Gun harmonisation
In the late 1920s and 1930s, electrically controlled firing mechanisms, (coupled with the advent of more reliable weapons systems that did not require a pilot close by to clear any malfunctions), allowed aircraft designers to place guns in the wings, negating the need for synchronisation.
This made the Supermarine Spitfire and the Hawker Hurricane the most heavily armed fighters in the world at the time,[4] but there arose a lively debate about how these guns should be converged.
[5] Early in World War II, the British were in favour of "pattern harmonisation", a shotgun-like tactic which disperses the fire of multiple guns to gain a greater chance of a hit.
[9] New Zealand's top ace Colin Falkland Gray expressed frustration at the recommended scheme, saying that the wide pattern and long distance penalized those pilots who were excellent shots.
[13] The vibration of the engine, the twisting pull of the propeller, and the flexing of the wings in flight would cause movement of the gun mounting which would affect the aim.
[18] The opposite situation was not so much of a problem; a distant bore-sight point would not usually stop a fighter from delivering damage at close range, though the hits would not be concentrated on target.
[24] Night fighter tactics using wing guns called for a surreptitious approach on the tail of the enemy, surprising him with fire at a chosen distance.
The American 86th Fighter Bomber Group flying Republic P-47 Thunderbolts increased the bore-sight distance of the eight .50 cal guns during operations in the Italian Alps in late 1944, to converge at 900 ft (270 m).
The highest scoring fighter pilot in the world, German Major Erich Hartmann, set the wing guns (later cannon) of his Bf 109 to converge at 50 m (160 ft) because of his preference for waiting to attack until very near his opponent.
[15] In the Pacific War in mid-1943, American Marine Fighting Squadron 213 harmonised the six .50 cal wing guns of their Mk I Vought F4U Corsairs to converge to a point 300 ft (90 m) ahead.
The squadron's usual tactic was to dive upon an enemy from the front and slightly to one side (a high-side attack using full deflection) and fire when at the convergence distance.
[26] American ace Major Bill Chick of the 317th Fighter Squadron based in North Africa in January 1944 bore-sighted the guns of his Thunderbolt to converge at 300 ft (90 m) because he did not care for deflection shots and instead attacked his targets from the rear at that distance.
[27] Soviet fighter design of the era favoured grouping all guns in the fuselage for accuracy and for keeping the wings as light as possible, resulting in improved manoeuvrability.
In fact, many Soviet pilots flying western aircraft, such as the Bell P-39 Airacobra, directed their armourers to remove some or all wing guns.
