being out of line when the
` fuse is unarmed and being in line when the fuse
is armed, a shaft for preventing rotation of the
striker and detonator holder relative to the fuse
body when the fuse is unarmed and providing
a delay during arming, and a propeller for arm
1 ing said fuse.
2. A bomb fuse comprising a fuse body having
?rst projections With intervening spaces thereon
and provided with a cavity therein, a striker hav
ing second projections with intervening spaces
thereon, a ?ring pin holder, a detonator holder,
ranged
by contracting
that it returns
is elongated
the fuse
during
to the
arming
unarmed
condition.
A spring may be designed to be in a compressed
condition when the fuse is unarmed so that the
force it exerts will assist in arming the fuse.
Again, it may be designed to exert suf?cient force
to arm the fuse without the action of a propeller,
the three latter parts having a common axis with
said cavity, said ?ring pin holder being secured in
the body of the fuse by means of a detent oper
ated from without the 'body of the fuse, said
detonator holder being at the bottom of the
40
armed position by means of a pin 94, Fig. 34,
cavity and having a stem passing through the
which passes through the striker and a projec
?ring pin holder and attached at the mouth of
tion 95 on the body of the fuse, the pin being
a cavity in said striker by a shearable connec
withdrawn by an arming wire 38 attached
tion,
said striker being mounted in the fuse body
thereto. The spring without a propeller gives a
so
that
it may rotate between stops, said ñrst
very quick arming arrangement, which may, if 45
in which case the fuse may be locked in the un
and second projections being in alignment in the
desired, have an initiating explosive train with
a delay su?iciently long to allow the aircraft to
unarmed condition and being opposite corres
ponding spaces in the armed condition, a ?ring
reach a safe distance before the bomb explodes.
pin, a detonator, a lead to an explosive charge,
In case it is desired to have a fuse that arms
I" the latter three elements being out of line when
very quickly when dropped from an aircraft trav- ,
the fuse is unarmed and being in line When the
eling at a Very high speed at a low altitude, the
fuse is armed, a shaft for preventing rotation of
moment due to the friction of the striker may be
the striker and detonator holder relative to the
reduced by substituting rollers 95 and 91, Fig. 35,
fuse body when the fuse is unarmed and provid
for the projections 63 of Fig. 13. The view of 3 ing a delay during arming, a ñrst propeller for
Fig. 35 is from below the striker. The rollers are
removing said shaft from the fuse, and a second
supported by bearings 98 attached to the striker.
propeller attached to the striker for rotating the
The rollers engage the inner surface of 59, Fig.
striker and detonator holder relative to the fuse
3, rolling thereon when the fuse arms. Rollers
body to the armed position.
96 do not touch the cylindrical portion of the
3. A bomb fuse comprising a fuse body having
striker and rollers 97 do not touch each other.
first projeotions with intervening spaces thereon
It is evident that these rollers may be used in
and provided with a cavity therein, a striker hav
lieu of the projections 53 of Fig. in any of the
ing second projections with intervening spaces
combinations of parts thatl have been previously
described.
thereon, a ?ring pin holder, a detonator holder,
The fuse may be designed to arm by a right 6,5 the three latter parts having a common axis with
said cavity, said ?ring pin holder being secured in
or left-hand rotation of the striker. When the
the body of the fuse by means of a detent oper
direction of rotation is selected, the threads on
atedV from without the body of the fuse, said
the base of the fuse should be such that the torque
detonator holder being at the bottom of the cavity
of the propellers does not tend to unscrew the
' and'having a stem passing through the ?ring pin
fuse from the bomb.
holder and attached at the mouth of a cavity in
It willV be understood that the above descrip
said striker by a shearable connection, said striker
tion and accompanying drawings comprehend
being mounted in the fuse body so that it may
only the general and preferred embodiments of
rotate between stops, said first and second projec
my invention, and that various changes in the
construction, proportion and arrangement of 75 tions being in alignment in the unarmed condi
76
2,407,844
13
tion and being opposite corresponding spaces in
14
being armed, whereby said ?rst and second pro
jections are opposite corresponding Spaces per
the armed condition, a ?ring pin, a detonator, a
lead to an explosive charge, the latter three ele
mitting longitudinal motion of said striker rela
ments being out of line When the fuse is un
tive to said fuse body.
armed and being in line when the fuse is armed,
6. A bom-b fuse comprising a fuse body having
a shaft for preventing rotation of the striker and
?rst projections thereon With intervening spaces,
detonator holder relative to the fuse body When
a striker rotatably mounted in said fuse body and
the fuse is unarmed and providing a delay during
having second projections thereon With interven
arming, a propeller for arming said fuse, and a
ing spaces, said ?rst and second projections being
spring for unarming said fuse at a predetermined 10 in alignment When the fuse is unarmed, and means
air speed in case it is accidentally armed.
for rotating said striker relative to said fuse body
4. A bomb fuse comprising a ifuse body having
When the fuse is being armed, Whereby said ?rst
?rst projections With intervening spaces thereon
and second projections are opposite corresponding
and provided With a cavity therein, a striker hav
spaces permitting longitudinal motion of said
ing second projections With intervening spaces 15 striker relative to said fuse body.
thereon, a ñring pin holder, a detonator holder,
7. A bomb fuse comprising a striker, a deto
the three latter parts having a common axis With
nator holder and means comprising a common axis
said cavity, said ñring pin holder being secured
about Which said striker and detonator holder
in the body of the fuse by means of a detent op
turns While the fuse is being armed.
erated from Without the body of the fuse, said 20
8. A bomb fuse comprising a. detonator holder,
detonator holder being at the bottom of the cavity
a plurality of detonators contained in said hold
and having a stem passing through the ñring pin
er, a ?ring pin, a lead to an explosive charge,
holder and attached at the mouth of a cavity in
said detonators being out of line With said ?ring
said striker by a shearable connection, said strikei`
pin and said lead to the explosive charge when
being mounted in the fuse body so that it may
the fuse is unarmed, and air pressure actuataible
rotate between stops, said ?rst and second projec
means for rotating said detonator holder relative
tions being in alignment in the unarmed condi
to and until a preselected detonator is in align
tion and being opposite corresponding spaces in
ment With said firing pin and lead to the `explosive
charge.
the armed condition, a ?ring pin, a detonator, a
lead to an explosive charge, the latter three ele 30
9. A bomb fuse comprising a fuse body having
ments being out of line When the fuse is unarmed
?rst projections With intervening spaces thereon,
and in line When the fuse is armed, a pin for pre
a striker having second projections with inter
venting rotation of the striker and detonator
vening spaces thereon, said ?rst and second pro
holder relative to the fuse body before launching,
jections being in alignment When the fuse is un
a spring to arm said fuse after launching, and a 35 anmed but being opposite corresponding inter
detent to maintain the fuse in the armed position.
5. A bomb fuse comprising a fuse body having
?rst projections thereon With intervening Spaces,
vening spaces When the fuse is armed.
10. A bomb fuse comprising ?ring mechanism
movable from an unarmed position to an armed
a striker rotatably mounted in said fuse body and
position and vice Versa, propeller means actuat
having second projections thereon with interven 40 able by air pressure to move said mechanism to
ing spaces, said second projections consisting of
the armed position, and means energized by said
rollers that roll on an inside surface of a part of
movement to the armed position effective to re
the fuse body and support the mass of the striker
turn said mechanism to the unarmed position
When the torque exerted by said propeller be
When the axis of the fuse is horizontal, said ?rst
and second projections being in alignment When 45 comes less than a predetermined value.
the fuse is unarmed, and means for rotating said
striker relative to said fuse body When the fuse is
ERNEST C. MORIARTY.
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