Submarines and their Weapons - Aircraft of World War II

AIR-TO-SURFACE MISSILES
plethora of names: the RLM called it the PC 1400X;
the Luftwaffe called it the 'Fritz-X'; and it has also
been referred to as the FX 1400 and simply as the FX.
However, its success was shortlived, despite having
been designed with cheapness and simplicity in mind.
It had as its starting point the Luftwaffe's standard
1400kg (30801b) bomb, either the cast-steel thickcased
SD (Sprengbombe Dickwandig) 1400 known as
'Fritz', or the forged-steel armour-piercing variant,
the PC (Panzersprengbombe Cylindrisch) 1400. The
original bomb, manufactured by Rheinmetall-Borsig,
of perfectly conventional shape, was a plain cylinder
with a rounded nose coming to a blunt point and a
conical tail with four sheet-metal fins partially
shrouded by a strengthening ring at the extremity.
Ruhrstahl modified the overall form somewhat for its
guided bomb, leaving the last part of the cylinder
intact but introducing an oversize ogival form to the
first two-thirds of its length.
In order to maximise its aerodynamic performance,
they gave it four relatively large fins, located
forward of the mid-point of the bomb's length, with
square leading edges and a pronounced sweep to the
trailing edges. These main fins were mounted asymmetrically,
as if they formed the diagonals of a rectangle
with sides in the ratio one-and-a-half to one.
The 12-sided framework which replaced the simple
fin-and-shroud empennage maintained that same
basic rectangular form, but with the corners cut off.
Within it were four smaller fins, set vertically and
horizontally and containing the spoilers themselves,
simple tabs which were actuated by electro-magnets
and which caused disturbance within the airflow over
the appropriate surface of the fin when they were
deployed. Deployment in turn caused the whole bomb
to alter course or angle of descent by swinging it
around the axis formed by the straight leading edge of
the main fins.
RADIO GUIDED
Guidance was by means of a radio link using the
Kehl/Strassburg system (but later, the wire-link control
system was adapted for use with the X-l too),
while flares, or battery-powered lamps on the tail for
use at night, helped the operator to keep track of the
missile in flight. It was a simple, fairly ingenious system,
and it worked well enough, so long as the bomb
was dropped from sufficient height. Released at the
minimum altitude of 4000m (13,125ft) it had a range
of up to 4.5km (2.8 miles); dropped from the maximum
height any of its carrying aircraft could attain of
92
8000m (26,250ft), the range was up to 9km (5.6
miles). It was capable of piercing 130mm (5.125 in) of
armour plate when dropped from 6000m (19,700ft).
Though it is often referred to as a glider bomb, that is
not actually the case. Its forward speed was that
imparted by the launching aircraft, and it certainly did
not 'fly' in any accepted sense. Its only major vector
was downwards, and all the spoilers could do was
modify its path to a small degree. That was often
enough to make the difference between success and
failure, as we shall see later when we look at operational
deployment of the ASMs. A total of 1386 X-ls
were produced between April 1943 and December
1944, when manufacturing ceased, and this was far
short of the planned figure of 750 per month. Less
than half of them - a total of 602 - were expended, in
testing, training and operations.
THE RUHRSTAHL X-1 IN ACTION
From 29 August 1943, III Gruppe/Kampfgeschwader
100 (HI/KG 100), equipped with Dornier 217K-2s
and operating out of Istres near Marseilles, was the
first unit to employ Ruhrstahl X-ls to attack Allied
shipping in the Mediterranean. Initially they were
unsuccessful, but within a fortnight they had scored
heavily and it soon became clear that the X-1 was a
very potent weapon indeed.
On 4 September, Italy abandoned the Axis and
reached a separate peace with the Allies, but there
were still no clear indications of which way the powerful
but until now seriously misused Italian Navy
would jump. On 9 September the Allies landed at
Salerno, and at 12 noon that day, reconnaissance
reported that the Italian Fleet was at sea, headed south
for Malta. Within two hours, 12 Do 217s of III
Gruppe, led by Major Bernhard Jope, each armed
with a single X-1, were in the air. They headed east at
low altitude, then, climbing as they neared the coast
of Sardinia, made out the shapes of three battleships
with an escort of six cruisers and eight destroyers,
Jope led his formation to 6500m (7108 yards) and
turned towards the ships, which were now zig-zagging
wildly and firing every one of their anti-aircraft
guns. The first missile, launched by Oberleutnant
Heinrich Schmelz (who was to be awarded the
Knight's Cross, and later go on to command the
group), struck the 40,000-tonne (39,368-ton) battleship
Roma amidships at a terminal velocity of about
330 metres (1080 feet) per second, punching straight
through her bottom to explode beneath the ship. A
second hit her just forward of the bridge, where her