Fritz X - WikiHQ

Fritz X was a German guided anti-ship glide bomb used during World War II. Developed alongside the Henschel Hs 293, Fritz X was one of the first precision guided weapons deployed in combat. Fritz X was a nickname used both by Allied and Luftwaffe personnel. Alternative names include Ruhrstahl SD 1400 X, Kramer X-1, PC 1400X or FX 1400 (the latter, along with the unguided PC 1400 Fritz nickname, is the origin for the name "Fritz X").

History

thumb|upright|American drawing of the PC 1400 armour-piercing bomb, the basis for the Fritz X PGM|alt=

Fritz X was a further development of the PC 1400 (Panzersprengbombe, Cylindrisch 1,400 kg) armour-piercing high-explosive bomb, itself bearing the nickname Fritz. It was a penetration weapon intended to be used against armoured targets such as heavy cruisers and battleships. It was given a more aerodynamic nose, four stub wings, and a box-shaped tail unit consisting of a roughly 12-sided annular set of fixed surfaces and a cruciform tail with thick surfaces within the annulus, which contained the Fritz Xs aerodynamic controls.

The Luftwaffe recognised the difficulty of hitting moving ships during the Spanish Civil War. German engineer Max Kramer, who worked at the Deutsche Versuchsanstalt für Luftfahrt (DVL), had been experimenting since 1938 with remote-controlled free-falling bombs and in 1939 fitted radio-controlled spoilers. In 1940, was invited to join the development, since they already had experience in the development and production of unguided bombs.

Fritz X was guided by a Kehl-Straßburg radio control link, which sent signals to the movable spoilers in the thick vertical and horizontal tail fin surfaces, within the annular tail fin structure. This control system was also used for the unarmoured, rocket-boosted Henschel Hs 293 anti-ship ordnance, first deployed on 25 August 1943. The Straßburg receiver antenna installations on the Fritz X were aerodynamically integrated into the trailing edge of the annular surfaces of the tail fin, non-metallically encapsulated within four "bulged" sections in the trailing edge. This design feature of the FuG 230 Straßburg receiver installation is like the Azon (US contemporary guided bomb), which had its receiving antennas placed in the four diagonal struts bracing the fixed sections of its tail fins.

Minimum launch height was – although was preferred – and a range of was necessary. As it was an MCLOS-guidance ordnance design, the operator had to keep the bomb in sight at all times (a tail flare was provided, as with the Azon, to assist the operator in tracking the weapon) and the control aircraft had to hold course, which made evading gunfire or fighters impossible.

Combat procedure

thumb|left|Annotated still from a 1946 USAAF-published film on Fritz X showing the location of control spoilers and autonomous roll gyro

The Fritz X was steered by the bombardier in the launching aircraft over a radio link between the aircraft's Kehl transmitter and the weapon's Straßburg receiver. The bombardier had to be able to see the target at all times, and like the Azon, the Fritz X had a flare in the tail so it could be seen from the controlling aircraft for its MCLOS-form guidance to control it properly. The disadvantage with this — in comparison to fully autonomous-guidance glide bombs like the operational U.S. Navy's Bat radar-homing glide bomb, used against Japan in 1944–45 — were that the aircraft had to be flown towards the target on a steady course and that as the missile neared its target it became possible to misguide it by jamming its radio channel.

Unlike the Hs 293, which was deployed against merchant ships and light escort warships, the Fritz X was intended to be used against armoured ships such as heavy cruisers and battleships. The Fritz X had to be released at least from the target. The plane had to decelerate immediately after bomb release so the bombardier could see the bomb and guide it; this deceleration was achieved by making a steep climb and then levelling out. The bombardier could make a maximum correction of in range and in bearing. The bomber was vulnerable to fighter attack and ship-based air defence weapons while maintaining a slow, steady course so the bombardier could maintain visual contact to guide the bomb. When working properly, the missile was able to pierce 130 mm (5.1 in)

Usage in combat

thumb|Fritz X guided bomb at the [[National Museum of the United States Air Force]]

The only Luftwaffe unit to deploy the Fritz X was Gruppe III of Kampfgeschwader 100 Wiking (Viking), designated III./KG 100; the bomber wing itself evolved as the larger-sized descendant of the earlier Kampfgruppe 100 unit in mid-December 1941. This unit employed the medium range Dornier Do 217K-2 bomber on almost all of its attack missions; in a few cases near the end of its deployment history, Dornier Do 217K-3 and M-11 variants were also used. The Fritz X had been initially tested with a Heinkel He 111 bomber, but was never taken into combat by this aircraft. A few special variants of the troublesome Heinkel He 177A Greif long-range bomber were equipped with the Kehl transmitter and proper bombracks to carry the Fritz X, and it is thought that this combination might have seen limited combat service, at least with the combinations known to have been involved in test drops. It was found that the launch aircraft had to "toss" the bomb slightly, climbing and then descending, to keep it in view ahead.

On 9 September, the Luftwaffe achieved their greatest success with the weapon. After Pietro Badoglio publicly announced the Italian armistice with the Allies on 8 September 1943, the Italian fleet had left La Spezia and headed to Tunisia. To prevent the ships from falling into Allied hands, six Do 217K-2s from III. Gruppe of KG 100 (III/KG 100) took off, each carrying a single Fritz X. The Italian battleship , flagship of the Italian fleet, received two hits and one near miss, and sank after her magazines exploded. 1,393 men, including Admiral Carlo Bergamini, died. Her sister ship, Italia, was also seriously damaged but reached Tunisia.

The Royal Navy's light cruiser was hit by a Fritz X off Salerno at 14:40 on 13 September. The Fritz X passed through seven decks and straight through her keel, exploding underwater just under the keel. The concussive shock of the Fritz X's underwater detonation close to Ugandas hull extinguished all her boiler fires, and resulted in sixteen men being killed, with Uganda taking on 1,300 tons of water. Uganda was towed to Malta for repairs.

Two merchant ships may have been hit by Fritz X bombs at Salerno, though the evidence is uncertain. SS Bushrod Washington was hit by a glide bomb, either a Fritz X or a Hs 293, on 14 September while offloading a cargo of fuel. SS James W. Marshall was set on fire by a conventional bomb, Hs 293 or Fritz X on 15 September. As with Bushrod Washington, the nature of the weapon that damaged James W. Marshall is uncertain. A witness aboard a ship nearby, Joseph A. Yannacci, attributes the attack to Ju 87 "Stuka" dive bombers, which were too small to carry glide bombs. An attack with a Fritz X cannot be ruled out, but there is at least an equal case that, if a glide bomb was involved, it was an Hs 293 from II./KG 100; Luftwaffe records show that II./KG 100, armed only with Hs 293 glide bombs, was active over Salerno that day.

thumb|right|Savannah hit by a Fritz X during the Salerno landings

KG 100 achieved another success with Fritz X while the British battleship was providing gunfire support at Salerno on 16 September. One bomb penetrated six decks before exploding in number 4 boiler room. This explosion put out all fires and blew out the double bottom. A second Fritz X near-missed Warspite, holing her at the waterline. She took on a total of 5,000 tonnes of water and lost steam and consequently all power, both to the ship herself and to all her systems, but although the damage had been considerable, Warspites casualties amounted to only nine killed and fourteen wounded. She was towed to Malta by tugs and , then returned to Britain via Gibraltar and was out of action for nearly 9 months; she was never completely repaired, but returned to action to bombard German positions in Normandy during Operation Overlord. as well as by reports from witnesses (in the case of Janus, either an Hs 293 or a conventional torpedo was responsible).

Operators

Luftwaffe (Nazi Germany)

References

Explanatory notes

Citations

External links

The Development of precision guided Bombs
USAAF-captured (1946) German wartime film on details of the Fritz X bomb
The Dawn of the Smart Bomb
German guided weapons of World War II
Smithsonian National Air and Space Museum
National Museum of the U.S. Air Force
Ruhrstahl AG Fritz-X – Royal Air Force Museum, Cosford (UK)
"How Radio-Controlled Bombs Were Jammed", C.I.C. (Combat Information Center), U.S. Office of the Chief of Naval Operations, Dec. 1945.