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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").
The Luftwaffe recognised the difficulty of hitting moving ships during the Spanish Civil War.Fitzsimons, Bernard, ed. "Fritz-X", in The Illustrated Encyclopedia of 20th Century Weapons and Warfare (London: Phoebus, 1978), Volume 10, p. 1037. 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 spoilers.Fitzsimons, "Fritz-X", p. 1037. In 1940, was invited to join the development, since they already had experience in the development and production of unguided bombs.Christopher, John. The Race for Hitler's X-Planes (The Mill, Gloucestershire: History Press, 2013), p. 134.
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.Christopher, p.134. 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. Approximately 1,400 examples, including trial models, were produced.
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.Bogart, Charles H. "German Remotely Piloted Bombs" United States Naval Institute Proceedings November 1976 pp.62–68 When working properly, the missile was able to pierce 130 mm (5.1 in) of armor.
Accuracy is the main reason for developing a weapon system of this kind, rather than continuing to use . A skilled bombardier could guide 50% of the bombs to within a 15 m (50 ft) radius of the aiming point, and about 90% hit within a 30 m (100 ft) radius (some sources say 60% hit within 4.6 metre radius).
The Fritz X was first deployed on 21 July 1943 in a raid on Augusta harbour in Sicily. Several attacks around Sicily and Messina followed, but no confirmed hits were made and it appears the Allies were unaware that the large bombs being dropped were radio-guided weapons.RL 10/493: Tätigkeitsbericht über Einsatzperiode das K.G. 100 mit F.K. in der Zeit von 12.7.43 – 30.4.44. Activity
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 American light cruiser was hit by Fritz Xs at 10:00 AM on 11 September 1943 during the invasion of Salerno, and was forced to retire to the United States for eight months of repairs. A single Fritz X passed through the roof of "C" turret and killed the turret crew and a damage control party when it exploded in the lower ammunition-handling room. The blast tore a large hole in the ship's bottom, opened a seam in her side, and blew out all fires in her boiler rooms. Savannah lay dead in the water with her forecastle nearly awash, and eight hours elapsed before her boilers were relit, allowing the ship to get under way for Malta. USS Savannah lost 197 crewmen in this attack. Fifteen other sailors were seriously wounded, and four more were trapped in a watertight compartment for 60 hours. These four sailors were rescued when Savannah had arrived at Grand Harbor, Valletta, Malta on 12 September.
Savannahs sister ship, , had been targeted earlier the same morning. The Fritz X just missed the ship, exploding about 15 metres away. Damage was minimal.See Barbara Tomblin's With Utmost Spirit: Allied Naval Operations in the Mediterranean, 1942–45 (Lexington: The University Press of Kentucky, 2004), 273. Tomblin cites as her source the original action reports filed by Philadelphia which clearly indicate the bomb missed. The erroneous notion that Philadelphia was hit emerged from an article in Proceedings in 1976 by Charles Bogart, and was subsequently repeated.
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.It remains uncertain today the exact cause of the loss of Bushrod Washington. Most accounts credit the attack to an Hs 293 launched from II./KG 100, and it is known from Luftwaffe records that II./KG 100 was active above Salerno around that time, flying nine missions from 9 to 30 September, three of them during the day. Eyewitness descriptions indicate that the side of the ship was blown out, more consistent with an Hs 293 attack than a Fritz X. The situation is further confused because original reports, possibly contrived to avoid mention of the glide bombs in accordance with U.S. policy at the time, suggest two conventional 250 kg bombs dropped from dive bombers were responsible. 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.
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.
The last Fritz X attack at Salerno lightly damaged the US light cruiser Philadelphia with two near misses on 17 September. This attack is sometimes reported as taking place on 18 September but US Navy records show the cruiser Philadelphia departed Salerno the night of 17/18 September. According to Luftwaffe records, III./KG 100, the Luftwaffe unit armed with the Fritz X, flew its last mission on 17 September. Other ships damaged by Fritz-X included Dutch sloop-of-war and British destroyer .
In early 1944, as the British and US Armies were engaged in the Battle of Anzio, the United Kingdom began to deploy its Type 650 transmitter, which employed a different approach to interfering with the FuG 203/230 radio link on a Fritz X, by jamming the Straßburg receiver's intermediate frequency (IF) section. The FuG 230 receiver's IF section operated at 3 MHz, and the Type 650 appears to have been quite successful in interfering with Fritz X ordnance deployments, especially because the operator did not have to attempt to find which of the eighteen selected Kehl-Straßburg command frequencies were in use and then manually tune the jamming transmitter to one of them. The Type 650 automatically defeated the receiver, regardless which radio frequency had been selected for a missile.
By the time of the Normandy landings, a combination of Allied air supremacy (keeping the Luftwaffe's bombers at bay) and ship-mounted jammers meant that the Fritz X had no significant effect on the invasion fleet. Some accounts report that the Norwegian destroyer was hit by a Fritz X at dawn on D-Day. This is unlikely, as III./KG 100, the unit which had carried the Fritz X into combat, had largely been re-equipped with the Hs 293 by that time for its anti-ship missions, and the attack on Svenner occurred before the first glide bombers launched their assaults on the Normandy beaches.
The Fritz X has been credited as responsible for the loss of the hospital ship at Salerno as well as the destroyer and the light cruiser at Anzio, but these ships were hit by Hs 293s, as demonstrated by the nature of the damage inflicted,DNC 6/R.322: "Report by the Admiralty Department of Naval Construction: Board of Enquiry 9 February 1944 in Naples." This is the official report on the loss of Spartan and identifies the Hs 293 as the weapon used; the nature of the damage, described in detail, is consistent with an Hs 293 and not with a Fritz X. as well as by reports from witnessesSee for example Captain John Eric Wilson's first-hand account as presented in "Sinking of the Hospital Ship SS Newfoundland", Newfoundland Times (published by the HMS Newfoundland Association) September 1994, pp.9–15. (in the case of Janus, either an Hs 293 or a conventional torpedo was responsible).
Explanatory notes
Citations
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