Rate of Fire: Yamato vs. Iowa

[GaryChildress]

Was just looking at the NavWeapons website and notice that the rate of fire for the Japanese 18" gun (3219lbs for AP round) which the Yamato used is rated at "1.5 to 2 rounds per minute". Looking at the rate of fire for the 16" Mk 7 gun (2700lbs for AP round) on the USS Iowa class BBs the rate of fire is 2 rounds per minute. Did the Yamato have a better loading system than the Iowa's or were Japanese sailors just more burley and stronger and therefore better able to handle the extra shell weight? It looks to me like the load time would be a bit longer for the heavier round. [&:]

EDIT: Or if the Yamato's RoF is 1.5 - 2.0 would that mean the Iowa's RoF is 2.0 - 2.5 or something like that?

[Canoerebel]

Gary, about three months ago somebody posted a link to a US Navy training film detailing the loading of the big gun on a WWII BB. The process was both complicated and highly mechanized. The men had to be strong (and I bet they perspired like anything), but the rate of fire was highly dependent on the speed of the machinery and the alacrity (not really the braun) of the gun crew.

But if an Iowa gun could fire twice per minute and the Yamato only 1.5 to 2.0 times per minute, that's actually a fairly significant difference.

[zuluhour]

I would guess with their knowledge of the British systems they possibly innovated with Yamato. I just don't trust source material as much anymore, I could never be part of the "tech" design aspect of war games.

[btbw]

You can read about firing cycle of 18-inch gun on NavWeaps. They have brilliant answer for you.

At the loading angle of +3 degrees, a firing cycle of about 30 seconds could be achieved.
The additional elevation and depression times required to reach an elevation of 41 degrees increased the firing cycle by about 11 seconds.
As can be seen in the Range Table below, most ship-to-ship actions would rarely exceed an elevation of 20 degrees, so an intermediate time of 35 seconds would seem to be reasonable for most battle-range engagements.

[Jorge_Stanbury]

This webpage is highly recommended for any BB vs BB analysis

http://www.combinedfleet.com/baddest.htm

[Cpt Sherwood]

ORIGINAL: Jorge_Stanbury

This webpage is highly recommended for any BB vs BB analysis

http://www.combinedfleet.com/baddest.htm

Interesting note from that site:

"In addition, it needs to be noted that at ranges above 15,000 yards or so, one would not be able to fire at full speed given the need to watch the fall of shot of previous salvos, which might take as long as a minute to reach their destinations. Firing cycles, then, are somewhat misleading in significance for large-caliber weapons such as these."

[warspite1]

ORIGINAL: Canoerebel

But if an Iowa gun could fire twice per minute and the Yamato only 1.5 to 2.0 times per minute, that's actually a fairly significant difference.

warspite1

Is the "only" in the wrong place?

[PaxMondo]

I think what he is suggesting is that 1.5 rpm vs 2 rpm is a 25% difference ... which is a lot.

[crsutton]

Well, technology in times of actual war tends to take quantum leaps forward. Comparing a ship launched in 1942 to a ship launched in 1944 might be problematical in itself. The 44 ship especially if Allied compared to an Axis ship commissioned in 1942 is just going to have better, more sophisticated technology. I know it is a stretch but you would not really want to compare a zero fighter to a mustang.

How does the Yamato's rate of fire compare to the Prince of Wales or the North Carolina? They might provide a better benchmark.

[warspite1]

ORIGINAL: PaxMondo

I think what he is suggesting is that 1.5 rpm vs 2 rpm is a 25% difference ... which is a lot.

warspite1

I was querying the placement of the "only", not the % difference.

[Canoerebel]

Warspite, I'm not sure what you mean. The "only" seems correctly placed to me. However, I did not like diagramming sentences in grade school, so if you know a better place to put it, let me know. I'm still trying to learn the grammar game (I'm in the business, so it behooves me to do so).

[warspite1]

You are right I got that completely arse about face [8|]

[jcjordan]

Another thing to consider would be how well they placed those shots as if those shots aren't even hitting the ocean then it wouldn't matter how fast/many you put out. I'd think that w/ the radar & plotting stuff the Iowa's were problably a little better in getting on target sooner & getting more hits per expenditure results.

[spence]

Looking at the original question and the statistics originally quoted it appears to me that the IOWA had the higher rate of fire at 2r/min vs 1.75r/min (average of 1.5 and 2) for the YAMATO. Since the two BBs never met in combat a review of their performance in different engagements might prove useful. Yamato fought in the Battle Off Samar in Oct 44: can't say that I've ever heard its performance was all that great (along the line of hits obtained/rounds fired). One of the Iowa's fired on IJN ships off of Truk in Feb 44: can't say that I've ever heard of any assessment of its performance either (hits obtained/rounds fired). Might be interesting to find out if anyone can find the stats.

[wdolson]

If an Iowa had been in a gunnery fight in late 44 I would expect the accuracy to be on par with Olendorf's BBs at Surgio Strait. At least those with comparable fire control radars. Good fire control radar was the solution not only the US Navy had been seeking, but so had everyone else since the late 1800s. Naval gunnery only became capable of longer ranges about the time of the Spanish American War and the introduction of the dreadnaught class of battlewagons. During the Spanish American War the USN realized their gun accuracy was horrible and everyone was scrambling to fix the problem. The Japanese solution was to put the best optics possible in their rangefinders.

Ultimately it was radar tied to a primitive computer that solved the problem, but the technology for that didn't exist until the 1940s and it wasn't until late war that all the pieces came together. By then the platform the technology was supporting was just about completely obsolete. Ironically it was some of the oldest battleships afloat that put that technology into action and helped decisively win the Surgio Strait battle. (I know the DDs and cruisers had already done severe damage, but it was ultra accurate fire from Olendorf's most updated BBs that finished off the Japanese force and showed what modern fire control radars could be capable of.)

I'm too lazy to look up which BBs had what radar by late 44, but I would guess the fast BBs were probably given priority for the more advanced fire control systems.

Bill

[Jorge_Stanbury]

Would it be easy to put a late war American radar into the Yamato? assuming obviously it was available

in other words, how "integral" was radar to the ship's design?

[wdolson]

Considering the US and British put advanced radars on WW I vintage ships it was probably possible to put fire control radar on just about anything. The fire control radars also were connected to computers (primitive by modern standards) that helped calculate the firing solution. The B-29 had such a system for the remotely controlled turrets and the Germans had tried some remote controlled turrets on their aircraft too. The Allies also used some early computers for code breaking.

I don't know of Japan developing any kind of computing devices during that time period, though they might have had some prototypes. The US, Britain, and Germany are the only countries I know of that employed any kind of computers during that time period.

If Japan had the same kind of fire control systems the US had by late 44, their gunnery at the Battle Off Samar would definitely have been better, but in the end it wouldn't have made much difference. That was the last gasp of the leviathans.

Bill

[spence]

From the TROM of HIJMS KATORI at Combined Fleet.com

40 miles NW of Truk. IOWA engages KATORI and fires forty-six 16-inch high capacity (non-armor piercing) rounds and 124 five-inch shells. She straddles KATORI with all eight salvos. KATORI launches a salvo of torpedoes at the Americans. Just after the IOWA's fourth salvo, KATORI starts to list to port. After being under fire for 11 minutes, the cruiser sinks stern first at 07-45N, 151-20E. Reportedly, a large group of survivors is seen where she sinks, but none are picked up. Later, Captain Oda is promoted Rear Admiral, posthumously.

Cdr (Rear Admiral, posthumously) Moriya Setsuji's (former CO of SUZUKAZE) destroyer NOWAKI flees the onslaught. Both American battleships - the fastest in the world - give chase at 32.5 knots. At 35,000 yards, NEW JERSEY and IOWA open fire and straddle NOWAKI with their first salvos. NOWAKI flees into the sun's glare, so at 38,000 yards both battleships fire under radar control. At 22 miles, these are the longest range shots ever fired by American battleships against an enemy vessel. At 39,000 yards, Admiral Spruance orders Cease Fire. NOWAKI escapes and eventually makes her way back to Yokosuka.

IOWA appears to have done pretty well firing on Katori: straddles the target with the first salvo, apparently hitting with the 2nd or 3rd salvo. The range may have been fairly short I suspect since earlier they had engaged Maikaze at 7000 yards (sunk by US cruisers) accompanying the BBs.

[String]

ORIGINAL: spence

From the TROM of HIJMS KATORI at Combined Fleet.com

40 miles NW of Truk. IOWA engages KATORI and fires forty-six 16-inch high capacity (non-armor piercing) rounds and 124 five-inch shells. She straddles KATORI with all eight salvos. KATORI launches a salvo of torpedoes at the Americans. Just after the IOWA's fourth salvo, KATORI starts to list to port. After being under fire for 11 minutes, the cruiser sinks stern first at 07-45N, 151-20E. Reportedly, a large group of survivors is seen where she sinks, but none are picked up. Later, Captain Oda is promoted Rear Admiral, posthumously.

Cdr (Rear Admiral, posthumously) Moriya Setsuji's (former CO of SUZUKAZE) destroyer NOWAKI flees the onslaught. Both American battleships - the fastest in the world - give chase at 32.5 knots. At 35,000 yards, NEW JERSEY and IOWA open fire and straddle NOWAKI with their first salvos. NOWAKI flees into the sun's glare, so at 38,000 yards both battleships fire under radar control. At 22 miles, these are the longest range shots ever fired by American battleships against an enemy vessel. At 39,000 yards, Admiral Spruance orders Cease Fire. NOWAKI escapes and eventually makes her way back to Yokosuka.

IOWA appears to have done pretty well firing on Katori: straddles the target with the first salvo, apparently hitting with the 2nd or 3rd salvo. The range may have been fairly short I suspect since earlier they had engaged Maikaze at 7000 yards (sunk by US cruisers) accompanying the BBs.

although straddles, they never actually hit the Katori. Katori was stricken in water already beforehand.

[dr.hal]

A quick comment about adjusting for the fall of shot and thus extending cycle time between salvos, this would only be done for ranging shots. Once range was established (either by radar, aircraft, spotting ship or one's own optical systems) then all restrictions are off and the ship's gunner would call for a rocking ladder tactic. Thus time of flight has no impact once range is established in terms of rate of fire.