Yamato vs. 2 KGV (night battle)

[northcape]

Hello everybody,

I'm new on this forum and delighted to see so many battleship and maritime experts around. I'm by far not as knowledgeable as many of you, but I want to discuss the following scenario: End of war, night engagement between Yamato on the one side and KGV, Duke of York and their screen of five to seven destroyers.
I'm aware that the 14inch guns will by no means penetrate the citadel or the main turrets of Yamato. But given the (far?) superior British radar with a possible combination of flashless cordite, I wonder if the 2 KGV's could keep the Yamato occupied such that the destroyers could successfully deliver their torpedoes. Of course, one or more 18inch hits on the british battleships would have serious effects, so it will depend largely on how well the British can lead the tactical situation - radar and independent high-speed steaming of the two vessels will be essential.
Would it make a difference if we substitute one KGV with the Rodney?

Cheers!

[Dave Saxton]

Six on one isn't a fair fight, even if the one is Yamato. I can't imagine a scenario were the Yamato would be completely unescorted, however. The Japanese were masters of night fighting even without radar, and they had superior torpedoes, whith which Yamato's destroyers could make things difficult for the six British warships.

By placing the time of the scenario at the end of the war it actually reduces the radar advantage enjoyed by the British. Yamato will have a 10cm firecontrol radar, Type 32, which was a lobe switching variant of their Type 22 centimetric surface search radar which had a range of 35km, or 38,000 yards.

The British radar advantage isn't as great as one might think. By 1945 the British battleships will have lost the services of the excellent Type 273Q surface search sets, having been forced to replace it with the not very good Type 277/293 system with 10,000 yards less range than Yamato's surface search radar. Thus the Japanese may get the drop on the British.

The British may have also replaced the 50cm Type 284M surface firecontrol sets with Type 274. The problem here is that Type 274 can not spot the fall of shot. (Type 284M could not for the most part either). Thus although Type 274 was an advanced radar, and the Japanese radars are more primative, in practice there is little difference in capability during the proposed night battle. The Japanese will use their superior star shell and night optics to spot the fall of shot, agumented by their new radar targeting capability. The British will likewise require starshell. This means it with be a a less than 15km affair and could get quite messy. The Japanese also had flashless powder. Given the likely presence of IJN destroyers and their Long Lance torpedoes, coupled with the IJN night fighting skills, the IJN may pull off an upset here.

[northcape]

I agree that an unescorted Yamato is rather unlikely. I'm surprised to hear that the Japanese had such powerful radar towards the end of the war! When did their development pick up so rapidly? From previous readings, I got the impression that the Japanses radar was inexistent to very poor at the beginning of the war? And why did the Brits downgrade their radar on purpose?

[Dave Saxton]

I'm surprised to hear that the Japanese had such powerful radar towards the end of the war! When did their development pick up so rapidly?

It depends on what you mean by "powerful". Do you mean in terms of capability or in terms of actual kilowatts? In terms of Kilowatts it was at least 100 times less powerful than late war British sets. Nonetheless, radar performance isn't all about raw power. The 10cm Japanese Type 22 radar used a cavity magnetron, invented independantly, but was only capable of a few kilowatts output. It could still get long range because of the use of long pulse durations. The illuminating power is the pulse duration x the pulse power. Long pulse durations also require less bandwidth at the receiver, which results in a far more sensitive receiver.

The resolution for both distance and bearing was terrible, but while good resolution performance are good; the single most important thing about any radar is the ability to measure range accurately enough and at a great enough distance to be useful. These they could do good enough to be useful.

The Japanese didn't suddenly develop these radars over night. Type 22 was deployed operationally as early as mid 1942 (on one ship), but they never gave it a priority to make it operational on many warships very quickly. The program languished for years. The lobe switching version took so long to develop that it wasn't ready until after they had no major warships left. By the end of the war though, one would certainly expect an operational Yamato to have such gear.

And why did the Brits downgrade their radar on purpose?

Bureaucracies set and enforce irrational policies all the time. It is the nature of bureaucracy, even in wartime. The inability of Type 274 to spot the fall of shot was the consequence of developing a very tight and focused transmitted beam to improve bearing resolution. Plus the desire to make the radar as countermeasure resistant as possible. Shell splashes that fell outside the tiny beam simply didn't get picked up. An add on radar for spotting was added to Vanguard in 1947.

[RNfanDan]

Keeping in mind that even the best-protected battleships in history could be knocked-out of the fight (fire control, radars and range-finding equipment were weak spots in ANY capital ship), it may not have been at all necessary to pound on Yamato to send her away. Moreover, if a favorable attack position could be gained by the two RN battleships, i.e., a 45-to-90°crosscut, the Japanese battleship might be forced to divide its fire (re: Graf Spee at River Plate).

In my opinion, it would be almost impossible for British shellfire to actually sink Yamato, but as has proven the case historically, it isn't absolutely necessary to sink an enemy ship in order to defeat it; It depends on the tactical situation and the task at hand. If the RN battleships could hold off and hold out until daybreak, aircraft could be called-up and change the situation, dramatically.

But for every what-if, there are at least two alternatives, so the whole exercise quickly becomes a tangling mesh of possibilities all the way round.

[northcape]

Dave, thanks for the detailed reply on the radar! From my understanding, long pulsewidth means low frequency means bad resolution. And don't you need high resolution to observe small targets, like fall of shot? Wasn't the British radar able to observe fall of shot at distances of 10 km or more? (At least this is my understanding of the battle of the Northcape, which however was in 1943).

I also see no way that you can sink Yamato with even 20 14-inch guns. But as RNfanDan points out, one could knock out many parts vital for effective combat. In that respect, the somehow well-balanced fleet of the RN worked quite well throughout the war. None of the big german ships was sank by heavy shelling alone, but by a combination of AC, battleships, cruisers and destroyers. I'm not too familiar with the Pacific war, but wasn't the loss of Hood actually the only account in WW2 when a big ship was sunk solely by gunfire from another big ship?

And coming back to the hypothetical scenario, Yamato might be alone - also Scharnhorst lost her destroyers in its poorly planned sortie.

[alecsandros]

I'm not too familiar with the Pacific war, but wasn't the loss of Hood actually the only account in WW2 when a big ship was sunk solely by gunfire from another big ship?

Kirishima, Bretagne were also shelled into submission.

Jean Bart would have been lost also, after the hits delivered by Massachussets, provided her magazines were properly loaded.
Dunkerque would have been sunk also, had it not been in a shallow harbor when under attack by HMS Hood.
---
It's not necessary to sink the ship immediately.
Severe shell fire damage can destroy all rangefinding equipment, damage the steering gear, and worst of all, make holes below the waterline [Hiei comes to mind here]

[northcape]

but jean bart and bretagne were confined in the harbour, so i would not compare that to a real engagement.

[Dave Saxton]

Dave, thanks for the detailed reply on the radar! From my understanding, long pulsewidth means low frequency means bad resolution. .

Well your part of the way to an understanding. Pulse width is the duration of the pulse and has nothing to do with wavelength or frequency.

Pulse width has an effect on the resolution for distance in most cases (but not all) but has no effect on the side to side or up and down resolution.

The wavelength or frequency is associated with the side to side (azimuthal or bearing) resolution and up and down (resolution in height or elevation) though.

Radar waves travel at the speed of light, which is 300 meters every millionth of a second or micro second (us). Therefore, the Duke of York's type 284M at North Cape using a 1 micro second (1us) pulse width had pulses 300 meters in length. Since the leading edge of the pulse will have already rebounded off the target before the trailing edge reaches the target the resolution for distance (range resolution or resolution for range) is actually about 1/2 of the pulse distance in most cases. Or about 150 meters in the case of Duke of York's Type 284M.

This means that the echoes from shell splashes within 150 meters of the target will be merged with the main target echo on the indicator. Shell splashes falling more than 150 meters from the target will show up as separate echoes on the radar scope. Fine range resolution is still possible using longer pulse widths, and even infinite pulse width of continuous wave radar, through the use of more sophisticated signal processing. The 10cm Japanese Type 22 radar had minimum pulse widths of 5us resulting in a resolution for range of ~ 750 meters (unless they were employing some advanced signal processing)

Accuracy for range is not a function of resolution for range, although it may be related. For example, the accuracy for range of the 10cm American MK8 radar was 0.1% of the range to target, +/- 15 yards, while the resolution for range was about 75 yards.

The resolution for bearing, or side to side resolution, is greatly influenced by the wave length or the frequency- in relation to the size of the antenna. In the case of Duke of York's Type 284M the bearing resolution was 4 1/2 degrees, because this was how wide the radar beam was. It is the result of this equation:

51.5cm wave length/ 9 wavelengths (effective antenna size) x ~.75 = ~ 4.5* beam width.

As you can see a shorter wave length, or higher frequency, results in finer bearing resolution while using a same size or smaller antenna. This is the main reason that shorter wavelengths are desirable. (antenna gain is also usually greater with shorter wave lengths as well) With longer wave lengths one needs much larger antennas to attain acceptable bearing resolution.

This does not affect bearing accuracy. For example, a bearing accuracy within 0.10* is possible with lobe switching regardless of beam width.

Type 274 used a 10cm wavelength and a relatively large antenna resulting in a beam width of less than 1*.

The Japanese Type 22 radar used 10cm wavelength as well, but a tiny antenna resulting a bearing resolution exceeding 10*

British documents complain about the inability of Type 284M to spot the fall of shot. This really was the result of the type of presentation or indicator used by Type 284 rather than the resolution specs. The indicator was a simple A-scope which presents no bearing information. On Type 284M it was known if the radar antenna was aimed directly at the target by if the trace flickered or held steady. Obviously this can not indicate shell splashes relative to the target for bearing. At North Cape, Duke of York used star shell to spot the fall of shot visually, but as the range increased to beyond the effective range of star shell, the Duke of York began asking other British warships if they could see her fall of shot and report it to the Duke of York.

A major factor for spotting shell splashes with radar is not the wavelength but the signal to noise ratio of the receiver.

Shorter wave lengths also do not pickup shells in flight better than longer wave lengths. For example, during the bombardment of Bismarck, KGV was using Type 284 to range the target. It was noticed that shells in flight could be picked up. After some minutes the Type 284 was knocked out by the shock from KGV’s own guns. They then switched to the 7.5 meter wave length Type 279 for ranging the target and found that the 750cm radar tracked shells in flight better than the 50cm radar did.

[alecsandros]

but jean bart and bretagne were confined in the harbour, so i would not compare that to a real engagement.

On the contrary,
Had it been in the open seas, and with magazines loaded, Jean Bart would have been sunk outright by Massachussets, with no hope of survival.
Massachussets firing that day is amongst the best I know of in terms of battleship capabilities.

Same case for Dunkerque... and Bretagne...

[dunmunro]

Note that Sheffield's type 273 could also spot FOS.

[Dave Saxton]

Duncan, the second page is cut in two.

The radars will be able to pickup shell splashes falling outside their resolution for limits. It would be shells splashes falling beyond or short of 150 meters of the MPI for distance for Type 284M. Shell plashes for bearing would not show up on the A-scope indicator accept by causing a possible trace flicker. Type 273Q would show shell splashes on it's PPI falling outside of Approx. 4* either side of the bearing track, and outside of 125 meters beyond or short of the target for range, if it's set up on the short pulse width setting.

Had DoY been equipped with the centimetric Type 274 it would not have been able to pickup shell splashes falling more than a 0.75* to the left or right of the bearing track.

There's no question that Duke of York was requesting by voice radio any other British warships to spot the fall of shot for it. This was picked up by B-Dienst and the transcription of the messages were presented to the OKM during a review of the war radar situation in March 1944. It was commented that apparently the Duke of York was not capable of pure blind fire.

Howse reports that the reason Duke of York was requesting any British warship to spot for it, was because Type 284 was not indicating fall of shot for bearing, and this was the reason that the Duke of York initially broke off the engagement at 1824 hours. Other sources say it was because the 284 developed a fault. ADM 220/27 lists a inability (or did they mean a poor ability?) for 284 to spot the fall of shot as among its short comings.

[dunmunro]

If you right click on the image, and chose "open in a new tab" the entire image should display in the new tab. You can also save the image and open in am image viewer.

I suspect that DoY was having problems with some salvos falling considerably out of line with the target, because she was firing on a forward bearing with the ship yawing considerably, so some salvos may have fallen out of the FoV of the type 284 radar display. Under calmer conditions or when engaging across the beam this would probably not have been a problem. However DoY did suffer a 284 radar fault when the forward tripod mast had it's electrical leads severed by Scharnhorst's only hit, IIRC.

[RF]

Hello everybody,

I'm new on this forum and delighted to see so many battleship and maritime experts around. I'm by far not as knowledgeable as many of you, but I want to discuss the following scenario: End of war, night engagement between Yamato on the one side and KGV, Duke of York and their screen of five to seven destroyers.

As I understand it, the IJN excelled at night fighting. The KGV class initially had problems with their 14 inch turrets. If your two KGV's were KGV and POW I would give them little chance, even with radar. However if we have Howe and Anson, things would be far more interesting.

With respect to the five or seven British destroyers, the Yamato has a battery of 6.1 inch guns which on paper could make short work of them.

Would it make a difference if we substitute one KGV with the Rodney?

Rodney wouldn't be fast enough to keep pace with either the KGV's or Yamato. Remember that on 26 May 1941 when Rodney joined Tovey in KGV that KGV had to reduce its speed so Rodney could keep up.

[alecsandros]

As I understand it, the IJN excelled at night fighting. The KGV class initially had problems with their 14 inch turrets. If your two KGV's were KGV and POW I would give them little chance, even with radar. However if we have Howe and Anson, things would be far more interesting.

...
Hi RF,
A very important aspect would be the quality of Japanese APC shells. IF they would use the type91 diving shells, with 0.4 seconds fuzes, it is probable that the KGV's would suffer extremely light damage.
The British shells on the other hand usually performed well, and could damage severely the entire top-side of Yamato...