Air-to-ground use photo of a rocket salvo fired at railway wagons in a siding at
Nordhorn, Germany (1945) Before the new weapon was released for service extensive tests were carried out by the Instrument, Armament and Defence Flight (IADF) at the
Royal Aircraft Establishment, Farnborough.
Hawker Hurricanes were fitted with rockets and rails and flown during June and July 1942. Further tests were undertaken from 28 September to 30 November to develop rocket-firing tactics. Other aircraft used were a
Lockheed Hudson, a
Fairey Swordfish biplane torpedo bomber, a
Douglas Boston medium bomber and a Sea Hurricane. For rockets only the Mk IIIA was the most successful – it was used on the
Lockheed Ventura and Hudson. The first operational use of the RP was in the
Western Desert campaign as a "tank-busting" weapon on
Hawker Hurricane Mk. IIEs and IVs. The 25-pound armour-piercing heads were found to be ineffective against the
Tiger I heavy tanks coming into German service. With the example of the success of
Royal Artillery gunners using high-explosive shells from their
Ordnance QF 25 pounder gun-howitzers, it was decided to design a new 60-pound semi-armour-piercing (SAP) head. These were capable of knocking turrets off tanks. A typical RP-3 installation was four projectiles on launching rails under each wing. A selector switch was fitted to allow the pilot to fire them singly (later omitted), in pairs, or as a full salvo. Towards the end of the war some
RAF Second Tactical Air Force (2 TAF)
Hawker Typhoons had their installation adapted to carry an additional four rockets doubled up under the eight already fitted. RP-3s were widely used during the battle the
Falaise pocket in mid-August 1944. During the battle German forces, retreating to avoid being trapped in a
pincer movement by Allied ground forces, came under air attack. Amongst the waves of light, medium and fighter bombers attacking the German columns the Typhoons of 2 TAF attacked with their rockets, claiming hundreds of tanks and "mechanised enemy transport". After the battle, Army and 2nd TAF
Operational Research Sections studying the battleground came to the conclusion that far fewer vehicles, 17 in total, had been destroyed by rocket strike alone. What was clear was that in the heat of battle it was far harder for pilots to launch the weapons while meeting the conditions needed for accuracy. Smoke, dust and debris in the target areas made accurate assessment of the damage caused almost impossible.
Anti-submarine . Soon after some encouraging results from the initial deployment, trials of the weapon were conducted against targets representing U-boats. It was discovered that if the rockets were fired at a shallow angle, near misses resulted in the rockets curving upwards in seawater and piercing the targets below the waterline. Soon
Coastal Command and the Royal Navy's
Fleet Air Arm aircraft were using the rockets extensively. The first U-boat destroyed with the assistance of a rocket attack was
U-752 (commanded by Schroeter), on 23 May 1943, by a Swordfish of
819 Naval Air Squadron (819 NAS). The rockets used on this occasion had solid, cast-iron heads and were known as "rocket spears". One of these punched right through the submarine's
pressure hull and rendered it incapable of diving; the U–boat was scuttled by its crew. On 28 May 1943, an RAF Hudson of
608 Squadron destroyed a U-boat in the Mediterranean, the first destroyed solely by rocket. The rockets were highly inaccurate when fired from a tank as they were being fired from a stationary point and had little slipstream over the fins. Despite this, the RP-3 was valued by tank crews for the destructive effect of its 60-pound warhead. In combat, they were also used for short-range, saturation bombardment of an area and were effective as an immediate counter to German ambushes. to 1957. Sweden had been experimenting with
caseless ammunition as a substitute for air-to-ground rockets during WWII as it was thought that caseless ammunition would be cheaper to produce. This however proved false and by the end of the war the Swedish air force had moved to rocket development instead. The remaining 8 cm prak m/46B rockets were modified with new sloped fins around 1953. Around 30% of the fin surface area was removed. This decreased the chance of the fins breaking off during launch and also increased accuracy. These fins were designated '
and when equipped on the ' the suffix changed to C, then becoming
(8 cm prak m/46C). The 8 cm prak m/46C remained in service until 1957. During its service life in the Swedish air force the rocket came to serve on several Swedish aircraft. To allow universal usage of the RP-3 the first and second generation of Swedish air-to-ground rockets used the same mounting system as the RP-3. == Variants ==