Ok, so maybe this will clear things up about the 20mm British Hispano Suiza.
In the buildup to the Second World War, the United Kingdom had embarked on a programme to develop cannon-armed fighters.
[4] 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 with powerful cannon-armed interceptors.
[5] The experience of the
Battle of Britain had shown the batteries of eight
rifle-calibre machine guns to be inadequate and prompted the adoption of auto cannon armament for the primary portion of
Royal Air Force (RAF) fighters.
[6] The Beaufighter highlighted the need for a belt feed mechanism; as a
night fighter the 60-round drums needed to be replaced in the dark by the
Radar/
Wireless Operator, often while the aircraft was manoeuvering to keep sight of its quarry. In addition, the early trial installations in the
Hawker Hurricane and
Supermarine Spitfirehad 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 for a brief period specifying 12-machine gun armament for new fighters.
[6]
Subsequently, a suitable belt-feeding system was developed by
Martin-Baker, and the new design was adopted by the RAF and
Fleet Air Arm in 1941 in a slightly modified form as the
Hispano Mk.II. Four cannon replaced the eight .303
Browning machine guns in the Hurricane
[7] and in some tropical versions of the Spitfire, becoming standard armament in later fighters. Most other Spitfires had only two cannon, because outboard cannon tended to freeze at high altitudes, along with four
0.303 calibre (7.7mm) or two
0.50 calibre (12.7mm) machine guns.
[8]
The British were concerned their production would be inadequate and licensed production of the Hispano to the US. However, the US production never became satisfactory and the British eventually gave up on the U.S. versions. British production was eventually increased to the point where this was no longer an issue. 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 them less vulnerable to freezing and mechanical stress. One of the main British fighters to use the
Mk. V was the
Hawker Tempest Mk. V Series II, which mounted two cannon in each wing.
[9] Ammunition types available included Semi-Armour Piercing, Incendiary (SAPI) and High Explosive, Incendiary (HEI).
[10] Around 42,500 Hispano cannon of various Marks were manufactured by
Birmingham Small Arms (BSA).
In the buildup to the Second World War, the United Kingdom had embarked on a programme to develop cannon-armed fighters.
[4] 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 with powerful cannon-armed interceptors.
[5] The experience of the
Battle of Britain had shown the batteries of eight
rifle-calibre machine guns to be inadequate and prompted the adoption of auto cannon armament for the primary portion of
Royal Air Force (RAF) fighters.
[6] The Beaufighter highlighted the need for a belt feed mechanism; as a
night fighter the 60-round drums needed to be replaced in the dark by the
Radar/
Wireless Operator, often while the aircraft was manoeuvering to keep sight of its quarry. In addition, the early trial installations in the
Hawker Hurricane and
Supermarine Spitfirehad 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 for a brief period specifying 12-machine gun armament for new fighters.
[6]
Subsequently, a suitable belt-feeding system was developed by
Martin-Baker, and the new design was adopted by the RAF and
Fleet Air Arm in 1941 in a slightly modified form as the
Hispano Mk.II. Four cannon replaced the eight .303
Browning machine guns in the Hurricane
[7] and in some tropical versions of the Spitfire, becoming standard armament in later fighters. Most other Spitfires had only two cannon, because outboard cannon tended to freeze at high altitudes, along with four
0.303 calibre (7.7mm) or two
0.50 calibre (12.7mm) machine guns.
[8]
In the buildup to the Second World War, the United Kingdom had embarked on a programme to develop cannon-armed fighters.
[4] 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 with powerful cannon-armed interceptors.
[5] The experience of the
Battle of Britain had shown the batteries of eight
rifle-calibre machine guns to be inadequate and prompted the adoption of auto cannon armament for the primary portion of
Royal Air Force (RAF) fighters.
[6] The Beaufighter highlighted the need for a belt feed mechanism; as a
night fighter the 60-round drums needed to be replaced in the dark by the
Radar/
Wireless Operator, often while the aircraft was manoeuvering to keep sight of its quarry. In addition, the early trial installations in the
Hawker Hurricane and
Supermarine Spitfirehad 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 for a brief period specifying 12-machine gun armament for new fighters.
[6]