34 thoughts on “Fighter aircraft gun comparision”

1. Another interesting article thanks Picard.
   About Rafale’s Gun philosophy there is bit more than that. In the requirement, for the Rafale, the AdlA wanted a gun that is slaved to computer calculation and helped by Fly commands.

   With a normal gun, aimed and fired by a pilot, you need dispersion high enough to compensate the errors of the pilot and low enough to have a good range. Those two requirements have to live together. But with the AdlA req for the Rafale the idea was to get rid of the pilot’s error by replacing it with computer calculation and FBW assisted fire. By reducing this main source of errors, dispersion and number of bullet fired can be reduced a lot. This leads to 30mm Gun (for ATA and ATG), very low dispersions rate, low number of rounds and short life per fired bullet for the cannon. The result is a significant increase in canon range, a reduced risk of collateral damage in ATG and (supposition of mine) increase in flight domain (nose pointing)

   But, because there always is a but, budget was reduced… and the worst happened, the canon was finished but the software is missing. As far as I know, the result is => not enough dispersion for pilots.

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   1. Yeah, thanks.

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2. Absolute truth about guns, but, we are in a dawn of gun era, when technology gets good enough to manage cooling of high power AESA T/R modules guns will become history as dirested energy weapons will replace them. Also lasers will come into the game, again, its just matter of power supply. Guess it will happen in next 20 years top. Maybe interim solution will be electric powered guns. Regards.

   ps: it wold be absolute pleasure to read your analyses about F-22 real RCS as you have the knowledge and C. Kopp never did it (as he did for PAK-FA and J-20) because 0.0001m2 is quite hard to buy. F-111 had rcs of 7m2 and f-117 had 0.025m2 so reduction in rcs in those two comparable planes was 270x. In the early 90-ties in literature 10000x reduction of rcs was a golden goal. Despite undoubtfull USA technological advance could this “jump” in rcs be achieved ? Even if it was, comparable to f-22 is f-15, so with its clean 10m2 rcs 10000x less is 0.001…thats why i dont buy 0.0001m2, but have no tech knowledge to sustain it..once Lochkeed officials stated that f-22 is marble size (in 90-ties), so someone calculated rcs of marble and thats how we got 0.0001 although marbles come in diferent diameters……….

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   1. “when technology gets good enough to manage cooling of high power AESA T/R modules guns will become history as dirested energy weapons will replace them. Also lasers will come into the game”

      Fighter’s energy output is limited by how much energy can engines generate, so even if high-powered lasers can be made small and powerful enough to shoot down other aircraft, it is questionable wether they can be employed. As for AESA, that can only help with jamming. It can’t disable an entire aircraft.

      “it wold be absolute pleasure to read your analyses about F-22 real RCS”

      I can’t really estimate aircraft’s RCS, there are too many variables involved. However, one has to understand that real RCS of a stealth fighter is always larger than estimates you can find, since said estimates are made for aircraft in pristine condition… but even one flight, especially supersonic, will lead to some degradation of stealth coating and thus RCS. Especially if aircraft flies through weather phenomena. In latter case, you also have to account for any icing and damage from ice particles.

      Further, even in clear air and with pristine aircraft, aircraft’s RCS will still be larger than that in tests since condensation, vortices and smoke particles from engines will cause some RCS increase. There is also the fact that you can never have all radar emissions come head-on (lowest RCS area), meaning that some radars will naturally catch areas of larger RCS… how larger depends on many factors.

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3. The Gripen is able to both use the gun in radar-mode and point the gun.

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   1. Thanks. Though I’d expect that most fighters should be able to do it – why make gun entirely dependant on radar – but maybe not.

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4. Would be interesting to see time of flight to 800m, especially for the 30-1 and GIAT. Whilst the 30 has a lower muzzle velocity it’s rounds should decelerate slower and make it a race. Also for the venerable 50 cal.

   A few nagging thoughts about the whole ACM and guns thing though…

   Pre WW2 the RAF in particular got their entire doctrine and dogma wrong, both in terms of the range that fighter engagements would happen at ( 450 yards zeroed) and in terms of the firepower required. Their only recent experience was with fighting aircraft which were basically wood and fabric construction, which probably lead to the 8 gun armament.

   As advances were made in aircraft construction it became clear that to seriously damage a flying aluminium tube explosive force was necessary. Hence the cannon, preferably of decent muzzle velocity, The RAF then adopted a German design, called it the Aden 30 and used it unchanged for 50 years, apparently without ( if you recall the comments from the MOD chap ) even having a way of modelling a gun’s effectiveness.

   Other than a Norwegian study which showed that splinters to the fuselage were the most effective way of disabling a modern fighter ( most likely puncturing either fuel or engines) has anything really changed?

   Well yes, aircraft construction has changed dramatically. What was effective for destroying aluminium tubes is probably overkill for destroying a carbon fibre tube. If I was going to design a hammer to wreck a 50’s era tennis racket then it would look very different to the hammer designed to wreck an 80’s aluminium racket. Similarly though whilst the hammer designed would be effective against a modern carbon fibre jobby, it is probably overkill.

   Also I’m pondering on a couple of your key tenets ( which I in no way dispute) which are likely to predict success in air combat. First off you’ve rightly mentioned a higher cruise speed than the opposition being a key determinant as most victims of air combat aren’t aware of the presence of the opposition ( I assume this is explicitly aware of the particular aircraft as in many dogfights the pilot would have been aware of the opposition, just not the one on his tail). However you do conflate this principle with supercruise ability in your designs, which isn’t necessarily the same thing. The ability to travel supersonically after all results in a great deal of friction on the aircraft’s skin, which will paint a pretty picture to IRSTs. Surely the key is rather a high cruise speed on minimal power subsonically, resulting in a longer patrol and therefore more opportunity to bounce. Getting twenty minutes or so supercruise is useful, though I would posit less useful than an hours worth of cruise.

   The other thing which has been bothering me is twofold. With the higher speeds and, presumably, agility of modern fighters are the parallels of the past still relevant? I haven’t sat through too many hud displays on youtube but from what I have seen gun engagements certainly tend to be at ranges which would have been considered extreme in previous conflicts ( 800m or higher). Modern fighters are bigger targets for sure for which the inverse square rule applies. A Su27 would be roughly the same sized target at 800m as the Mig21 would have been at 400m. A Eurofighter may have the same wingspan as a Spitfire but will still be a larger target from all angles. A spit could turn at 33 degrees per second at 200 kts so was certainly agile in comparison to many modern designs in some parts of the flight envelope, which if manouvreing would certainly make it a difficult target.

   Looking at the aircraft which have either been successful against their opponents, or particularly at those which have been surprisingly successful, leads us to about five notable types that I can think of. The Ajeet was noticeably superior to the F86 ( despite the types previous success), Israeli Mirages turned the sky red against all opposition, F5’s were markedly superior at least in training, The Sea Harrier easily saw off the Argentinian Mirages and the ME109 remained in production throughout WW2 despite there being arguably superior designs which never appeared to dislodge it.

   Hence assuming no use of off board or active on board sensors and equal levels of training and awareness could it be that a key determinant is that whoever spots the opposition first, based on the luminosity ( and in the modern era IR luminosity as well) and size of the airframe, is actually more important and possibly the most important criterion?

   I’m not sure whether there is a direct correlation, particularly in WW2. The F4 was Zero fodder, whils the F6 turned the tables for instance. F15 trounced everything both in Israeli service and elsewhere.

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   1. “However you do conflate this principle with supercruise ability in your designs, which isn’t necessarily the same thing.”

      Most modern fighters can sustain cruise speeds of cca Mach 0,9 for usable amount of time, and some of them (Gripen NG, F-22, Su-35, possibly Rafale and Typhoon) can sustain supersonic speeds for usable amount of time as well. So yes, in order to cruise faster than the enemy, supercruise is a must.

      “The ability to travel supersonically after all results in a great deal of friction on the aircraft’s skin, which will paint a pretty picture to IRSTs. Surely the key is rather a high cruise speed on minimal power subsonically, resulting in a longer patrol and therefore more opportunity to bounce.”

      Not really. Yes, to travel supersonically does result in high IR signature. However, if you recall a RAND study I have mentioned, PIRATE for example can detect a subsonic fighter at 90 km head-on (which is to say, just from skin friction), and 145 km tail-on. “Subsonic” is likely Mach 0,9, which is kinda-standard combat cruise speed. Cruising at Mach 1,7 increases detection range by 10%, to 100 km and 160 km, respectively.

      I will have fighters A (attacker) and D (defender). Now, assume that both fighters have AIM-120D missile and are cruising at 40.000 ft. At that altitude, and assuming equal cruise speed, missile’s range is 90 km head-on or 20 km in tail chase. If we assume tail chase (prefered option for the attacker), then 20 km is true if both cruise at the same speed. However, 100 knot speed advantage modifies range by some 5-25%. If attacker cruises at Mach 0,9 and defender at Mach 1,2 (172 kts difference), missile’s range is 11,4-18,3 km. If defender cruises at Mach 1,5 (344 kts difference), it drops to 2,8-16,5 km. However, if attacker cruises at Mach 1,5 and defender at Mach 0,9, then missile’s range is 23-37 km.

      Mach 1 = 573 kts at 40.000 ft

      “With the higher speeds and, presumably, agility of modern fighters are the parallels of the past still relevant?”

      They always are, you just have to know how to apply them.

      “leads us to about five notable types that I can think of”

      And if you take a look at your list, most of them were smaller than the opposition (except maybe Mirages, but with them – and Harriers – training was the primary variable).

      “Hence assuming no use of off board or active on board sensors and equal levels of training and awareness could it be that a key determinant is that whoever spots the opposition first, based on the luminosity ( and in the modern era IR luminosity as well) and size of the airframe, is actually more important and possibly the most important criterion? ”

      Correct.

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5. Hmm … the perfect gun would probably be one that:

   High muzzle velocity (will come at the expense of barrel wear, but that’s a minor issue)
   Very high “burst” rate for the first 0.5s (strong spinup time)
   Very dense projectiles (could use tungsten even)

   I suppose with a dense enough projectile, HE might even be counterproductive. Otherwise, lots of HE is desirable.

   Some degree of scatter might be desirable as well.

   A slightly denser round for the GIAT with a longer barrel would make a deadly HE based gun. Oh, and none of them seem to carry enough bursts for a sustained fight.

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   1. Well there is the HIVAP which made it to the frontlines in Vietnam.

      Check. 1350 m/s mv.
      30,000 rpm, though the designers though it could double that.
      Fired fletchettes, which can be as dense as you like depending upon the materiel used ( tungsten, steel, depleted uranium etc).

      Further development sought to make it unjammable ( the triangular cases were plastic which the feed mechanism would just rip to shreds and carry on) and lighter than comparable systems, partly due to the lack of brass in the cartridges.

      Typically a fletchette will retain it’s velocity far better than a cannon round as it is more efficient at penetratng the air, hence you have critically reduced time of flight before the rounds intercept the target. I can’t find velocity drop with range data though the 40mm CT fletchettes only drop 120 m/s of their initial 1600 m/s velocity over 1000 yards.

      Add in that a modern fighter might be travelling at 300 m/s itself and a fletchette round has at least a 50% advantage in muzzle velocity, which would become more extreme as range increased. Most cannon shells seem to lose half of their initial velocity within 6-800m so 1000m/s will still equate to well over a second between firing and interception. Fletchettes less than half this.

      There was also a smooth barelled 50 cal which shot DU fletchettes at 14-1500 m/s. It was not progressed when the accuracy was found to be poor ( 12 mil groupings) though this might even be an advantage in air combat. Firing a cone of projectiles which would roughly equate to about 24 foot at 1000m would be very handy provided sufficient weight of fire could be guaranteed.

      Given that the Norwegian study found the optimum damage type to modern aircraft was splinters along the centreline such that engines, fuel and other vital components were hit I suspect this is the optimum configuration for a fighter’s armament. At most likely ranges a sub calibre penetrator would almost certainly exit the other side of any modern fighter

      A cannon will provide far fewer firing solutions due to inferior ballistics, will be less likely to score hits even given a solution as the target is still manouvreing and is far heavier and bulkier requiring valuable fuselage space to be used. For one fuselage mounted GIAT 30 you could easily have 4 M3 50cals mounted within wing or centreline pylons for 4800 rpm with no spin up time. Cheap SLAP, Fletchette or DP ( HE) ammo to mix and match target types. Hence space freed up and a configurable weapons load dependant upon mission. Of course there is no reason why any of the cannon mentioned couldn’t simply have fletchette ammunition developed for them.

      Terminal ballistics might be debateable. I suspect a fletchette or sub calibre penetrator would be more lethal along the length of the fuselage whereas a cannon hit more lethal across the wing sections.

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      1. Sounds nice.

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      2. “There was also a smooth barelled 50 cal which shot DU fletchettes at 14-1500 m/s. It was not progressed when the accuracy was found to be poor ( 12 mil groupings) though this might even be an advantage in air combat. Firing a cone of projectiles which would roughly equate to about 24 foot at 1000m would be very handy provided sufficient weight of fire could be guaranteed. ”

         Actually, you need sufficient accuracy to ensure lethal damage with a single burst, assuming the same is on the target. That is one of reasons why revolver guns are better than rotary ones, as they tend to be more accurate.

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6. “Actually, you need sufficient accuracy to ensure lethal damage with a single burst, assuming the same is on the target. That is one of reasons why revolver guns are better than rotary ones, as they tend to be more accurate.”

   There was a single barrelled version of the HIVAP which used a revolver chamber, it didn’t have quite the same extreme rate of fire but it was still high ( can’t find a reference to it). Development was dropped once if became clear that neither the Navy or Air Froce were going to persue it, partly because their Vulcan’s were still relatively new. Similarly the smooth barrelled 50 was thought of as an anti-armour weapon, with the Air Force obsessed with missiles and nuclear war fighting it appears it wasn’t even considered.

   Given that the time of flight for the stream of projectiles is going to be significantly different for a cannon compared to something firing fletchettes the chance of lethal damage is going to be hugely different. The last cannon round fired in a .5 second burst will arrive at point of aim after about 1.5 seconds, and the first after about a second. The target would have moved an extra 150 metres at anything up to about 40 degrees off the angle of track by that time.

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   1. Essentially it is very similar to the APFSDS weapons that you find on modern tanks.

      I suspect that with some development, it could prove to be quite a lethal weapon, assuming the scatter was acceptable.

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7. No one mentioned DART ammunition, Italian made 76mm and 127mm guided shells. How long it will take to employ this tech to 30mm caliber, or 35mm even 40mm? Still believe directed energy weapons are the future, look at the Russian Ranets-E which operates at X band and is truck mounted. Can truck mounted generator compete with jet engine in terms of produced power ? And it has (Ranets) effective range of 3.8 to 7nm, when i say effective i mean to burn electronics completly, just to disturb electronics range is twice than that. Ok, Faraday cage can solve this…but as usual its always the game of cat and mouse….

   “Fighter’s energy output is limited by how much energy can engines generate, so even if high-powered lasers can be made small and powerful enough to shoot down other aircraft, it is questionable wether they can be employed”

   Compare B-1 and B-2 parameters and power of their engines, seems like B-2 is overpowered for capabilities it has, ok i guess its engines does not have aftherburn option buth again…than, the question is, if development of jet engines continue as it was, on what that power will be used, on mach 3 or mach 5 supercruise or something else, as we are easily approach to aircraft maneuvrability levels that humans will not be able to sustain…Not to mention that special generator for such DE weapons can be employed in a same way as roumored Russian plasma-stealth generator on Su-27. Regards.

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   1. I’m not sure they ever sold any but that DART ammunition combined with the ottomatic 76mm would make for a very interesting combination…

      If nothing else it would be quite an asset as SPA as the 76 can pump out about 100 shells a minute… Good old fashioned flak or almost overkill on supression. No idea how much they were but I’m betting significantly cheaper than an equivalent missile system.

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      1. They sold the DART system and associated ammo to the Italian and Colombian Navies. Both Navies conducted successful tests of the systems in the Mediterranean Sea (Italian Navy) and the Caribbean Sea (Colombians) last year. 27 systems have been ordered so far.

         http://www.otomelara.it/-/dart-strales-76mm
         http://www.otomelara.it/-/dart-colombia
         http://www.otomelara.it/-/dart

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      2. Was thinking of these..

         http://en.wikipedia.org/wiki/Otomatic

         Rather than the naval mounts, which are extensively used.

         Swap out some of the SPA from an armoured regiment for a dozen or more of these beasties, some sort of cooperative engagement capability and you have a cheap AD solution out to 20,000 feet or more.

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      3. The concept is weak because Oto Melara are lazy and took take the naval turret and simply mounted on a chassis. This resulted in very high profile, an inefficient use of internal space and small ammo loading (about 20 rounds which is very small for a 76mm weapon), because the ammunition is mounted vertically.
         If they would have bothered to do some reaserch they might have come up with something looking like this:

         http://jedsite.info/tanks-hotel/hotel/hstvl_series/hstvl-series.html

         or this

         http://www.jedsite.info/tanks-romeo/romeo/rdf_series/rdf-series.html

         better look at the high elevation of the gun here:

         http://tanknutdave.com/the-american-hstvl-tank/

         This tanks had 60 rounds of 75mm or 76 mm ammo and had very high elevation guns. Now take into consideration that the Denel GT 4 76 mm gun on the Rooikat ( https://en.wikipedia.org/wiki/Rooikat ) which is basically an Oto Melara 76mm can fire an APFSDS round with a muzzle velocity of 1500m/s that means with kinetic energy and performance similar to a 120mm APFSDS, and a very interesting concept appears.

         With a little research and maybe collaboration with AAI which produced the HSTV(L) and RDF series Oto Melara might have come up with a very interesting concept for the OTOMATIC: an helicopter transportable light tank Anti-air self propelled artillery tank destroyer, the perfect vehicle for both 4 gen warfare as well as 3rd gen warfare.

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      4. Seems the concept has been given new life in the form of DRACO…

         http://www.armyrecognition.com/weapons_defence_industry_military_technology_uk/draco_oto_melara_76mm_multipurpose_surface_and_c-ram_counter-rocket_artillery_mortar_system_2007144.html

         A sub 20 tonne light tank would be an interesting concept too.

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      5. The problem of the big profile still remains. Look at that thing it must be close to 4 meters with the radar antenna stowed. Compared with the HSTV(L)/RDF series I linked earlier it’s huge. And the carried ammunition is still appallingly low, 36 rounds. The high profile leads to a high center of gravity which decreases off-round performance significantly. It’s a product characteristic of the armaments industry of our time, low-risk, high-cost with very little in the way of innovation. The thing is that if they would really look into building something like the HSTV(L)/RDF the chassis wouldn’t be to much of a risk or great R&D effort, technology has come a long way since the 70s in the way of compact power-plants, hub mounted electric motors and compact sensors.

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      6. Trying to put AAA, SPA and armoured direct fire into a single type sounds a bit optimistic to me, though I take your point regarding the simplicity and utility of such a type compared to the behemoth MBTs which have little utility outside equisitely supplied theatres. Even there the threat of mines tends to limit their use.

         Something along the lines of the S-tank with batteries and engine up front might be interesting, though I always wondered why more tanks didn’t mount a shovel or excavator. Might as well make the buggers useful for the 99.999% of the time they aren’t plinking T72s..

         “And the carried ammunition is still appallingly low, 36 rounds. ”

         76mm rounds are relatively small so I’m sure any formation would have plenty of supply vehicles. Enough for 6 AA engagements or a decent battery. As long as reloading was a swift process this wouldn’t worry me too much as supply vehicles will always be close at hand. Any decent sized truck or whatnot could carry hundreds of them ( basically the same size shell as the old 25 pdr).

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8. I would have preferred a tracked versus a wheeled vehicle, but yes, a 25 ton or under vehicle with good strategic mobility I think will be important for any conventional military.

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13. Hi, how many 20mm vs 30mm rounds are needed to destroy a Su-27 sized target from above, i.e. in high angle deflection shot along the center line?

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    1. I don’t know. I’m not sure anybody does, I don’t recall Su-27s ever being in a dogfight. As far as destructiveness of guns goes, you have two measures: mass of projectiles thrown in a unit of time (first 0,5 or 1 seconds, typically) or mass of HE(I) mix thrown during that same time. I believe I had compared these measures in the article here.

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       1. Sure, i noticed those. My thinking is — if 20mm is powerful enough, you wont need to use heavier rounds with their drawbacks (lower rate of fire, less ammo, more recoil, higher weight).

          If you read about the Korean war, the F-86 managed pretty well against the MiG-15 with 6x .50 cal. machine
          guns (not cannons) and those didn’t have explosive shells, but rained a hail of bullets on the MiG’s flight path.

          There is a tremendous advantage of having high number of bullets flying at the same time when you shoot at high angle. An example (from a WW2 flight sim) for high angle deflection shooting —

          https://forum.il2sturmovik.com/topic/10876-deflection/?p=166197

          The shooter doesn’t even see its target at the moment of firing, just aligns on the targets flight path and opens fire in advance, but has plenty of cannons and MGs to saturate the space and score a hit. Much like a shotgun shooting ducks. A large single slug could have the same weight as a bunch of small balls but the chance of hitting is much smaller… (I say this in regard to the mass per second measure).

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       2. I know, but question is, is 20 mm powerful enough?

          In Korea, F-86 did well due to its hydraulic control system and good cockpit visibility. Its machine guns were the weakest part of it, and I remember reading somewhere that most MiGs that were seemingly “shot down” were repaired and came back up very quickly because F-86s armament was insufficient to cause lethal damage. So while kill:loss ratio seemed to be 10:1, it was really closer to 2:1.

          Most important systems tend to be somewhat buried, and unless those are damaged or destroyed, aircraft will still be a threat. Cockpit is unlikely to be hit, as aiming is done for the center of mass. In fact, you can see weight of armament of most major powers gradually increasing – only US stuck to .50 cal until 1950, most others went to 20+ mm armament even during World War II. And between larger size and need to tolerate higher stresses, modern aircraft are even tougher.

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14. I found interesting presentation of a newer type of ammo, Diehl’s Penetrator with Enhanced Lateral Effect (PELE) for the 20×102 mm caliber. There are couple of tests against aircraft targets. Link:

    Click to access GloudePresentation.pdf

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    1. Basically, a hollowpoint for aircraft guns. Interesting concept. And since more damage is done to the internals of the aircraft than to the aircraft skin, it could be more effective than HE ammunition, in theory at least.

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       1. Yes, exactly. The larger round for the 27 mm Mauser even has prefabricated balls (pellets?) inside, see the image — https://ammoart.files.wordpress.com/2017/04/pele.jpg

          I read that the motivation to develop it is that explosive shells did excellent against parts with large internal volume like the thick hollow wings of WW2 aircraft (because of the gas expansion), but modern fighters are very densely packed and the effect is decreased.

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