The idea behind the 45mm was indeed to take out a bomber in a single shot from long range and was developed specifically by Stalins request for such gun.
While the NS-37 was intended as a tank buster, which didn’t turn out very successful.
The gun was too powerful for the IL-2 to handle and on the Yak-9T the recoil probably made accurate follow up shots difficult. The IL-2 also suffered accuracy issues due to the uneven firing time of the guns.
For air combat the gun was too heavy and the RoF wasn’t ideal, hence the N-37.
But like the NS-37 the NS-45 was also tried on the IL-2 but of course the result was worse than the NS-37 so it wasn’t put into service.
But I think, putting it on the IL-2, the intend was there for the gun to also be used in a ground attack or tank busting role.
While an APCR round was developed, the NS-37 already could use the 37mm APCR developed for the 37mm AA gun.
However the APCR was apparently never used as ammunition for planes.
And the reason is probably that APCR limits your targets basically to tanks while the round is overkill for lighter armored vehicles.
Combined with the subpar accuracy, it was probably determined that it wasn’t worth using.
And since the IL-2 already could drop PTAB cluster bombs, the need for a large cannon to attack tanks was probably a low priority when you instead can have a fighter doing fighter things.
So even though AP rounds were developed, it seems unlikely that they were ever used with the Yak-9K.
While it makes perfect sense for all the aircraft that were designed as ground attack aircraft, where you can also have a mixed belt of AP and HE or just APCR for attacking tanks.
On the Su-8, four cannons would probably had the effect of increased accuracy and number of rounds in the air to be effective in this role.
So personally I think it makes the most sense:
- To remove all AP rounds from the Yak-9K
- Only have a 50:50 APHE:HE mix on other aircraft for ground attack
- Keep the pure APCR belt for ground attack aircraft
So the Yak-9K can be a fighter that specializes in attacking bombers, while the ground attack aircraft can attack ground targets with AP and APCR.
Even though at the moment APHE completely blows APCR out of the water in penetration and damage.
But maybe that wouldn’t even be necessary, if the recoil actually affected the plane in any way.
Right now there’s practically no noticable recoil that affects the plane in any way other than slowing it down like every other gun. It’s like shooting BBs.
That’s probably the main issue here. The recoil force is immense but it has no affect on the planes orientation, allowing rapid accurate shots even with Sim controls.
The NS-45 is in the ballpark of a 40mm Bofors, which is mounted to 8.5t or heavier trucks, which are still shook by the recoil.
But mounted in a 3.5t aircraft, the NS-45 seems to have no recoil at all.
Even if the muzzle break reduced the recoil by 30-50%, the weight difference would still mean a noticable effect.