Unrotated Projectile
Encyclopedia
The Unrotated Projectile, or UP, was a short range rocket
-firing anti-aircraft weapon
developed for the Royal Navy
to supplement the 2 pounder Pom-Pom gun
due to a critical lack of close-range anti-aircraft weapons. It was used extensively by British
ships during the early days of World War II
. The UP was also used in ground-based single and 128-round launchers known as Z Batteries
.
tubes, fired ten at a time. A small cordite
charge was used to ignite a rocket motor which propelled the fin-stabilized 7 inches (17.8 cm) diameter rocket out of the tube to a distance of about 1000 feet (304.8 m) where it exploded and released an 8.4 ounces (238.1 g) mine attached to three parachutes by 400 feet (121.9 m) of wire. The idea was that a plane hitting the wire would draw the mine towards itself where it would detonate.
. In November 1939, Winston Churchill
as First Lord of the Admiralty asked Dr. Crow to produce urgently a means of laying an aerial minefield and to consider other methods of protecting ships against aircraft. It is likely that Churchill was influenced in his request by his friend and advisor Frederick Lindemann
who had previously advocated a scheme for "dropping bombs hanging by wires in the path of attacking aircraft". A high-altitude barrage was developed: an aerial minefield up to 19000 feet (5,791.2 m), the fast aerial mine up to 2000 feet (609.6 m), the PE fuse up to 18000 feet (5,486.4 m) and the UP up to 20000 feet (6,096 m). All three services, including the Home Guard, used the UP in various forms.
or Bofors 40 mm gun
.
A demonstration of the weapon for Churchill on Admiral Jack Tovey's flagship at Scapa Flow
dramatically exposed a flaw in the concept. Practice bombs were fired and, when there was an unexpected change of wind, they drifted back onto the ship and some became entangled in the rigging and superstructure. The dummy rounds caused little or no damage but Tovey was amused at the embarrassment thus caused to the weapon's advocates, Lindeman and Churchill. The installation was soon removed.
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...
-firing anti-aircraft weapon
Anti-aircraft warfare
NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces...
developed for the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
to supplement the 2 pounder Pom-Pom gun
QF 2 pounder naval gun
The 2-pounder gun, officially designated the QF 2-pounder and universally known as the pom-pom, was a 1.575 inch British autocannon, used famously as an anti-aircraft gun by the Royal Navy. The name came from the sound that the original models make when firing...
due to a critical lack of close-range anti-aircraft weapons. It was used extensively by British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
ships during the early days of 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...
. The UP was also used in ground-based single and 128-round launchers known as Z Batteries
Z Battery
The Z Battery, was a short range rocket-firing anti-aircraft weapon which fired 3-inch diameter rockets, used in ground-based single and multiple launchers for the air defence of the United Kingdom in World War II.- See also :...
.
Operation
The name Unrotated Projectile comes from the fact that the projectile was not spin-stabilized. The weapon had 20 smoothboreSmoothbore
A smoothbore weapon is one which has a barrel without rifling. Smoothbores range from handheld firearms to powerful tank guns and large artillery mortars.-History of firearms and rifling:...
tubes, fired ten at a time. A small cordite
Cordite
Cordite is a family of smokeless propellants developed and produced in the United Kingdom from 1889 to replace gunpowder as a military propellant. Like gunpowder, cordite is classified as a low explosive because of its slow burning rates and consequently low brisance...
charge was used to ignite a rocket motor which propelled the fin-stabilized 7 inches (17.8 cm) diameter rocket out of the tube to a distance of about 1000 feet (304.8 m) where it exploded and released an 8.4 ounces (238.1 g) mine attached to three parachutes by 400 feet (121.9 m) of wire. The idea was that a plane hitting the wire would draw the mine towards itself where it would detonate.
Development
The UP was developed by Sir Alwyn Crow who was the director of the Projectile Development Establishment at Fort HalsteadFort Halstead
Fort Halstead is a research site of Dstl, an Executive Agency of the UK Ministry of Defence. It is situated on the crest of the Kentish North Downs, overlooking the town of Sevenoaks...
. In November 1939, Winston Churchill
Winston Churchill
Sir Winston Leonard Spencer-Churchill, was a predominantly Conservative British politician and statesman known for his leadership of the United Kingdom during the Second World War. He is widely regarded as one of the greatest wartime leaders of the century and served as Prime Minister twice...
as First Lord of the Admiralty asked Dr. Crow to produce urgently a means of laying an aerial minefield and to consider other methods of protecting ships against aircraft. It is likely that Churchill was influenced in his request by his friend and advisor Frederick Lindemann
Frederick Lindemann, 1st Viscount Cherwell
Frederick Alexander Lindemann, 1st Viscount Cherwell FRS PC CH was an English physicist who was an influential scientific adviser to the British government, particularly Winston Churchill...
who had previously advocated a scheme for "dropping bombs hanging by wires in the path of attacking aircraft". A high-altitude barrage was developed: an aerial minefield up to 19000 feet (5,791.2 m), the fast aerial mine up to 2000 feet (609.6 m), the PE fuse up to 18000 feet (5,486.4 m) and the UP up to 20000 feet (6,096 m). All three services, including the Home Guard, used the UP in various forms.
Combat effectiveness
The weapon was never very effective as planes could simply avoid the wires, and was also slow to load; it was replaced later in the war by the 2 pounderQF 2 pounder naval gun
The 2-pounder gun, officially designated the QF 2-pounder and universally known as the pom-pom, was a 1.575 inch British autocannon, used famously as an anti-aircraft gun by the Royal Navy. The name came from the sound that the original models make when firing...
or Bofors 40 mm gun
Bofors 40 mm gun
The Bofors 40 mm gun is an anti-aircraft autocannon designed by the Swedish defence firm of Bofors Defence...
.
A demonstration of the weapon for Churchill on Admiral Jack Tovey's flagship at Scapa Flow
Scapa Flow
right|thumb|Scapa Flow viewed from its eastern endScapa Flow is a body of water in the Orkney Islands, Scotland, United Kingdom, sheltered by the islands of Mainland, Graemsay, Burray, South Ronaldsay and Hoy. It is about...
dramatically exposed a flaw in the concept. Practice bombs were fired and, when there was an unexpected change of wind, they drifted back onto the ship and some became entangled in the rigging and superstructure. The dummy rounds caused little or no damage but Tovey was amused at the embarrassment thus caused to the weapon's advocates, Lindeman and Churchill. The installation was soon removed.
Specifications
- Rocket length: 32 inches (81.3 cm)
- Rocket weight: 35 pounds (15.9 kg)
- Horizontal range: 3000 feet (914.4 m)
- Sinking speed of mine: 16 to 23 feet per second (5 to 7 m/s).
- Mounting weight: 4 tonnes (4 MT).
See also
- Z BatteryZ BatteryThe Z Battery, was a short range rocket-firing anti-aircraft weapon which fired 3-inch diameter rockets, used in ground-based single and multiple launchers for the air defence of the United Kingdom in World War II.- See also :...
: British 3-inch land-based anti-aircraft rocket launcher - AA Mine DischargerAA Mine DischargerThe AA Mine Discharger was a Japanese anti-aircraft weapon of the Second World War. The device was a simple tube like an infantry mortar of 70 mm or 81 mm caliber. Instead of a standard mortar bomb, the projectile was a tube containing seven individual mines, each approximately 11/16ths...
, a JapanJapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
ese anti-aircraft mortar. - Holman ProjectorHolman ProjectorThe Holman Projector was an anti-aircraft weapon used by the Royal Navy during World War II, primarily between early 1940 and late 1941. The weapon was proposed and designed by Holmans, a machine tool manufacturer based at Camborne, Cornwall...
, a steam powered anti-aircraft grenade launcher.