Henschel Hs 293

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.

History
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 - it used an autopilot to maintain a straight course. The intention was that it could be launched from a bomber at sufficient distance to be out of range of anti-aircraft fire. Henschel developed it the following year by adding an HWK 109-507 rocket motor underneath it, providing a 600 kg thrust of ten second duration - this allowed the bomb to be used from a lower altitude and at an increased range.

The first flight attempts took place between May and September 1940, with unpowered drops from Heinkel He 111 medium bombers used as carrier aircraft, with the first Walter rocket motor-powered tests occurring by the end of 1940.

The weapon consisted of a modified standard SC 500, 500 kg bomb with an added "kopfring" on the nose for maritime use, with a thin metal shell and a high explosive charge inside, equipped with a rocket engine under the bomb, a pair of wings, and an MCLOS guidance and control system, consisting of an 18-frequency-capability Funk-Gerät (FuG) 230 Strassburg radio receiver, getting its signals from an FuG 203 Kehl transmitting set in the carrier aircraft. Only the elevator, operated with an electrically powered jackscrew as the only proportional control, with the ailerons operated with solenoids provided flight control through the Kehl-Strassburg radio 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 1400 m the Hs 293 had a range of about 12 km.

The Hs 293 was intended to destroy unarmoured ships, unlike the unpowered, armour penetrating Fritz X, similarly MCLOS-guided with the Kehl/Strassburg radio guidance gear. The operator controlled the radio-guided missile with the Kehl transmitter's joystick. Five colored 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.

The Allies put considerable effort into developing devices which jammed the low-VHF band (48.2 MHz to 49.9 MHz) radio link between the Kehl transmitter aboard the launching aircraft and the Strassburg receiver in the missile. Early jamming efforts by the United States Naval Research Laboratory (NRL) produced the XCJ jamming transmitter installed aboard the destroyer escorts USS Herbert C. Jones and Frederick C. Davis in late September 1943. The XCJ was ineffective because the frequencies selected for jamming were incorrect. This was updated in time for Operation Shingle at Anzio (Italy) with the XCJ-1 system, installed aboard the two destroyer escorts mentioned above as well as the destroyers USS Woolsey, Madison, Hilary P. Jones and Lansdale. These six ships rotated service at Anzio, with three deployed at any time. This system met with some success, though because of its manual interface, it was cumbersome to use and easily overwhelmed if large numbers of missiles were engaged. 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 at Salerno, Italy.

Meanwhile, as attacks were taking place at Anzio, the United Kingdom began to deploy its Type 650 transmitter which employed a different approach. This system jammed the Strassburg receiver's intermediate frequency of 3 MHz, and appears to have been quite successful, especially as the operator did not have to attempt to find which of the 18 Kehl/Strassburg command frequencies were in use and then manually tune the jamming transmitter to one of those frequencies. This system automatically defeated the receiver regardless of which radio frequency had been selected for an individual Luftwaffe missile.

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 in Southern France. This included an updated XCJ-2 system from the Naval Research Laboratory (produced as the TX), the modified airborne AN/ARQ-8 Dinamate system from Harvard's Radio Research Laboratory, NRL's improved XCJ-3 model (produced as the CXGE), the British Type 651 and the Canadian Naval Jammer. Perhaps most impressive of all was 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. Even more sophisticated jammers from NRL, designated XCK (to be produced as TY and designated TEA when combined with the upgraded XCJ-4) and XCL, were under development but were never deployed as the threat had evaporated before they could be put into service. 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 a television-guided variant (Hs 293D) was planned but was not made operational before the war ended.

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, radar-guided unit.

Combat performance
On August 25, 1943, an Hs 293 was used in the first successful attack by a guided missile, striking the sloop HMS Bideford (L43), though as the warhead did not fully 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 sunk the troop transport HMT Rohna killing over 1,000 personnel.

Other ships sunk or damaged by the Hs 293 include:


 * Banff class sloop HMS Landguard (slightly damaged with Bideford in Bay of Biscay 25 August 1943)
 * HMCS Athabaskan (G07) (heavily damaged by confirmed hit with Egret in Bay of Biscay 27 August 1943)
 * HMHS Newfoundland (heavily damaged and later sunk by Allied gunfire)
 * SS Bushrod Washington (sunk 14 September 1943 during Operation Avalanche)
 * SS James W. Marshall (damaged 15 September 1943 during Operation Avalanche and subsequently used as part of the Mulberry harbour - possibly hit by a "Fritz X")
 * HMS LST-79 (sunk)
 * SS Samite (damaged)
 * SS Hiram S. Maxim (damaged)
 * SS Selvik (damaged)
 * USS Tillman (DD-641) (slightly damaged 6 November 1943 while escorting Mediterranean convoy KMF-25A) though more likely a torpedo was the cause)
 * HMS Rockwood (damaged slightly, later written off)
 * HMS Dulverton (L63) (heavily damaged and scuttled)
 * MV Marsa (sunk)
 * SS Delius (damaged)
 * HMS Jervis (F00) (damaged off Anzio during Operation Shingle 23 January 1944)
 * HMS Janus (F53) (sunk—possibly by an Hs 293, or a torpedo)
 * USS Prevail (AM-107) (damaged—possibly by an Hs 293)
 * USS Mayo (DD-422) (damaged—possibly by an Hs 293 or a mine)
 * SS John Banvard (damaged)
 * SS Samuel Huntington (sunk off Anzio during Operation Shingle 29 January 1944)
 * HMS Spartan (95) (sunk off Anzio during Operation Shingle 29 January 1944)
 * USS Herbert C. Jones (DE-137) (damaged off Anzio during Operation Shingle 15 February 1944)
 * SS Elihu Yale (sunk off Anzio during Operation Shingle 16 February 1944—LCT 35 alongside was also destroyed)
 * HMS Inglefield (D02)
 * HMS Lawford (K514) (sunk—probably by an Hs 293, official report states "aerial torpedo")
 * HMCS Matane (damaged)
 * USS LST-282 (sunk during Operation Dragoon)

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./KG 40 and II./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.

Variants

 * Hs 293A (later Hs 293A-1), the original version.
 * Hs 293B was wire-guided to prevent jamming; it was never put into production, because jamming was never serious enough to prevent the radio-guided version from being effective.
 * Hs 293C (production version designated Hs 293A-2) had a detachable warhead.
 * Hs 293D was television-guided. Twenty were built and tested, but it was never used operationally as the television equipment was unreliable.
 * Hs 293E, an experimental model to test spoiler controls as a replacement to ailerons; never put into series production. This modification was put into the final version of the Hs 293A-2 but by then the Luftwaffe had no aircraft available for anti-shipping operations and it was never deployed.
 * Hs 293F, a tailless variant; never got further than the design phase.
 * Hs 293H, an experimental variant designed to be launched from one aircraft and controlled from another. Abandoned because allied air superiority had reached the point where it was felt that the second aircraft would be unable to remain in the vicinity of the ship for long enough.
 * Hs 293 V6, the sixth prototype airframe of the entire Hs 293 series, designed for launching from the Arado Ar 234 jet bomber at 720 km/h. The main change was reducing the wing span of the missile to allow it to be carried within the aircraft. The missile did not proceed past the design stage.

Operators

 * Luftwaffe