Welcome to the WWII Forums! Log in or Sign up to interact with the community.

Advanced Japanese Destroyers of World War II ..

Discussion in 'Ships & Shipborne Weaponry' started by sniper1946, Oct 5, 2010.

  1. sniper1946

    sniper1946 Expert

    Joined:
    Jun 11, 2009
    Messages:
    12,560
    Likes Received:
    1,017
  2. TiredOldSoldier

    TiredOldSoldier Ace

    Joined:
    Sep 14, 2008
    Messages:
    3,223
    Likes Received:
    449
    The the Japanese DD had some big shorcommings as well, the 5", despite the HA capability of most mounts, IIRC only the first group of the "specials" had low angle mounts, was not a good AA weapon and the 25mm MGs were pretty poor, had the Japanese adopted foreign designs like the Bofors and Oerlikon USN planes would have had a much tougher job.

    The Akitsuki were closer to the British Daring or Battle class DDs, or some L class that carried 4 twin 4" AA instead of the standard 4.7" than to true AA cruisers like the Dido and Atlanta as they had no armour.
     
  3. SymphonicPoet

    SymphonicPoet Member

    Joined:
    Sep 7, 2009
    Messages:
    701
    Likes Received:
    130
    The 25mm was a foreign design: Hotchkiss as I recall. Just an inferior foreign design.
     
    TiredOldSoldier likes this.
  4. formerjughead

    formerjughead The Cooler King

    Joined:
    Dec 29, 2008
    Messages:
    5,625
    Likes Received:
    995
    Judging by the dates I think a couple of those became artificial reefs off Wake Island; Date of loss 18 and 21 December 1941.

    "Sorry about your new destroyers Tojo!!!"

    I stand corrected.....the two I was referencing were sunk by the Dutch?!!!
     
  5. TiredOldSoldier

    TiredOldSoldier Ace

    Joined:
    Sep 14, 2008
    Messages:
    3,223
    Likes Received:
    449
    The two destroyers lost at Wake, Hayate and Kisaragi, were old ships of the Kamikaze and Mutsuki class roughly comparable to USN four stackers. The Japanese "advanced destroyers" listing correctly begins with the later Fubuki/specials so you won't find them there.
     
  6. formerjughead

    formerjughead The Cooler King

    Joined:
    Dec 29, 2008
    Messages:
    5,625
    Likes Received:
    995
    Thanks TOS, I realized that after I posted and in lieu of totally deleting my post I added the footnote.

    I made my assumptions based on the dates of the sinking not the locations.

    Sorry for any confusion it may have caused.
     
  7. Carronade

    Carronade Ace Patron  

    Joined:
    Feb 17, 2010
    Messages:
    2,336
    Likes Received:
    379
    They also had a 40mm copy of the British Vickers 2-pounder pom-pom, used on WWI era ships and some small craft in WWII, single mounts only. This was replaced in major warships by the 25mm, usually in twin or triple mounts.

    Incidentally the British did the same thing, replacing hand-worked single 2-pounders with power-operated twin Oerlikon mounts in ships like the Modified Flower class corvettes; the twin Oerlikon was especially popular with the Canadians. Then later some of the power-operated mounts were converted to single 2-pounders for more hitting power against kamikazes.

    Most WWII navies had 37-40mm guns, backed up by 20mm or similar. As the war went on, more and more 40mm Bofors guns and the like were mounted, especially on US ships. The Japanese could only pile on more 25mm or even 13.2mm machine guns.
     
  8. SymphonicPoet

    SymphonicPoet Member

    Joined:
    Sep 7, 2009
    Messages:
    701
    Likes Received:
    130
    Even the 25s might have been more effective if they'd had a better feed arrangement or better fire control. The U.S. 1.1"s of the early war take a lot of flack (pun intended), but they claimed quite a few more kills than anything else either the U.S. or the Japanese were fielding. (Per my recollection of the data in First Team.) But Japanese AA fire control had stable elements in only two dimensions, necessitating a barrage arrangement. (Per my recollection of Shattered Sword.) Further, if it was anything like IJN main gun directors it probably had fewer automated computations and required human input at more stages, slowing it down and increasing the instance of input errors.

    Don't quite recall the particulars of the feed problem, but I think it involved the placement of the clips. (Which needed to be replaced manually.) However, the effect reportedly diminished the rate of fire by something between a third and half. (Nominally, it was pretty good: say 200 rpm or better. In practice it was apparently much lower: more like 110.)
     
  9. lwd

    lwd Ace

    Joined:
    Jul 24, 2007
    Messages:
    12,312
    Likes Received:
    1,230
    Location:
    Michigan
    Here's a link to an article on the Japanese 25mm AA guns:
    25mm/60 AA
    Other writeups are available on that site.
     
  10. Takao

    Takao Ace

    Joined:
    Apr 27, 2010
    Messages:
    7,836
    Likes Received:
    1,677
    Location:
    Reading, PA
  11. T. A. Gardner

    T. A. Gardner Genuine Chief

    Joined:
    Aug 5, 2003
    Messages:
    5,945
    Likes Received:
    757
    Location:
    Phoenix Arizona
    The Japanese 25mm had no fire control. It basically had nothing but ring sights and manual controls. There are two operators on the triple mount (the standard). One is the layer (elevation) and the other the trainer (direction). The mount itself is not stabilized or powered.
    To make matters worse the Japanese grossly overestimated the effectiveness of their AA fire and had a doctine of withholding fire, partially to conserve ammunition, until an attacking aircraft was quite close to the ship under attack.
    Additionally, there was no specific doctrine until fairly late in the war for ship formations specifically to deal with air attack. Instead, ships steamed in traditional formations and when under air attack generally maneuvered independently to evade those attacks. This is far less effective than the US use of circular sector formations that maneuvered as a formation.
     
  12. lwd

    lwd Ace

    Joined:
    Jul 24, 2007
    Messages:
    12,312
    Likes Received:
    1,230
    Location:
    Michigan
    Not only less effective as defence but I believe it occasionally resulted in collisions. Not what you want to happen at any time but especially bad in the middle of an air raid.
     
  13. SymphonicPoet

    SymphonicPoet Member

    Joined:
    Sep 7, 2009
    Messages:
    701
    Likes Received:
    130
    Takao:

    Very true, but I was thinking there was also something that was genuinely awkward about the way the clips needed to be replaced. It might be little more than that the rounds were completely enclosed in said "clip" where the bofors 40 was often fed from something rather like a hopper that could be continuously reloaded. But I seem to recall that the placement of the clips also made reloading awkward. In any even, it greatly hampered the ROF.

    T.A.Gardner:

    I'm no expert in Japanese weapons systems, but I did remember reading about a gun director for IJN light AA. Per the Nauticos sight discussing the identity of the Midway wreckage (a project in which one of both of the combined fleet guys was involved) at least on Kaga they used the type 95 director:

    "Light AA weapons were controlled by the Type 95 system introduced in 1935. This system was typically located somewhere close by the guns it controlled, as a pointer would have to manually point out targets to the guns being directed. (Remote power control of 25mm mounts was apparently only available in the triple barreled version, and seemingly towards the end of the war.)"

    You can read the particulars here:

    Midway

    The quote goes on to discuss Hiryu's outfit at time of loss, which seems to be somewhat unclear. Nauticos is apparently drawing in part at least on the Hasagawa text Nihon no Kokubokan, which seems to have a decent enough reputation. (I don't read Japanese, so I can't really evaluate it directly.)

    There are some diagrams of the director in the Nauticos article, and it was fitted at least to some of Japans aircraft carriers and cruisers specifically for use with 25mm AA mounts. Whatever else it may be, it looks rather more sophisticated to me than "ring sights" and looking at diagrams of Kaga, she seems to have had at least six of them. (Rather more than you would need for control of the heavy AA, even if you used one per battery.)

    Japanese Cruisers of the Second World War by Lacroix and Wells, which I skimmed a little through Google Books, seems to corroborate the use of the type 95 director with the twin 25mm mounts. (See p. 517 describing the "machine gun fire control" on the modified Tone class cruisers by way of example.) And this is a pretty in depth Naval Institute Press publication, so I'm inclined to suspect it's reliable.

    Again, I've not seen detailed diagrams of the type 95 director, but it seems at a glance more sophisticated than a simple ring sight. Shields for the director include three slits for what would appear to be multiple optical elements. Further, the director alone has a pretty robust mount. And if it has the capability to direct multiple 25mm mounts, it must have at least a follow the pointer capability. (Not that this is really saying much.)

    Further, the triple mount seems to have been powered at least part of the time. (Else there'd be no need to question whether or not Hiryu had powered triple mounts.) The double mount was clearly more common, but even unpowered, they seem to have had directors. What's your source on the crew? I find it difficult to believe an unpowered double or triple mount could be operated at all effectively by such a small crew. (Which might, perhaps explain a few things. In any case, I'd probably enjoy any good source on WWII AA. Settle my nerves more next time I see a firefight over who's whizbang packed more punch.)

    In any event, yes, the effective range and ROF of the 25mm certainly limited it quite a lot. I would guess them to be a good bit more effective than an Oerlikon 20, but they're certainly not in a class with the Bofors, and IJN ship handling doctrine hampered them even more.
     
  14. SymphonicPoet

    SymphonicPoet Member

    Joined:
    Sep 7, 2009
    Messages:
    701
    Likes Received:
    130
    T.A.: The stable element business in Shattered Sword was probably in reference to the main AA gun directors. Whatever these are, they're surely more primitive than the directors for the heavy AA, so I must concede at least that.
     
  15. Takao

    Takao Ace

    Joined:
    Apr 27, 2010
    Messages:
    7,836
    Likes Received:
    1,677
    Location:
    Reading, PA
    Lacroix & Wells also discuss this in the Chapter "Prewar Modernization of the 'A' Class Cruisers, pg 243-45. Not all multiple 25mm mounts were power driven, some were manually operated. All multiple mounts were fitted with a "La Prieur" type sight, on the powered mounts, this was a back-up to the Type 95 FCS. I would guess that the powered mounts were the ones fitted during the prewar modernizations and the manual mounts were the ones hastily fitted during the war to beef up a ship's AA defenses.

    Also, the Type 95 director could not cope with the high speeds of later aircraft and an etched ring sight was added to the commander's telescope to help with speeds above the limits(500kph) of the director.
     
  16. Carronade

    Carronade Ace Patron  

    Joined:
    Feb 17, 2010
    Messages:
    2,336
    Likes Received:
    379
    Using the highly sophisticated analytical technique of looking at the picture, it looks like the Type 95 might be comparable to the Mark 51 used with 40mm guns in the USN. As I understand it, that was basically a lead-computing gunsight, which brings up another point, automatic AA weapons were largely for self-defense against aircraft which would be heading directly at the ship, somewhat simplifying the fire control problem.

    Individual Mark 51s were usually provided for each multiple Bofors mount, but the director could control multiple mounts; for example the Commencement Bay class CVEs had pairs of twin 40s controlled by one Mark 51. Apparently the Type 95 controlled several multiple 25mm mounts. Single guns of both types were usually manually aimed and operated.
     
  17. T. A. Gardner

    T. A. Gardner Genuine Chief

    Joined:
    Aug 5, 2003
    Messages:
    5,945
    Likes Received:
    757
    Location:
    Phoenix Arizona

Share This Page