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Comment by jug6ernaut | Hacker News Reader

While off topic, i found this interesting bit of information on the a10's gun wiki page.

"The recoil force of the GAU-8/A[16] is 10,000 pounds-force (45 kN),[3] which is slightly more than the output of one of the A-10's two TF34 engines (9,065 lbf / 40.3 kN each).[17] While this recoil force is significant, in practice cannon fire only slows the aircraft a few miles per hour in level flight."

The gun firing produces more force through recoil on the plane then is produced by one of the plane's engines. That is simply amazing.

Edit: The guns wiki page(it has a wiki page).

http://en.wikipedia.org/wiki/GAU-8_Avenger

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It's also mentioned in an XKCD "what if":

https://what-if.xkcd.com/21/

> The GAU-8 Avenger fires up to sixty one-pound bullets a second. It produces almost five tons of recoil force, which is crazy considering that it’s mounted in a type of plane (the A-10 “Warthog”) whose two engines produce only four tons of thrust each. If you put two of them in one aircraft, and fired both guns forward while opening up the throttle, the guns would win and you’d accelerate backward.

> To put it another way: If I mounted a GAU-8 on my car, put the car in neutral, and started firing backward from a standstill, I would be breaking the interstate speed limit in less than three seconds.

More likely, you would have a cabrio in 1.62 seconds.

you mean you'd have to cut off the roof to mount it?

http://i.imgur.com/CFtOzAD.jpg

;)

And make sure everyone was clear of the 'exhaust' for a few miles.

When you (jokingly, obviously) mention mounting it on a car, does this imply that you think the gun is mounted on the A-10?

When we look at cutaway drawings of the A-10, we see that it's almost more like the A-10 is mounted on the GAU-8 Avenger. Seriously, it's a pretty major part of the fuselage!

http://www.foodman123.com/cut42.jpg http://img143.imageshack.us/img143/5306/v38136usa10fairchild...

The next part is the funniest though...

As good as this gun would be as a rocket pack engine, the Russians built one that would work even better. The Gryazev-Shipunov GSh-6-30 weighs half as much as the GAU-8 and has an even higher fire rate. Its thrust-to-weight ratio approaches 40, which means if you pointed one at the ground and fired, not only would it take off in a rapidly expanding spray of deadly metal fragments, but you would experience 40 gees of acceleration. This is way too much. In fact, even when it was firmly mounted in an aircraft, the acceleration was a problem:

[T]he recoil … still had a tendency to inflict damage on the aircraft. The rate of fire was reduced to 4,000 rounds a minute but it didn't help much. Landing lights almost always broke after firing … Firing more than about 30 rounds in a burst was asking for trouble from overheating …

But if you somehow braced the human rider, made the craft strong enough to survive the acceleration, wrapped it in an aerodynamic shell, and made sure it was adequately cooled... ... with a GSH-6-30, you could jump mountains.

The A-10 is a truly amazing airplane, in large part due to the main gun, and has proved its usefulness again and again in real combat situations. Its extended air-to-ground capabilities (which are the vast majority of our air power needs in modern warfare) are unmatched by any other plane or chopper on the armed forces, and for all that it was a remarkably inexpensive plane to build. But despite all that, no new A-10s have been produced in 20 years, they're being retired at the rate of two each month, and the Air Force wants to replace them with the debacle that is the F-35.

The A-10 is extremely vulnerable to man-portable air defense systems (MANPADs), which are difficult to spot and nearly impossible to avoid at the low altitudes within which the A-10 best performs. MANPADs are more and more common on the modern battlefield, and the supply exploded after the 2011 Libyan Civil War. Furthermore, the GAU-8, while an impressive weapon, doesn't hold its own against any tank built within the last twenty years. This leaves the A-10 as a slow, unstealthy delivery platform for AGM-65 Maverick missiles and JDAMs, a role better performed by higher-performance aircraft.

I say all that as a huge fan of the A-10c, with many hours spent in the DCS sim. People seem to get bizarrely hyperbolic over the capabilities of this plane, but it's really a dinosaur.

The A-10 is extremely vulnerable to man-portable air defense systems (MANPADs), which are difficult to spot and nearly impossible to avoid at the low altitudes within which the A-10 best performs.

How about building a ground support platform that can deal with this? Apparently, the Army has tried with helicopters with instrument pods above their rotors, so they can target enemies from behind cover. Perhaps the solution will be many small drones taking the place of one manned aircraft.

A-10s have a missile warning system that is tied directly to the flare dispenser.

Thanks for this. I don't see why people think 30 mm slugs are effective against tanks designed to resist 120 mm penetrators or shaped charges, including top armor hits. And simply enduring battle damage is insane against modern MANPADS with large warheads. The A-10, along with the B-17, is one of the most over-romanticized aircraft of all time.

Yep, the A-10c can take a real beating, but there's a huge gap between combat readiness and limping back to base for expensive repairs, assuming you survive the initial SAM strike. Much better to never be hit (or even seen!) in the first place.

Uh huh. You're saying this based on how many deployments?

Jeez. Tanks?

You're neglecting one of the most valuable roles for the A-10: close air support for ground troops in contact.

In that situation (read: the entirety of our conflict in Afghanistan/Iraq) tanks had NO ROLE. You're fighting a highly mobile ground force that often have an armament/position advantage and that's where the A-10 CAS really really makes a difference. Nobody fought TANKS in Afghanistan.

Ask anyone who's been in contact with the enemy how they feel when they hear that distinctive "BRRRRRRRAAAAAP!"

It's like FSCKING CHRISTMAS.

This, right here.

Doing close air support you want A-10 pilots or Marines.

I think this needs illustration: http://www.youtube.com/watch?v=xuYmn_xYB78

My father worked on A-10s in the Air Guard, I thought was very familiar with them... but it wasn't really until I saw that video that I realized how terrifying they are in the appropriate situation. While the above video is a friendly-fire close call, you're probably not going to find video like that from the other side of the line.

Thanks for posting that video. Very informative!

Wow, it sounds just like a dragon's roar there. It must have a hell of an effect on morale...

When the Air Force first wanted to retire the A-10, there was an article [1] proposal: Give the A-10s to the Marine Corps.

Even if the machine could not be retrofitted for carrier operations, the Corps could fly them from airfields ashore, and would really value an excellent ground-attack aircraft, and would take good extra-special care of them.

[1] in the Marine Corps Gazette I think.

What about the depleted uranium bullits the A-10 uses? I read they are are threat to friendly ground forces when they cross the fields the A-10 fired up on? Targets hit by the A-10 basically become biohazard... http://en.wikipedia.org/wiki/Depleted_uranium

Ask a soldier or Marine if they'd make that trade. Dead now or dead much much later?

The A-10 can fire lead ammo as well. The uranium stuff is only needed for tank armour.

Yeah, apparently the problem with using high speed jets if they can't hang out close to look out the window and figure which people are the bad guys. Helicopters are too lightly armoured and get shot down and current drones are a bit lightly armed to hold off loads of enemy troops. Maybe in the future when the drones are more like http://youtu.be/zjympX1bxI4?t=18s retiring the A10 would make sense

The problem isn't the drone airframe. It's taking the person OUT of the airframe.

Having that pilot in that seat removes the need to replicate the kind of situational awareness you have when you're flying your plane 100-1000 feet off the ground and making passes to identify who is who so you avoid a friendly fire incident. Until we have the kind of immersive, low-latency, realtime kind of virtual reality you'd need, using drones for CAS is a pipe-dream.

Yes, the A-10 is outdated and couldn't tear through the armor of a modern tank like it could to the tanks of Yore. But you also need to remember that the chain breaks at its weakest link. A strafing run from the GAU-8 will absolutely shred the tracks, gun, and exterior sensors of anything it comes near. Sure the crew might live through the concussions and blunt force trauma, but that vehicle is no longer in the fight.

Sometimes an M-Kill is better than destroying the entire thing because you can target support troops when they bring in a wrecker.

Most assmetric warfare in current theatres is not fought against tanks of the caliber of the modern western main battle tanks. Until these types of conflicts are unlikely, I don't see why you would prefer an f-35 in CAS vs a comination of A10s and (if really a problem) drones or F16s.

Yeah but that good Armour is on the front of the tank - you know the bit thats radically sloped.

The top of a tank not so much and if you blow a track of that's a mobility kill - almost as good as a full brew up.

>I don't see why people think 30 mm slugs are effective against tanks designed to resist 120 mm penetrators or shaped charges, including top armor hits.

Because tanks only have that sort of armour on their frontal aspect and turret sides, and the top armour is very thin. Even if the turret top is armoured enough it is likely the engine deck can be penetrated and produce a mobility kill.

Also, hardly anyone besides the US and extremely close allies has ultra-modern tanks like late series Abrams or the Challenger II (and I have seen no evidence that those tanks are immune to the GAU-8).

P.S. There are also cheap ways to reduce shape charge effectiveness that don't work against solid penetrators. Things like the TUSK upgrade are designed to defeat RPGs not 30mm cannon.

Well yes. Of course 30mm rounds are effective against tanks. It's simply a matter of how MANY you throw at the beast. At 3,000 rounds/minute you can hit the tank up real good.

Secondly, not every enemy has the latest tank. In fact, most potentially hostile nations (speaking from the POV of NATO) do NOT have modern tanks.

it's not just the caliber of the ammo, it's also the velocity. I'm certainly not an expert, but I did my military service in a base used for tank training. Back then, it was already a done deal : no armor could resist the amount of energy released by anti-tank ordnance, in particular kinetic penetrators. I've seen up close old tanks which were used for training. On the entry side of the impact you have a perfectly cut circular hole a few cm in diameter, with slits all around like petal flowers. On the exit side you have a big open tear. In between, there was a jet stream of molten metal. Bottom line : a spotted tank is a dead tank.

That was a fairly long time ago, but unless armor has made huge progress since then, producing something hard enough to deflect this kind of force and yet light enough that the tank can move, I'd still bet on an A10 against anything rolling on the ground.

I'll keep track of all this for the next time I play Civilizations.

When was the last time an A-10 was shot down by a MANPAD? And what is your proof that it is ineffective against modern tanks?

I ask as an actual A-10C pilot, with many more hours flying it than you have in a "sim".

When was the last time an A-10 was shot down in air-to-air combat? Never? They must be unstoppable!

But, seriously, there's that old saying: the only way to bring down an A-10 is to put a suicidal pilot in the cockpit.

Do you know anything about changes in tactics related to MANPAD threats, then? I read some about the Soviet war in Afghanistan, where we supplied MANPADs to the rebels for use against Soviet helicopters. Reportedly, they didn't actually shoot down very many helicopters, but they were very effective in that the threat of them forced the helicopters to engage from much further away from the battle and move at higher speeds to limit their vulnerability, but also limiting their effectiveness.

I wonder if there has been an affect like that on the A10s. And I wonder if anybody who knows is actually allowed to tell us.

They can also take an incredible amount of damage, to the point of being able to be brought back to base missing one of the wings.

No An A-10 has successfully returned to base with half of one wing missing. Big difference. It's not the only plane to claim this (notably, the B-17).

Also, an Israeli F-15 flew back to base after having one entire wing sheared off in a mid-air collision.

http://skeptics.stackexchange.com/questions/9884/did-an-f-15...

An F-8 Crusader Navy jet could take off with its wings still folded, then come around and land again.

http://en.wikipedia.org/wiki/Vought_F-8_Crusader#Operational...

(Search for "wings folded". I like the part about the pilot complaining that the controls felt "heavy.")

On a truck? No A-10 can fly while missing an entire wing. :)

http://www.youtube.com/watch?v=1BecNTYPYbU

This one came back with bullet holes, but still had both wings.

Forgive my ignorance. I thought the AC-130 was starting to fill more of the A-10 roles given a lack of enemy fighter aircraft in recent conflicts and the desire to carry more armaments.

Quoting my own comment from another subtree below. AC-130s circle low and slow, and cannot maneuver quickly, which makes them very very good SAM targets.

After an AC-130 was shot down in Iraq, they only fly at night.

I am sort of thinking that someone in the pentagon is thinking drones for the future of this type of mission...

Guns producing more recoil than an aircraft's powertrain is nothing new. In WW2 fighters would be slowed when firing larger calibre weapons, noticeably impacting airspeed, especially with repeated firing.

http://www.ww2aircraft.net/forum/aviation/can-gun-recoil-rea...

There is a difference between just slowing the craft and producing recoil force on the same order as the engines. If a plane is flying at a constant speed, then its in equilibrium. The engines are producing an equal amount of thrust to the amount of drag on the plane. Any recoil force will upset this and slow the plane down. This doesnt mean that they are producing more force than the powertrain.

The A10 doesnt do this either of course. It produces more recoil force than one engine, but not both.

Guns producing more recoil than an aircraft's powertrain is nothing new.

Yes, but AFAIK, the A-10 is the only plane that was designed by starting with a BFG, then building a plane around it.

Upvoted for the elegant use of "BFG."

Sometimes "elegant" == "obvious"

You are forgetting the Bell P-39 Aircobra and P-63 King Cobra, both airframes designed around their cannon.

Ah, yeah, though I wasn't aware they really did start with the particular gun and work their out. Ok, yeah, they even had the specific gun in mind! The Oldsmobile T9 Cannon, you learn something new everyday!

http://en.wikipedia.org/wiki/Bell_P-39_Airacobra#Circular_Pr...

This part is interesting too :

The A-10 engines were initially susceptible to flameout when subjected to gases generated in the firing of the gun. When the GAU-8 is being fired, the smoke from the gun can make the engines stop, and this did occur during initial flight testing. Gun exhaust is essentially oxygen-free, and is certainly capable of causing flame-outs of gas turbines. The A-10 engines now have a self-sustaining combustion section. When the gun is fired the igniters come on to reduce the possibility of a flame-out.

Used for propulsion, the GAU-8 would run out of "fuel" after only 18 seconds, and would burn out its barrels after 5 minutes.

Yes, yes, but what a glorious 18 seconds!

At top speed, the Bugatti Veyron's tires only last 15 minutes. But that's OK, because the fuel tank only lasts 12 minutes.

This reminded me of driving the tanks in the video game Grand Theft Auto, Vice City. If you wanted to go faster, a good option was to turn the turret backwards and fire.

I remember seeing the gun at air shows as a kid. It was fascinating.

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