Fighter aircraft gun comparison

[Manticore]

Posted by picard578 on February 1, 2015

Introduction

Despite repeated proclamations about the “end of the dogfight”, gun has always remained an important part of fighter aircraft’s armament. There are several reasons. Having a gun provides a psychological security of having a fallback option if missiles are expended. Gun also has far lower minimum range than even most agile of modern dogfighting missiles (very short ranges reduce missile kill probability even if target is not within missile’s minimum range), and is the most versatile weapon aircraft has – it can be used in dogfight (shooting down aircraft), in air policing (warning shots) and ground attack. While some fighter aircraft sent into Vietnam war didn’t have onboard cannons, low kill probabilities of missiles – especially long-range radar-guided missiles – resulted in guns being reintroduced. Another issue is that, even today, visual identification of target is the only reliable way of identifying it – and many fighter aircraft still do not have imaging IRST or other optical sensor capable of identifying targets at beyond normal identification range of several hundred meters.

Measures to be used in comparision

Due to the nature of air combat, firing opportunities are very brief – only rarely will the enemy present most favorable aspect, and will even more rarely keep up a steady-state maneuver. This means that high-deflection shots, and especially snapshots, are very common, and length of burst is almost never greater than 1,5 seconds, and is often shorter (typically 0,5-1 second).

Thus, a fighter gun has to have:

• heavy firepower
• large number of bursts
• good effective range

Firepower depends on following factors:

• number of projectiles fired
• projectile mass
• HE-I content

Number of bursts depends on:

• number of shots fired per burst
• number of shots carried

Effective range depends on:

• muzzle velocity
• projectile crossectional density
• drag coefficient

Guns compared will be those of fighter aircraft in comparision of modern fighter aircraft done earlier: Eurofighter Typhoon, Saab Gripen (BK-27), Dassault Rafale (GIAT 30), F-22 (M61A2), F-35 (GAU-22/A), HAL Tejas (GSh-23), JF-17 (GSh-23-2), J-10 (GSh-23-2?), J-11 (GSh-30-1), Su-30 (GSh-30-1), Su-35 (GSh-30-1).

*while many sources claim a higher rate of fire of 6600 rpm, it is not confirmed, and General Dynamics states 6000 rpm

Thus we have:

Number of burst per aircraft is as follows: Gripen C (BK-27): 9,2, Typhoon (BK-27): 11,5, Rafale (GIAT-30): 6,6, F-22 (M61A2): 13, F-35 (GAU-22/A): 11,3, HAL Tejas (GSh-23): 7,3, JF-17 (GSh-23-2): unknown, J-10 (GSh-23-2?): unknown, J-11 (GSh-30-1): 12,5, Su-30 (GSh-30-1): 12,5, Su-35 (GSh-30-1): 12,5.

Conclusion

As it can be seen from table, GIAT 30 is by far the best cannon when it comes to firepower, and combination of good muzzle velocity and projectile crossectional density results in good effective range. BK-27 has very good effective range thanks to high muzzle velocity and excellent projectile crossectional density, but limited (albeit still good) firepower. Russian guns also have good firepower and excellent projectile crossectional density but are let down by low muzzle velocity, suggesting an orientation towards the ground attack. US M61A2 has good muzzle velocity, but low crossectional density limits effective range, while low HE-I content and rotary design limit effective firepower. GAU-22/A has better HE-I content but less throw weight; still, good muzzle velocity and projectile crossectional density result in good effective range, though it may be limited by dispersion due to rotary design.

Since most important factors in gaining kills are mass of the projectile, HE-I portion, muzzle velocity and rate of fire, GIAT 30 is overall the most effective cannon when it comes to ACM (dogfight) employment. However, Rafale has a relatively limited number of gun bursts avaliable (adequate for a single kill). On face of it, best balance between number of gun bursts and their effectiveness seems to be achieved by Gripen and Typhoon. This may not be as great shortcoming on Rafale’s part, however, since GIAT 30 offers an option to reduce rate of fire to 1.500 rpm; this leads to 11 projectiles fired in first 0,5 s, weighting 3,03 kg with 0,529 kg of HE-I, allowing for a total of 11,4 bursts while achieving similar effectiveness to the BK-27 (and better than any other gun compared). Overall, European approach seems to be the most effective, with US sacrificing firepower, accuracy and response time in exchange for lower barrel wear and greater ammunition capacity, while Russians sacrificed muzzle velocity and HE-I content for greater round weight. This suggests that while European focus is on dogfight performance, US focus is on shooting down bombers while Russian focus is on ground attack performance.
@Picard578
Fighter aircraft gun comparision « Defense Issues

 

[vsdave2302]

Russian Guns are best in fire power. they use heavy bullet with a very high Muzzle velocity. The one on Mig 27 is deadly. It is proposed to be used on Tejas also.

 

[C130]

BK-27 is my favorite right now.

 

[Penguin]

Tony WIlliams has a nice (2009) article on modern fighter gun effectiveness
Modern Fighter Gun Effectiveness

12.7x99 (.50 M3),
20x102 (M39/M61),
20x110 USN (Mk 11/Mk 12),
23x115 (NS-23, NR-23, AM-23, GSh-23, GSh-6-23),
25x137 (GAU-12/U),
27x145B (Mauser BK 27),
30x113B (Aden/DEFA 550),
30x150B (GIAT 30M791),
30x155B (NR-30),
30x165 (GSh-301, GSh-30, GSh-6-30),
30x173(1) (Oerlikon KCA),
30x173(2)(GAU-8/A),
37x155 (N-37, NN-37)

Russian Guns are best in fire power. they use heavy bullet with a very high Muzzle velocity. The one on Mig 27 is deadly. It is proposed to be used on Tejas also.

To this, Tony WIlliams says:

An interesting comparison can be made between the two principal Western fighter guns, the M61A1 and the BK 27. The rotary clearly has the advantage in rate of fire, but it fires much smaller and lighter shells. Another difference between the two is that the externally-powered rotary gun takes time to spin up to its maximum rate of fire, whereas the revolver has an instant response. In the first 0.5 second, the M61 fires 18 rounds totalling 1.8 kg: whereas the BK 27 fires 14 rounds weighing over 3.7 kg. In the first second, the M61 fires 68 rounds weighing 6.9 kg, the BK 27 fires 28 rounds weighing over 7.4 kg. In weight of fire, as well as the destructiveness of the individual projectiles, the Mauser clearly has an advantage, albeit one that the faster-accelerating M61A2 reduces somewhat. This is significant in that dogfights frequently permit only the briefest of firing opportunities, and although a skilled pilot anticipating a firing opportunity can 'spin up' a rotary in advance, such notice cannot always be guaranteed. The Mauser projectiles are also heavier, which means they will retain their initial velocity out to a greater range. Incidentally, the choice of an even heavier projectile fired at a moderate velocity for the Russian 30 mm guns implies that ground attack has a higher priority than aerial combat in Russian strategy.
The ideal gun for aerial combat will, of course, combine the best of all worlds: a high rate of fire, instantly achieved; a high muzzle velocity to minimise flight time; and projectiles large enough to inflict serious damage with each hit (requiring a calibre in the 25 mm – 30 mm range). The optimum weapon among those currently developed may well be the new GIAT 30M791 revolver, although its weight means that two GSh-301s (or a GSh-30) could be carried instead, with a higher rate of fire. If the Russian guns' 30 x 165 (shell diameter and cartridge case length in mm) ammunition were loaded with lighter projectiles for a higher muzzle velocity, their aerial combat capabilities would be improved, at the cost of some loss of ground attack effectiveness.
For general ground attack (as opposed to 'tankbusting'), the Russian 30 x 165 round is ideal, and there are three weapons capable of firing it, with one, two or six barrels. Which is best depends on-the limitations on weight, space and 'recoil management' of the aircraft concerned.

WILL THE FIGHTER GUN SURVIVE

There are 3 rounds (2 projectiles) that are heavier than Russian 30x165. These rounds are 30x155B, 30x173 and 37x155 (projectiles are 30x155B and 37x155). However, no less than 6 cannon/rounds have greaer muzzle velocity than 30x165. These are 20x102, 20x110 USN, 25x137, 27x145B, 30x150B and 30x173.
Modern Fighter Gun Effectiveness