This bomb is designed to be dropped from aircraft. It is reported to
produce large quantities of greenish-black smoke for about 20 minutes. An
authoritative German military writer states that in cooperation with friendly
ground forces, aircraft may drop smoke bombs to cover or screen hostile troops
for a short time in limited areas. Presumably aerial smoke bombs would only
be used for this purpose where, for one reason or another, more economical
means than the airplane are either unsuitable or not available. Conceivably
aerial smoke bombs might also be used to screen the dropping of parachute
troops or to designate a target to bombers.
This bomb is similar in appearance to the normal 50-kilogram (110-pound) HE bomb. The
marking "N C 50" painted on the bomb is probably an abbreviation
for "Nebel Cylinder 50 (kilograms)," that is "Smoke Cylinder 50 (kilograms)." The
nose is painted white for 4 1/2 inches from the tip; from that point 4 white
bands, 1 inch wide, run back to the shoulder where the nose is welded to the
The over-all length of the bomb and tail is 3 feet 7.3 inches, the bomb
itself being 2 feet 2.5 inches long with a diameter of 8 inches. The thickness of
the casing is 1/8 inch. The smoke-producing filling consists of:
Aluminum powder 8.5%
Probably iron oxide and silica 0.4%
The bomb is made up in two parts (see accompanying sketch), the cylindrical
portion (1) being welded to the nose (2) along the circumference at (3). In
the nose is a screw plug (4) which can be removed to accommodate a lug for
vertical suspension. The lug for horizontal suspension screws into a block (5) which
is secured to the inside of the bomb casing. The closing plate (6) at the
rear end of the bomb is made of sheet steel. The edge of this plate is pressed
inwards and then turned over so as to form a recess in which a rubber ring (7) is
placed to seal the filling. To the plate is welded the igniter pocket (8) which
contains the igniter (9). The latter consists of a steel tube 3 inches long
and 1 inch in diameter. It is closed at its lower end by an aluminum disk, and at its
upper end has an igniter cap pressed in.
The plate (6) has four equally spaced holes (10) which are covered by aluminum
disks soldered in the position shown in the sketch.
Above the plate (6) and resting on it is the steel casting (11) which is secured to the
bomb by eight screws. The base of this casting is perforated by 4 holes to correspond
with those in the plate below it. At the center of the casting are 4 webs (12) supporting
the fuze body (13).
The fuze is simple in construction and consists of a striker (14) supported
on a creep spring (15). Into the base of the body is screwed the cap holder (16). The
cap (17) is housed in the recess in this holder and secured by burring over
the top edge of the recess. The hole (18) takes the safety pin (19), which projects
through a hole in the casting (11) and a slot (20) in the tail cone. Between the fuze
and the igniter is a perforated coiled spacer (21).
The tail is similar in general appearance to that of a 50-kilogram HE bomb. It is
made of sheet steel and is in 4 pieces. Each piece has a flat area to form the fin
and a portion shaped to form the cone of the tail. The 4 pieces are welded together
to form the complete tail. In the upper portion of the tail cone, 4 holes (22) are
cut to provide suitable outlets for the smoke when the bomb functions. The tail is
attached to the face of the casting (11) by 8 screws.
On release of the bomb from the aircraft the safety pin (19) is withdrawn and the
fuze is then armed. On impact the striker (14) compresses the creep spring below
it and fires the cap (17). This in turn fires the igniter cap in the head of the
igniter (9). This igniter contains a thermite mixture consisting of magnetic
oxide of iron, magnesium, and aluminum powders. The weight of this
mixture is 2.6 ounces.
The thermite on ignition melts the solder on the disks (10) and provides an exit
for the smoke. The main filling is ignited when the aluminum closing disk in the
base of the igniter burns through.
c. To Render Safe
If the safety pin (19) is not in place, the bomb may be rendered safe by first
unscrewing the 8 screws securing the tail to the bomb, and removing the tail; a cotter
pin or nail should then be inserted into the hole (18) and in the striker (14). If
the safety pin is not in place, jolting the bomb before rendering it safe may
cause it to function.