Certain characteristics of fragmentation bombs are described in the following article, reprinted
from issue No. 12 of AFGIB (Air Forces General Information Bulletin). Included
in the summary is a reference to a few types of Axis bombs in this category, particularly those
of a "combination" character.
* * *
In the category of "fragmentation" bombs are included certain bombs of small size designed
for destructive effect on personnel, animals, and light materiel targets such as motor
transport, and aircraft on the ground or in flight. Bombs of this class are generally less
than 100 pounds in total weight, and are often termed antipersonnel bombs.
Whereas general-purpose demolition bombs depend for destructive effect primarily on their violence of
detonation, with fragmentation a secondary consideration, fragmentation bombs depend primarily
on the projection at high velocity of bomb-body fragments. The design of the bomb-body, and
the charge/weight ratio, are determined with this end in view. Thus, with our demolition bombs
the high explosive charge may approximate 50% of the total bomb weight; where with fragmentation
bombs it may approximate only 15%...
Fragmentation bombs may be dropped singly or in clusters, bound or held together during a portion
of their fall and then released, or in containers which operate in a similar manner. The purpose of
dropping in clusters or containers is to ensure a closer concentration of bombs dropped from high
levels, since bombs dropped singly would tend to disperse considerably during their fall. Such
clusters or containers are generally provided with either an explosive cartridge or a spring-loaded
mechanical device, which functions after a predetermined period to break open the cluster or
container and free the bombs...
The normal fuzing is, therefore, with instantaneous impact-type nose fuze. However, time (delay) fuzing
may be necessary if the bombs are to be dropped from low level, in order that the aircraft
may be beyond the danger space when the bomb explodes.
In dropping from low level, the disadvantage of time fuzing is somewhat counterbalanced by the fact
that the bomb is more apt to ricochet and come to rest on the ground surface, and less liable to
bury itself, than if dropped from higher levels. However, low-level drop with instantaneous
fuzing has been made feasible by the provision of a chute attachment for the bomb. This greatly
retards the flight of the bomb, allowing the aircraft to get beyond the danger zone before the
bomb reaches the ground and detonates. Release of this bomb is possible at 100 feet, and
lower if tactically required.
In addition to normal types of fragmentation bombs, the Axis nations have employed some which are
unusual in design, or of a "combination" character. A few of these are noted below.
The German SD* 2-kilogram "butterfly" bomb differs markedly in appearance from ordinary
types. The small drum-shaped body is enclosed in a hinged shell of thin metal which opens
in flight and acts as a metal braking drogue similar to a parachute attachment. The usual
fuze allows either instantaneous burst or time delayed action of 3 to 5 seconds. It
is thought that in some cases a disturbance-operated (antihandling) fuze may be fitted, of
a type such that bombs which have come to rest on the ground are thereafter exploded
by the least jar or movement.
The Italian 4 A.R.** (thermos) bomb is normally equipped with an anti-disturbance fuze which
functions if the bomb is moved or jarred after coming to rest on the ground. This bomb
resembles a thermos bottle in general size and shape, and may attract the curious to pick
it up, kick it, or otherwise disturb it -- to their extreme misfortune. It partakes of the
nature of a booby trap, though it is distributed by airplanes.
It may be pointed out that antipersonnel bombs equipped with these anti-handling fuzes are
not only fatal to the unwary -- they are annoying and difficult to dispose of even when
their nature is thoroughly understood. Thus they serve to hamper operations on ground
where they have been dropped.
The Japanese 50-kilogram phosphorous pellet bomb is a dual-purpose bomb combining antipersonnel
and incendiary effects. On detonation, the steel bomb-body fragments are projected at high
velocity in a flat cone, and numerous phosphorous-impregnated pellets are scattered. This
bomb is described as being quite effective for antipersonnel uses.
The German 2.2-kilogram I.B.E.N. (incendiary bomb with explosive nose) similarly combines
incendiary and antipersonnel effect; but this bomb is primarily an incendiary, with the
high-explosive and antipersonnel component added to hamper and delay fire fighters. The
antipersonnel component may break off and come to rest at a distance from the incendiary
portion of the bomb, yet function nevertheless. It explodes from 1 to 7 minutes (approximate
time) after the incendiary portion has functioned. The delay is unpredictable, and varies
with individual bombs.
During the Japanese raid on Rangoon, 23 December 1941, some ten or a dozen antipersonnel
bombs fell in an open space of about 150 by 250 yards, which was laced with slit
trenches. But the people were on top of the trenches and even ran out of them, with the
result that 250 were killed on the spot in a few minutes. The wounds were generally terrible
leg and stomach injuries. The most fatal zone was within 50 to 60 yards of the
burst, but some individuals were killed up to 300 yards away.
Had these people remained in the trenches, even without overhead cover,
the casualties would have been negligible by comparison. The slit trench or foxhole
provides excellent protection against small fragmentation bombs. Wherever
they may be expected, a little "digging in" will pay dividends.
Corresponding destruction has been achieved on aircraft or motor transport caught undispersed
in the open.
While the SD 2 "butterfly" bomb and the 4 A.R. "thermos" bomb are especially to
be avoided, unexploded specimens of any fragmentation bomb should be given a wide
berth. Failure of the fuze to function normally on impact may nevertheless leave the
bomb in a highly sensitive condition; and the disposal of such "duds" can be safely
undertaken only by specially trained personnel.
*[SD is the designation for a bomb with a thick casing, which achieves its effect chiefly by fragmentation.]
**[Armamento Ritardato - delayed action.]