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US Navy Nomenclature Question

Discussion in 'Ships & Shipborne Weaponry' started by Daryl Morning, Feb 21, 2022.

  1. Daryl Morning

    Daryl Morning New Member

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    Something I have been wondering and not finding a definitive answer anywhere is with the name changes of the 18"/48 caliber Mark 1 – United States Naval Gun which was relined into the 16"/56 caliber Mark 4 gun and then after the Washington Naval Treaty 18"/47 caliber Mark A gun. Why Mark A and not Mark 2?
     
    Daryl Morning, Feb 21, 2022
    #1
  2. OpanaPointer

    OpanaPointer I Point at Opana Staff Member WW2|ORG Editor

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    18-inch/48-caliber Mark 1 gun - Wikipedia
    "18"/47 caliber Mark A[edit]
    In 1938, with Japan's refusal to sign the Second London Naval Treaty and worsening situation in Europe and Asia, battleship studies once again considered 18-inch caliber main guns. During the early design stages of a 45,000-ton "slow" battleship alternative to the "fast" battleship design that would eventually result in the Montana class, the 18"/48 cal gun option was considered in several proposals.[3][4] The 16"/56 cal Mark 4 had its threaded tip cut off and was then relined to 18-inches; this weapon was then designated as the 18"/47 cal Mark A and was used to test a 3,850 lb (1,746 kg) "Super Heavy" AP shell, which the gun fired at a nominal 2,400 ft/s (732 m/s) muzzle velocity, with a range of 43,453 yd (39,733 m) at 40° elevation. The highest energy shot was with a 3,848-lb projectile fired at 2,508 ft/s (764 m/s) with a maximum pressure of 19.91 tons per square inch.

    Ultimately, the General Board decided that a 16"/50 cal gun offered the best combination of performance and weight, and the new 16"/50 caliber Mark 7 gun was used by the Iowa-class battleship design. The preeminence of naval aviation ended further developments into large caliber naval guns.

    While the 18"/47 cal Mark A was used to test the new "Super Heavy" 18-inch AP shell, if the caliber had been selected, a new lightweight 18"/48 cal Mark 2 gun would have been built. The new lightweight 18-inch gun would have fired the 3,850 lb "Super Heavy" shell at 2,500 ft/s (762 m/s) muzzle velocity, with a design similar to the contemporary 16"/50 cal Mark 7 gun rather than the 1920s technology used in the 18"/47 cal Mark A construction.[5]"
     
    OpanaPointer, Feb 21, 2022
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  3. Carronade

    Carronade Ace

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    Letter designations were used for prototypes, though it seems not always to have been consistent. This quote from navweaps, about 14" guns, illustrates the usage:

    "The 14"/50 (35.6 cm) Mark B was the original gun intended for the North Carolina (BB-55) class battleships. This weapon was the most powerful 14" (35.6 cm) gun ever designed by the United States and it was considerably simpler and lighter than the older 14"/50 (35.6 cm) gun. The prototype of this weapon was never completed as its development was abandoned when the 14" (35.6 cm) treaty limit was rescinded in 1937, allowing these new battleships to be armed with 16"/45 (40.6 cm) guns. For this reason, the 14" (35.6 cm) Mark B design was never assigned a standard numerical Mark designation.

    Nomenclature note: The 14" (35.6 cm) Mark A was the ballistic prototype of all 14" (35.6 cm) guns. This prototype was developed around 1910 from a 13" (33 cm) Mark 2 bored out and relined for the larger projectiles. The finished gun was 33 calibers long. The 14" (35.6 cm) Mark C was a Mark 4 Mod 8 reworked as a prototype for the Mark 11."
     
    Carronade, Feb 25, 2022
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