Journal of the Royal Naval Scientific Service. Volume 27, Number 2 ...

Torpedo History: Kirby 87
in 1942 an experimental system, named
BOJE (= buoy), was built to confound the
experts. Although the acquisition ranges were
generally less than for passive weapons the
active system had certain advantages particularly
in the presence of noisemakers and
against slow or stationary targets.
Although BOJE never reached service it
stimulated an enormous quantity of research
into reverberation; this being of considerable
importance to the success of active homing
systems. Indeed, the Germans carried out
much basic research on the radiated noise of
ships and torpedoes and its directional properties.
Their research on the noise of
propellers, carried out both at sea and in
water tunnels at Gotenhafen, and the effects
of sea surface reflection of propeller noise to
the homing system are, even today, sufficiently
relevent to forbid detailed description here.
The successor to BOJE was GEIER
(= Vulture) which had an active acquisition
range of 280 yards. The transducer was pendulously
mounted to stabilise the variation of reverberation
with time from transmission. Two
receiver amplifiers were used, these being a
time varied gain type to follow the decay of
the reverberation and the second was an
A.G.C. type to compensate for variations from
day to day due to sea state changes. As a
result of experience with GEIER I the GEIER
2 was produced. The listening hydrophone
operated over two different bandwidths. The
self-noise was different in the two channels
but the echo was the same level. Thus, by
appropriate amplification and subtraction the
self-noise was effectively greatly reduced giving
a much improved signal to noise ratio. Another
improvement incorporated in GEIER 2 was
the facility for " preferred side " homing in
which the weapon only responds to echoes
from a certain pre-determined side.
The first pre-production GEIER weapons
appeared in March 1944 and the GEIER 2
started test running in the Autumn of 1944.
They reached the fleet as operational weapons
only a few months before the end of the war.
In conclusion, I will briefly describe some
experimental homing weapons that never
reached the production stage. IBIS (= Ibex)
used acoustic echoes from a ship's wake to
weave along the wake to the ship. Pings were
transmitted normal to the weapon axis and
the torpedo steered towards the echo to give
a weaving course as shown in Fig. 35. The
idea was tested but dropped in 1944 in favour
of the GEIER. FASEN (= Pheasant), like
FIG. 35. IBIS Wake Following Procedure.
IBIS detected the echoes received from a ship's
wake but having entered the wake the weapon
went into a pre-set pattern running procedure.
This svstem was also drooped in favour
of GEIER. MARC HEN (= Fairy tale ! !) was
a magnetic homing weapon which achieved
acquistion ranges onto large non-degaussed
ships of several hundred yards but it was
cancelled on account of the variability of ship
magnetic fields with position on the Earth's
surface. Finally we note the wake weaver
devised by Professor Ackermann at the Danzig
Technical College. The presence of the wake
was detected by its turbulence and this in
turn was detected by two pressure tap points
near the nose and tail. The turbulence effects
were too small to enable a reliable indication
of the wake to be given. (It is interesting to
note that a similar system was devised in
Britain over forty years earlier !)
The Germans developed or studied over
fifty types of torpedo including the famous
peroxide types and the less well known wireless
controlled weapons. They also tested a
fiat torpedo propelled by a flapping fin and
the British revived the flywheel weapon. All
of these and more will be introduced in the
next of these articles.
Part 4
Abstract
The continuing development of American and
British homing torpedoes is described over the period
of World War II followed by the important propulsion
improvements such as the German " Ingolin "
weapons as well as the bizarre " flapping fin " and
flywheel torpedoes.
The post-war development of torpedoes, both in
Britain and the U.S.A. is described. This includes
the 500 knot ' flying torpedoes ' as well as less fabulous
weapons such as the ill-fated PENTANE and
FANCY projects. It is shown that the British torpedo
programme since 1945 has produced three service
weapons out of at least nineteen projected, and in
many cases experimentally tested, designs.