Home Forums Air and Sea Naval Help: Did range of shot increase/decrease likelihood of magazine hit/explosion?

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  • #85884
    Sharpe_95
    Participant

    Hi everyone,

    I am trying to do a little research on the risk of magazine hits/explosions during WW1/WW2. I thought I might take a straw poll (so to speak) of the wider knowledge pool here as well.

     

    What I am trying to understand is this:

    If we consider battleship and battlecrusier main gun shots, and use the generic terms ‘long range’, ‘medium range’, and ‘close range’ to refer to 66-100% of maximum practicable range, 33-66% of maximum practicable range and 0-33% of maximum practicabe range respectively – how likly was a magazine hit (penetration) and/or subsequent explosion?

     

    What I am driving at here is this:

    Were heavy ships (when targeted by other heavy ships) more at risk of magazine penetrations/explosions when subjected to longer ranger fire than when subjected to closer ranged salvos (or did the highest risk sit somewhere in the mid ranges?

     

    Many thanks in advance, I have no doubt there are lots of knowledgeble people out there on these forums.

     

    – Sharpe

    • This topic was modified 3 years, 3 months ago by Sharpe_95.
    • This topic was modified 3 years, 3 months ago by Sharpe_95.
    #85887
    John D Salt
    Participant

    Four points I would make, all of which suggest the question isn’t answerable as framed:

    1. A very large number of magazine explosions were caused by underwater hits (mines or torpedoes), aerial bombing, or ammunition handling accident.
    2. Because of the desirability of keeping A arcs open, and the lack of cross-levelling in fire control systems, WW1-era gunnery fights tended to be fought broadside on, so range did not vary as much as you might think.
    3. The heavy loss to British warships at Jutland can be ascribed to unsafe propellant technology (bagged charges, sensitive cordite) and especially to dangerous ammunition handling practices (stacking up charges and leaving openings unclipped to improve rate of fire).
    4. Once Jutland is discounted, the number of capital ship vs capital ship gunnery engagements in the whole of the 20th century is probably not large enough to have any useful statistical confidence in any results you might come up with.

    Unless someone can come up with some convincing mechanism to explain why vulnerability to magazine explosion should vary with range, the sensible thing seems to be to assume that it doesn’t. I usually hear naval wargamers mutter about “plunging fire”, but I never seem to see them calculate the angle of fall. Since the maximum elevation of the British 15-inch in WW1-era mountings was only 20 degrees, I doubt that the angle of fall would be sufficient to make a vast difference to the question.

    All the best,

    John.

    #85888
    Etranger
    Participant

    The loss of the Hood would be the most frequently quoted example from WWII, although again ammunition handling practices may have been the issue. There isn’t much realevidence one way or the other since the wreck is a long way down, only theories, but it’s summarised fairly well on Wiki, https://en.wikipedia.org/wiki/HMS_Hood

    • This reply was modified 3 years, 3 months ago by Etranger.
    • This reply was modified 3 years, 3 months ago by Etranger.
    #88549
    grizzlymc
    Participant

    Looking at the plans in Janes, it seems that there is little obvious choice to be made in terms of horizontal or vertical impacts, or much in between.  However, horizontal protection was generally thinner than vertical protection which would mean that if you hit with plunging fire you would be more likely to penetrate.

    John, in a vacuum, most WWI ships would plunge at 20 degrees to the horizontal at maximum range.  However, a long time ago I saw some numbers on the German 11 inch (no I can’t remember which one) and at its maximum range it was plunging at over 45 degrees.  You are right, if you take out Jutland and the close calls at Dogger Bank, there are few cases of magazine explosions on record and those which are tend to have been big non penetrating explosions causing sympathetic donation.

    #88581
    Tony Hughes
    Participant

    The angle of impact varies with a number of factors. The relationship and influence of each factor varies with the other factors so isn’t easy to predict or generalise on.

    The higher the muzzle velocity the flatter the trajectory (so angle of impact nearer to horizontal) but a low calibre shell looses velocity quicker than a high calibre one so big guns tend to have flatter trajectories than smaller ones (at the same range & the same MV). Obviously higher elevation is needed to get longer ranges so range affects the AoI significantly too. Poor shell design can increase resistance, causing increased AoI too – still an issue in WW1 but hardly at all by WW2.

    To get effective ‘plunging fire’ you need to have an AoI of over about 30deg (over 45 even better) AND hit the deck. At that angle the deck actually presents a larger target than the ship’s side so, in theory, you probably do get a better chance of hitting the weaker deck armour at longer ranges. The problem is that the AoI is shallow enough to make penetration a bit hit and miss if it is much lower than 45deg and, for most WW1/2 guns, this would only happen close to extreme range, where hitting the target at all is a low probability.

    All things considered I think you’d have difficulty proving that plunging fire hitting a magazine at longer ranges was any more likely than flatter trajectory fire at shorter ranges – where penetration of weak spots on and through the superstructure and gun positions make it possible.

    Turn the time back to the pre-Dreadnought era and I think you might have to consider it a possibility but not with WW1 era weapons and armour and beyond.

     

    • This reply was modified 3 years, 2 months ago by Tony Hughes.
    #88608
    John D Salt
    Participant

    However, horizontal protection was generally thinner than vertical protection which would mean that if you hit with plunging fire you would be more likely to penetrate.

    Not necessarily; angle of impact has a considerable, and at angles more than 60deg, dominating (assuming impact velocities below 1000m/s as would invariably apply to naval gunnery) effect on penetration of thick plate.

    However, a long time ago I saw some numbers on the German 11 inch (no I can’t remember which one) and at its maximum range it was plunging at over 45 degrees.

    Wikipedia gives the following maximum elevation angles for several German 11-in guns:

    28cm SK C/34 (40,930m, 40 deg elevation)
    28cm SK C/28 (36,475m, 40 deg elevation)
    28cm SK L/40 (25,640m, 30 deg elevation)

    It seems safe to assume that the angle of fall you saw quoted applied to a WW2 weapon, so never as far as I have ever heard responsible for touching off a magazine explosion. It is also worth remembering that the longest-range hit ever scored in naval surface-to-surface gunnery was no more than about 26,000 yards (23775m), so we can I think be reasonably sure that hits with angles of fall greater than 30 deg never occured in the whole history of naval gunnery.

    Turn the time back to the pre-Dreadnought era and I think you might have to consider it a possibility but not with WW1 era weapons and armour and beyond.

    In the pre-Dreadnought era I feel quite confident in saying the probability of a hit with any projectile ariving at 30 degrees or more was zero. If anyone has a story about Bangbert the Lucky Bomb Ketch, I’m all ears.

    All the best,

    John.

    #88609
    Brian Weathersby
    Participant

    “Bangbert the Lucky Bomb Ketch”

    Well, you can consider THAT turn of phrase stolen for my future use. 

    I'm lucky to be here
    With someone I like
    Who maketh my spirit to shine
    --Warren Zevon

    #93690
    grizzlymc
    Participant

    John

     

    The elevation angle at which the shot is fired is always going to be less than the angle of fall of the shot at impact.  This is because friction slows the horizontal component of velocity more than it slows the vertical component.

     

    From memory the 11″to which I was referring was the SK L/50 of WWI which had a 16 degree max elevation.

    Magazine explosions were a comparatively rare event in destroyer and cruiser actions where penetration was almost a given.  Given that main belt and deck penetrations were rare, they should be very rare excepting Beatty’s command on der Tag.

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