The ' Wasserfall ' - The world's first radar guided SAM, page 1

The radar guided vesion didn't reach production, but maybe if the German's had another year or two, who knows ?

With the increasing Allied bombing of Germany, new methods were needed to bring down the enemy bombers. The methods currently used (antiaircraft guns and fighter aircraft) were somewhat effective, but costly in ammunition and fuel expended, lost pilots and airframes. Thus, the guided antiaircraft (or FLAK) rocket was envisioned. One of these, perhaps the most ambitious, was the Wasserfall (Waterfall), developed at Peenem�nde.

The guiding system consisted of a ground operator, who steered the Wasserfall missile to the target by use of a joystick by line-of-sight. The missile was gyroscopically controlled in roll, pitch and yaw, and could be controlled from the ground via radio link in azimuth and elevation. This was achieved by the four graphite rudders placed in the rocket exhaust at the slower starting speeds, and later by the four air rudders mounted on the tail once higher speeds were reached. There was also a proposed radar control system, known as Rheinland, which consisted of a radar set, direction finder set, comparator computer and a control transmitter. The radar set was to track the targets and then trigger a transponder aboard the Wasserfall missile. Then the signal from the transponder would be received by the direction finder set, thus establishing the azimuth and elevation of the missile. The information would then be fed into the comparator computer, where it was compared to the target information obtained by the radar. At this point, the necessary corrections were calculated and then relayed to the control transmitter to bring the missile into the radar beam, and once in the beam, the Wasserfall would ride up the beam to the target. Another proposed method was to use two radar sets that employed rotating dipoles giving conical scans, so that if the missile was off track, it would receive a modulated signal to bring it back on target. It was felt, using either radar system, that because of the supersonic speed of the Wasserfall, the radar system would be inadequate to control the missile when it got to within a few miles of the target, so a proximity or infrared homing system would take over near the end of the flight.

Originally, the warhead was to contain 100 kg (220 lbs) of explosive, but this was later increased to 306 kg (674 lbs), including a liquid explosive to increase the explosive diameter. Detonation could be achieved either by remote control, or by a proximity fuse. The Wasserfall's purpose was to bring down enemy bombers by a large blast area effect, conceivably several bombers could be brought down by each missile.
The original intent was to set up Wasserfall antiaircraft batteries to defend all German cities with a population over 100000, which would come to approximately 200 Wasserfall batteries, deployed in three lines about 80 kilometers (50 miles apart). Also, given up to 300 missile batteries, it was possible to defend all of Germany from enemy bomber attacks. For this grandiose plan, 5000 missiles would be needed monthly, and each missile was estimated to take 500 manhours (it took 4000 manhours for each A-4 (V-2) rocket for comparison) to complete. The first Wasserfall site could have been set up as early as November 1945, with a total of 20 more sites set up within an additional four months with 100 Wasserfalls available for each site. It was also estimated that production figures would reach 900 missiles per month by March 1946.

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