US2190374A - Aerial bomb fuse - Google Patents

Description

Feb. 13, 1940.

F. w. BOLD El AL 2,190,374

AERIAL BOMB FUSE Filed Dec. 22, 1957 5 Sheets-Sheet 1 1- [djzz 3 .UOL 441 47 4 Nim- I ravewfioruttoimeg Feb. 13, 1940. w, D 1- AL 2,190,374

AERIAL BOMB FUSE F. w. BOLD El AL 3 AERIAL BOMB FUSE Filed Dec. 22, 1937 5 SheetskSheet 3 Feb. 13, 1940. F. w. BOLD ET AL AERIAL BOMB FUSE Filed Dec. 22, 1937 5 Sheets-Sheet 4 g aiforfieg Feb. 13, 1940.

F. W. BOLD ET AL AERIAL BOMB FUSE Filed Dec. 22, 193? 5 Sheets-Sheet 5 Patented Feb. 13,

UNITED STATES PATENT OFFIC AERIAL Bonn FUSE Frederick w. Bold and Arthur w. Bold, Chelsea,

Mass,

assignors to Waltham Horological Our present invention is directed to the construction of firing and safety mechanisms intended for use primarily with aerial bombs.

Important features of our present invention comprise novel, efficient, and compact mechanism whereby the firing pin and the timing mechanism are arranged concentrically, permitting the firing pin to pass the timing mechanism and thereby arranging the timing mechanism in a central location and concentric with the firing pin, with the releasing controlled by the timing mechanism also concentrically arranged. I I

Further important features consist in the provision of novel and efllcient safety devices preventing premature orfaccidental discharge of the bomb by. the operation of the fuse even though it is'subjected to a heavy impact on the firing pm. A further and important feature consists in the provision of a plurality of safety factors which are released only during the flight ofthe bomb after it is dropped from an aeroplane, dirigible, or the like, thereby effecting the setting of the fuse and the starting of the timing mechanism v to fire the same.

A further feature consists in the provision of .means which will permit the fuse to fire the explosive to which it is attached either by impact or by the timing mechanism, whichever op-- erates first. Thusif the timing mechanism is set for eleven seconds and the fuse strikes the earth or an object in ten seconds, it will function even though the timing mechanism has not yet completed its cycle for release of the firingpin.

"A further ii'nportant and novel feature con-- sists in the provision of a-difierential movement effected by a rotative action of the propeller shaft operative when the bomb is dropped, which is one of the primary safety features toprevent premature explosion but which will release the safetylocking devices and permit the'firing pin to become operative by either the timing mechanism or impact. y

In carrying out our invention we provide a fuse construction with the firing pin adapted to extend centrally thru the firing mechanism and with the several safety devices operable only after the bomb has been dropped from the aerial vessel carrying the same by the withdrawal of a lanyard, or arming wire, which has one end attached to the vessel from which the bomb is drOPped.

In the preferred embodiment and as herein shown we arrange this lanyard to lock a propeller on the head of the fuse as well as to lock also one or more of the other safety devices which are only released when the bomb and fuse drop below the length of the lanyard and the lanyard is thus withdrawn from locking engagement with the propeller and such other of the safety devices as it controls. 'I'hereupon, the propeller will rotate during the further 'falling of the fuse, releasing certain of the locking blocks or devices, and permitting the timing mechanism also to operate, as will be hereinafter described and explained.

Further details, novel combinations, improvements, and advantages will be hereinaftermore fully described and claimed.-

Referring to the drawings illustrating preferred embodiments: I

Fig. 1 is a plan view of an aerial bomb equipped with our improved fuse;

Fig. 2 is an enlarged side view of the fuse before the releasing. lanyard is drawn;

Fig. 3 is a fragmentary side view after the release of the lanyard; v I

Fig. 4 is an enlarged cross-sectional view of our improved fuse construction;

Fig. 5 is a fragmentary view on theline 5--5 of Fig. 4;

Fig. 6 is a cross-sectional view on the line 6-6 of Fig. 4; Y

Fig. 7 is a cross-sectional view on the line of Fig. 4;

Fig. 8 is a cross-sectional view on the line 8-8 of Fig. 4;

Fig. 9 is a' fragmentary cross-sectional view after the propeller has rotated from the start of the position shown in Fig. 4 and illustrates the completion of the operation with the firing pin in position to strike the primer either by impact or by the releasing of the timing mechanism, whichever will occur first;

Fi 101s a further cross-sectional view illustrating the firing pin in firing action;

Fig. 11 is a cross-sectional view on the line Il-ll of Fig. 10; r

v Fig. 12 is a cross-sectional view on the line Fig. 14 is a fragmentary side view of a modification;

Fig. 151s an enlarged view partly in'longitudi.

nal cross-sectional .view of this modification;

F18. i6 is a cross-sectional view on the line i6--I6 of Fig. 15 prior to release of the operating devices shown therein;

Fig. 17 is a view illustrating the release of the devices of Fig. 16 permitting the firing pin to act;

Fig. 18 is a still further modification illustrating the same in partly longitudinal cross-section;

Fig. 19 is a cross-sectional view on the line iii-l6 of Fig. 18;

Fig. 20 is a cross-sectional view on the line 2020 of Fig. 18, and

Fig. 21 is a partial fragmentary view of this modification looking from the right of Fig. 18.

Referring to the drawings, Figs. 1 to 13, illustrating one preferred'embodiment of the invention, I designates the main casing of our improved fuseand timing construction which is of cylindrical form withthe'lower open end closed by a hollow plug 2 fitting within the interior diameter of the cylindrical casing l, and having an outwardly extending flange 3 which is united to the casing l by'three or more'bolts 4 threaded into correspondingly tapped recesses 5, as best shown in Figs. 4, 9, and 10. The opposite or upper end of the casing I, viewed in the drawings, is formed with a projecting stem 8 arranged centrally of the casting i and of lesser diameter, thus providing an annular shoulder ID. A threaded collar I2 is fitted around the stem 8 and has the outer circumference formed with threads adapted to fit into the correspondingly threade recess in the cap M, which in turn is secure to a shell i5 of the body portion of the bomb. The main structure of the bomb may be of any suitable or desired contour and,

- as herein shown, has a centrally arranged primer I6 against which the firing pin 20 strikes to explode the bomb.

As herein shown, the explosive material i1 is contained within the bomb structure, which may comprise a series of rings l8 and the tail and rudder portion IQ for steering the bomb'in its flight. Our improved fuse structure. is attached to the aerial bomb by constituting the fuse as a complete unit capable of being handied andthreaded into the bomb structure with the various safety devices which we have devised 'in position to prevent the actuation of the firing pin 20 until released by the timing train or by the impact.

The firing pin 20 projects slightly beyond the length of the fuses and timing elements and is rigidly secured to a mushroom head 2i either by a pin 22 passing thru a hub 23 formed integral with the mushroom head 2| or by threading the hub on the pin 20. The firing pin 20 extends thru a central recess in the plug 2 and stem 8 within striking distance of the primer IS, a central cap 25 being in alignment with the inner end of the firing pin 20 to set off the primer and explode the charge in the bomb when the firing pin is actuated to strike the same.

We provide the central cap 2 with a depending stem 26 closed at its lower end except for a bored recess 21 to receive the stem 20 in a closely sliding fit and with a central recess substantially larger than the diameter of the firing pin 20 to receive a coiled spring 28 encircling the firing pin pin 20 against the cap 25 and exploding the charge when the timing mechanism releases the firing pin or when the mushroom head 2| strikes against the earth or other ufllciently solid imarc ers pact to shear the pin 33, which passes thru the collar 36 and the shank of the firing pin 20. Prefby the spring 28 when the timing mechanism releases the firing pin.

In order to allow for the hub 36 we enlarge the recessin the plug 2, as shown at 35, which recess is of sufficient diameter and length to allow for a free lengthwise movement of the collar 34 throughout the length necessary for the firing pin 26 to strike against the cap 25 or from the position of Fig. 4 to that of Fig. 10.

Secured to the flange 3 of the cap 2 by the bolts 4 is a depending hollow cap-shaped member 46 flange 42 constitutes on its outer surface a ballbearing raceway for a series of balls 45-45 which cooperate with the,grooved raceway formed in a ring 46 carrying the pair of aerial propellers 41-4'i, said ring 46 being secured to a rotatable sleeve 50 which extends within the cup-shaped member 40 and has an exterior ring 5| extending froni'the sleeve 50 and overlapping the inner surface of the inturned flange 42 of said cup-shaped member.

In order to assemble and secure the ring 46 carrying the propeller blades 4'! to the sleeve 56, we form the outer portion of the sleeve 56 of slightly less diameter, providing a shouldered construction around which the inner surface of the ring 46 fits and then swage over said ring 46 the end portion of the sleeve 50, as best shown at 52, Fig. 10, thus firmly securing the ring 46 and sleeve '50 together.

.tion shown in Fig. 4 and in a direction to lift or raise the hub as it slides on the stem 26 will serve to lift said hub to the position shown in Figs.

8 and 9; and thereupon continued rotation of the sleeve 56 caused by the action of the propeller blades 42 will have no further effect on the relative movement between the hub 55 and the sleeve 50. v

To cause such relative movement between the hub and sleeve we provide a gear 56 and on the exterior of thehub 55 a similar gear 58 but having a difl'erential in the number of teeth. Thus, for example, we form the gear teeth' 56 on the sleeve 56 with sixty-five teeth and the gear teeth 58 on the hub 55 with sixty-four teeth. In order to arrange for the actuation and, hence, the unthreading of the hub 55 from the sleeve 56 we arrange a barrel pinion 60 with its axle 6i fitted in a corresponding recess in the plug 2, and with the barrel pinion 60 extending into the cupshaped member 40 in alignment to engage the gear teeth 56 and 58, and continue such engagement throughout the relative lengthwise movement provided between the hub 55 and sleeve 5 as long as their cooperating externaland internal gear'teeth are in mesh.

Rotation of the sleeve 50 is effected by the action provided with a circular flange 4| thru which the areas-7e of the propeller blades 51-31 when the bomb is dropped, the pressureof the air during the downward flight of the bomb onthe propeller blades acting to rotate the sleeve 50 on the ball bearings- 55. The set of the blades 41 and the rotation of the sleeve 50 relatively with the threads on the interior of the sleeve 50 and the exterior of the hub 55 operating thru the differential in the number of gear teeth 55 on the sleeve and 50 on the hub thru the engagement of the idler pinion 60 acts to move, lift, or raise the hub 55 within the cup-shaped member 40 from its threaded position of Fig. 4 to the unthreaded position of Figs. 9 and 10, whereupon continued rotation of the hub 50 will have no further effect in moving the hub 55.

The operation just described is to lift or remove the projecting rim portion 55 of the hub 55 from immediate proximity of the mushroom head 5|, thereby permitting the firing pin 20 to be thrown against the cap 25.

Referring to the position shown in Fig. 4, it

will be seen that the projecting rim 65 extends within close proximity of the inner face of the head 2| and this might be'so extended as to actually bear against the inner face of the head 2| and, hence, prevent any movement of the firing pin 20 by its spring 28 until the lifting of the hub 55 by the differential action above explained.

However, we prefer to provide in addition to.

the rim 65 a set of locking blocks as a further safety feature and which blocks can be quickly and readily removed by falling or dropping out of position when the hub 55 has been raised sumciently to permit said blocks to drop out.

For this purpose we form a set of three or more blocks 66, 51, and 50, forming the same'as circular segments adapted to fit around the hub 23 of the head 2| and between the head 2| and the shaft 46 carrying the propeller blades. Thesesegments are also formed with the inner deepseated grooved portion, as indicated at 6949,

I 66, 61, and 68 constitute an eflective positive stop against longitudinalmovement of the firing pin. Only after a substantial time has elapsed during the flight of the bombdownwardly and the rotation of the sleeve 50 by the propellers 41, producing a relative movement of thehub .55 thru the difierential in rotative movement caused by the lesser number of gear teeth 58 from that of the number of gears 56 thru rotation onthe pinion 50, the blocks 65, 51, and 58 drop or fall out when the rim 65 holding them has been lifted from the groove 59, as shown in Fig. 9. Y

The firing pin 20 is nowfree to be either moved by the spring 28 when released by the timing shouldered surface I 0, the securing bolt 1| being covered-by the threaded collar I2 fitting around the stem 0. Any suitable interlocking connection between the threaded collar I2 and the stem 8 may be provided,'but as herein shown we arrange 8 a coiled spring 12 adapted to fit within a circular recess I8 formed on the inner diameter of the collar I2 approximately midway of the length of said collar. One end of the spring,12 is bent, as shown at 14, to fit within a bored recess in lo the stem .8 and with the opposite end of the f spring I2 inclined outwardly, as shown at 15, to form a 'point'or comer engaging the walls of the collar I2 and holding the same in engagement.

The timing mechanism contained within the casing 10 is illustrated diagrammatically and contains suitable spring-actuated clock mechanism to rotate the driving gear 80, which is keyed to a sleeve .8I encircling the firing pin and thru which sleeve the firing pin- 20 may slide.

The sleeve 8| extends beyond the casing 10 and carries a setting disc 02, as best shown in Figs. 4,

7, and 10. This setting disc is positioned in a space'between the timing mechanism and the inner portion of the plug 2, as clearly shown in Figs. 4 and 10.

- In order to arrange for the novel construction of the firing pin extending centrally thru the timing elements, as well as thru the driving gear ,and setting disc, we have devised anovel escapement for the timing train. For this purpose (see Fig. 8) we have mounted a lever-85 on a pivotflIi at one side of the firing pin 20 to a plate shown in fragmentary lines, Fig. '8, with a pair of depending members'01 and 88 adapted to rock and engage the teeth of the escapement wheel 90, thus constituting an escapement construction.

' The hair spring 9| operating the oscillations of the lever 05 may be adjusted by attaching the same to' a movable threaded block 92 operating on a screw 93 and accessible thru an opening 9494' 1 thru a plate 95 in the clock mechanism, as also shown in Fig. 8. a

' Thetiming elements or clock mechanism areunder the tension of a wound spring (not shown), as is usual, to exert a rotative action on the gear 80,.sleeve 8|, and setting disc 82, which setting disc is normally held from rotation by engagement of an arm 99. of a latch I00 pivoted on a stud IOI, with said arm 99 engaging a notch I02 in the disc, as shown in FigQ'I. The opposite arm I03 is held against a pin I05.

This pin I05 (see Fig. 4) is fitted to slide within a recess I06 provided therefor in. the walls of the casing I in alignment to contact with said .arm I00 of the latch I00, and with the lower portion'of the stem formed asap enlarged'plunger I01 extending thru an opening in the flange 4| in allgnmentwith said recess I06, and is provided with a coiled spring I08 encircling that 50 portion of the pin I05 between the enlarged end of' the plunger portion I01 and the opposite walls of the, recess I05, see Fig. 4, which spring exerts an expansible action on the pin and plunger to throw out the same and release the arm v I03 of the latch I00 upon withdrawal of a toggle arm IIII, against which the plunger end bears.

This toggle arm. is pivoted at I12 to the under surface of the fiangefil and is moved against the tension of-a spring II4 to engage between a H0 in position and underneath the lugs IE5 until the lanyard is withdrawn. This lanyard extends lengthwise of the bomb and fuse thru a guiding eyelet I2I secured to oneof the rings I8 (see Fig. 1) thru a second guiding eyelet- I22 on the casing I, thru the recess I I8 in the lugs I I5 to hold the latch H0 and thence thru a hole I23 in one of the propeller blades 41 and is engaged by a clip I25 below the propeller.

The opposite end of the lanyard I20 is secured to the aerial vessel from which the bomb isreleased with a sufficient length of line to permit the bomb to be well clear of the vessel from which it is dropped so that the bomb will be a substantial distance therefrom when the continued flight of the bomb will draw the lanyard I20 thru the propeller 41, snapping off the clip I25 thru the recesses H8 and the guiding eyelets, thus freeing the toggle IIO, which swings outwardly to the dotted line position of Fig. 6 thru the influence of its spring II4, thereby permitting the pin I05 to be forced outwardly by the action of the spring I08 and thereby releasing the arm I03 of the latch I00 and permitting the clock mechanism to actuate the setting disc 82 in the direction of the arrow, Fig. '7.

Bearing on the edge of the setting disc 82 is an upstanding flange I30 on a rocker arm I3| pivoted at I32 on thetop of the plug 2, having its opposite end I33 in the form of a hook to engage an upstanding stud I34 on a barrel I35, which is fitted in a circular recess I36 formed in the plug 2 and opening into the central recess 35 thru which the firing pin 20 and its attached collar 30 are adapted to pass. ,A V-shaped slot, shown in dotted lines in Fig. 4, from the circular recess I35 permits the pin I34 to rock when released by the hook I33 on the rocking arm I3l.

This hook I33,'however, is not released until the notch I02, in the setting disc 82 reaches the upstanding fiange I30; whereupon said flange will be forced into said notch as the arm I3I is rocked on its pivot by the pin. I34 sliding off the hooked end I33 by the tension of the spring 28 around the firing pin, as will be readily understood in viewing Fig. 4. The engagement between the rocking toggle I35 and the upper end of the collar leases the action of the firing pin which is forced against the cap 25 and explodes the charge in the bomb. The previous'removal of the blocks 65, 61, and 68 permit this lengthwise movement of the firing pin 20, as previously explained.

The time between which the setting disc 82 leaves its latch I00 and'reaches a position to register with the upstanding flange I30 of the rocking arm I 3I determines the time of firing from the Withdrawal of the lanyard at the starting of the mechanism. Usually this timing element is fixed at eleven seconds although any time can be fixed, as desired. Meanwhile the rotation of the propellers 41 will have acted to move the hub 55 upwardly, freeing the locking blocks 66, G1, and 68, which will fall to the ground and the fuse will be ready for firing by impact or actuation of the timing element. Should impact occur first before the flange I30 has engaged the notch I02, then the pin 33 will be sheared ofi by the firing pin 20 and the cap and primer ignited.

The assembling of the various parts, as well as the operation of the same, will be readily appreciated from the foregoing description. The mechanism when assembled is under a positive safety areasra look by the interposition of the blocks 36, 81, and 33, preventing any impact on the head 2! from causing a premature explosion after the fuse is fitted to the bomb. Allprevious assembling and setting of the mechanism is accomplished when the fuse is separate from the bomb. Then the same is attached and with the locking blocks 66, 61, and 08 in positive control of the firing pin, which blocks can only be removed by the action of the propellers 41 and rotation thereof during flight and after release from the aerial vehicle carrying same and the movement of the hub 55 upwardly, withdrawing its rim from holding the blocks in position.

Referring to the modification shown in Figs. 14 to 17 inclusive, we have herein illustrated an arrangement of the firing pin passing concentrically thru the timing and setting elements but with a somewhat diiferent releasing arrangement. In this form, the main casting I 50 has an enlarged central recess I5I to receive the timing element contained in its'casing and thru which the firing pin 20 passes. The head 2| on the firing pin 20 is locked against operation by blocks I52, I53, and I54 similar to the locking blocks 56, 61, and 68 previously described.

In this form, we have arranged the propeller blades I55 attached to the ring I56 and operating the relative movement of the hub 55 from this sleeve 50 within the cup-shaped member 40, as previously described, to drop out the locking blocks I52 and I531 In this form the casing I50 is closed by a plate I 51 and the timing mechanism is secured directly to the plate I51 by one or more screws I59 passing thru the plate I51, which screws will be covered and protected by the assembling of the cup-shaped member 40 thru the bolts 4, attaching the flange M to the casing I50. The plate I51 is provided with a depending hollow stem I58 thru which the firing pin 20 passes and the mechanism for controlling and releasing the locking'blocks by rotation of the propeller blades is identical to that previously described in connection with Figs. 1 to 13. In the present form. wherein the arrangement and fuse mechanism is more compact, we have also devised novel releasing means as well as providing an additional safety locking pin.

In the form as shown in Figs. 14 to 17 the casing I50 has an enlarged bored recess thru the upper part, as shown at I60, which recess is enlarged by a counterbored opening I6I providing a shoulder I62 against which the firing spring I83 bears, the opposite end bearing against a shoulder I64 formed on or secured to the firing pin 20. Surrounding that portion of the firing pin 20 within the opening I60 and the counterbored portion IBI is a sleeve I05 attached to the firing pin 20 by a shearing pin I66, as shown in dotted lines,

Fig. 15.

This sleeve I55 has an annular recess I61 which is engaged by a cut-away portionv of a barrel I50 identical in construction and function with the barrel I35 previously described which, however, is fitted in a cylindrical recess I69 with a pin I10 depending from the barrel to be engaged by a latch I1I pivotally secured by a screw I12 (see Fig. 16) threaded into the casing I50. The

free arm of the lever "I, thus freeing also the pin I 10, permitting the barrel I88 to be rotated, which is under the tension of the firing pinsprihg I 63, and releasing the firing pin.

The setting disc 82 is normally in position as rotate in the direction of the arrow and holding the trigger I15 against release of the lever I1I until the notch I02 reaches the flange I16, as will be readily understood.

The locking end of the bell crank I11 is, however, held in engagement with the walls ofthe notch I02 by one end of a pin I80 fitting thru a bored and counterbored recess I 8| in the wall of the casing I50, and is held in' this position by the locking lever I82, to be described.

An additional safety locldng element is provided in this form of the invention consisting in a headed pin I85 fitted in a bored and counterbored recess I88 radially in the wall of the casing I50 and preferably in alignment with the recess I8! and the pin I80, to be also engaged by the locking lever I82, which pin I85 is of sufiicient length to extend thru a hole bored thru the sleeve I-and firing pin 20 to positively engage bcth, as shown in dotted lines, Fig. 15. In the counterbored portion of the recess I86 a spring I81 encircles the stem of this pin bearing against the head, and with its opposite end against the shoulder formed by the counterboring and also held in position against the tension of the encircling spring I81- by the locking lever I82. 1 This lever has its upper end in the form of a hook to fit around a pin I85 held by a lock I86 threaded into the side of a tapped recess in the casing I50. The lever I82 extends downwardly from its hooked engagement and over a stud I88 to hold and guide said lever, and with a further extension arranged to engage a notch I88 on the rim I90 of the ring I56 carrying the propeller blades I55. I

Thru the stud I88 is a bored opening to receive an arming wire I 8i to which a clip I82 is secured at the lower end, the upper end being attached to the aerial vessel carrying the bomb. During the flight of the bomb after it is dropped from its carrying vessel and when it reaches the end of the arming wire I8I, the latter is pulled thru the recess thru the stud I88 during the downward flight of the bomb; and thereupon the locking lever I82is thrown out, being disengaged from its hook and dropping free of the bomb thru the force of the spring. I81, which also simultaneously throws out the locking pin I85, releasing the pin I86 and frees the propellers I55. Consequently the spring I19 acts to rock the bell crank lever I11 on its pivot, thus freeing the opposite arm from engagement with the notch I02 in the setting disc 82 and permitting the clock mechanism in the timing train. to start, and rotate the setting disc, which rotation continues until the notch I02 is in register with the flange I16 of the trigger I15, which trigger thereupon swings on its pivot, permitting the flange I18 to fall into said notch with the parts as shown in Fig. 17 and, hence, releasing the lever I11 and, thereupon, the firing pin under the intinued impulse of the spring I68 impels the firing pin against the primer 25 and explodes the charge, meanwhile the rotation of the propeller blades having acted to free the blocks I52, I58, and I58. 7

Referring to the modification illustratedin Figs. 18, 19, and'20, a construction is shown permitting an adjustment of the setting disc relatively with its engaging members and particularly adjusting the position of the notch I02 on the .disc 82 with regard to the time which it will reach the rim-engaging flange of the lever or trigger to release the firing pin.

' In this form, also, a compact structure is arranged, together with asmooth exterior, eliminating projecting lugs, latches, flanges, or the like from the side of the fuse, which are objectionable. Substantially the same arrangement of casing I and block 2 is herein shown, utilizing the mushroom head 2I on the firing pin 20, together with looking blocks 81 and 88, and the means for freeing the same as described in connection with the preferred form shown in Figs. 1 to 13.

In this form the arming wire 200 is lead within the circumference of the casting .I to hold and, hence, to release when withddrawing the .timing mechanism. In this latter form the'flanges on the block 2 and cup-shaped member are shortened and are rotatably .held by an encircling flanged ring 20I, having an uncut flange 202 adapted to engage and hold the cup-shaped member 40 and .the block 2 in their respective assembled positions with the casing I, a series of bolts 203 passing thru the ring 20I and engaging tapped recesses in the rim of the casing I, as. shown in Fig. 18. V

This construction thereby enables the entire plug 2 and its attached parts to be moved relatively with the setting disc 82 and, hence, to adjust the time of explosion; whereas in the former constructions the time of release by the clock mechanism was fixed although it could, of course,

206 is set in the top of the disc 82 and is engaged from the center of the casing I being formed to permit the outer arm of the lever 208 to engage said barrel 2I2. The barrel 2I2 extends downwardly where a portion of the ring 2I0 is cut away, leaving an opening 2I5, and in alignment therewith at the lower end of the barrel 2 I2 is fitted a pin 2I6 into the lower end of the barreli2l2, the outer end of the pin being in position to be engaged and held by the arming wire 200 when the latter is threaded thru the bored recesses 2 I8 above and 2-I9 just below the'opening 2I5, as shown in Figs. 19 and 21;

A recess 220 is also formed on the exterior of the casing l to facilitate the threading of the arming wire 200 thru the bored passages H8 and 2| 9 and downwardly to the propeller blades 41. In order to hold the mechanism after it has been set and for shipping purposes prior to fitting of the arming wire 200, a small bored opening 22! may be positioned parallel with the bored opening H8 and a wire threaded thru same and wrapped around the pin 2H5, thus holding the mechanism when set and assembled until the arming wire 200 is applied; whereupon the temporary binding wire thru the opening 22E is removed.

In order to permit a rotative adjustment of the device when threaded into the cap of the bomb, the top stem of the casing l is formed with aslight shoulder around the top of the stem 8 and the corresponding part of the threaded collar H2 in which a washer 224 is applied and secured in position by heading over the adjacent metal in the stem 8, as indicated at 225. Thisgives a frictional engagement between the stem 8 and collar I2, which is ordinarily sufficient to either thread in and tighten the entire fuse or to un thread the same. In order, however, to permit rotative movement between the stem 8 and collar l2 if the strain involved is greater than thefrictional engagement afforded by the ring 224 and the heading of the rim 225 thereover, a positive stop is provided. This consists in a depending pin 226 projecting into a recess 22'! formed in a casing l at the base of the stem 8 and the fitting of a similar pin 228 in said recess, thus providing substantially full circumferh ential rotation before the two pins strike a given positive contact from then on in either direction.

The various modifications of the improved fuse constructions above described provide a unit capable of complete assembly with positive and absolute safety blocks'interposed to keep the firing pin from any longitudinal movement entirely independent of the ordinary locking and releasing latches. In fact, this fuse construction permits dropping of the entire bomb with the fuse at tached and with the lanyard or arming wire detached from the aerial vessel carrying the same;

so that it will not be withdrawn from the propell- .er and locking engagements with the starting devices without danger of discharging the bomb. Tests of the same dropped-from a height of eight thousand feet have established the efliciency of the assembly blocks. 1

This feature is of great importance as it enables an aerial vessel or bombing plane to carry a large number of bombs equipped with these fuses to drop only a part of the number, 'andthen return to the landing field and release the lanyards and 'undropped fuses, which may be dropped to the field before the plane lands and mined explosive time, such as eleven seconds as above noted, which will enable a *plane to fly to a height above an. object or place which can be reached by the flight of the bomb in eleven seconds, say, aproximately two thousand feet, and thereupon releases the aerial bombs with these fuses which will explode when approximately a drop of two thousand feet has occurred, or by impact, whichever occurs first.

Furthermore, it is found that the centrifugal action imparted to the blocks 69, 81, and 88 by the rotative action of the propeller blades and the retaining rim 85 meets a positive removal or throwing action as soon as the rim 65 is withdrawn from the grooves 59 in these blocks, thuspositively removing them, preventing any accidental jamming or retaining of these safety blocks in position to prevent longitudinal movement of the firing pin .This is an important feature as it acts positively and does not leave to chance the dropping out or removal of the blocks.

Various additional modifications and variations in the invention other than those herein illustrated will readily occur to those skilled in the art, and are intended to be coveredv by the appended claims.

We claim: 1. In a fuse, a casing, a cap on the casing rotatable during flight and mmprising a sleeve and gear with a different number of teeth than the hub, and a pinion carried by the casing and meshing with both gears, and air-operated means to rotate the cal).

2. In a fuse, a casing, a cap on the casing rotatable during flight, a firing pin passing thru the cap, and having a head externally of the casing, removable blocks between the cap and the head of the firing pin, a hub threaded in the cap and concentric with the firing pin and having a portion projecting outwardly of the cap and engaging the blocks to restrain them against radial displacement, and gearing between the cap and hub for rotating the hub to withdraw it into the casing and disengage it from the blocks, and air-operated means to rotate the cap.

mmmrcx W. BOLD. ARTHUR W. BOLD.

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