Ruhrstahl X-4
Encyclopedia
Air-to-air missile
An air-to-air missile is a missile fired from an aircraft for the purpose of destroying another aircraft. AAMs are typically powered by one or more rocket motors, usually solid fuelled but sometimes liquid fuelled...
designed by Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. The X-4 did not see operational service and thus was not proven in combat. The X-4 was the basis for the development of experimental, ground launched anti-tank missiles that became the basis for considerable post-war work around the world, including the Malkara missile
Malkara missile
The Malkara missile was one of the earliest anti-tank guided missiles . It was jointly developed by Australia and the United Kingdom between 1951 and 1954, and was in service from 1958 until gradually replaced by the Swingfire missile in the late 1960s...
.
History
United States Army Air Forces
The United States Army Air Forces was the military aviation arm of the United States of America during and immediately after World War II, and the direct predecessor of the United States Air Force....
's Eighth Air Force mounted a series of heavy raids against Germany. Despite disastrous bomber losses, these prompted Luftwaffe
Luftwaffe
Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....
research into considerably more powerful anti-bomber weaponry in order to reduce the cost in lost fighter aircraft
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...
and aircrew. A massive development effort resulted in a number of heavy-calibre 30mm to 75mm autocannon
Autocannon
An autocannon or automatic cannon is a rapid-fire projectile weapon firing a shell as opposed to the bullet fired by a machine gun. Autocannons often have a larger caliber than a machine gun . Usually, autocannons are smaller than a field gun or other artillery, and are mechanically loaded for a...
designs, air-to-air rocket
Air-to-air rocket
An air-to-air rocket or air interception rocket is an unguided projectile fired from aircraft to engage other flying targets. They were used briefly in World War I to engage enemy observation balloons and in and after World War II to engage enemy bombers...
s, SAM
Surface-to-air missile
A surface-to-air missile or ground-to-air missile is a missile designed to be launched from the ground to destroy aircraft or other missiles...
s and the X-4.
Work on the X-4 began in June 1943, by Dr Max Kramer
Max Kramer
Dr. Max Kramer was a German scientist who worked for the Ruhrstahl AG steel and armaments corporation...
at Ruhrstahl. The idea was to build a missile with enough range to allow it to be fired from outside the range of the bombers' guns (what is now called a stand-off weapon), while being guided with enough accuracy to guarantee a "kill". The X-4 met these specifications and more; its BMW 109-448 rocket motor accelerated the missile to over 1,150 km/h (715 mph) and kept it there during its "cruise", between 1.5 and 4 km (0.9-2.5 mi), while the defensive guns had a maximum effective range of about 1000 m (1,094 yd). The rocket burned a hypergolic mixture of S-Stoff (nitric acid
Nitric acid
Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...
with 5% iron(III) chloride) and R-Stoff (an organic amine-mixture of 50% dimethylaminobenzene and 50% triethylamine
Triethylamine
Triethylamine is the chemical compound with the formula N3, commonly abbreviated Et3N. It is also abbreviated TEA, yet this abbreviation must be used carefully to avoid confusion with triethanolamine, for which TEA is also a common abbreviation....
called Tonka 250) as propellant, delivering 140 kg (308.6 lb) thrust initially, declining to 30 kg (66.1 lb) over the 17 second burn. As there was no room for a fuel pump, the fuels were forced into the engine by pistons inside long tubes, the tubes being coiled (as with a coil spring
Coil spring
A Coil spring, also known as a helical spring, is a mechanical device, which is typically used to store energy and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces...
) to fit inside the airframe. S-Stoff was so corrosive
Corrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...
, it dissolved all base metals and was extremely difficult and dangerous to handle. The Germans planned to replace the engine with a solid fuel
Solid fuel
Solid fuel refers to various types of solid material that are used as fuel to produce energy and provide heating, usually released through combustion....
design as soon as possible.
The missile was spin-stabilized at about 60 rpm. Thus any asymmetrical thrust from the engine or inaccuracies in the control surfaces would be evened out. Signals to operate control surfaces on the tail were sent via two wires, which unwound from spools mounted in the missile body. A gyroscope
Gyroscope
A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation...
kept track of "up" so that the control inputs from the pilot's joystick in the launch aircraft could be translated into yaw and pitch as the missile spun. Flares attached to two of the mid-section wings were used to keep the missile visible through the smoke of its engine.
The warhead consisted of a 20 kg (45 lb) fragmentation device that had a lethal radius of about 25 feet (8 m). It was thought that the guidance system would allow the pilot to get the missile into this range in terms of pitch and yaw, but at the ranges that the missile could operate at it would be almost impossible to judge range to anywhere near this accuracy. For this reason the missile mounted a proximity fuze
Proximity fuze
A proximity fuze is a fuze that is designed to detonate an explosive device automatically when the distance to target becomes smaller than a predetermined value or when the target passes through a given plane...
known as Kranich, an acoustical system that was tuned to the 200 Hz sound of the B-17's engines in cruise. The trigger range was 7 m (23 ft).
The first flight test occurred on August 11, 1944 using a Focke-Wulf Fw 190
Focke-Wulf Fw 190
The Focke-Wulf Fw 190 Würger was a German Second World War single-seat, single-engine fighter aircraft designed by Kurt Tank in the late 1930s. Powered by a radial engine, the 190 had ample power and was able to lift larger loads than its well-known counterpart, the Messerschmitt Bf 109...
for the launch platform. Subsequent tests used the Junkers Ju 88
Junkers Ju 88
The Junkers Ju 88 was a World War II German Luftwaffe twin-engine, multi-role aircraft. Designed by Hugo Junkers' company through the services of two American aviation engineers in the mid-1930s, it suffered from a number of technical problems during the later stages of its development and early...
and Messerschmitt Me 262
Messerschmitt Me 262
The Messerschmitt Me 262 Schwalbe was the world's first operational jet-powered fighter aircraft. Design work started before World War II began, but engine problems prevented the aircraft from attaining operational status with the Luftwaffe until mid-1944...
, although they were not launched from the latter. The X-4 had originally been intended for use by single-seat fighters, but the problems in guiding both the missile and the aircraft at the same time proved this to be unworkable. Instead the X-4 was re-directed to multi-seat aircraft like the Ju 88, while the R4M rocket
R4M rocket
The R4M rocket, nicknamed the Hurricane due to its distinctive smoke trail when fired, was an anti-aircraft rocket. It was developed by the German Luftwaffe during World War II.-Development:...
was to be used on the single-seaters.
The X-4 was designed to be easily assembled by unskilled labour. It is possible some X-4s were used in the closing weeks of World War II, although it was never delivered to the Luftwaffe. The fighter
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...
-interceptor
Interceptor aircraft
An interceptor aircraft is a type of fighter aircraft designed specifically to prevent missions of enemy aircraft, particularly bombers and reconnaissance aircraft. Interceptors generally rely on high speed and powerful armament in order to complete their mission as quickly as possible and set up...
designed to use this missile as its primary weapon was the Focke-Wulf Ta 183 Huckebein, which was just a "paper" and wind tunnel prototype.
After the war, French engineers tried to develop a domestic version of the X-4, called AA-10. 200 units were manufactured between 1947 and 1950. However, the program was disbanded due to the dangerous pre-flight refuelling involved (the nitric acid and Tonka combination was highly explosive).
X-4 air-to-air missile
- Primary function: short-range air-to-air missileAir-to-air missileAn air-to-air missile is a missile fired from an aircraft for the purpose of destroying another aircraft. AAMs are typically powered by one or more rocket motors, usually solid fuelled but sometimes liquid fuelled...
- Propulsion: BMW 109-448 liquid rocket motor giving 30–140 kg (66.1–308.6 lb) thrust for 17 seconds
- Length: 201 cm (79.1 in)
- Diameter: 22 cm (8.7 in) (maximum)
- Wingspan: 72.6 cm (28.6 in)
- Launch weight: 60 kg (132.3 lb)
- Speed: 325 m/s (1,066.3 ft/s)
- Warhead: 20 kg (44.1 lb)
- Range: 1.5 - 3.5 km
- Fuzes: Kranich acoustic proximity fuzeProximity fuzeA proximity fuze is a fuze that is designed to detonate an explosive device automatically when the distance to target becomes smaller than a predetermined value or when the target passes through a given plane...
- Guidance system: FuG 510/238 "Düsseldorf/Detmold" MCLOSMCLOSMCLOS is a first-generation method for guiding guided missiles.With an MCLOS missile, the operator must track the missile and the target simultaneously and guide the missile to the target. Typically the missile is steered with a joystick, and its path is observed through a periscope-type...
visual guidance with wire control - Unit cost:
- Date deployed: never
X-7 anti-tank missile
- Primary function: anti-tank guided missileAnti-tank guided missileAn anti-tank missile , anti-tank guided missile , anti-tank guided weapon or anti-armor guided weapon is a guided missile primarily designed to hit and destroy heavily-armored military vehicles....
- Powerplant: solid rocket motor
- Length:
- Diameter:
- Wingspan: 0.726 m
- Launch weight: 9 kg
- Speed: 245 m/s
- Warhead: 2.5 kg hollow charge
- Penetration: over 200 mm (7.9 in) at 30°
- Range: 1,000 m
- Fuzes: impact (?)
- Guidance system: MCLOSMCLOSMCLOS is a first-generation method for guiding guided missiles.With an MCLOS missile, the operator must track the missile and the target simultaneously and guide the missile to the target. Typically the missile is steered with a joystick, and its path is observed through a periscope-type...
visual guidance with wire control
- Unit cost:
- Date deployed: never