R4M rocket
Encyclopedia
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
.
, but it was found that it took an average of twenty 20 mm hits to shoot down a typical four engined bomber. The 20 mm cannons, also fitted to the Bf 109
in drag-producing underwing gun pod
s, were then supplemented with or replaced by the 30 mm MK 108 cannon
, in slightly larger underwing pods, which could bring down a bomber with an average of one to three hits. However the MK 108 was much heavier and the larger ammunition made it difficult to carry more than one or two "passes" worth. Worse, the low muzzle velocity
of this gun meant it had a very short range and extreme curvature of trajectory, of over 41 meters at 1,000 meters range. In approaching close enough to get hits, the fighters placed themselves within the range of the bomber's defensive guns. The more powerful MK 103 cannon
had higher muzzle velocity and increased range, at the cost of greatly increased weight, size and much lower rate of fire: 380-420 RPM vs. 600-650 RPM for the MK 108.
Also, the Nebelwerfer
42-derived Werfer-Granate 21
(Wfr. Gr. 21) rockets fitted to Messerschmitt Bf 109 and Bf 110, and Focke-Wulf Fw 190 fighters, used to break up the USAAF
combat box
bomber formations, had launch tubes that were not only drag-producing, from their exposed five-strut under-wing mounting setup, but also from the fact that the launch tubes needed to be aimed upwards at some 15° from level flight, to counter the rocket's considerable ballistic drop after firing, adding to the already considerable drag the launch tube mountings created, as well as the Wfr. Gr 21's relatively slow projectile velocity of 1,150 km/h (715 mph).
The solution was to replace the underwing gun pods, and draggy large-calibre underwing rocket launch tubes, with a small diameter solid-fuel rocket engine-propelled projectile, mounting a warhead similar to that of the cannon shell. Although each "round" was heavier than the corresponding gun-fired shell, the lack of a gun reduced the overall weight considerably. The weight difference was so great that even a much larger and longer ranged rocket was still lighter than the guns it could replace.
The anti-aircraft version of the R4M used a large warhead of 55 mm with 520 g (17.6 ounces) of Hexogen explosive charge, nearly guaranteeing a kill with one hit. Each R4M weighed 3.2 kg and was provided with enough fuel to be fired from 1000 m, outside the range of the bomber's defensive guns. The main body of the rocket consisted of a simple steel tube with flip-out fins on the tail for stabilization. A battery typically consisted of two groups of 12 rockets and when all 24 were fired at once they would fill an area about 15 by 30 m at 1000 m, a density that made it almost certain that the target would be hit. The R4Ms were usually fired in four salvos of six missiles at intervals of 0.07 seconds from a range of 600 m, and would streak towards their target at a sixty percent higher velocity than the Wfr. Gr. 21's rockets would, at a speed of roughly 1,890 km/h (1,175 mph). Two warheads were available for the R4M, the common PB-3 with a 0.4 kg charge for anti-aircraft use and the larger shaped charge, similar in construction to the Panzerschreck
, the Panzerblitz II (PB-2), for anti-tank use.
s and the ground attack version of the Fw 190s, which mounted them on small wooden racks under the wings.
The Luftwaffe found the R4M missiles to have similar trajectory to the 30 mm MK 108 cannon
in flight, therefore the standard Revi 16B gunsight was utilized effectively.
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...
. It was developed by the German
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...
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....
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...
.
Development
The R4M was developed in order to deal with the increasing weight of anti-bomber weapons being deployed by Luftwaffe fighters. Their design had started out with the 20 mm MG 151/20 cannons, compact enough to be mounted in an internal wing bay mounting in the Focke-Wulf Fw 190Focke-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...
, but it was found that it took an average of twenty 20 mm hits to shoot down a typical four engined bomber. The 20 mm cannons, also fitted to the Bf 109
Messerschmitt Bf 109
The Messerschmitt Bf 109, often called Me 109, was a German World War II fighter aircraft designed by Willy Messerschmitt and Robert Lusser during the early to mid 1930s...
in drag-producing underwing gun pod
Gun pod
A gun pod is a detachable pod or pack containing machine guns or automatic cannon and ancillaries, mounted externally on a vehicle such as a military aircraft which may or may not also have its own guns....
s, were then supplemented with or replaced by the 30 mm MK 108 cannon
MK 108 cannon
The MK 108 was a 30 mm caliber autocannon manufactured in Germany during World War II by Rheinmetall-Borsig for use in aircraft.-Development:...
, in slightly larger underwing pods, which could bring down a bomber with an average of one to three hits. However the MK 108 was much heavier and the larger ammunition made it difficult to carry more than one or two "passes" worth. Worse, the low muzzle velocity
Muzzle velocity
Muzzle velocity is the speed a projectile has at the moment it leaves the muzzle of the gun. Muzzle velocities range from approximately to in black powder muskets , to more than in modern rifles with high-performance cartridges such as the .220 Swift and .204 Ruger, all the way to for tank guns...
of this gun meant it had a very short range and extreme curvature of trajectory, of over 41 meters at 1,000 meters range. In approaching close enough to get hits, the fighters placed themselves within the range of the bomber's defensive guns. The more powerful MK 103 cannon
MK 103 cannon
The Rheinmetall-Borsig MK 103 was a German 30 mm caliber autocannon that was mounted in German combat aircraft during World War II. Intended to be a dual purpose weapon for anti-tank and air-to-air fighting, it was a development of the heavy MK 101. Compared to the MK 101, it was lighter,...
had higher muzzle velocity and increased range, at the cost of greatly increased weight, size and much lower rate of fire: 380-420 RPM vs. 600-650 RPM for the MK 108.
Also, the Nebelwerfer
21 cm Nebelwerfer 42
The 21 cm Nebelwerfer 42 was a German multiple rocket launcher used in the Second World War. It served with units of the Nebeltruppen, the German equivalent of the American Chemical Corps...
42-derived Werfer-Granate 21
WGr 21 rocket launcher
The Werfer-Granate 21 rocket launcher, also known as the BR 21 in official Luftwaffe manuals, was a weapon used by the German Luftwaffe during World War II and was the first on-board rocket in service by the Luftwaffe and was introduced in mid 1943. The weapon was developed by Rheinmetall-Borsig...
(Wfr. Gr. 21) rockets fitted to Messerschmitt Bf 109 and Bf 110, and Focke-Wulf Fw 190 fighters, used to break up the USAAF
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....
combat box
Combat box
The Combat box was a tactical formation used by heavy bombers of the U.S. Army Air Forces during World War II. The combat box was also referred to as a "staggered formation"...
bomber formations, had launch tubes that were not only drag-producing, from their exposed five-strut under-wing mounting setup, but also from the fact that the launch tubes needed to be aimed upwards at some 15° from level flight, to counter the rocket's considerable ballistic drop after firing, adding to the already considerable drag the launch tube mountings created, as well as the Wfr. Gr 21's relatively slow projectile velocity of 1,150 km/h (715 mph).
The solution was to replace the underwing gun pods, and draggy large-calibre underwing rocket launch tubes, with a small diameter solid-fuel rocket engine-propelled projectile, mounting a warhead similar to that of the cannon shell. Although each "round" was heavier than the corresponding gun-fired shell, the lack of a gun reduced the overall weight considerably. The weight difference was so great that even a much larger and longer ranged rocket was still lighter than the guns it could replace.
The anti-aircraft version of the R4M used a large warhead of 55 mm with 520 g (17.6 ounces) of Hexogen explosive charge, nearly guaranteeing a kill with one hit. Each R4M weighed 3.2 kg and was provided with enough fuel to be fired from 1000 m, outside the range of the bomber's defensive guns. The main body of the rocket consisted of a simple steel tube with flip-out fins on the tail for stabilization. A battery typically consisted of two groups of 12 rockets and when all 24 were fired at once they would fill an area about 15 by 30 m at 1000 m, a density that made it almost certain that the target would be hit. The R4Ms were usually fired in four salvos of six missiles at intervals of 0.07 seconds from a range of 600 m, and would streak towards their target at a sixty percent higher velocity than the Wfr. Gr. 21's rockets would, at a speed of roughly 1,890 km/h (1,175 mph). Two warheads were available for the R4M, the common PB-3 with a 0.4 kg charge for anti-aircraft use and the larger shaped charge, similar in construction to the Panzerschreck
Panzerschreck
Panzerschreck was the popular name for the Raketenpanzerbüchse , an 88 mm calibre reusable anti-tank rocket launcher developed by Nazi Germany in World War II. Another popular nickname was Ofenrohr ....
, the Panzerblitz II (PB-2), for anti-tank use.
Operations
Only a small number of aircraft were fitted with the R4M, mostly Messerschmitt Me 262Messerschmitt 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...
s and the ground attack version of the Fw 190s, which mounted them on small wooden racks under the wings.
The Luftwaffe found the R4M missiles to have similar trajectory to the 30 mm MK 108 cannon
MK 108 cannon
The MK 108 was a 30 mm caliber autocannon manufactured in Germany during World War II by Rheinmetall-Borsig for use in aircraft.-Development:...
in flight, therefore the standard Revi 16B gunsight was utilized effectively.