Wasserfall the Surface-to-Air Missile

The Wasserfall missile development began during World War II under the guidance of German engineer and rocket scientist Werner von Braun.

It was conceptualized as part of Germany’s extensive rocket development program, which famously included the V-2 rocket. The impetus for the Wasserfall project was primarily driven by the need for an effective defense against Allied bombing raids, which were increasing in frequency and intensity.

Unlike the V-2, which was designed as a ballistic missile, the Wasserfall was intended to be a SAM, capable of intercepting high-altitude targets. The project was initiated around 1942-1943, and the development was carried out at Peenemünde, a German military research center on the Baltic coast.


High-Speed Rocket

The Wasserfall Ferngelenkte FlaRakete, translating to “Waterfall Remote-Controlled Anti-Aircraft Rocket,” was a German project during World War II focused on creating a guided, supersonic surface-to-air missile. The project, however, was not finalized before the war’s end, and consequently, the missile was never deployed in combat.

The goal was to create a missile capable of intercepting high-altitude bombers, a task that required precision, speed, and an effective guidance system
The goal was to create a missile capable of intercepting high-altitude bombers, a task that required precision, speed, and an effective guidance system

This system borrowed extensively from the technologies established for the V-2 rocket program. In fact, the missile was essentially a significantly miniaturized version of the V-2’s structure. Its rocket motor was designed to use novel fuels, anticipating long-term storage in a ready-to-launch state.

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Moreover, the guidance system was uniquely designed, utilizing external fins for directional control rather than solely depending on the maneuverability of the rocket motor’s exhaust.

The development faced numerous challenges, notably in controlling the high-speed rocket. This led to the innovation of a radio control system, which involved an operator using a reclining chair to better view and target overhead aircraft.

Another major issue was the absence of an effective proximity fuse. Such a device was necessary because it was impossible for the operator to visually gauge the rocket’s proximity to a target directly above. While a radar-assisted system was in development, it was not ready for practical application at the time.

Wasserfall Missile

The Wasserfall missile was a derivative of the V-2 rocket, tailored specifically for anti-aircraft purposes. It shared the V-2’s overall design and aerodynamic profile but was significantly smaller, about one-fourth the size of the V-2.

Wasserfall rocket displayed at the National Museum of the United States Air Force,
Wasserfall rocket displayed at the National Museum of the United States Air Force

This reduction in size was feasible because the Wasserfall only needed to reach the altitudes of attacking bombers and required a smaller warhead for effective engagement. Additionally, the design incorporated an extra set of fins mid-fuselage, enhancing its maneuverability.

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During its initial launch phase, steering was controlled by four graphite rudders situated in the rocket’s exhaust stream, similar to the V-2 system. However, at higher airspeeds, control shifted to four air rudders mounted on the tail of the rocket.

Hypergolic Fuel

A crucial difference between the Wasserfall and the V-2 was in their operational readiness and fuel systems. The Wasserfall was engineered to be on standby for up to a month and be launch-ready on short notice.

Consequently, the V-2’s volatile liquid oxygen fuel was unsuitable for this purpose. To address this, a new engine design was developed by Dr. Walter Thiel, utilizing a hypergolic fuel mixture of Visol (vinyl isobutyl ether) and SV-Stoff, or red fuming nitric acid (RFNA), composed of 94% nitric acid and 6% dinitrogen tetroxide.

This flak rocket was given the name Wasserfall and the designation C-2 8/45
This flak rocket was given the name Wasserfall and the designation C-2 8/45

This mixture was fed into the combustion chamber by pressurizing the fuel tanks with nitrogen gas from a separate tank. The planned launch sites for Wasserfall, code-named Vesuvius, were designed to withstand potential leaks of these hypergolic fuels in case of launch failures.

Dropped by Bombers

The Wasserfall missile was equipped with a rudimentary radio control manual command to line of sight (MCLOS) guidance system, intended for use against targets in daylight.

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This system was operated through a joystick using a modified version of the FuG 203/FuG 230 “Kehl-Straßburg” (code-named Burgund) radio-guidance system. This technology, originally developed for guiding anti-ship missiles from bombers, was previously employed in the control of both the unpowered Fritz X and the rocket-boosted Henschel Hs 293.

The first successful test launch in 1944 was a significant milestone
The first successful test launch in 1944 was a significant milestone

For the anti-aircraft role, the control mechanism was set up next to a chair on a frame that allowed the operator to recline and easily observe overhead targets, rotating as necessary to maintain visual contact with the target.

Night operations posed a greater challenge due to the difficulty in visually tracking both the target and the missile. For such scenarios, a new system named Rheinland was in development. This system comprised a radar for target tracking and a transponder within the missile for in-flight location.

Wasserfall Radar Beam

An elementary analog computer was employed to guide the missile into the radar beam as soon as possible post-launch, using a radio direction finder and the transponder for localization. Once the missile entered the radar beam, its transponder reacted to the radar signals, creating a distinct blip on the radar display. The operator would then maneuver the missile using the joystick to align the blips.

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Initially, the missile was designed to carry a 100 kg (220 lb) warhead. However, due to concerns about precision, this was later replaced with a significantly larger 306 kg (675 lb) warhead, using a liquid explosive.

The guidance system represented one of the most innovative aspects of the Wasserfall.
The guidance system represented one of the most innovative aspects of the Wasserfall

The rationale behind this change was to generate a substantial blast radius within the enemy bomber formation, potentially downing multiple aircraft with a single missile. For daytime operations, the warhead’s detonation would be remotely controlled by the operator.

Wasserfall Missile Prototypes

The conceptual phase of the Wasserfall missile began in 1941, with its final design specifications being established on November 2, 1942. The first prototypes underwent testing as early as March 1943.

However, the project encountered a significant setback in August 1943, a consequence of the Operation Hydra bombings, which marked the commencement of the Operation Crossbow bombing campaign targeting V-2 production facilities. This event was particularly detrimental as it resulted in the death of Dr. Walter Thiel, a key figure in the project.

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Despite these challenges, the first successful test firing of the Wasserfall (using the third prototype) occurred on March 8, 1944. By the end of June 1944, three trial launches of the Wasserfall missile had been successfully completed.

However, not all tests were successful; for instance, a launch attempt on January 8, 1945, resulted in failure when the engine malfunctioned, propelling the missile to only 7 km altitude at subsonic speeds. Nevertheless, progress was evident in February 1945 with a successful launch that achieved a supersonic speed of 770 m/s (2,800 km/h) in a vertical trajectory.

Bäckebo Rocket

In total, thirty-five trial firings of the Wasserfall missile were conducted before the evacuation of the Peenemünde site on February 17, 1945.

In a related event, the Bäckebo rocket, which was essentially a V-2 rocket equipped with Wasserfall radio guidance, crash-landed in Sweden on June 13, 1944. This incident highlighted the ongoing experimentation and cross-application of technologies within the German rocket program during this period.

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Based on the accounts of Albert Speer and Carl Krauch, there was a belief that the Wasserfall missile had the potential to wreak havoc on the Allied bomber forces. Speer, who served as the Reich Minister of Armaments and War Production for Germany, later made assertions regarding this:

To this day, I am convinced that substantial deployment of Wasserfall from the spring of 1944 onward, together with an uncompromising use of the jet fighters as air defense interceptors, would have essentially stalled the Allied strategic bombing offensive against our industry. We would have well been able to do that – after all, we managed to manufacture 900 V-2 rockets per month at a later time when resources were already much more limited.

— Albert Speer, Reich Minister of Armaments and War Production, memoir.

Missiles in Combat

Historian Michael J. Neufeld has presented a contrasting view, suggesting that Germany’s ability to deploy Wasserfall batteries before its defeat was implausible due to the extensive development required. He attributes the prolonged duration of the project to bureaucratic inertia within the German military and a sense of desperation among the German leadership.

Neufeld also expressed skepticism about the effectiveness of the missiles in combat, citing the absence of proximity fuses (which Germany never successfully developed) and the impracticality of their guidance system.

In a similar vein, a volume from the book series “Germany and the Second World War” points out that the Wasserfall was one of several missile systems the Luftwaffe ambitiously committed to develop, despite a clear lack of resources to see them to completion or actual deployment during the war.