16" Naval Gun; Two 16-Shot Groups. Accurate?

[Bart B.]

Naval gun barrel "caliber" is its number multiplied by projectile diameter in inches. 16 inches times 50 calibers equals 800 inches of barrel length.

The liner gets stretched from projectile friction and sticks out the muzzle a half inch every some dozen rounds. A huge "crowning" tool was clamped on the barrel then turned it off flush with the main pressure tubes. If not done, that liner would crack and break chunks off causing poor accuracy.

 

[Kaeto]

Caliber is the length of the barrel in increments of bore diameter. EXE: 16"/50 is the barrel length is 50 times the bore.

 

[salt&battery]

Actually, the explosive (or "bursting") charge in a 16" Mark 8 cannon shell was no more than 153 pounds of HE. The HC, or high capacity, shell, weighed 1900 pounds, with 153 pounds of explosive. At max range of 37,000 yards, it could leave a crater 50 feet across and 20 feet deep, and the lethal radius for concussion and shrapnel was over 300 feet. HC rounds were used for soft target shore bombardment (vehicles, personnel and unarmored structures) AP, or armor piercing shells weighed 2700 pounds, with a bursting charge of only 41 pounds of HE. At 35,000 yards, they could penetrate 30 feet of reinforced concrete, or 14 inches of steel armor plating. Much of their destructive force was the kinetic energy of their mass, travelling over 2000 feet per second (muzzle velocity was 2700 fps, and the shells were actually accelerating from their ballistic apex after slowing to below 2000 fps (max range). AP shells were used against hardened shore targets and other ships.

As for accuracy, a salvo of shells didn't really need to hit close to each other to create widespread damage, but for the technology of the day, and at the ranges fired, they were quite accurate with good forward artillery spotting. At max range, these guns were shooting beyond the visible horizon, so the gun directors aboard ship were essentially useless, and the aiming depended on ballistics tables and shore-directed fire or spotter aircraft. At closer ranges, within line-of-sight, they were very accurate. Ship's motion was accounted for, the guns were stabilized much like the main gun on the M1 Abrams, and could maintain aim while the ship rolled and pitched. The difficulty in hitting a moving ship from another moving ship was complicated in part by the travel time over the distances the guns were fired. At max range, travel time could be in excess of one and a half minutes. At even half this distance, ships could maneuver quickly enough to make precise targeting difficult.

I took this information directly from the definitive text on the USS North Carolina, written by her chief intelligence officer, who served aboard her the entire war. The North Carolina and South Dakota class ships mounted Mark 7 16 in/45 caliber guns, where the Iowa class had the Mark 8 16 in/50 caliber guns. They both fired the same type shells, but the longer barrels of the 50 caliber guns gave slightly greater velocity and range.

all of that sounds real good but when in practice like WWI where millions of shells fired for days non stop did not do much at all as the ones bombed came out of makeshift dugouts and repulsed the enemy. same as the islands like iwo jima etc bombed for days with not much effect. at the Dardanelles in WWI british navy tried to pulverize the forts holding the straits before landing troops and were mowed down upon landing.
it seems like a good way to waste money for little in return which most militaries excel at

 

[JohnMc]

I think the Bizmarck being disabled by an obsolete aircraft marked the beginning of the end of battle ships

IIRC, that aircraft's torpedo hit the rudder and messed up the Bismark's turning ability, it was actually scuttled by its crew after a pounding by traditional naval gunnery.
Billy Mitchell's sinking of WWI battleships in the 1920's, albeit with some controversy, signaled the end of the battleship, IMHO.
The sinking of the Roma in 1943, by a single guided bomb dropped from a Do-217 put any argument to rest.

 

[mjsdwash]

IIRC, that aircraft's torpedo hit the rudder and messed up the Bismark's turning ability, it was actually scuttled by its crew after a pounding by traditional naval gunnery.
Billy Mitchell's sinking of WWI battleships in the 1920's, albeit with some controversy, signaled the end of the battleship, IMHO.
The sinking of the Roma in 1943, by a single guided bomb dropped from a Do-217 put any argument to rest.

sure enough. In any case, the idea a single aircraft, could destroy the greatest war weapon of the millennium, really ended it. Strange though, at this point, with the enemies we face in most conflicts, the battle ship could still be useful. We're not exactly fighting on equal terms these days, and a single battleship could defend an extensive cost. Oh well, we can do it with destroyers too.

 

[Sunray]

Lack of accuracy is kind of a misnomer considering close range for a 16" gun is 18 km away. And it hits a moving target that's approximately 108 feet x 887 feet(Iowa). Those HE craters are about 50 feet wide and 20 feet deep. And could defoliate trees 400 yards from the POI.
Battleship were decommissioned because of their age, the cost to operate 'em and the lack of personnel.

 

[jim in Anchorage]

Here is a training film on the 16" Battleship guns showing how they were loaded and fired.

Watching that loading ramp slam up and down made me wonder how many gruesome accidents it caused. Not a job to show up drunk for.
Also watching those guys loading the powder bags made my back hurt bad.

 

[Merle1]

Turret captain of New Jersey's no. 2 turret told me blast zone in Vietnam jungles defoliate trees over 50 yards from high capacity rounds detonation point. Had lunch with him on board in 1968. He mentioned those hi caps were sometimes used to clear a landing site for helicopter missions.

But the gun barrels are virtually still in space.

A gyroscope gave ship roll and pitch angles via gear train to the mechanical computer calculating deck plane gun train and elevation angles electrically sent to turrets compensating for ship motion. Gun angles were kept within a few MOA in space about ballistic caculations for target range, course and speed.

Key word there is "virtually" - at 14 miles that small error makes a BIG difference!

 

[Bart B.]

50 caliber machine gun ball ammo's accuracy specs is 4 to 5 feet at 600 yards. That's over 8 MOA.

 

[Deaf Smith]

The 16" guns on the USS Alabama BB-60 are classified as 45 caliber Mk6, but she was a South Dakota class ship instead of an Iowa class which was a newer design. Not sure how the caliber designation was determined.

16 inch 45 cal means 16 inch bore and the weapon is 16x45 inches long (720 inches.. 60 feet.) 16x50 is 800 inches or 66.66 feet.

Yes the Iowa class had 66.66 feet length barrels.

They both used the same 2700 lb AP shell (that is the Iowa, South Dakota, and North Carolina class.) Just different muzzle velocities (2500 and 2300 fps respectively.)

Both could shoot past 40,000 yards but realistically they kept it around 30k yards.

NavWeapons, http://navweaps.com/ has all the data.

Deaf

 

[Deaf Smith]

You have to remember folks, when firing at other ships they have to a) take in to account the enemy's ships movements, b) their ships movements, c) any rolling fore and aft and to the sides, d) wind, e) barometric pressure, f) barrel wear (yes the wear from shot to shot is significant.) g) barrel heating (again, hot barrels will shoot a bit differently than cold ones) and other factors.

As a result, chance of hits at 30,000 yards are deemed to be around 3 percent. But with nine guns firing, that goes up somewhat.

Deaf

 

[Carl N. Brown]

As to the accuracy of that OP target: if those were craters in a Japanese Army airfield, it would be hard to fill them quickly and get back into service.

I'll grant that the aircraft carrier is more versatile and flexible, and able to fill more roles, which in recent times have included disaster relief, than the battleship. It's easy to see the twilight of the gray ladies in 20/20 hindsight. US Navy had fifteen battleships at the start of WWII, had two permanent losses at Pearl Harbor (USS Arizona and USS Oklahoma), added ten new battleships with dual purpose 5"/38 caliber side armament aimed by Mark 37 fire control directors feeding target info to Ford MKI ballistic computers. Several of the older ships were retrofitted with 5"/38 cal.s and M37s. There were no losses of USN battleships after Pearl Harbor. Lessons were learned. Battleships went from the main force of the navy to secondary roles, providing anti-aircraft artillery protection for aircraft carriers and main gun shore bombardment to cover amphibious landings.

 

[GBExpat]

Nevermind ...

 

[kitsapshooter]

Lack of accuracy was a major reason why the battleships were retired. At extreme range, all they could hit was another battleship, somewhere, with their main armament.

You are wrong about that. The reason was cost. BB's cost a million dollars a day to operate when they retired for the last time. Maybe a lot but if you ever saw a BB it is worth every penny.

 

[Kevin Rohrer]

I would say that the accuracy at both ranges is very good. Am wondering if the vertical stringing is due to barrel whip.

Note: the 25k shoot was 8x, while the 36k shoot was probably 6x. That is pretty darn good for those ranges.

 

[Bart B.]

dual purpose 5"/38 caliber side armament aimed by Mark 37 fire control directors feeding target info to Ford MKI ballistic computers.

I operated and maintained that system on my first two ships; WWII era destroyers from 1957 to 1960.

 

[Deaf Smith]

As to the accuracy of that OP target: if those were craters in a Japanese Army airfield, it would be hard to fill them quickly and get back into service.

I'll grant that the aircraft carrier is more versatile and flexible, and able to fill more roles, which in recent times have included disaster relief, than the battleship. It's easy to see the twilight of the gray ladies in 20/20 hindsight. US Navy had fifteen battleships at the start of WWII, had two permanent losses at Pearl Harbor (USS Arizona and USS Oklahoma), added ten new battleships with dual purpose 5"/38 caliber side armament aimed by Mark 37 fire control directors feeding target info to Ford MKI ballistic computers. Several of the older ships were retrofitted with 5"/38 cal.s and M37s. There were no losses of USN battleships after Pearl Harbor. Lessons were learned. Battleships went from the main force of the navy to secondary roles, providing anti-aircraft artillery protection for aircraft carriers and main gun shore bombardment to cover amphibious landings.

Except when they met the Japanese battleships Kirishima, Fusō, and Yamashiro.... and sank them all. USS Washington got the Kirishima, and a combination of battleships Mississippi, Maryland, West Virginia, Tennessee, California, and Pennsylvania (but the Pen never fired a shot due to their radar, an older set, not being able to give a good azimuth) sent the other two to the bottom.

Deaf

 

[cfullgraf]

USS Washington got the Kirishima,...

Learn something everyday. I kind of though the only battleship vs battleship action in the Pacific was during the Battle of Leyte Gulf late in the war.

The USS Washington sank the JDS Kirishima at Guadalcanal.

 

[CapnMac]

Of course, computing power of electronic devices today have improved vastly since 1980 so I'm sure a smart phone would provide more accurate calculations today.

This is a common perception.
But not one that can be conclusively proved.
The use of cams and geared vectors allowed the mechanical computers to simultaneously calculate multiple conic section calculus without a significant digit issue. The targeting computers did this all mechanically, and with multiple mechanical inputs. Which could be 10 or 11 inputs at once.
Now, modern computing does have all sorts of cool abilities, but is still limited by short integer limits for calculations--with a significant problem of human programmers only thinking within 5 or 6 significant digits. So, yes, a digital watch has more computing power than the computer used on the LEM for lunar landings, but our programming has not necessarily improved to match Moore's Law (remember, it was just 20 years' ago we were worried about the significant digits in year dates).

To help prevent throat erosion, large bore (12" or greater) shells had driving bands which were (slightly) loose fit and pre-engraved to the rifling. On ramming, the bands slipped around to fit the rifling, which then mashed the bands back into contact with the shell. All of which was needful as the 660# powder charge was very close to a plasma at ignition in the 27,000 cubic inch chamber.

 

[Havok7416]

Learn something everyday. I kind of though the only battleship vs battleship action in the Pacific was during the Battle of Leyte Gulf late in the war.

The USS Washington sank the JDS Kirishima at Guadalcanal.

There was also the battle between Duke of York (the ship) and Scharnhorst north of Finland.

 

[Robert]

There was a story I heard from a Viet Nam vet about a patrol that came under heavy enemy fire. They called out to Yankee Station for some off shore fire. They were expecting a destroyer to lob a few 5" shells Then they heard a sound like a freight train coming and 16" shells began raining on the enemy position. The New Jersey was on Yankee Station!

A friend of my father that had fought in Vietnam told me almost the exact same story right down to the sound of a freight train going over head.

 

[DanTheFarmer]

IJN Fuso was not sunk by US battleships. While steaming with IJN Yamashiro, she was sunk by destroyer launched torpedoes before getting in range of the battleships. The two Japanese battleships were sister ships and there are some sources that state that it was Yamashiro that was sunk first and then Fuso by the US battleships but in either case the US battleships sunk just one of them.

Also don't forget the USS Massachusetts putting the partially complete French Jean Bart out of commission with a hit on the face of its one working gun turret from a range of 20 miles! Visit the USS Massachusetts in Fall River Mass and see the actual shell that was fired, clanged of the armor into the harbor, and was recovered when the Allies took over the port.

Dan

 

[pintler]

On the subject of mechanical fire control computers, TFB put this out a few years ago:

http://www.thefirearmblog.com/blog/2010/02/15/naval-fire-control-computers-in-the-1950s/

I dunno if the links still work, but as a computer nerd I found them fascinating.

 

[Bart B.]

I would say that the accuracy at both ranges is very good. Am wondering if the vertical stringing is due to barrel whip

Barrel whip is probably the most repeatable part of a bullet shooting system when they're free floated. 16" naval gun barrels are free floated. Their muzzle axes droop down from chamber axes a couple inches. Our rifle barrels droop, too. No big deal. All barrels whip when fired before whatever they shoot leaves them. Grade school physics at work.

Atmospheric, projectile balance and gun aiming variables cause 70% of the shot group size on target. Fire control technicians measure turret roller path tilt angle and axis relative to that if the gun director then make adjustments to the turrets' "deck tilt corrector" mechanics modifying gun elevation orders sent from the plotting room computer. They put a bore scope in the barrel breech then bore sight relative to director sights aiming at the horizon every 10 or 20 degrees of train. As the ship rolls the man in the director says "mark" when his sight set at zero deck elevation has its reticle cross the horizon on the down roll and the man at the gun's bore scope adjusts its elevation to coincide. Each turret has a different train angle and amount its high point is. The angle differences the gun is from the director are recorded then set in that guns deck tilt corrector. It'll change over time as the ship twists and bends taking a different set over time.

These "horizon checks" are made after "shoot the moon" is done aiming all guns and their directors at the moon at night in port so all's aligned to one axis in calm water. Parallax correctors in each gun turret or mount compensate for their horizontal distance from their directors. At sea, ships bend and twist with sea conditions. The best laid plans of man with machines are changed at any sea state above zero the gun battery was aligned in.

This is "battery alignment;" happened a few times every year. In later years, I oft times operated test equipment in an airborne helo measuring guided missile track and guide radar beam alignments so missiles would hit what they were aimed at. That later was replaced with a tower ashore with antennas placed in the same physical axis offsets the three radar beams in each director had. Much the same as "batten boards" used to align aircraft machine guns to the sight in the cockpit.

 

[lysanderxiii]

About 100 MOA according to my (mental) calculations.

Edit: What does 50 cal mean? I assumed 16" meant a 16" diameter projectile from a ship based gun.

50 calibers is the length of the rifling. One caliber is the bore diameter.

So, a 16"/50 caliber gun has a rifled tube length of 800 inches.