Generally speaking, French bombs are fuzed in nose or tail (or in both) with mechanical fuzes (i.e. containing strikers and detonators, and with a wind-vane arming device), some-what similar to U.S. fuzes.

Bombs failling without initial speed and without rotation cannot become armed by em-ploying the effects of setback or centrifugal force. On the other hand, in order to pre-vent premature functioning of the fuze in the vicinity of the airplane, arming must not take place until the bomb is sufficiently clear of the machine. The arrangement for arm-ing, therefore, is also a safety arrangement, and often takes the form of a vane screwed spindle which immobilizes the striker and holds it apart from the flash cap.

For transportation, the vane itself is held fast by a safety pin. The vanes having been freed, when the bomb is dropped, the rush of air causes the vanes to rotate. The spindle either screws down or unscrews in order to bring striker into the functioning position, and the fuze is then armed. Fuzes (except bomb flare V.M. which acts in a special manner) act on impact either by the striker being forced onto the cap or by the effect of inertia causing a movable part to sit forward.

1. Percussion fuzes: In these, the arming is effected either by the resistance of the air operating a vane (fuzes a helice) or by the speed of descent (fuzes R.S.A.).

The main feature of this R.S.A. percussion system is that there is no special means of arming this fuze. It is, in fact, armed when the bomb has acquired the requisite speed. This speed is normally attained after a fall of at least 66 feet.

2. Aeral-burst fuze: These may operate by the action of a vane, a certain number of rotations being necessary to cause the fuze to function, or by the burning of a powder pellet, the length of the pellet determining the time.

These types are for explosive bombs, with instantaneous action or delay of 0.05 or 0.15 seconds. In additions to the usual safety device, a supplementary security mechanism called "secuirty largable" is used in some fuzes.

Most fuzes, if unarmed and not badly deformed by impact, may be removed from the bomb with the use of special tools.

Unexplosed bombs (if armed) are dangerous to handle, as a jar in one direction, similar to the blow of impact (but much less) may make a striker pierce a detonator; or a jar in the other direction may withdraw a striker from a partially pierced but unfired detonator. The result of either from of movement or shock will probably cause detonation.

Arming vanes should not be screwed or unscrewed nor any parts pushed in or pulled out (this calls for great care in the use of the probe when locating). Adhesive tape should be used to lock the fuze and arming device before bombs are moved, provided this can be effected without movement of the parts.

4. By a fraction indicating the dimensions of the fuze; e.g. 24/31, 36/67.5. Here the nu-merator indicates the diameter, in millimeters, of the threaded portions which screws into the bomb, while the denominator gives the diameter of the base; i.e., the portion which abuts onto the bomb casing.

Raymondie being the name of manufacturer and "sans armament" meaning whitout arming device.

6. Also - all fuzes bear markings indicating the factory or origin, lot number, and year of manufacture, in addition to any designation symbols.

Secondary safety devices are used with some French fuzes. These are known as "dispo-sitif de securite largable", and are of three types, as follows:

1. Safety device Model 1928: This device is incorporated with the 1928 and 1929 Mo-dels of the R.S.A. Fuze when used for horizontal suspension of 10 and 50-kg bombs, and is shown at the top of Figure 262. It is also used in a slightly modified form with R.S.A. Fuze Model 1925. It consists of two symmetrical steel hoods joined by a band of spring steel. The interior of these hoods is shaped to conform with the contour of the fuze head. The safety device is closed by means of a clip to which cord and a ring are atta-ched. The latter is attached to the ball-release cord, so that the clip is pulled away when the bomb is relesead. The safety device then opens during the descent of the bomb and falls away.

2. Safety device, Sch.R. ("Schneider-Raymondie"): This device, shown in the lower portion of Figure 262, is used with R.S.A. Fuze Models 1928 and 1929, for vertical sus-pension of 10- and 50-kg bombs. It consists of a steel sleeve through which passes the suspension lug. Attached to the base of the latter is a spring-steel collet, each steel strip having the projection to grip the fuze head. The sleeve can slide over the collet guided by two screws. When the bomb is released, the sleeve remains with the dropping gear by means of the projection. The collet travels with the fall of the bomb for the length of the sleeve, at which point the strips can open out sufficiently to allow the fuze head to be freed from the releasing gear.

3. Safety device for use with the R.S.A. Fuze 30/45, Model 1930: This is shown in figure 266. It consists of a single piece of bronzed steel in the shape of a hood. Inside of the apex of the hood is a spring which holds the head of the fuze away from the hood, and assists in the removal of the hood after the bomb is released. The hood is held in the head of the fuze by three spring-loaded pins, which pass through the lower portion of the wall of the hood, and are held in position by a spring collar. When the collar is closed by the clip, the pins are pressed into a groove on an adapter, which screws into the bomb. When the bomb is released, the clip is pulled away, the three pins are free to move, and, with the assistance of the spring, the safety hood falls away from the path of the bomb.

Figure 262
Secondary Safety Devices