US2409205A - Bomb fuse - Google Patents

Description

wt. E5, 1946.. R, L.. GRAUMANN BOMB FUSE Filed Marh 2, 1932 2 Sheets-Sheet 2 l-wepor:

Granma l 53, d, azrrzeg Patented Cct. 15, 1946 BOMB FUSE Raymond L. Graumann, Alexandria, Va.

Application March 2, 1932, Serial No. 596,364

7 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757

This invention relates to bomb fuses, and more particularly to fuses for bombs launched from aircraft in which the fuse is armed by the action of the air on a propeller.

The objects of this invention are, first, to provide a fuse that has sufcient delay action that it will not arm until after it is clear of the airplane;

Second, to provide a fuse that has instantaneous action on impact;

Third, to provide a fuse that will automatically disarm at a predetermined reduced air speed;

Fourth, to provide a fuse that, after arming, so locks the arming mechanism that after disarming at a reduced air speed, it cannot be re-armed;

Fifth, to provide a fuse that is easily removed from the bomb and is safe during shipping; and

Sixth, to provide a fuse that is safe from accidental firing.

With the above and other objects in view, this invention consists of such construction and arrangement of parts as will be more fully described hereinafter in connection with the accompanying drawings, in which:

Fig. 1 shows the fuse in the unarmed condition;

Fig. 2 is a cross-section of the fuse on line 2--2 of Fig, l;

Fig. 3 is a cross-section of the fuse on line 3-3 of Fig. l;

Fig?. 4 is a cross-section of the fuse on line l-ll of Fig. 1;

Fig. 5 shows the fuse in the armed condition;

Fig. 6 is a crosssection of the fuse on line 6-6 of Fig. 5;

Fig. 7 is a cross-section of a part of the fuse on line l-l of Fig. 2;

Fig. 8 is a view of the arming nut; Fig. 9 shows the arming nut guide;

Fig. l shows the detonator holder.

The Cotter pin I-I insures the safety of the bomb during shipping and is removed when the bomb is placed in the racks on the airplane. The armlng wire I2 is secured to the airplane and is pulled out of the fuse by the weight of the bomb as it is released. Once the bomb is launched, the air act--l ing on propeller I3 turns shaft VIll until stop pin I strikes stop pin I5. As the velocity of the bomb through the air increases, the pressure on the propeller and hub overcomes the spring Il, forcing the shaft IA and arming nut I8 inward until the guide pins I9 reach the bottom of the slots 42, Fig. 9, in arming nut guide 20. The ball race 2l, due to securing pin 22 and collar 23, is carried inward with the shaft at the same time, which m0- tion is suioient to cause stop pin I5 to clear stop pin IS so that the propeller and shaft may again turn. The shaft will advance relative to the fuse body until shear pin collar 24 rests against the top of housing 25. Thereafter, the arming nut I8 will move outward relative to the fuse body. Resistance to turning of the shaft is small, due to the ball race 12| which has a stationary part resting against spring I'I and a moving part pinned to the shaft with the balls in between. If at any time the pressure on the propeller and hub is reduced below that required to compress the spring Il, the shaft will be forced outward so that the stop pins l5 and I6 again strike and further rotation is prevented. However, during the continued rotation of the shaft, arming nut I8 advarices until it strikes collar 23, when guide pins 'I9 are clear of the slots in the arming nut guide 2li, and the firing pin 28 is clear of the arming nut, but rotor arming pin 2'6 carried outward by nut it is still projecting slightly into detonator rotor .il,Fig. 6, and further rotation of the shaft carries the arming nut with it and they move until guide pins I9 rest against the shoulders on the top of the arming nut guide, Fig. 5. In this position the guide pins are above slots 29 which permit suiiicient movement of the arming nut to fire the fuse. During the turning of the arming nut after pins I9 have moved clear of slots 42, rotor arming pin 2S carries the detonator rotor around an equal amount. The point of the firing pin 28 is then at the other end of groove 30, Fig. 3, directly over` detonator 3i, Fig. 5. The detonator and lead 32 to booster charge 33 are then in line and ready for firing. Arming nut lock pin 34, Figs. 2 and '7, is so located that during the rotation of the arming nut it passes over the bottom of slot 29 without engaging it, but engages elongated opening 35 when the armed position has been reached, as in Fig. 5. This elongated opening must allow sutilcient inward movement of the arming nut to eX- plode the fuse, and suicient outward movement to disarm it. Upon impact, the arming vane, hub, shaft and nut are driven rearward, shearing the pin 36 and the thin flange 43 on the firing pin` driving the firing pin into the detonator which through the lead and booster charge detonates the bomb.

In case the fuse is accidentally armed while the carrying airplane is diving at high speed, and is not dropped, a safety feature is provided to unarm the fuse before the airplane lands. It comprises a spring 31, one end of which is anchored in the arming nut guide and the other in the detonator rotor. This spring is slightly wound about its longitudinal axis in the unarmed prevents the rotation of the other parts, the Y fuse cannot be re-armed without being disassem;

bled.

fuse may be removed from the bomb. The-'arming nut guide is prevented from turning'in the fuse body by dowel pin 39. It isfurther secured in the fuse body by the housing 25 which nts against it and is held in4 the fuse body by locking screw 4B.

f A delay in the arming of the fuse is provided to insure its clearing the airplane before it arms. This is accomplished by the small pressure angle on the propeller blades in combination with the ne pitch of the screw threads in the arming nut.

The locking nut assures an explosion on impact by holding the fuse in the proper armed position.

`The detonatorbeing out of line in the unarmed position makes the fuse safe in shipping, and prevents accidental firing of the bomb.

It will be understood that the above description and accompanying drawings comprehend only the general' and preferred embodiment of my invention, and that minor changes in the details of construction and arrangement of parts may be made within the scope of the appended claims withoutrsacricing any of the advantages of this invention.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

f l, A bomb fuse comprising a fuse body having a'cavity therein, a detonator holder, an arming nut, an arming nut guide, a fuse body housing, a shaft Vpenetrating said fuse having screw threads on the inner-end, said screw lthreads being engaged by said arming nut, said arming nut guide preventing rotation of said arming nut until after a; predetermined number of revolutions of said shaft, a propeller and hub attached to said shaft, a rst spring located in said fuse body, means associated with said shaft whereby said shaft and propeller are prevented from rotating until the longitudinal force exerted by the air on said propeller and hub is sufficient to overcome said' first spring, a firing 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 second spring associated with said detonator holder, means associated with said arming nut to move said detonator holder'to the armed position, said means and second spring operating to return said detonator from the armed to the unarmed position when the longitudinal force exerted by the The fuse body sa is threaded in order that die 4 air on said propeller and hub ceases to be sufcient to overcome said rst spring.

2. A bomb fuse comprising a fuse body having a cavity therein, a ring pin mounted in said cavity, an arming nut housing a portion of said firing pin in the unarmed position, a threaded shaft engaged by said arming nut to translate said nut and unhouse said ring pin, an arming nut guide which prevents rotation of the arming nut until said firing pin has been completely unhoused, a detonator rotor having in it a detonator out of line with said firing pin in unarmed position,.andmeans connecting said rotor to said nut whereby rotation of said nut moves said detonator into line with said firing pin.

3. A bomb fuse comprising a firing pin, a detonator holder, a detonator out of line with said ring pin in the unarmed position, a propeller `vand shaft for moving said detonator holder to the armed position, and means for returning said detona'tor holder to the unarmed position when the longitudinal force exerted by the air on said propeller is reduced below a predetermined amount.

4. A bomb fuse comprising a threaded shaft, an arming nut engaging said shaft, and an arming nut guide for preventing said arming nut from turning until after a predetermined number of revolutions of said shaft, and thereafter permitting turning of said arming nut through a predetermined ang'le to the armed position, said guide permitting suiicient longitudinal movement of said arming nut in the armed position to explode said fuse.

5. VA bomb fuse comprising a shaft having a threaded portion, an arming nut engaging said shaft, an arming nut guide preventing the turning of said nut until after a 'predetermined number of revolutions of said shaft, and thereafter restricting its turning to a predetermined angle to the armed position, and means for locking said nut in the armed position. y

6. A bomb fuse comprising a fuse body, a spring located in said fuse body, a shaft penetrat-Y ing said fuse body, a ball race having a nrst part secured to said shaft and a second part held in position by a collar on said shaft, said spring pressing against said second part, a i'lrst stop pin in said fuse body, and a second stop pin vin said first part engaging said rst stop pin uutilsaid shaft and ball race are forced into said fuse body against said spring pressure a predetermined distance.

'7. A bomb fuse, comprising a rotatably mounted shaft, a propeller on said shaft,- means initially preventing rotation of said shaft` through a complete revolution, yieldable means acting upon said shaft, said shaft being longitudinally movable against said yieldable means by air pressure above a predetermined magnitude to render the first said means ineffective to prevent rotation of said shaft, amember rotatable by said shaft from aninitialposition to a second position to arm the fuse, and means to move said mem-n loer to the unarmed position when the torque ex-` erted by said shaft'becomes less than a predetermined minimum before impact of the bomb upon an object. l

RAYJIOND L. GRAUMANN.V

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