R4M

R4M rocket
The anti-tank version of the R4M rocket known as the Panzerblitz on display at the Steven F. Udvar-Hazy Center
Type	Rocket
Place of origin	Germany
Service history
In service	1944-1945
Used by	Luftwaffe
Wars	World War II
Production history
Designed	1944
Manufacturer	Heber AG, Osterode, Germany
Variants	Air-to-air & Air-to-ground
Specifications
Weight	3.85 kg
Length	812 mm
Width	55 mm
Muzzle velocity	525 m/s (1,175 mph)
Effective firing range	600-1,000 m
Maximum firing range	1,500 m
Filling weight	520 g Hexogen for air-to-air role

The R4M (German: Rakete, 4Kilogramm, Minenkopf) rocket, nicknamed the Hurricane (German: Orkan) due to its distinctive smoke trail when fired, was an anti-aircraft rocket. It was developed by the German Luftwaffe during World War II.

The R4M was developed in order to deal with the increasing weight of anti-bomber weapons being deployed by Luftwaffe fighters. The primary anti-bomber weapon of the Luftwaffe for much of the war was the 20 mm MG 151/20 , which was compact enough to be mounted in an internal wing bay mounting in the Focke-Wulf Fw 190 (up to 4 cannon, or 6 with optional twin-gun underwing pods) and also fitted on the centerline of Bf 109G fighters, firing through the propeller spinner as a Motorkanone. This could be supplemented by an additional pair of cannon in drag-inducing underwing gun pods, but it was found that it took an average of twenty 20 mm hits to shoot down a typical four-engined Allied bomber. The MG 151/20 was subsequently supplemented with or replaced by the 30 mm MK 108 cannon, which replaced the centerline Motorkanone-mount MG 151/20 on many Bf 109's, and could be fit into slightly larger underwing pods, which could be used on either the Bf 109 or Fw 190. This heavier-caliber cannon could bring down a bomber with an average of one to three hits. However the MK 108 was much heavier and the larger calibre 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 suffered a ballistic drop of over 41 metres at 1,000 metres range after firing. In approaching close enough to get hits, the fighters placed themselves within the range of the dozens of AN/M2 "light barrel" Browning defensive machine guns that a combat box formation of a typical USAAF heavy bomber raid possessed, from nearly any approach direction. The more powerful MK 103 cannon had higher muzzle velocity and increased range, at the cost of greatly increased weight, size (barrel length of 1.34 meters, or 52-3/4 inches) and much lower rate of fire: 380-420 RPM vs. 600-650 RPM for the MK 108.