GAU-8 Damage

[Elmar Bijlsma]

More interestingly, why don't all tanks sport 30mm cannon?

[Lanzfeld]

If the cannon on the A-10 is powerful enough to reliably destroy MBTs, why do they bother arming it with ATGMs, too?

Easy...

Standoff range.

[Lanzfeld]

More interestingly, why don't all tanks sport 30mm cannon?

easy...An A-10 can hit the top armour of of a tank. If all tanks could do that with D.U. 30mm they would.

[Lanzfeld]

Keep in mind the GAU-8 is no normal 30mm.

Also....that coloringbook is from 1977. There may have been significant improvements to the shell since then. I am not sure but I would not be surprised.

[c3k]

This page, http://www.fas.org/man/dod-101/sys/ac/equip/gau-8.htm gives a penetration of 38mm at 1,000 meters. 69mm at 500 meters.

244,775 Joules Muzzle Energy (430 gram API round, 1067 m/s muzzle velocity). 240KJ is nice. (The M1's M256 cannon firing the M829A1 round has the following characteristics: Muzzle velocity of 1680 m/s; penetrator mass 8.165 kg. This yields a muzzle energy of 11,522,448 Joules; 47 times more energetic than the GAU 8 API round. (Note that the improved M829A3 penetrator should be in service and has better penetration/high velocity). )

These websites were also useful. The second is a paper on a non-DU penetrator. (Note that the radiation effects, decay, and other concerns regarding DU are totally non-scientific. The effects due to metal exposure, such as would be gained by breathing lead vapor from standard firearms, is a different issue. Any metallic vapor inhalation is harmful. The radiological nonsense is repeated verbatim in many websites. It seems to be cut and paste time. (Please note the dosage obtained from eating a banana compared to handling DU.))

http://www.economicexpert.com/a/GAU:8.htm

http://www.dtic.mil/ndia/2001gun/Tasson2.pdf

[Redwolf]

easy...An A-10 can hit the top armour of of a tank. If all tanks could do that with D.U. 30mm they would.

Yeah but can it hit the top armor at 90 degrees?

90 degree dive bombing went out of fashion around 1943.

[Apocal]

If the cannon on the A-10 is powerful enough to reliably destroy MBTs, why do they bother arming it with ATGMs, too?

Shilka and Zeus. Gun-dueling either is not conducive to a long flying career. But also note the A-10 originally wasn't supposed to receive the Maverick. That came after a few pilots really broke down Soviet air defense organization and realized that even at echelons as low as battalion they'd be encountering rapid-fire, radar-directed AAA.

More interestingly, why don't all tanks sport 30mm cannon?

Size, weapon has relatively poor range compared to a larger gun, questionable terminal effects against protected areas, etc.

Keep in mind the GAU-8 is no normal 30mm.

Also....that coloringbook is from 1977. There may have been significant improvements to the shell since then. I am not sure but I would not be surprised.

I imagine that MBT armor has had more advances, though I could be wrong. AFAIK, there have been no major capability upgrades for the 30mm API round.

[hcrof]

Right, the following is from Wikipedia but it gives an idea as to the relative protection of a T-62 vs a T-72. Note that the figures are for Soviet model tanks, not the Monkey models sold to Syria which were typically 1 generation behind what the Soviets were using at the time.

T-62 - Cast turret, 242 mm turret front armour. (Cast turrets typically have lower armour values than RHA due to worse quality grain structure in the metal)

T-72 - 500 mm composite armour

Add ERA to both of them and suddenly a 30mm cannon starts to look a little insufficient to start taking on the front of even an old MBT, let alone a modernised T-72. As far as I know, if an attack is to succeed in producing a catastrophic kill, it has to be done to the sides or rear of the vehicle.

[Lanzfeld]

yes but what I think might be nerfed is all the top hits from the GAU-8 dont SEEM to kill the tank.

[flamingknives]

The GAU-8 is no normal 30 x 173mm gun. Being an aircraft gun, sabot rounds are likely to be unsafe, so no APDS, let alone APFSDS.

Even with the forward speed of the aircraft, the same cartridge with APFSDS will be more effective.

[Apocal]

At this point, I'd like to request a steeper dive angle for A-10 gun runs. Given the likely air defense environment of Syria, relatively few intact, operating high-altitude defenses, lots of short range air defense assets left intact, along with legacy AAA systems, they'd probably attack from altitude, steeply, to minimize their exposure to the greater threat. You saw a similar thing in ODS. The Iraqis had some higher level air defenses, but they were either destroyed or suppressed early on. What proved too numerous to neutralize were the 7000+ AAA barrels they had.

So the Hogs were restricted to altitudes greater than 15K, later lowered to 10K. At that altitude your dive has to be steep (at least steeper than the angle we get now) or your slant range is going to be further than you can reasonably expect to see a tank.

[MikeyD]

One 'problem' may be that the gun may be too accurately modeled. 40mm penetration, individually tracked bullets. If the game is firing the cannon from too shallow an angle of attack the bullets will be bouncing off the hullsides instead of going through the roof. They can't just type in "increase % of penetrations to 50%" because that's not how penetrations are modeled, they'd have to adjust the angle of attack to increase the likelihood of hulltop hits.

[Redwolf]

One 'problem' may be that the gun may be too accurately modeled. 40mm penetration, individually tracked bullets. If the game is firing the cannon from too shallow an angle of attack the bullets will be bouncing off the hullsides instead of going through the roof. They can't just type in "increase % of penetrations to 50%" because that's not how penetrations are modeled, they'd have to adjust the angle of attack to increase the likelihood of hulltop hits.

I don't think A-10s in real life go for very steep dives to increase penetration.

Remember that just because you hit the roof doesn't mean you hit it at a suitable angle. You can always hit the roof as long as you fly higher than the tank drives, but the angle is the issue.

[Lethaface]

I run quite some tests, in some ones I couldn't destroy 1, other times every run took out 1. After that, I stopped testing

Hope someone who knows about it (ingame) can say anything about potential penetration on different tanks.

Cheers!

[Dietrich]

My understanding is that due to the GAU-8's ultra-über-mega rate of fire, the sheer multitude of rounds impacting more or less the same area on a tank eats through the armor. Rather than any given round penetrating, each round each chips away at the armor a little bit, but the rate of fire is so high and thus the frequency of impacts is so great that by the time the A-10 has finished its 0.66-second (or thereabouts) burst, the tank is Swiss cheese.

Were a 30mm 'autocannon' (like a slightly larger-caliber version of the Bushmaster) to fire at the same spot on a tank (preferably the side armor) for half an hour, perhaps the rounds would start penetrating.

It makes me think of photos I've seen of Tiger front armor after prolonged combat -- in several places the armor is deeply gouged; definitely no penetrations, but perhaps if two 57mm shells had hit the same spot, the second would have scored at least a partial penetration.

[c3k]

Hmmm, absent Rexford's sorely missed knowledge, I would think the GAU-8's abilities are due to finding weak spots rather than the odd chance of impacting in a previous hit. With the rate of fire, the barrel movement, aircraft vibration, etc., the odds of hitting the same spot twice seem remote. But, spraying a hundred or two rounds of penetrating anti-armor rounds against a tank's engine deck seems a surefire method of destroying the engine and possibly igniting it. There may well be some penetration of the fighting compartment as well.

To me, it's the top attack/rear attack aspect coupled with the weight of fire which produces the kills.

Regards,

Ken

[Apocal]

I don't think A-10s in real life go for very steep dives to increase penetration.

Decreased range dispersion and staying out of the envelope of gun-based antiaircraft defenses are two other great reasons. The shallow, three degree attack angle of the early Hog was the result of breaking down Soviet air defenses and seeing that missiles constituted a greater threat than guns. So they were flying low (100-500ft AGL), below the effective envelope of SAMs, and using correspondingly shallow attack angles.

Since we've proven pretty good at taming the SAM threat, the A-10s should be able to use high-altitude, high(er) angle dive attacks as they did historically in ODS and OIF I.

Remember that just because you hit the roof doesn't mean you hit it at a suitable angle. You can always hit the roof as long as you fly higher than the tank drives, but the angle is the issue.

That's true, but you figure a one second burst gives you sixty chances to get lucky. And the top of the rear deck, holding fuel tanks, exhausts, engine, etc. isn't greatly protected by any stretch of the imagination.

[Redwolf]

All good points but if you want to spray a burst just along the rear deck then that also limits you to a simple angle of attack. That angle might not be available due to terrain features or enemy AA units. A smart enemy unit might also position itself to protect the rear of their tanks.

In practice I think that most A-10 gun burst will go over the tank from any random angle that happened to look least dangerous to fly. Not too different from ground units.

That's the reason why these things carry ATGMs. Wrong angle? Too far? Just blow the whole thing up.

But it's not realistic to always align the gun with a burst along the engine deck.

[rune]

Guys,

I know Apocal is Air farce [grin], but going to add some things he may not know. The A-10 gun was designed to attack at a 30 degree dive, obviously it can do more or less, but that is the optimal angle.

During the invasion of Iraq, it is quite the opposite of what Apocal states. Talked to many warthog drivers, and they were not allowed to get below a ceratin altitude in general. [Of course there were and are exceptions] The guns were fired at long range, and many times failed to destroy the targets. Add in the factor that mavericks were also used, the target was not considered destroyed unless high volumes of smoke, and the friendly tanks on the ground shot at anything that even looked intact, the amount of gun kills really isn't known. A gun run from the front generally would NOT take out a T-62 during trials of the gun. This was countered by attacking from the sides or rear of the tank.

3900 rounds per second [the a-10 no longer has a switch for different speeds for the gun] the first second of the gun not as many rounds are fired as the speed of the gun winds up. however, enougth rounds on the deck is going to mobility kill any modern tank, however a lot of reports of tank smouldering were reported, which were not counted for kills.

For what it is worth.

Rune

[Apocal]

During the invasion of Iraq, it is quite the opposite of what Apocal states.

I think you mixed up my first paragraph, where I was describing tactics for a hypothetical WW3, with the second, when I was describing what actually happened in ODS/OIF I.

Other than that, right on.

In practice I think that most A-10 gun burst will go over the tank from any random angle that happened to look least dangerous to fly. Not too different from ground units.

Troops in contact CAS (type I and II) the controller specifies a run-in heading, generally perpendicular to the troops closest to the target.

[rune]

Apocal,

I saw, what I meant, and it came out badly [apologies] is they did do it in OIF, but did not do it in the invasion of Iraq. I talked with several warthog drivers, and felt their frustration at having to fire the gun at long range. Add into it the lack of night vision [the upgrades are fixing this issue, if not already fixed], and there were some unhappy pilots. Some of the work arounds were ingenious [working in pairs with one using the ir of the maverick].

Did they ever finish repainting allt he warthogs to grey? I know the dark green was considered a possibile reason of a couple losses.

For others keeping score, the OA-10 is basically the same thing as the regular a-10, but equiped with more smoke hydras to mark targets.

Rune