In service 1943- 1944 | ||
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Manufacturer Henschel Flugzeug-Werke AG | ||
The Henschel Hs 293 was a World War II German anti-ship guided missile: a radio controlled glide bomb with a rocket engine slung underneath it. It was designed by Herbert A. Wagner.
Contents
Development
The Hs 293 project was started in 1940, based on the "Gustav Schwartz Propellerwerke" pure glide bomb that was designed in 1939. The Schwartz design did not have a terminal guidance system; instead, it used an autopilot to maintain a straight course. It was intended to be launched from a bomber at sufficient distance to keep the aircraft out of range of anti-aircraft fire. A Henschel team, under Dr. Herbert Wagner, developed it the following year by adding an Walter HWK 109-507 rocket engine underneath, providing 590 kg (1,300 lb) thrust for ten seconds. This allowed the bomb to be used from a lower altitude and at an increased range. Some examples used the BMW 109-511 of 600 kg (1,323 lb) thrust.
The first flight attempts took place between May and September 1940, with unpowered drops from Heinkel He 111 medium bombers used as carrier aircraft; the first Walter rocket motor-powered tests had been conducted by the end of 1940.
The weapon consisted of a modified standard 500 kilogram SC 500 bomb with an added "Kopfring" on the nose for maritime use, to help ensure a relatively perpendicular axis of impact, with a thin metal shell and a high explosive charge inside, equipped with a rocket engine beneath the bomb, a pair of aileron-fitted wings, and a Kehl-Straßburg MCLOS guidance and control system. The elevator was operated with an electrically powered jackscrew as the only proportional control, while the ailerons were operated with solenoids. Remote flight control was provided through the Kehl-Straßburg link, with the Hs 293's control setup having no movable rudder on the ventral tailfin. The rocket provided for only a short burst of speed making range dependent on the height of launch. From a height of 1,400 m (4,600 ft) the Hs 293 had a range of about 12 km (7.5 mi; 6.5 nmi).
The Hs 293 was intended to destroy unarmoured ships, unlike the unpowered, armour-piercing Fritz X, which used the same Kehl-Straßburg system. Five coloured flares were attached to the rear of the weapon to make it visible at a distance to the operator. During nighttime operations flashing lights instead of flares were used.
One drawback of the Hs 293 was that after the missile was launched the bomber had to fly in a straight and level path at a set altitude and speed parallel to the target so as to be able to maintain a slant line of sight and it could thus not manoeuvre to evade attacking fighters without aborting the attack.
Electronic countermeasures
The Allies put considerable effort into developing devices which jammed the radio link between Kehl transmitter and Straßburg receiver. Jammers aboard U.S. Navy destroyer escorts were ineffective at first, but improved frequencies selected for jamming were incorrect. On balance, the probability that a Hs 293 launched (and seen as responding to operator guidance) would actually strike a target (or achieve a damage-inflicting near miss) was about the same at Anzio as it was during Operation Avalanche.
Meanwhile, as attacks were taking place at Anzio, the United Kingdom began to deploy its Type 650 transmitter which employed a different approach, which proved quite successful. The Type 650 transmitter employed a different approach to interfering with the FuG 203/230 gear's radio link, by jamming the Straßburg receiver's intermediate frequency section, which operated at a 3 MHz frequency and appears to have been quite successful, 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 an individual missile, be it Fritz X or Hs 293.
Following several intelligence coups, including a capture of an intact Hs 293 at Anzio and recovery of important components of the Kehl transmitter from a crashed Heinkel He 177 on Corsica, the Allies were able to develop far more effective countermeasures, all in time for the invasion of Normandy and Operation Dragoon. These included AIL's Type MAS jammer, which employed sophisticated signals to defeat the Kehl transmission and to take over command of the Hs 293, steering it into the sea via a sequence of right-turn commands.
In contrast to the experience at Anzio, the jammers seemed to have had a major impact on operations after April 1944, with significant degradation observed in the probability that a Hs 293 launched at a target (and responding to operator guidance) would achieve a hit or damage-causing near miss.
To improve control of the weapon and reduce vulnerability of the launching aircraft, wire-guided Hs 293B and television-guided Hs 293D variants were planned; neither was operational before the war ended. There was also a tailless delta winged Hs 293F. In addition, there was a Hs 293H air-to-air model.
Over 1,000 were built, from 1942 onwards.
The closest Allied weapon system in function and purpose to the Hs 293 series was the US Navy's Bat unpowered, autonomously radar-guided unit.
Later developments
The Hs 293 also served as the basis for a number of developments, none completed. These included the Hs 294, "designed specifically to penetrate the water and strike a ship below the waterline", with a long, conical shaped forebody and a pair of the Hs 293A's standard Walter HWK 109-507 booster engines at the wing roots; the Hs 295, with longer fuselage, larger warhead, and Hs 294 wings; the Hs 296, with Hs 294 afterparts, Hs 295 warhead, and Hs 293 Kehl-Straßurg MCLOS control systems.
Operational history
On August 25, 1943, an Hs 293 was used in the first successful attack by a guided missile, striking the sloop HMS Bideford; however, as the warhead did not detonate, the damage was minimal. On August 27, the sinking of the British sloop HMS Egret by a squadron of 18 Dornier Do 217 carrying Hs 293s led to anti-U-boat patrols in the Bay of Biscay being temporarily suspended. On November 26, an Hs 293 sank the troop transport HMT Rohna killing over 1,000 personnel.
Other ships sunk or damaged by the Hs 293 include:
Although designed for use against ships, it was also used in Normandy in early August 1944 to attack bridges over the River See and River Selume. One bridge was slightly damaged for the loss of six of the attacking aircraft.
The Hs 293 was carried on Heinkel He 111, Heinkel He 177, Focke-Wulf Fw 200, and Dornier Do 217 planes. However, only the He 177 (of I and II.Gruppen/KG 40), certain variants of the FW 200 (of III./KG 40) and the Do 217 (of II./KG 100 and III./KG 100) used the Hs 293 operationally in combat.