[Graham Boak]

The P-39 was of significantly poorer performance than the Typhoon and the Mustang, and no less vulnerable. Its engine was no more armoured, the central position making no difference to a flak gun, and it is mainly hits to the radiators and piping that make an inline-engine design vulnerable. It had no advantage to either of the other types, and considerable disadvantages. Not least the problems of introducing yet another type, for only a specialised role.

It may be possible to have developed the P-39 to take either the Vickers or RR gun as a replacement for the central cannon, but why? Half the firepower of alternatives, on a basic airframe nice enough perhaps, but that simply provided nothing not already available elsewhere in the inventory.

The Hurricane Mk.IId was replaced by the Hurricane Mk.IV, which did have armour. If you have knowledge that armour was prepared but not issued for the Mk.IId that saw action, please share it, otherwise this seems like pure invented slander. Despite the mixed results in service, the RAF continued to develop the big gun approach, testing it on both the Typhoon and the Mustang, and retaining Hurricane Mk.IV units in the UK until mid-1944. The problems always remained that it required a slow approach and overflight of the target area, with a low rate of fire, whilst permanently limiting the performance and agility of the platform. The actual guns available were seen as unable to penetrate the armour of the forthcoming generation of German tanks, which the rocket could and did, and the future operational environment deadly. (That the heavier German tanks only appeared in limited numbers was fortunate, but not clearly foreseeable.) The guns were retained on Mk.IVs in quieter theatres, remaining until the end of the war in Burma, where their specialised advantages could be used without their disadvantages.