Friday, June 24, 2011

That's not a gun, this is a gun.

Everybody at Robb's place the other day was swooning over the GAU-8 Avenger, the famous 30mm tank-busting cannon around which they built A-10 Warthogs. It fires a projectile weighing just less than a pound at some 3,500fps, giving it a muzzle energy of 178,427 ft/lbs. Also, its high rate of fire corrects the biggest shortcoming of the previous super-heavy U.S. aircraft champ (forward-firing division*), the 75mm T13 on the B-25 Mitchell, which chugged out its 16lb/2300fps shells so slowly that only a couple could be gotten off on a single strafing run.

Of course, compared to the Army's 120mm M256, flying cannons are mere popguns. The depleted uranium long-rod penetrator from the main gun of an Abrams weighs the next thing to 18 pounds and is tooling along at 5500 ft/sec or so.

Let's see... 18 pounds is... 126,000 grains... at fifty-five-hundred feet a second, that comes to... umm... carry the one...

About 8,465,485 foot pounds of muzzle energy, which is definitely going to make Major.

All of these, though, are small potatoes when compared to the now-sadly-extinct Mark 7 16"/50 caliber Naval Rifle, which accelerated a 2,700lb projectile to twenty five hundred feet a second in the length of its 66-foot-long barrel. (What's a minute of angle at 32,000 yards?)

50 comments:

Retardo said...

Minute-of-Akagi, you mean?

Keads said...

If the Mk7 was loaded with the Mark 23 shell, MOA was much more forgiving!

Tasso said...

And sumdood in an air conditioned bunker just ran through his checklist on a Minuteman III -- 800 lb RV at 22000 fps and a little extra umph at the last nanosecond just to settle the argument.

There's always a bigger gun.

Joseph said...

A-10 < Battle ships, just sayin'

Also, how could you not mention the AC-130 that packs a 105mm M102?

Free-range Oyster said...

1 MOA @ 32,000 yards = about 28 feet

Anonymous said...

MOA at 32000 yards if your receiving? not enough :D

Rabbit said...

They're surplussing a bunch of 16 inch tubes as surplus scrap.

Homebuilt job, anyone?

http://www.govliquidation.com/auction/view?id=4363825&convertTo=USD

New Jovian Thunderbolt said...

How many ft/lbs to you need to launch a bad guy back through a plate glass picture window to look really cool in front of the movie camera?

CTone said...

"1 MOA @ 32,000 yards = about 28 feet"

And the casualty radius of a 16" shell has to be 150 yards or more. That's some serious precision, all things considered.

Anonymous said...

120mm Abrams gun is more like a 5 mile sniper. The fire control tables automatically count each round fired and compute in the barrel wear. Since holding the line at Fulda Gap, the biggest complaint about the Abrams main gun has been "over penetration". Nothing else moves as fast while shooting as accurately while weighing 60+ tons. The Abrams makes tank warfare look boring.

Jake (formerly Riposte3) said...

I'm waiting for these.

They got 33MJ (24,339,550 foot pounds) in the last test. An earlier test hit 10.64MJ by accelerating a 3.2KG projectile to just over Mach 7.

Aaron M Brown said...

I did some quick conversions via Wolfram Alpha. The muzzle energy from that Abrams is 3.188 kilowatt-hours. Wolfram Alpha tells me that this is about $0.25 worth of energy in my market. (Link: http://www.wolframalpha.com/input/?i=8%2C465%2C485+foot+pounds+to+kilowatt-hours)

It's also enough energy to run my television for four and a half hours.

Or to run 32 earth-slaying, 100-watt incandescent bulbs for an hour.

And that's generated in a fraction of a second every time the Abrams fires its main gun. Pretty damned cool.

Mojo said...

The feed mechanism on the GAU-8 is a piece of crap. Whenever A-10's were around it was guaranteed that at least 1 plane out of a 4 ship would come back from every sortie Code 3 (Zoomie speak for seriously broke) for "hung gun". One particularly nasty incident during monsoon season at Osan AB a few years back saw the 25th FS with 6 hung guns out of 12 operational aircraft.

Anonymous said...

Yamato class battleships had 18.1 inch guns, surpassing the U.S., and the British were planning on 20 inchers. But the all time champ of guns that have actually been used in combat: the German Schwerer Gustav. It fired a 7 tonne projectile at 2700 fps. from its 80cm. (31 in.) barrel.

Wayne said...

The Navy railgun project is on the chopping block, along with a free-electron laser project.

perlhaqr said...

a 2,700lb projectile to twenty five hundred feet a second in the length of its 66-foot-long barrel

Spinal mount on a 747, anyone? :D

staghounds said...

The best description of naval gun capability comes from C. S. Forester.

"Hit a tennis court from twenty miles away."

I know it understates the accuracy, but it is a very clear image.

Anonymous said...

I seem to remember they once hooked up end to end a couple of 16" barrels and sent a projectile into earth orbit.

Ed Foster said...

They really do shoot minute of angle. So does the Abrams 120mm. And the Marine Corps wants the battleships back as fire support, and is willing to give up a regiment to finance it.

Which is why Congress is holding two New Jersey class battleships in mothballs. The carrier admirals are dragging their feet, but it might happen yet.

Nine 16 inch shells detonating at 100 yards above ground level, spaced evenly across a square half mile on a side, equals the same overpressure as a tactical nuke, with none of that annoying radiation stuff.

Old NFO said...

Ed is correct on ALL counts... :-) And if you ever saw a full up broadside, it was IMPRESSIVE!!!

Stretch said...

Uncle Jim was at Chosen. The two most valued people? Corpsmen and Navy Forward Observers.
Once within 20 miles of the shore the FOs came into their own.
Uncle Jim saw a single broadside destroy a ChiCom Division. What few Chinese made it back to their own lines made sure the rest kept knew to keep 20 miles away from the shore.

The Iowa and Wisconsin would make short work of pirates, training cams, Yemen ...

Drang said...

I knew a guy who was Armoered Cav in The Nam during The Tet. Was trying to get someone who could spare a tube or two to fire a desperately needed mission. Everyone was booked up. Suddenly a voice came up with "I can fire that, shot, over."
"Shot out"
"Shot out."
"shot out."
WTF?
"Splash, over."
"Splash, ou..."
BAM!
"WHO THE HELL ARE YOU, ANYWAY?!"
And you all already know the next line, don't you?
"BB62, gave a nice day."

of course, an earlier (by a couple of years) post by Tamara about believing war stories applies...

Desertrat said...

A USMC described a salvo from the Mizzou as, "Hill 350 became Hill 300."

Lanius said...

Battleships may seem impressive, but aren't fuel-air explosive multiple rocket launchers more cost effective at delivering overpressure..?

http://www.youtube.com/watch?v=QqdryWA7tTU

Russkies levelled Grozny with a couple of batteries of those.

Anonymous said...

The Mk7 isn't extinct. It's just sleeping.

Robin said...

Visiting the Normandy invasion beaches, you can see the rusted out gun positions at Longue Sur Mer. There a US cruiser dueled a battery of coastal guns in concrete emplacements. The shell hits on the emplacements and gun shields from what were I think six inch guns are visible. And if you imagine having to stand there and service the guns while receiving incoming, quite disturbing.

Anonymous said...

Heh.

Don't they have fully automatic 8" naval gun turrets that can do something in the 20-30 rpm these days? ( at least until the barrel melts)

And with all the electronics, ranging and correcting software basically drop them into a garbage skip from 30miles, from a moving ship, in heavy weather, in driving rain?

And with variable trajectory you could time-on-target-as-makes-no difference an appalling number of them.

I recall a slightly smaller gun than that, in trials, having the observers call back that, once the smoke cleared and the crud fell to the ground, that quite frankly "it's the firehose of death" effectiveness was judged 100% the target bunkers, dug in armoured vehicles and entrenchment system had simply ceased to exist.

They were firing extreme range, in horrid weather.

Anonymous said...

Drang, my CSM was an Americal 11B. He told the tale of getting his first PH. They were calling in NGF and like an idiot he stood up to watch the impact as he had no clue what a 16 inch projo would do. IIRC, impact was half a klick away and his wounds were from debris.

Al T.

Tam said...

Of course, the bursting charge on the 16" HE shell was 154 lbs (out of a 1900-lb shell) whereas a Mk.84 with a JDAM kit has almost 950 lbs of explosives and a TLAM packs a 1,000 lb warhead and both are way more accurate than even the best battleship salvos...

Ed Foster said...

The primary advantage of tube artillery is cost per shot and repeat fire. $500 buys you a 16 inch shell, $4500 buys you a broadside, and you can engage targets all day with the same launcher.

Rockets and bombs need expensive delivery systems. Expensive as in 10,000% to 100,000% more per comparable bang. The rocket carries it's delivery system to the target and wastes it, and aircraft get shot down easier and easier nowadays.

Try to stop a spin stabilized ton or ton-and-a-half (AP) projo with even the most accurate burst of 20mm or 75mm. Spitting into the wind.

Even the old "dumb" shells have incredible penetration, capable of screwing themselves dozens of yards into tight packed earth and/or concrete before torching off.

With modern micro explosives (about 4 to 5 times more powerful than TNT), and a dedicated support round packing a ton of nasty inside the AP shell's 2,800 pound profile, there would be less and less need for the more than half million dollar Tomahawk missle.

Cut the charge of OMC or HMX explosive to a half ton and stick in a rocket motor. All the development work was done by the Navy 20 years ago on the SALVO 8 inch project.

Add terminal guidance and you have 100 shots (5 or 6 grand apiece) on targets out to 120 miles, for the cost of a single Tomahawk, and they can't get shot down or spoofed.

As the AAA environment becomes more and more difficult to penetrate, tube artillery makes more and more sense.

If that tube artillery is housed abord the most survivable floating platform in the world, which is also doubling as a command ship (old Navy line, "admirals weigh 50 tons"), we get even more bang for our buck.

Ed Foster said...

Not to mention (but I am, aren't I) anti-aircraft capabilities of a dedicated AAA shell. Picture 9 tons of OMC, spaced a hundred yards apart vertically and horizontally, going off in front of an attacking element of Backfires, 15 or 20 miles from the target.

Considering the very real and growing Chinese threat to our carriers, an extra and mostly foolproof layer between them and the Chinese Backfires might not be amiss.

Lanius said...


The primary advantage of tube artillery is cost per shot and repeat fire. $500 buys you a 16 inch shell, $4500 buys you a broadside, and you can engage targets all day with the same launcher.

That's actually a disadvantage.

To Raytheon's bottom line, but what's good for the syndicate is good for the military.. and that's how it'll always be ;-)

Ed Foster said...

Lanius, far too true. I can see the military wanting to maintain what's left of it's manufacturing base (of which I am a part), but sometimes they can get rediculous.

And, sadly, there are those (you know who you are over there at Colt's) who are looking to feather their bed after retirement.

What bothers me most is that even the military admits they could skin a hundred billion out of their budget tomorrow, if they didn't have to buy all the crap Congress forces on them.

Airfields too short to land fixed wing aircraft, forced buy lots of200 planes when they need 86, et cetera et ad nausium.

All to keep Congress-Critters in office, by their being able to say "Look at all the work I brought into the district". After their signing off on an equal amount of makework in every other Congressional district.

Sigman said...

My Dad was on the Wisconsin in Korea. He told me that a broadside salvo of all three turrets would push the ship (over 1000' long) 6feet SIDEWAYS. Talk about recoil!

Anonymous said...

A couple of other points;
16" shells come in both armor piercing and a general purpose blow things up round. They also don't make them anymore and the stock isn't what it once was.
Also those guns are the worlds biggest black powder rifles, since that's what they use for propellant.
Once read that ONE
Iowa class BB could deliver more ordnance on a coastal target than round the clock operations from all the carriers combined.
Having once seen the Iowa come in through the Golden Gate at 2 in the morning under lights and water cannon with thousands of people lining the shores I can say it's a damn impressive sight. We need them back - if just for that.

Ed Foster said...

'Nony: They call it black powder because it's black in color, but it's actually a controlled burn smokeless of huge individual grain size. You couldn't get those kind of velocities out of traditional black powder. A questionable bit of nomenclature on the government's part.

Sigman: My cousin Gene Devaux was portside secondary batteries firecontrolman on the Whiskey from '57 to '61. When did your dad get out?

Tam said...

Sigman,

Actually, that's a sea story. Even a full nine gun broadside had no measurable effect on the ship's position in the water. (See interminable geeky physics discussion here.)

Tam said...

Trivial pursuit answer: A full warshot used 660 lbs of powder.

Ed Foster said...

My cousin Gene told me that it was considered poor form to try a trailing shot (with a turret pointing more than 90 degrees off centerline). Seems it didn't bother the guys in the turrets, but the folks below in the loading spaces were more than bummed when the rivets started bouncing around.

He was in a Mark 37 firecontrol mount running the 5 inch 38's on the portside, but got to fire the big guns from his station several times a year.

We have a cute picture he took of the forward turrets opening fire. He was hanging in the hatch of his mount snapping the picture when things went bang and he fetched up quite a bit below. It's blurry and jangled, but hell for leather colorful.

Interestingly, one of his 5 inch mounts broke the stop while traversing on a towed sleeve during AA drill and took off part of the bridge.

Some folks have all the fun.

Anonymous said...

Lanius wrote
That's actually a disadvantage.

To Raytheon's bottom line, but what's good for the syndicate is good for the military.. and that's how it'll always be ;-)


Huh, shows what you know. Raytheon also produces tank & arty rounds. They are likely agnostic about which Raytheon product you use to whack the enemy: fewer missiles, more arty rounds. It's all good.

SoupOrMan said...

My only question is "How do we get the Mk256 onto a forward-firing hardpoint for an airframe? Or better, two of them for strafing runs?" Who could build an airframe that could handle that much recoil?

Then again, I see all the T-37s in the Boneyard and think "You could set a couple of ANG units up with A-37s for border defense/COIN roles." You can do that with drones, too, I suppose, but they can't always carry the direct firepower needed.

Sigman said...

Hi Ed, he was on 51-55. I took him to see her at Norfolk a few years before he passed. As soon as he saw her, he stood straighter and quietly looked at her for a long time. As we walked the decks, he pointed out where AA mounts used to be and the twin 5" mounts that were removed for the tomahawk batteries. He often told me his time aboard were the best of his life. While there we took the harbor tour. If I was a young Marine about to invade a hostile shore and I had my choice of several modern ships with the single automatic cannon or a battleship alone I'd take the battleship.

Larry said...

"and both are way more accurate than even the best battleship salvos..."
but nowhere near as impressive.

Colorado Joe said...

My uncle was crew chief on the first live fire flight of what later became the B-25H (75mm cannon) during his second tour in WWII.

On the first test, they fired the weapon as planned, but then had to RTB because of control problems with the aircraft. When they landed, they discovered that the recoil had "wrinkled" the airframe just behind the wingroots, shortening the aircraft enough to cause slack in the control cables leading to the tail. The airframe was a total loss.

Lanius said...

@Anonymous C..

But no doubt more can be charged for producing guided missiles than dumb artillery rounds.
Higher revenue possible there, I bet.

Anyone thinks ^ is not true?

Tam said...

Considering you'd need to produce more shells to do the same job, I think it would probably be a wash.

Bram said...

Anonymous above mentioned the Des Moines class cruisers.

They sported 9 8-inch auto-cannons. Each cannon capable of firing seven shots a minute. Do the math. Ringo had some fun with them.

Anonymous said...

" Ed Foster said...
My cousin Gene told me that it was considered poor form to try a trailing shot (with a turret pointing more than 90 degrees off centerline). Seems it didn't bother the guys in the turrets, but the folks below in the loading spaces were more than bummed when the rivets started bouncing around."

The USS Texas (in Houston) has a "hard hat tour". You can see the forward and aft crew heads. THe forward crew head still has nice ceramic tile. The aft tile is broken and cracked. The tour guide said this was when they fired the 14" guns over the stern. It cracked the tile.

Sigivald said...

Wasn't/isn't the winner (in terms of operationally used "big", if not "big and FAST") still the 105mm M102 on the AC-130E/H/U?

(I can't imagine it loaded particular slower than that 75mm in the B-25...)

Sigivald said...

(Also, I see Joseph beat me to it. Which irks, because I swear I actually looked at the comments first to see if someone had.

But of course, how could I notice that BEFORE posting?)