Thanks for reply . I guess past experience is important and weapon designers and purchases must take into account past performance . In this respect , reliable data is needed from actual air combat kills using guns . By various modern jets . Problem is that apart from Korea and Vietnam , there is very little reliable data from jet on jet , dog fights and kills by guns . We should therefore carry out tests , by using different guns by real pilots against target drones . This , short of actual combat , would give most reliable answers .
Aircraft gun design isn't just a case of making the guns lighter and faster firing and x level of accuracy at y range.
The Soviets in particular have a range of weapon options for different purposes for the role of bringing down enemy targets and shooting at targets on the ground.
Their current solution for most fighters is a single barrel 30mm cannon for air to air use... it is very compact and very light and with a good rate of fire and muzzle velocity but also with a good heavy HE projectile able to do serious damage to most types of aircraft.
The MiG-31, being a specialised aircraft has a specialised gun, a 23mm gatling gun with a ridiculous rate of fire (between 10 and 12 thousand rounds per minute).
A direct comparison between US 20mm gatlings and the MiGs 23mm gatling shows a serious superiority for the Soviet weapon.
The only real superiority of the US weapon was in its higher muzzle velocity but that is a conscious choice... if the Soviet round had a light weight penetrator projectile, its muzzle velocity would be comparable, but they prefer slower moving heavier projectiles with more HE punch, but at a very high rate of fire so bursts deliver a cluster of rapidly arriving impacts that lands like a shotgun blast rather than a stream of rounds.
The old model M61 Vulcan weighed 112kgs bare weight of just the gun, while the improved model weighs 92kgs without the feed system and electric motor that powers it.
The GSh-6-23 weighs 76kgs and does not need an electric motor to power it... it is gas powered by the ammo being fired... which also means it spools up to max fire rate much faster than the electric Vulcan.
The muzzle velocity of the Vulcan is 1km/s with a 100 gramme SAPHE projectile, while the GSh-6-23s round moves at just over 700m/s, but fires a much heavier 185 gramme HE projectile.
Note the Vulcan fires a 20x102mm cartridge, while the Soviet weapon is a 23x115mm round... so more case capacity and larger calibre.
Rates of fire are 6,000rpm for the Vulcan and 10-12,000 rpm for the Soviet gun... so up to 200 rounds per second...
It was one of the reasons I started taking an interest in Soviet equipment.... I had always believed the western myths of inferior but brutal equipment... this proved those theories wrong.
Just as importantly, while the US pretty much had the 20mm gatling as its standard aircraft gun, except for the A-10, the Soviets had a range of guns including 23mm single and twin and 6 barrel weapons, and also 30mm single and twin and 6 barrel models too.
Performance wise they are all excellent weapons each with different features regarding weight and size and rate of fire requirements...
Some of them, like the single barrel 23mm cannon on the Shilka, and several of the 6 barrel 30mm cannon used by the navy had a built in water cooling system... and not just a simple water cooling jacket... a sophisticated evaporation system...
On automated radar or IR guns , I must say that , this of course will improve performance . But in a hostile electronic environment , such as radar jamming or IR counter measures or EMP . Then pilot must be able to shoot in old fashion way . And must practice for it . I think you would agree , that modern pilots need to be able to use guns in dog fights . And must train for them . In case of all else failing . The modern materials for jet body must be known . And factored in , when installing guns . I think we pay more attention to armour on a personnel carrier , in designing our guns . But do we really think about aircraft body , when we install guns ? I heard that the F22 body , in part was made of paper / resin mix . In places . Now paper , used to be used as body armour , in the days of old !
Certainly a pilot needs to learn to navigate by compass, but in a real combat situation it makes sense to take advantage of everything that still works like satellite navigation.
The fire control computer on the MiG-29 can use range input from the radar or a laser rangefinder built in to the IRST to track the target and give range and angle information for the fire solution continuously calculated in real time. There is also a line in the HUD that assists the pilot to show them where they need to place the nose of their aircraft to hit the target so as they manouver around eventually things will line up correctly and the gun will automatically fire a burst when it is aligned and should hit. (the pilot holding the fire trigger while manouvering to confirm he wants the gun to fire).
The British have just announced that drone swarms will be used to suppress enemy air defences . They will most probably mimic bigger aircraft in RCS and signals , and put out ECM . So a pilot has to go up and shoot each one . Cheaply . So in this case small calibre high volume fire is needed . Saving SAM for bigger fish later . Alternatively a drone could be used for close air to air . Using data link . But that may be a few years in the future .
To be honest if the enemy put up drone swarms, the best weapon to use is not actually a machine gun... it is a shot gun... so rather than putting a gun pod with a rifle calibre machine gun on your latest fighters (incidently the Soviets had a gun pod for their Hind attack helos that had a single four barrel 12.7mm calibre HMG gatling gun the same as the weapon in the nose of the D model Hinds, as well as two 7.62mm calibre four barrel gatlings... the HMG with 500 rounds and the two rifle calibre weapons with 1,500 rounds each for hosing down soft targets like infantry in the open.) the problem would be you could fire a lot of rounds for each kill and those rounds could be going in all directions around the base you are defending... rounds that miss the target or go right through don't just suddenly disappear... they can do all sorts of damage to friendly forces.
I think the best solution to a UAV swarm is EM type weapons, plus a UCAV armed with something like a 40mm grenade launcher... the large calibre would allow a lot of fragments in each round with a base fuse set for 30-40m or so. It doesn't have to be an expensive and complex variable time fuse... just set them for a specific range and fly the UCAV around and fire at the enemy UAVs from a distance where the 40mm round explodes 3-7m short of the target so when it explodes and sends forward a blast of fragments it will be like a super shotgun round that is fired at close range to the target.
A shotgun is the ideal weapon for an air target... but it has a very limited effective range. Using a 40mm grenade with the front of the round fragmented to blow forward like a Claymore mine means it is an air delivered shotgun blast that is not that expensive, but should be very effective against light airborne targets.
A flight distance of 30-40m means the target will have little time to avoid the round exploding before detonation.
Laser range finders on the UCAV can ensure optimum distance for firing... a turret mounted gun could make multiple shots at targets all around the UCAV without having to do a lot of manouvering.
Fragments are not usually very aerodynamic so while they start off moving at enormous speeds, they rapidly slow down and become rather less dangerous... at more than 50m from the detonation location of the grenade the fragments would probably be starting to become harmless depending upon their weight.
Very light fragments are still lethal if they are moving fast but light fragments slow down faster and become less lethal faster.
Light fast fragments means a dense pattern of fragments so small UAVs are less likely to get by unscathed, but too light and they might just bounce off.
Of course there is not reason why only one round needs to get kills... for some targets a burst of a couple of rounds could be fired to ensure a kill.
Note this is not new, the standard 30mm aircraft cannon in the Soviet Union had what they called a cargo round that had a fixed fuse that detonated the round at a distance of about 1.8km from the muzzle and it contained fragments in the nose of the round that were blown forward like a shotgun blast. It was to be used against soft targets like aircraft parked on the ground or exposed infantry, and unarmed vehicles.