Патент USA US2407846код для вставки
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.