Submarines and their Weapons - Aircraft of World War II

Above: The 'Rheintochter' 1 on its launch ramp. Guidance
was provided by the small vanes at the nose, which were
controlled from the ground via radio signals.
and the chief difference between 'Wasserfall' - as the
surface-to-air missile was known - and the A4 was to
be in its propulsion plant. From the outset it was clear
that the operational requirements for the two rockets
were quite different. Whereas A4 could be fuelled as
and when required, in a more or less leisurely fashion,
and fired when it was ready, the SAM would be
required to be held at instant readiness, perhaps for
months, and this was simply not practical if a cryogenic
propellant like liquid oxygen was employed.
Instead, it would be fuelled by Salbei (90 per cent
nitric acid, 10 per cent sulphuric acid to inhibit corrosion)
and a type of Visol, the fuel - which ignited
spontaneously on being combined - being delivered
to the combustion chamber by pressurising the propellant
tanks with inert nitrogen, rather than by using
cumbersome high-pressure steam turbines. Because
the two components of the fuel reacted so violently,
pre-launch and launch-time safety procedures very
important, and there was an elaborate system of interlocks
involving metal membranes which would rupture
only in predetermined circumstances.
'WasserfaU' was about half the length of the A4, at
7.84m (25.7ft), and weighed 3500kg (77201b) all-up,
as opposed to 12,900kg (28,4401b), but it was still by
far the biggest of all the German surface-to-air
106
weapons, even though its warhead was smaller, at
235kg (5201b), than that of the 'Enzian'. It was very
similar in shape to the bigger missile, but unlike the
A4 it had four stabilising fins located about one third
the way back from the nose.
35 TEST LAUNCHES
'Wasserfair was designed to operate at greater range
and altitude than the other SAMs. Its 8000kg-
(17,6301b-) thrust engine burned for 40 seconds and
gave it a range of up to 50km (30 miles) and an altitude
of 20,000m (65,000ft), even though the latter
was far higher than any aircraft attained. Its guidance
system was manual and ground-based, with course
corrections transmitted to the rocket by radio signals,
but since it was launched vertically, it also carried the
A4's basic inertial guidance system, to point it in the
approximate direction of the target. It is difficult to
imagine visual tracking and control being at all effective
at anything like extreme range and altitude, and
given its high launch speed, guiding it manually at all,
whether through a sighting telescope or by superimposing
dots on an oscilloscope, generated by tracking
radars, must have presented problems. The first successful
launch occurred at Peenemiinde on 29
February 1944, and it is believed that about 35 test
launches were made in total. Series production was to
have been at the biggest underground factory of them
all, Bleichrode, but in the event even the factory itself
had not been built when the war ended in May 1945.