Unrotated Projectile
The UP-3 was used as the basis of the Z Battery anti-aircraft weapons and later developed in air-to-ground form as the RP-3, used against ground forces and shipping by aircraft like the Hawker Typhoon and the Bristol Beaufighter.
The research threw up more problems; the charges had to be packed in non-inflammable material and a substance had to be developed that was impervious to rapid acceleration and differential gas pressure.
The cordite propellant had to be formed in unusual shapes which made extrusion a much more elaborate process but by 1936, the Director of Ballistics Research, Alwyn Crow reported that the rockets should be considered as practical weapons of war.
[1] In November 1939, Winston Churchill as First Lord of the Admiralty asked Crow urgently to design a means of laying an aerial minefield and to consider other methods of protecting ships against aircraft.
Frederick Lindemann, the chief scientific advisor to the government, had previously advocated a scheme for "dropping bombs hanging by wires in the path of attacking aircraft".
[4] On 14 November 1939, in his first numbered memo as First Lord of the Admiralty, Winston Churchill, requested weekly reports on the rocket development programme.
Churchill wanted plans be made to fit four projectors apiece on five battleships, a pair each onto six cruisers and one on the monitor HMS Erebus under the impression that the rocket armament would make the ships invulnerable to air attack.
By April 1940, about forty projectors were ready, firing a container for a parachute, cable and a bomb or a mine, intended to drift into the paths of attacking aircraft.
[6] Several launcher types were designed for naval use to defend merchant ships and as a means of illumination but only the Mk II (also known as the Pillar Box mount) was used on land at sites on the south coast.
The Army waited on trials of the rockets conducted in Jamaica in early 1939, which were judged to be satisfactory and the Sub-Committee on air Defence Research recommended that the 3-inch UP be taken into service.
The decision was postponed because the Director of Artillery judged the rocket lacked the accuracy for medium and high altitude fire.
There was a paradox in trying to predict the position of an aircraft in time and space when the direction, height and speed of an aeroplane were inherently unpredictable.
It had not been possible to test conventional anti-aircraft fire under wartime conditions, to calculate a statistical norm for the number of shells needed to shoot down a Luftwaffe aircraft.
By September, the firm had completed 1,000 launchers from the order for 2,500 as the Mark 1 for the Army and 3-inch Harvey L. S. Projector for the Navy, most of which were fitted to merchant ships.
A hand wheel elevated the projector, traverse was by hand-crank and the rocket motors were launched by electrical ignition from a battery.
[11] Work on a 5-inch artillery rocket was unsatisfactory because of dispersion and short range but the device was adopted by the navy as a shore bombardment weapon.
The First Canadian Army showed an interest and after a trial firing in July asked for a battery of twelve projectors.
A lighter version for jungle warfare had 16 barrels, weighed 835 lb (379 kg) and could be towed by a Willys MB (quarter ton) jeep but the war ended before it went into service.
[4] By 1943, Coastal Command decided that RP-3 rockets could be more than a supplement for torpedoes in attacks on merchant ships in the North Sea.
On 22 June 1943, the North Coates Strike Wing used the RP-3 in an attack on an Axis convoy off the Dutch coast between The Hague and Den Helder.
[13] In late March 1945, during the invasion of Germany, an attempt to capture Lingen by coup de main failed and a deliberate attack with artillery support was planned.
[4] A demonstration of the naval rocket containing canisters filled with a parachute, wire and an explosive device to be fired at dive bombers, was laid on for Churchill on HMS Hood, part of the Home Fleet (Admiral Jack Tovey) at Scapa Flow which dramatically exposed a flaw in the concept.
Practice rockets were fired and due to an unexpected change of wind, drifted onto the ship and became tangled in the rigging and superstructure.
[5] Five projectors for twenty rockets each were installed on Hood but they misfired twice in action and in one firing managed to burn some sailors in harbour.
[19] In 2011, David Edgerton wrote that in The Wizard War a chapter in volume II of his wartime memoirs, Winston Churchill defended his interest in anti-aircraft rocket research which had begun in the 1930s.
Churchill wrote that anti-aircraft guns only became effective towards the end of The Blitz, just as the rockets he championed were coming into service.
[23] In 1966, Archibald Hill wrote in his memoirs that UP was the "dearly beloved pet of Lindemann" and that it was "a most infernal waste of time, effort, manpower and material".
Hill thought that the development and introduction costs over two years had been between £30 and £160 million, absorbed 87,000 long tons (88,000 t) of steel and 400 per cent more cordite than would have been needed for the same number of 3.7-inch anti-aircraft shells.
