The 'Shark' anti-submarine projectile.

Discussion in 'Weapons, Technology & Equipment' started by Peter Clare, Oct 27, 2014.

  1. Peter Clare

    Peter Clare Very Senior Member

    THE " SHARK " ANTI-SUBMARINE PROJECTILE


    A projectile has been developed for use in 4-in. guns for the attack of U-Boats on the surface. During development the projectile was known by the camouflage name of " Shark." Its official name will be " projectile, 4-in., anti-submarine." The " Shark" is intended to hit the water just short of the U-Boat and strike the boat underwater when the water tamping will make its detonation more effective.

    The purposes underlying development are that :‑

    When attacking U-Boats on the surface the target in a vertical plane, on which lethal damage can be done, is very small. Even if this small target be hit, S.A.P. shell are likely to glance off the pressure hull.
    If these shell hit the conning-tower, they often go on before bursting and, even if they burst, are unlikely to prevent the boat diving. H.E. shell will detonate if they hit the target anywhere but only under exceptional circumstances will the fragments from a 4-in. shell hole the pressure hull. Larger calibres are more successful.

    The " Shark " is shown in Plate 10 (sorry to say I do not have Plate 10 in my collection)which is self-explanatory. It is heavy and unwieldy but its A.P. head enables it to pierce tanks or superstructure before bursting. It is immune from ricochet, at all angles greater than 3r, which means that, if fired from a gun mounted not less than 15 ft. above the waterline, it will not ricochet at any angle of gun elevation. Its fuze gives sufficient delay to permit penetration and its charge, 25 lbs. of Torpex, will cause a large hole in the pressure hull.

    On hitting the water the " Shark " continues to move substantially along the same trajectory but loses its velocity rapidly. It follows that the " Shark " is essentially a short range weapon, because the greater the range the more steeply is the trajectory inclined downwards and the projectile will miss under the U-Boat unless it falls very close to her.
    Owing to the unhandiness of the projectile the rate of fire will be slow particularly with motion of the ship. Starting with the gun loaded, it would be a smart crew that fired three rounds in a minute.

    The muzzle velocity is only 500 ft. a second, which means that the " forecast " to be applied by the gunlayer when there is motion on the ship would need to be five times that required by an ordinary shell. This would be so difficult to assess that it is advisable to restrict firing to the end of the roll towards—there may be insufficient depression to be able to fire on the roll away—when no forecast will be required. This is unlikely to reduce the rate of fire further than it is already reduced by the unhandiness of the projectile and in any case the small number of rounds carried will preclude a high rate of fire. Firing will always be in Quarter Firing, range being set on a special " Shark " scale on the Range dial.

    To establish that the projectile would be lethal, a special target was designed by " Undex " to represent the structure of modern German U-Boats. This target was 19 ft. long and divided by a longitudinal bulkhead and by two transverse bulkheads into six compartments. The intention was that each compartment should receive one round. All compartments other than the one being attacked were flooded in order to submerge the target.

    This target was moored in a position where it would be covered at high water but dry at low water. The firing ship H.M.S. " Kingfisher," was moored at 100 yards range. One round was fired which (as intended) struck about 20 yards short and hit the centre compartment 5 ft. below water. It pierced the saddle tank and detonated.
    It caused a hole in the pressure hull approximately 8 ft. by 5i ft. and holed the compartment on each side of the one attacked and the one corresponding compartment on the other side of the ship. This damage was judged to be so much in excess of what was necessary that no purpose would be served by further firing. The remaining compartments will be utilised for the 3-in. projectile.
    Firings for more accurate determination of Range 'fables and of the underwater movement are proceeding.

    The present projectile can be fired from all marks of 4-im gun, but each mark requires a different propellent charge.
    It is anticipated that a small number of these projectiles will be available for Western Approaches by the end of March, 1944. A larger order will begin to mature in May.
    Other possible uses of the projectile, such as for sinking small merchant vessels, will no doubt receive consideration.

    " Sharks " are also being designed for 3-in., 12-pdr., 4.5-in. and 4.7-in. guns. For the two former it is not yet established that the weapon will be lethal.

    Anti-U-boat Warfare Division Of The Naval Staff. February 1944.

    Attachments

    1. Target representing a full scale section of a 500 ton U-boat
    2. View showing the damage caused by explosion on one 4-in 'Shark' projectile
    3 Close up view of the hole caused by the projectile
     

    Attached Files:

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