The Fritz X – also known as the Ruhrstahl SD 1400 X or the Kramer X-1 – was an advancement in German anti-ship armaments. Engineered for superior armor penetration, the weapon underwent rigorous refinement to bolster its accuracy and effectiveness, proving highly successful in combat.
Despite these enhancements, however, the Fritz X had its drawbacks: it was significantly vulnerable to Allied aircraft.
Modified PC 1400
Conceived by Max Kramer and manufactured by Ruhrstahl AG, the Fritz X came from the PC 1400 (1,400 kg) bomb. Weighing 3,450 pounds, it had a formidable 710-pound warhead that was capable of penetrating up to 28 inches of armor when deployed between 18,000 and 20,000 feet.
In 1940, various iterations were made to ascertain the optimal design. The X-2, engineered for higher speeds and equipped with an infrared homing device, saw its development halted, with only a single unit produced. Conversely, the X-3, which was larger and heavier in comparison, boasted impressive speeds of up to 900 MPH. Nonetheless, the X-1 emerged as the preferred choice, due to its streamlined operation and developmental simplicity.
By 1941, the Luftwaffe began rigorous testing of the missile. Two years later, the project advanced to the manufacturing phase.
Fritz X specs
The Fritz X boasted a cutting-edge aerodynamic design and boasted a sophisticated guidance system – the Kehl-Strasbourg joystick radio-control. Its tail was a marvel of engineering, featuring a twelve-sided frame cradling four elegant fins. Two of these fins were elongated and equipped with spoilers for precise course adjustments. Stability was ensured by a pair of gyroscopes, while a set of asymmetrical cruciform wings were positioned in the front section.
Launched from Dornier Do 217K-2 and Heinkel He 177A Greif aircraft, these weapons relied on bombardiers who used tail flares to track their descent. The radio-controlled spoilers allowed the Fritz X to execute maneuvers with pinpoint accuracy, as long as Allied radio jamming didn’t disrupt the signal.
Success in the Mediterranean Theater
The Fritz X made its debut in combat on July 21, 1943, during a raid on the Port of Augusta in Sicily. At that time, no confirmed hits were reported, and the Allies remained largely unaware of the Germans’ use of radio-guided missiles. However, the Fritz X achieved its most notable success in a subsequent attack on the Italian fleet in September 1943.
Following the arrest of Benito Mussolini, the Italian government entered into negotiations with the Allies. On September 8, the Supreme Allied Command in Europe announced the signing of an armistice. A plan was devised to transfer the Italian naval fleet to Allied ports in Tunisia and Malta. However, the Germans quickly caught wind of the plan and devised their own strategy to intercept the convoy, aiming to prevent the ships from reaching their intended destinations.
Sinking of Roma (1940)
A squadron consisting of three battleships – Roma (1940), Vittorio Veneto and Italia (1943) – accompanied by six cruisers and eight destroyers, navigated the western coastline of Corsica, making their way toward Sardinia and Tunisia. At midday, six Do 217K-2 aircraft from Gruppe III of Kampfgeschwader 100 Wiking approached the fleet, each carrying a single Fritz X missile.
The most significant success was the sinking of the Italian flagship Roma. A Fritz X missile pierced the battleship’s starboard side, detonating beneath her keel. The resulting explosion inflicted severe damage, flooding Roma‘s boiler and engine rooms while disabling two of her four propeller shafts. This reduction in speed and a series of electrical fires further compounded the crisis.
Fritz X missiles sink the HMS Spartan (95) and others
Just seven minutes later, another Fritz X hit the Roma, this time detonating in her forward engine room and causing a catastrophic magazine explosion. The force of the blast killed Vice Adm. Carlo Bergamini, the ship’s captain, and 1,393 crew members. Within 30 minutes of the first hit, Roma split in two and capsized.
In the days that followed, Luftwaffe pilots continued to deploy Fritz X missiles, sinking the British cruiser HMS Spartan (95) and destroyer Janus (F53), as well as several merchant ships in the area. They also inflicted severe damage on the British warship HMS Warspite (03) and cruiser Uganda (66), along with the American light cruisers USS Philadelphia (CL-41) and Savannah (CL-42).
The Fritz X made German aircraft vulnerable
While the Fritz X initially displayed potential, its limitations soon became apparent. Bombers had to fly straight and level while carrying the missile, and after releasing it, they needed to quickly decelerate, relying on visual guidance for accuracy.
Aircraft equipped with the Fritz X became vulnerable targets – an issue that was quickly exploited by the Allies. The most effective defense against German aircraft carrying the missile was Allied fighters, which prevented them from maintaining stable flight. As well, generating smoke proved effective in obscuring the missiles and complicating guidance for bombardiers.
Furthermore, the Allies rapidly deployed electronic countermeasures to disrupt radio signals, significantly increasing challenges for the German forces.
Fritz X failed to meet the Luftwaffe‘s expectations
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Originally, the plan aimed to manufacture 750 Fritz X missiles monthly. However, from April 1943 until the program’s conclusion in December of the following year, only 1,386 were produced, with 602 allocated for training and testing purposes. Moreover, the missiles failed to meet the Luftwaffe‘s expectations for accuracy, striking their targets merely around 20 percent of the time.
Despite its shortcomings, the Fritz X served as a precursor to the development of future spoiler-controlled missiles.