RP-3

RP-3
Loading 3in 60-pdr SAP/HE rocket projectiles onto a Hawker Typhoon
Type	Unguided air-to-surface rocket
Place of origin	United Kingdom
Service history
In service	1943–1968
Used by	Royal Air Force, Royal Navy, Royal Australian Air Force
Wars	World War II
Specifications
Weight	82 pounds (37 kg)
Length	55 inches (140 cm)
Diameter	3 in (76 mm) rocket body
Warhead	High explosive (TNT or TN/RDX) when used
Warhead weight	12 lb (5.4 kg) to 60 lb (27 kg)
Engine	Solid fuel rocket
Propellant	Cordite
Operational range	1,700 yards (1,600 m)
Speed	1,600 feet per second (480 m/s)
Guidance system	unguided
Launch platform	Aircraft, Sherman Tulip, LCT (R)

The RP-3 (from Rocket Projectile 3 inch) was a British rocket projectile used during and after the Second World War. Though primarily an air-to-ground weapon, it saw limited use in other roles. Its 60 lb (27 kg ) warhead gave rise to the alternative name of the "60 lb rocket"; the 25 lb (11.3 kg) solid-shot armour-piercing variant was referred to as the "25 lb rocket". They were generally used by British fighter-bomber aircraft against targets such as tanks, trains, motor transport and buildings, and by Coastal Command and Royal Navy aircraft against U-boats and shipping. The "3 inch" designation referred to the diameter of the rocket motor tube.

The first use of rockets fired from aircraft was during World War I. The "Unrotated Projectiles" were Le Prieur rockets which were mounted on the interplane struts of Nieuport fighters. These were used to attack observation balloons and were reasonably successful. Sopwith Baby and Pup and Home Defence B.E.2 fighters also carried rockets. With the war ended the Royal Air Force, intent on retrenching, forgot about firing rockets from aircraft. The British Army, however, did see a use for rockets against low-flying aircraft; from late 1940 parts of Britain were defended by increasing numbers of "Z-Batteries" 2-inch (51 mm) rockets supplementing the conventional anti-aircraft guns.

When German forces under the command of Rommel intervened in the Western Desert from early 1941, it became clear that the Desert Air Force lacked weapons capable of damaging or destroying the large numbers of armoured fighting vehicles, particularly the heavier Panzer III and Panzer IV tanks possessed by the Germans. Consequently, in April 1941 Henry Tizard, the Chief Scientist, called together a panel to study "Methods of Attacking Armoured Vehicles."