‘ wt. E5, 1946.. 2,409,205 R, L.. GRAUMANN BOMB FUSE Filed Marèh 2, 1932 2 Sheets-Sheet 2 27 ` v l-îweìœpor: Granma 53, - , d,aíízrrïzeg l ¿49,205 Patented Cct. 15, 1946 narran stares PATENT OFFICE 2,409,205 BOMB FUSE Raymond L. Graumann, Alexandria, Va. Application March 2, 1932, Serial No. 596,364 7 Claims. (Cl. 102-8L2) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757 ) l 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 pro vide a fuse that has sufñcient delay action that it will not arm until after it is clear of the air plane; Second, to provide a fuse that has instantane ous action ‘on impact; 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 10 at any time the pressure on the propeller and hub is reduced below that required to compress the Third, to provide a fuse that will automatically spring Il, the shaft will be forced outward so that disarm at a predetermined reduced air speed; the stop pins l5 and I6 again strike and further Fourth, to provide a fuse that, after arming, so rotation is prevented. However, during the con locks the arming mechanism that after disarming 15 tinued rotation of the shaft, arming nut I8 ad at a reduced air speed, it cannot be re-armed; varices until it strikes collar 23, when guide pins Fifth, to provide a fuse that is easily removed 'I9 are clear of the slots in the arming nut guide from the bomb and is safe during shipping; and 2li, and the firing pin 28 is clear of the arming Sixth, to provide a fuse that is safe from acci nut, but rotor arming pin 2'6 carried outward by dental firing. ’ With the above and other objects in view, this 20 nut it is still projecting slightly into detonator rotor ‘.il,Fig. 6, and further rotation of the shaft invention consists of such construction and ar carries the arming nut with it and they move un rangement of parts as will be more fully described til guide pins I9 rest against the shoulders on the hereinafter in connection with the accompanying top of the arming nut guide, Fig. 5. In this posi drawings, in which: . Fig. 1 shows the fuse in the unarmed condition; 25 tion the guide pins are above slots 29 which permit suiiicient movement of the arming nut to fire the Fig. 2 is a cross-section of the fuse on line 2--2 fuse. During the turning of the arming nut after of Fig, l; pins I9 have moved clear of slots 42, rotor arming Fig. 3 is a cross-section of the fuse on line 3-3 pin 2S carries the detonator rotor around an equal of Fig. l; amount. The point of the firing pin 28 is then at 30 Fig?. 4 is a cross-section of the fuse on line «l-ll the other end of groove 30, Fig. 3, directly over` of Fig. 1; ' detonator 3i, Fig. 5. The detonator and lead 32 Fig. 5 shows the fuse in the armed condition; to booster charge 33 are then in line and ready for Fig. 6 is a cross»section of the fuse on line 6-6 firing. Arming nut lock pin 34, Figs. 2 and '7, is of Fig. 5; Fig. 7 is a cross-section of a part of the fuse on 35 so located that during the rotation of the arming nut it passes over the bottom of slot 29 without line l-l of Fig. 2; engaging it, but engages elongated opening 35 _ Fig. 8 is a view of the arming nut; when the armed position has been reached, as in - Fig. 9 shows the arming nut guide; Fig. 5. This elongated opening must allow sutil Fig. l0 shows the detonator holder. The Cotter pin I-I insures the safety of the bomb 40 cient inward movement of the arming nut to eX plode the fuse, and suñicient outward movement during shipping and is removed when the bomb to disarm it. Upon impact, the arming vane, is placed in the racks on the airplane. The arm hub, shaft and nut are driven rearward, shearing »lng wire I2 is secured to the airplane and is pulled the pin 36 and the thin flange ¿43 on the firing pin` out of the fuse by the weight of the bomb as it is released. Once the bomb is launched, the air act--l 45 driving the firing pin into the detonator which through the lead and booster charge detonates ing on propeller I3 turns shaft VIll until stop pin the bomb. I5 strikes stop pin I5. As the velocity of the bomb In case the fuse is accidentally armed while through the air increases, the pressure on the pro the carrying airplane is diving at high speed, and peller and hub overcomes the spring Il, forcing the shaft IA and arming nut I8 inward until the 50 is not dropped, a safety feature is provided to unarm the fuse before the airplane lands. It guide pins I9 reach the bottom of the slots 42, comprises a spring 31, one end of which is an Fig. 9, in arming nut guide 20. The ball race 2l, chored in the arming nut guide and the other in due to securing pin 22 and collar 23, is carried in the detonator rotor. This spring is slightly ward with the shaft at the same time, which m0 wound about its longitudinal axis in the unarmed tion is suñioient to cause stop pin I5 to clear stop 3 2,469,265 condition and still further so wound in the armed condition, so that when rotor arming pin 2S is completely Withdrawn from the 'detonator rotor while the fuse is armed, the spring will cause it to turn, moving the detonator out of line with the firing pin, thus disarming the fuse almost instantly. The Withdrawal of pin 26 is caused .by spring Il overcoming the pressure on the pro peller and forcing sto-p pin l5 against the top of the fuse housing, Fig. 5. Since locking pin 34 prevents the rotation of the other parts, the Y fuse cannot be re-armed without being disassem; " bled. 4 air on said propeller and hub ceases to be sufñ cient to overcome said ñrst spring. 2. A bomb fuse comprising a fuse body having a cavity therein, a ñring pin mounted in said cavity, an arming nut housing a portion of said firing pin in the unarmed position, a thread ed shaft engaged by said arming nut to translate said nut and unhouse said ñring pin, an arming nut guide which prevents rotation of the arming nut until said firing pin has been completely un housed, a detonator rotor having in it a detona tor out of line with said firing pin in unarmed position,.andmeans connecting said rotor to said The fuse body sa is threaded in order that die _ ._ nut whereby rotation of said nut moves said det fuse may be removed from the bomb. The-'arm 15 -onator into line with said firing pin. ing nut guide is prevented from turning'in the 3. A bomb fuse comprising a firing pin, a det fuse body by dowel pin 39. It isfurther secured onator holder, a detonator out of line with said in the fuse body by the housing 25 which nts against it and is held in4 the fuse body by lock ing screw 4B. ~ f A delay in the arming of the fuse is provided ñring pin in the unarmed position, a propeller `v»and 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 to insure its clearing the airplane before it arms. This is accomplished by the small pressure angle propeller is reduced below a predetermined on the propeller blades in combination with the ñne pitch of the screw threads in the arming nut. 25 4. A bomb fuse comprising a threaded shaft, an The locking nut assures an explosion on impact arming nut engaging said shaft, and an arming by holding the fuse in the proper armed posi nut guide for preventing said arming nut from tion. turning until after a predetermined number of `The detonatorbeing out of line in the unarmed revolutions of said shaft, and thereafter permit position makes the fuse safe in shipping, and 30 ting turning of said arming nut through a pre prevents accidental firing of the bomb. determined ang'le to the armed position, said It will be understood that the above descrip guide permitting suiiîcient longitudinal move tion and accompanying drawings comprehend ment of said arming nut in the armed position only the general' and preferred embodiment of to explode said fuse. ` my invention, and that minor changes in the de 35 5. VA bomb fuse comprising a shaft having a tails of construction and arrangement of parts threaded portion, an arming nut engaging said may be made within the scope of the appended shaft, an arming nut guide preventing the turning claims withoutrsacriñcing any of the advantages of said nut until after a 'predetermined number of this invention. , of revolutions of said shaft, and thereafter re The invention described herein may be man 40 stricting its turning to a predetermined angle to ufactured and used by or for the Government of the armed position, and means for locking said the United States of America for governmental nut in the armed position. y ' purposes without the payment of any royalties 6. A bomb fuse comprising a fuse body, a thereon or therefor. spring located in said fuse body, a shaft penetrat-Y - I claim: ing said fuse body, a ball race having a nrst part f l, A bomb fuse comprising a fuse body having secured to said shaft and a second part held in po a'cavity therein, a detonator holder, an arming sition by a collar on said shaft, said spring press nut, an “arming nut guide, a fuse body housing, ing against said second part, a i'lrst stop pin in a shaft Vpenetrating said fuse having screw threads said fuse body, and a second stop pin vin said 50 on the inner-end, said screw lthreads being en first part engaging said ñrst stop pin uutilsaid gaged by said arming nut, said arming nut guide shaft and ball race are forced into said fuse body preventing rotation of said arming nut until after against said spring pressure a predetermined a; predetermined number of revolutions of said distance. ' ' . î shaft, a propeller and hub attached to said shaft, '7. A _bomb fuse, comprising a rotatably mount a ñrst spring located in said fuse body, means ed shaft, a propeller on said shaft,~ means ini associated with said shaft whereby said shaft and tially preventing rotation of said shaft` through propeller are prevented from rotating until the a complete revolution, yieldable means acting longitudinal force exerted by the air on said upon said shaft, said shaft being longitudinally propeller and hub is sufficient to overcome said' movable against said yieldable means by air pres first spring, a firing pin, a detonator, a lead to 60 sure above a predetermined magnitude to render an explosive charge, the latter three elements the first said means ineffective to prevent rota being out of line when the fuse is unarmed and tion- of said shaft, amember rotatable by said being in line when the fuse is armed, a second shaft from an‘initialposition to a second position spring associated with said detonator holder, to arm the fuse, and means to move said mem-n 65 means associated with said arming nut to move loer to the unarmed position when the torque ex-` said detonator holder'to the armed position, said erted by said shaft'becomes less than a prede means and second spring operating to return said termined minimum- before impact of the bomb amount. detonator from the armed to the unarmed po sition when the longitudinal force exerted by the . upon an object. l RAYÃ‘JIOND L. GRAUMANN.V .