The HS.404 is an autocannon originally designed and produced by Spanish/French company Hispano-Suiza in the mid-1930s. It was widely used as an aircraft, naval and land-based weapon by French, British, American and other military services, particularly during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

. The cannon is also referred to as Birkigt type 404, after its designer Marc Birkigt and later versions based on British development are known as 20 mm Hispano. Firing a 20 mm calibre projectile, it delivered a significant load of explosive from a relatively light weapon. This made it an ideal

anti-aircraft weapon Anti-aircraft warfare, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes surface based, ...

for mounting on light vehicles, as well as a fighter aircraft gun, replacing the 7.62 mm (.30 calibre) and .303 inch (7.7 mm)

machine gun A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifles) ar ...

s commonly used in military aircraft of the 1930s. The HS.404 was produced by the French subsidiary of Hispano-Suiza, and under license by a variety of companies in other countries.

Development

From Oerlikon to Hispano

The first widely used 20 mm aircraft cannon was the Becker model, introduced into German service in

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

. The Becker introduced the advanced primer ignition blowback (API) design for autocannons, a concept that was quickly taken up by other companies. Notable among these was the Swiss Oerlikon FF S, which was based on the Becker but introduced a number of improvements. In the 1930s, Hispano-Suiza was asked to develop a 20 mm cannon to fire through the propeller shaft (as a ''moteur-canon'') of a gear-reduction inline aviation engine like the

Hispano-Suiza 8BeC The Hispano-Suiza 8 was a water-cooled V8 SOHC aero engine introduced by Hispano-Suiza in 1914, and was the most commonly used liquid-cooled engine in the aircraft of the Entente Powers during the First World War. The original Hispano-Suiz ...

. They took out a license on the Oerlikon FF S and made minor modifications to produce the Hispano-Suiza Automatic Cannon Type HS.7 and HS.9. Shortly after production began, the Hispano-Suiza and Oerlikon companies disagreed over patent rights and their business connection came to an end. In 1933, the chief engineer of Hispano-Suiza, Marc Birkigt, began work on the design of a new weapon to replace the Oerlikon contract, based on a locking mechanism patented in 1919 by the American machine-gun designer Carl Swebilius. The result was the Type 404 or HS.404. While the HS.404 resembled the parent Oerlikon FF S in many respects, its repeating mechanism was a gas-operated locking bolt. On firing the 404, when the projectile passes a hole cut in the barrel, about half way along its length, high pressure gas behind the projectile is siphoned off and operates a piston that drives a rod, running along the top of the barrel, back against a cam on the bolt, unlocking it and allowing the remaining high pressure gases in the barrel to propel it and the spent cartridge backwards in a delayed sequence that allows the bolt to remain closed until the bullet has exited from the barrel. This maximizes muzzle velocity and since the bolt was locked during firing, it could be lighter than that of the Oerlikon, thus facilitating an increase in rate of fire to 700 rounds per minute (rpm), a gain of about 200 rpm. In 1938, Birkigt patented it and started production in their Geneva factory.

Anti-aircraft gun

The HS.404's predecessor, the Oerlikon type S auto-cannon, was rather heavy, and the movement of the heavy bolt made it best suited in static and maritime anti-aircraft defence. The lighter bolt of the HS.404 made it well suited to mounting on vehicles. The M16, an anti-aircraft version of the

M3 Half-track The M3 half-track was an American armored personnel carrier half-track widely used by the Allies during World War II and in the Cold War. Derived from the M2 half-track car, the M3 was extensively produced, with about 15,000 standard M3s and mo ...

, could be equipped with single or double American made copies of the Hispano-Suiza auto-cannon. This variant of the M3 Half-track was used by US and Commonwealth forces late in the

Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...

, in the

Korean War , date = {{Ubl, 25 June 1950 – 27 July 1953 (''de facto'')({{Age in years, months, weeks and days, month1=6, day1=25, year1=1950, month2=7, day2=27, year2=1953), 25 June 1950 – present (''de jure'')({{Age in years, months, weeks a ...

and was further developed by Israel in the post-war era.

Aircraft gun

In 1938, an aircraft based version of the HS.404 was produced at the request of the French government. It was installed on a wide range of pre-war French fighter aircraft, notably in installations firing through the

propeller shaft A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power and torque and rotation, usually used to connect ...

of the

Hispano-Suiza 12Y The Hispano-Suiza 12Y was an aircraft engine produced by Hispano-Suiza for the French Air Force before the Second World War. The 12Y became the primary French 1,000 hp (750 kW) class engine and was used in a number of famous aircraft, i ...

engine, a system referred to as a ''moteur-canon'' (engine cannon). Due to the closed-bolt design the cannon was also suitable for synchronisation gear. The HS.404 was fed by drum magazines that could accommodate 60 (or in a fixed mount 160) rounds.. Since in most installations the latter was more popular, the small ammunition capacity was a weakness. In 1940, Hispano-Suiza was developing a belt-feeding system, as well as derivatives of the HS.404 in heavier calibres such as 23 mm but these projects were halted with the German occupation of France.

British production

Before the Second World War, the United Kingdom had embarked on a programme to develop cannon-armed fighters. They acquired a licence to build the HS.404, which entered production as the Hispano Mk.I intended as aeroplane armament. Its first use was in the Westland Whirlwind of 1940 and later in the more powerful Bristol Beaufighter, providing the

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...

(RAF) with powerful cannon-armed interceptors. The experience of the

Battle of Britain The Battle of Britain, also known as the Air Battle for England (german: die Luftschlacht um England), was a military campaign of the Second World War, in which the Royal Air Force (RAF) and the Fleet Air Arm (FAA) of the Royal Navy defende ...

had shown the batteries of eight rifle-calibre machine guns to be inadequate and prompted the adoption of autocannon armament for the primary portion of RAF fighters.March, P.R. (2007): The Hurricane story. Sutton Publishing Limited (The History Press, 2009). 118 pages The Beaufighter highlighted the need for a belt feed mechanism; as a

night fighter A night fighter (also known as all-weather fighter or all-weather interceptor for a period of time after the Second World War) is a fighter aircraft adapted for use at night or in other times of bad visibility. Night fighters began to be used i ...

the 60-round drums needed to be replaced in the dark by the

Radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, we ...

Wireless Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most ...

Operator, often while the aircraft was manoeuvring. The early trial installations in the

Hawker Hurricane The Hawker Hurricane is a British single-seat fighter aircraft of the 1930s–40s which was designed and predominantly built by Hawker Aircraft Ltd. for service with the Royal Air Force (RAF). It was overshadowed in the public consciousness b ...

and Supermarine Spitfire had shown a tendency for the gun to jam during combat manoeuvres, leading to some official doubt as to the suitability of cannon as the sole main armament. This led to the

Air Ministry The Air Ministry was a department of the Government of the United Kingdom with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964. It was under the political authority of the Secretary of State ...

for a brief period specifying 12-machine gun armament for new fighters. A suitable belt-feeding system was developed by

Martin-Baker Martin-Baker Aircraft Company Limited is a British manufacturer of ejection seats and safety-related equipment for aviation. The company's origins were originally as an aircraft manufacturer before becoming a pioneer in the field of ejection s ...

and the new design was adopted by the RAF and

Fleet Air Arm The Fleet Air Arm (FAA) is one of the five fighting arms of the Royal Navy and is responsible for the delivery of naval air power both from land and at sea. The Fleet Air Arm operates the F-35 Lightning II for maritime strike, the AW159 Wil ...

in 1941 in a slightly modified form as the Hispano Mk.II. Four cannons replaced the eight .303 Browning machine guns in the Hurricane and in some tropical versions of the Spitfire, becoming standard armament in later fighters. Most other Spitfires had only two cannons because the outboard cannon tended to freeze at high altitudes. These were complemented with four 0.303 calibre (7.7mm) or two 0.50 calibre (12.7mm) machine guns.Williams, A.G & Gustin, E. (2003): Flying Guns World War II, Development of Aircraft Guns, Ammunition and Installations 1933-45. Crowood Press, Ramsbury, Great Britain. 352 pages The British were concerned their production would be inadequate and licensed production of the Hispano to the US but this production never became satisfactory and the British eventually gave up on the US versions. British production was eventually increased to the point where this was no longer necessary. The ultimate version of the British wartime Hispanos was the Hispano Mk. V, which had a shorter barrel, and lacked the cocking cylinder thus requiring manual cocking before flight. It was lighter and had a higher rate of fire (desirable in aircraft armament), although at the expense of some muzzle velocity. The shorter barrel meant that the weapon could be housed within the wing of a fighter plane, reducing drag and making the gun less vulnerable to freezing and mechanical stress. One of the main British fighters to use the Mk. V was the

Hawker Tempest The Hawker Tempest is a British fighter aircraft that was primarily used by the Royal Air Force (RAF) in the Second World War. The Tempest, originally known as the ''Typhoon II'', was an improved derivative of the Hawker Typhoon, intended to a ...

Mk. V Series II, which mounted two cannon in each wing. Ammunition types available included Semi-Armour Piercing, Incendiary (SAPI) and High Explosive, Incendiary (HEI). Around 42,500 Hispano cannon of various marks were manufactured by

Birmingham Small Arms The Birmingham Small Arms Company Limited (BSA) was a major British industrial combine, a group of businesses manufacturing military and sporting firearms; bicycles; motorcycles; cars; buses and bodies; steel; iron castings; hand, power, and ...

(BSA).

US production

The British version was also licensed for use in the United States as the M1, with the

United States Army Air Corps The United States Army Air Corps (USAAC) was the aerial warfare service component of the United States Army between 1926 and 1941. After World War I, as early aviation became an increasingly important part of modern warfare, a philosophical r ...

(USAAC) and

U.S. Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage o ...

, which concluded that a single HS404 is analogous to three .50 machine guns in firepower while weighing less than twice as much, planning to switch to the 20 mm calibre as soon as the gun could be produced in sufficient numbers. In 1941 a very large building program was established, along with the production of ammunition. When delivered, the guns proved to be extremely unreliable and suffered a considerable number of misfires due to the round being lightly struck by the

firing pin A firing pin or striker is a part of the firing mechanism of a firearm that impacts the primer in the base of a cartridge and causes it to fire. In firearms terminology, a striker is a particular type of firing pin where a compressed spring ...

.Chinn, G.M, Oblt. (1951): The Machine Gun. History, Evolution, and Development of Manual, Automatic, and Airborne Repeating Weapons, vol I. Issued by the ''Bureau of Ordnance Department of the Navy'', Washington, USA. Available for download a
PDF
/ref> The British were interested in using this weapon to ease the demand on production in England but after receiving the M1 they were disappointed. British wing-mounted fighter weapons by this period were cocked on the ground by the aircraft armourers before flight, the pneumatic cocking mechanism used previously being regarded as unnecessary weight and detrimental to aircraft performance; any stoppage in flight made the gun unusable until it could be cleared on the ground. The misfires also had the tendency to cause aircraft with wing-mounted guns to yaw away from the wing with the failed gun when the guns were fired, due to the unequal

recoil Recoil (often called knockback, kickback or simply kick) is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, as according to Newton's third law the force r ...

, throwing off the pilot's aim. First Lieutenant H

In April 1942 a copy of the British Mk.II was sent to the U.S. for comparison. The British version used a slightly shorter

chamber Chamber or the chamber may refer to: In government and organizations * Chamber of commerce, an organization of business owners to promote commercial interests *Legislative chamber, in politics * Debate chamber, the space or room that houses delib ...

and did not have the same problems as the U.S. version of the cannon. The U.S. declined to modify the chamber of their version but nonetheless made other modifications to create the unreliable M2. By late 1942 the USAAF had 40 million rounds of ammunition stored but the guns remained unsuitable. The U.S. Navy had been trying to switch to using cannon on all its combat aircraft throughout the war but the conversion never occurred. As late as December 1945 the U. S. Army Chief of Ordnance was still attempting to complete additional changes to the design to allow it to enter service. Some variations of the 20 mm guns used on the Lockheed P-38 Lightning aircraft were produced by

International Harvester The International Harvester Company (often abbreviated by IHC, IH, or simply International ( colloq.)) was an American manufacturer of agricultural and construction equipment, automobiles, commercial trucks, lawn and garden products, household e ...

.International Harvester Corporation. "Mr. Dealer Plan Now for the Future", ''Harvester World'', Volume 34, Number 11, November 1943, p. 16. Harvester Press, Chicago, 1943. The P-38's nose-mounted M2 featured a built-in cocking system and could simply be re-cocked in flight after a misfire, which made the misfires less of a problem than with other aircraft. The U.S. followed the British development closely and when the Mk.V was designed, the Americans followed suit with the A/N M3 but unreliability continued. After the war the

United States Air Force The United States Air Force (USAF) is the Aerial warfare, air military branch, service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part ...

(USAF) adopted a version of the M3 cannon as the M24, similar in most respects except for the use of the addition of electrical cocking, allowing the gun to re-cock over a lightly struck round. The problems of the American weapons led to most US fighters being equipped with the AN/M2 .50 cal Browning light-barrel machine gun throughout the war.

Post-war development

After the war, the Hispano variants disappeared fairly quickly as fighter armament due to the introduction of

revolver cannon A revolver cannon is a type of autocannon, commonly used as an aircraft gun. It uses a cylinder with multiple chambers, like those of a revolver handgun, to speed up the loading-firing-ejection cycle. Some examples are also power-driven, to fur ...

, based on the prototype versions of the un-built German wartime

Mauser MG 213 The Mauser MG 213 was a 20 mm aircraft-mounted revolver cannon developed for the ''Luftwaffe'' during World War II. It was never put into service, but the principles formed the basis for several post-war developments by the Allies. A 30 mm ver ...

design. The British introduced the powerful revolving

30 mm 30 mm caliber is a specific size of popular autocannon ammunition. Such ammunition includes NATO standard 30×113mmB and 30×173mm (STANAG 4624), Soviet 30×155mmB, 30×165mm, and 30×210mmB, Yugoslav 30×192mm, Anglo-Swiss 30×170mm, an ...

ADEN cannon in most of their post-war aircraft, while the French used the similar DEFA cannon, firing similar ammunition. The USAF introduced the 20 mm

M39 cannon The M39 cannon is a 20 mm caliber single-barreled revolver cannon developed for the United States Air Force in the late 1940s. It was used on a number of fighter aircraft from the early 1950s through the 1980s. Development The M39 was developed ...

to replace the M24, while the Navy combined the original Hispano design with a lighter round for better muzzle velocity in the

Colt Mk 12 cannon {{Infobox weapon , name= Colt Mk 12 , image= 20 mm Mk 12 cannon of RNZAF A-4K Skyhawk 1984.jpg , image_size = , caption= Mk 12 cannon of a RNZAF Douglas A-4K Skyhawk. , origin= United States , type= Autocannon , is_ranged= yes , service= 1950 ...

. As a ground vehicle-mounted gun, either anti-aircraft or as a general-purpose autocannon, the HS.404 lasted into the 1960s. A powered turret variant is still in production in Honduras and is used as a light anti-aircraft gun by the army and navy in several nations. The AN/M3 was developed into the Mk12 Colt 20 mm automatic cannon, one of the main weapons on boats of the

Mobile Riverine Force In the Vietnam War, the Mobile Riverine Force (MRF) (after May 1967), initially designated Mekong Delta Mobile Afloat Force, and later the Riverines, were a joint US Army and US Navy force that comprised a substantial part of the brown-water n ...

in the

Vietnam War The Vietnam War (also known by other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vietnam a ...

and also used on some larger amphibious ships.

Properties

The Hispano fired a 20 mm diameter projectile from a long casing, the whole round weighing . Lengths of the projectiles varied with type but were set to variable depth in the casing to produce a total full round length of regardless of projectile type. The gun had a muzzle velocity between , depending on barrel length. Rate of fire was between 600 and 850 rounds per minute. The gun was long, weighing between . The British Mk V and American M3/M24 weapons were lighter and had higher rates of fire than the early HS.404 guns.Mk 5 20mm Hispano Cannon
/ref>

Users

France

* HS.404 ** Bloch MB.152 ** Breguet 693 ** Dewoitine D.500 ** Dewoitine D.520 ** Lioré et Olivier LeO 45 ** Morane-Saulnier M.S.406 **

Potez 631 The Potez 630 and its derivatives were a family of twin-engined, multirole aircraft developed for the French Air Force in the late 1930s. The design was a contemporary of the British Bristol Blenheim (which was larger and designed purely as a ...

UK & other Commonwealth countries

* Hispano Mk. I ** Gloster F.9/37—a design not taken into service ** Westland Whirlwind—the RAF's first cannon-armed fighter. ** Bristol Beaufighter—early aircraft Hurricane IV KZ321

* Hispano Mk. II **

Blackburn Firebrand The Blackburn Firebrand was a British single-engine strike fighter for the Fleet Air Arm of the Royal Navy designed during World War II by Blackburn Aircraft. Originally intended to serve as a pure fighter, its unimpressive performance and ...

** Blackburn Firecrest ** Bristol Beaufighter **

CAC Boomerang The CAC Boomerang is a fighter aircraft designed and manufactured in Australia by the Commonwealth Aircraft Corporation between 1942 and 1945. Approved for production shortly following the Empire of Japan's entry into the Second World War, t ...

Consolidated Liberator I Consolidated Liberator I was the service name of the first Consolidated B-24 Liberator four-engined bombers to see use with the Royal Air Force (RAF). A small number of B-24s were purchased for the RAF but assessment showed that they were not ...

(4 guns on 20 aircraft) ** de Havilland Mosquito ** Douglas Boston III (Intruder) **

Fairey Firefly The Fairey Firefly is a Second World War-era carrier-borne fighter aircraft and anti-submarine aircraft that was principally operated by the Fleet Air Arm (FAA). It was developed and built by the British aircraft manufacturer Fairey Avia ...

Gloster Meteor The Gloster Meteor was the first British jet fighter and the Allies of World War II, Allies' only jet aircraft to engage in combat operations during the Second World War. The Meteor's development was heavily reliant on its ground-breaking turb ...

** Hawker Hurricane Mk IIC and IV ** Hawker Tempest Mk V Srs I ** Hawker Typhoon Mk IB ** Martin-Baker MB 3—prototype ** North American Mustang IA ** Supermarine Spitfire

Marks V Marks may refer to: Business * Mark's, a Canadian retail chain * Marks & Spencer, a British retail chain * Collective trade marks, trademarks owned by an organisation for the benefit of its members * Marks & Co, the inspiration for the novel '' ...

to Mark 20 SAAF-Avro Shackleton-003

* Hispano Mk. V **

Aérospatiale Alouette III The Aérospatiale Alouette III (, ''Lark''; company designations SA 316 and SA 319) is a single-engine, light utility helicopter developed by French aircraft company Sud Aviation. During its production life, it proved to be a relatively popular r ...

(

South African Air Force "Through hardships to the stars" , colours = , colours_label = , march = , mascot = , anniversaries = , equipment ...

cabin mounted) ** Avro Lincoln (when fitted with mid-upper turrets) **

Avro Shackleton The Avro Shackleton is a British long-range maritime patrol aircraft (MPA) which was used by the Royal Air Force (RAF) and the South African Air Force (SAAF). It was developed by Avro from the Avro Lincoln bomber, which itself had been a develo ...

Bristol Brigand The Bristol Brigand was a British anti-shipping/ground attack/dive bomber aircraft, developed by the Bristol Aeroplane Company as a replacement for the Beaufighter. A total of 147 were built and were used by the Royal Air Force in Malaya duri ...

** de Havilland Hornet & Sea Hornet **

de Havilland Vampire The de Havilland Vampire is a British jet fighter which was developed and manufactured by the de Havilland Aircraft Company. It was the second jet fighter to be operated by the RAF, after the Gloster Meteor, and the first to be powered by ...

de Havilland Venom The de Havilland DH 112 Venom is a British post-war single-engined jet aircraft developed and manufactured by the de Havilland Aircraft Company. Much of its design was derived from the de Havilland Vampire, the firm's first jet-powered comb ...

de Havilland Sea Venom The de Havilland Sea Venom is a British postwar carrier-capable jet aircraft developed from the de Havilland Venom. It served with the Royal Navy Fleet Air Arm and with the Royal Australian Navy. The French Navy operated the Aquilon, develo ...

** English Electric Canberra B.Mk.6 & B(I).Mk.8 ** Hawker Fury & Sea Fury **

Hawker Sea Hawk The Hawker Sea Hawk is a British single-seat jet day fighter formerly of the Fleet Air Arm (FAA), the air branch of the Royal Navy (RN), built by Hawker Aircraft and its sister company, Armstrong Whitworth Aircraft. Although its design origina ...

** Hawker Tempest Mk V Srs II and subsequent

Marks Marks may refer to: Business * Mark's, a Canadian retail chain * Marks & Spencer, a British retail chain * Collective trade marks, trademarks owned by an organisation for the benefit of its members * Marks & Co, the inspiration for the novel ...

** Martin-Baker MB 5—prototype ** Saunders-Roe SR.A/1 **

Supermarine Attacker The Supermarine Attacker is a British single-seat naval jet fighter designed and produced by aircraft manufacturer Supermarine for the Royal Navy's Fleet Air Arm (FAA). The type has the distinction of being the first jet fighter to enter oper ...

** Supermarine Seafang ** Supermarine Spiteful ** Supermarine Spitfire (late Merlin-powered variants)#Mk XVI (type 361) Mk.XVIe ** Supermarine Spitfire (Griffon powered variants)#Mk XIVe Mk.XIVe,XVIII,21,22,24 ** Westland Welkin **

Westland Wyvern The Westland Wyvern was a British single-seat carrier-based multi-role strike aircraft built by Westland Aircraft that served in the 1950s, seeing active service in the 1956 Suez Crisis. Production Wyverns were powered by a turboprop engine dri ...

United States

* M1 **

Bell P-39 Airacobra The Bell P-39 Airacobra is a fighter produced by Bell Aircraft for the United States Army Air Forces during World War II. It was one of the principal American fighters in service when the United States entered combat. The P-39 was used by t ...

- some early 20mm-armed models and RAF ''Bell Airacobra I'' ** Lockheed P-38 Lightning - some early 20mm-armed models and RAF ''Lockheed Lightning I'' * AN/M2 ** Bell P-400 (P-39 Airacobra diverted from export for USAAF usage) ** Boeing B-29 Superfortress - In tail gunner position with two 0.5 in machine guns **

Curtiss SB2C Helldiver The Curtiss SB2C Helldiver is a dive bomber developed by Curtiss-Wright during World War II. As a carrier-based bomber with the United States Navy (USN), in Pacific theaters, it supplemented and replaced the Douglas SBD Dauntless. A few surviv ...

North American P-51 Mustang The North American Aviation P-51 Mustang is an American long-range, single-seat fighter and fighter-bomber used during World War II and the Korean War, among other conflicts. The Mustang was designed in April 1940 by a team headed by James ...

- NA-91 models were fitted with four AN/M2s. **

Douglas A-1 Skyraider The Douglas A-1 Skyraider (formerly known as the AD Skyraider) is an American single-seat attack aircraft in service from 1946 to the early 1980s. The Skyraider had an unusually long career, remaining in front-line service well into the Jet Age ...

Douglas F3D Skyknight The Douglas F3D Skyknight (later designated F-10 Skyknight) is an American twin-engined, mid-wing jet fighter aircraft manufactured by the Douglas Aircraft Company in El Segundo, California. The F3D was designed as a carrier-based all-weath ...

** Grumman F6F-5N Hellcat **

Grumman F9F Panther The Grumman F9F Panther is one of the United States Navy's first successful carrier-based jet fighters, as well as Grumman’s first jet fighter. A single-engined, straight-winged day fighter, it was armed with four cannons and could carry a wi ...

Grumman F-9 Cougar The Grumman F9F/F-9 Cougar is a carrier-based fighter aircraft for the United States Navy and United States Marine Corps. Based on Grumman's earlier F9F Panther, the Cougar replaced the Panther's straight wing with a more modern swept wing. Th ...

** Lockheed P-38 Lightning **

Northrop P-61 Black Widow The Northrop P-61 Black Widow is a twin-engine United States Army Air Forces fighter aircraft of World War II. It was the first operational U.S. warplane designed as a night fighter, and the first aircraft designed specifically as a night figh ...

** Chance Vought F4U-1C Corsair * T31 ** Martin AM-1 Mauler **

Douglas A2D Skyshark The Douglas A2D Skyshark was an American turboprop-powered attack aircraft built by the Douglas Aircraft Company for the United States Navy. The program was substantially delayed by engine reliability problems, and was canceled because more prom ...

* AN/M3 ** F4U-4B and all following versions ** Chance Vought F6U Pirate ** Chance Vought F7U Cutlass **

Douglas A-3 Skywarrior The Douglas A-3 Skywarrior is a jet-powered strategic bomber that was developed and produced by the Douglas Aircraft Company. It was designed by Douglas on behalf of the United States Navy, which sought a carrier-capable strategic bomber. D ...

** Grumman F8F Bearcat - used M3s from the F8F-1B on **

* M24 **

Convair B-36 The Convair B-36 "Peacemaker" is a strategic bomber that was built by Convair and operated by the United States Air Force (USAF) from 1949 to 1959. The B-36 is the largest mass-produced piston-engined aircraft ever built. It had the longest win ...

Boeing B-47 Stratojet The Boeing B-47 Stratojet (Boeing company designation Model 450) is a retired American long- range, six-engined, turbojet-powered strategic bomber designed to fly at high subsonic speed and at high altitude to avoid enemy interceptor aircraft ...

Douglas B-66 Destroyer The Douglas B-66 Destroyer is a light bomber that was designed and produced by the American aviation manufacturer Douglas Aircraft Company. The B-66 was developed for the United States Air Force (USAF) and is heavily based upon the United Stat ...

** Northrop F-89C Scorpion

Yugoslavia

* HS.404 **

Ikarus IK-2 The Ikarus IK-2 was a 1930s high-wing, single-seat, monoplane fighter aircraft of Yugoslav design built for the Royal Yugoslav Army Air Force. The IK-2 was designed by French-trained engineers Kosta Sivčev and Ljubomir Ilić, who saw the desir ...

Rogožarski IK-3 The Rogožarski IK-3 was a 1930s Yugoslav monoplane single-seat fighter, designed by Ljubomir Ilić, Kosta Sivčev and Slobodan Zrnić as a successor to the Ikarus IK-2 fighter. Its armament consisted of a hub-firing autocannon and two fusel ...

Sweden

* ''LvAkan m''/41 "HS 404" (anti air cannon) * ''Akan m''/41A "HS 404" (built in Sweden) ** Saab 21 "J 21A-1" **

Saab 18 The Saab 18 was a twin-engine bomber and reconnaissance aircraft, designed and built by Svenska Aeroplan AB (SAAB) for use by the Swedish Air Force in response to a 1938 design competition. Due to delays, it did not enter service until 1944, bu ...

"T 18B" ** Saab 24 "not built" * ''Akan m''/46A "Hispano Mk. II Mod 46" ** J 28 (

FB 1 "J 28A") ** J 30 ( de Havilland Mosquito NF.XIX) * ''Akan m''/47B "Hispano Mk. V" 150-round magazine. Some built in Sweden. ** J 28 (

FB.50 "J 28B", two-seater DH 115 "SK 28C") ** J 33 (

NF 51) * ''Akan m''/47C "Hispano Mk. V" 180-round magazine. Some built in Sweden. **

Saab 29 Tunnan The Saab 29 ''Tunnan'', colloquially ''Flygande tunnan'' or just ''Tunnan'' ( en, "The flying barrel", "The barrel"),. is a Swedish fighter that was designed and manufactured by Saab in the late 1940s. It was the second turbojet-powered comb ...

"A, B, D, E, F" * ''Akan m''/47D "Hispano Mk. V" Initially 130-round belt-fed ( HE) and 10-round magazines ( AP). Later 30-round box magazine ( MPHC-T). **

Pansarbandvagn 302 Pansarbandvagn 302 (pbv 302), meaning roughly ''armoured tracked carrier vehicle 302'',), are instead only called wagons (chassis description) to denote that they are tracked but more specialized and less universal. was a Swedish high-mobility infa ...

tracked armoured personnel carrier. The vehicle used a single akan m/47 cannon re-purposed from scrapped Saab 29 and Venom aircraft. ** ''Pansarterrängbil'' 203A wheeled armoured personnel carrier. The 203A reuses old Pansarbandvagn 302 turrets.

Switzerland

* 20 mm Flugzeugmotorkanone Hispano-suiza FM-45 HS and 20 mm Flugzeugflügelkanone Hispano-suiza FF-45 HS. Swiss variant with 780 rpm and 875 m/s velocity. ** Doflug D.3802 "D.3802A" ** Doflug D.3803 **

EKW C-36 The EKW C-36 was a Swiss multi-purpose combat aircraft of the 1930s and 1940s, built by the Eidgenoessische Konstruktionswerkstaette. It was a single-engined monoplane with a crew of two. It entered service during World War II in 1942, and desp ...

04 * 20 mm Kanone 1948/73 "Hispano Mk. V" ** Schützenpanzer 63/73 American-built M113 APC's equipped with the same Swedish turret as

Argentina

* Hispano Mk. II ** I.Ae. 24 Calquin * Hispano Mk. V ** I.Ae. 30 Ñancú ** FMA IAe 33 Pulqui II

Specifications HS.404

* Type: single-barrel automatic cannon * Calibre: 20 mm × 110 (0.79 in) * Operation:

gas operated Gas-operation is a system of operation used to provide energy to operate locked breech, autoloading firearms. In gas-operation, a portion of high-pressure gas from the cartridge being fired is used to power a mechanism to dispose of the spent ...

, delayed blowback * Length without muzzle brake: * Length with muzzle brake: * Weight without drum magazine: * Weight (complete): * Rate of fire: 600–700 rpm * Muzzle velocity: * Recoil force: with muzzle brake * Ammunition: Ball, Incendiary, HE (High Explosive) * Projectile weight: HE and HEI: , AP-T: * HE and HEI rounds explosive filler:

Ammunition

United States

World War II

Ammunition was shipped in rectangular 10-shell fiberboard cartons. There were 12 cartons per metal-lined wooden packing crate (120 rounds). * 20mm Ball Mk. I ** Weight (Projectile): ** Weight (Complete Round): each. ** Weight (Packing Crate):. ** Volume (Packing Crate): 1.45 Cubic Feet. * 20mm High Explosive - Incendiary Mk. I ** Fuze: No.253 Mk.IA Direct Action (Percussion) Fuze. ** Weight (Projectile): ** Weight (Payload): of high explosive and incendiary fillers. ** Weight (Complete Round): each. ** Weight (Packing Crate): . ** Volume (Packing Crate): 1.45 Cubic Feet. * 20mm Armour Piercing - Tracer M75 ** Weight (Projectile): ** Weight (Complete Round): each. ** Weight (Packing Crate): . ** Volume (Packing Crate): 1.45 Cubic Feet.

Post-War

The M90 series of shells were ballistically matched to make it easier to use different types without losing accuracy. Ammunition was shipped in 25-round metal canisters. There were 6 metal canisters per wooden crate (150 rounds). * 20mm Drill M18A2 ** Weight (Projectile): ? ** Weight (Complete Round): ? each. ** Weight (Packing Crate): ? ** Volume (Packing Crate): 1.5 Cubic Feet. * 20mm HEFI-SAP (High Explosive Fragmentation Incendiary-Semi Armor-Piercing) M18A2 * 20mm Armour Piercing - Tracer M95 (T9E5) ** Weight (Projectile): ** Weight (Complete Round): each. ** Weight (Packing Crate):. ** Volume (Packing Crate): 1.5 Cubic Feet. * 20mm Incendiary M96 (T18) ** Weight (Projectile): ** Weight (Complete Round): each. ** Weight (Packing Crate):. ** Volume (Packing Crate): 1.5 Cubic Feet. * 20mm High Explosive - Incendiary M97 (T23) ** Weight (Projectile): ** Weight (Complete Round): each. ** Weight (Packing Crate):. ** Volume (Packing Crate): 1.5 Cubic Feet. * 20mm Training-Practice M99 (T24) ** Weight (Projectile): ** Weight (Complete Round): each. ** Weight (Packing Crate):. ** Volume (Packing Crate): 1.5 Cubic Feet.

References

War Department Training Manual TM 9-227 ''20mm M1 Automatic Gun & 20mm AN-M2 Automatic Gun''
(November 19, 1942).

External links

* {{DEFAULTSORT:Hispano-Suiza Hs.404 20 mm artillery Aircraft guns Autocannon World War II weapons of France World War II weapons of the United Kingdom World War II weapons of the United States Military equipment introduced in the 1930s

Development

From Oerlikon to Hispano

Anti-aircraft gun

Aircraft gun

British production

US production

Post-war development

Properties

Users

France

UK & other Commonwealth countries

United States

Yugoslavia

Sweden

Switzerland

Argentina

Specifications HS.404

Ammunition

United States

World War II

Post-War

See also

References

External links