Operational 1/20th scale US Navy WW2 21" Mk14 Torpedo

The modelling objective is an operational 1/20th scale WW2 US Navy Mk14 Torpedo. This was the torpedo used on PT109 and other later Elco PT boats (following on from the Mk8 torpedo's) and prior to the fitting of the much lighter Roll Off Racks and the use of the shorter, faster and lighter aircraft style 22.5" diameter Mk13 torpedo's.


I have completed the warhead and tail bodies for a 1/20th scale Mk14 mod 0 torpedo, I have them being made at Shapeways currently (March 2019). The midsection will be made of 26mm OD carbon fibre tube and the printed circuit board for the German G7A should almost fit if cut down a little. The detail on the Mk14 is very similar to the Mk13 as the original torpedo's were designed at the same time and used common or similar components, the Mk14 body was smaller in diameter than the Mk13 at 21".

I will do a longer warhead for the later models at some stage and probably a 1/35th scale version.


I recently redrew the Mark 14 Torpedo, these were used thoughout most of WW2 and fitted the above torpedo tubes, I have given the dimensions for full scale. My measurements for the individual sections in this drawing are calculated from various photographs so they may not be spot on..




Reference: From torpedo boat manual 1st February 1943.

Mark XIV torpedo, diameter, fully charged, 21.060 inches; length, 240 inches; weight in service condition, 3,017 pounds; permissible pressure on afterbody, 100 pounds per square inch.

The same torpedo (Mark XIV) with elongated warhead could also be fitted to the torpedo tubes. In this case the length was increased by 6 inches and the weight by 200 pounds. The head was the only part affected by these increases.

An alternative torpedo was the Mark VIII-3D, diameter fully charged, 21.060 inches; length with warhead, 250.88 inches; weight in service condition, 3,050 pounds; permissible pressure on afterbody, 75 pounds per square inch (instantaneous only).

Reference: http://www.navalunderseamuseum.org/mk-14/


The MK 14 was the primary submarine-launched, anti-surface ship torpedo of World War II before the introduction of the electric MK 18. Initially considered problematic and unreliable, the MK 14 torpedo became the most effective, destructive U.S. Naval weapon of the war after flaws with its successive exploders and depth setting mechanism were addressed.

In 1930, the Naval Torpedo Station (NTS) at Newport, RI, was tasked with designing three new torpedoes: the MK 13 for aircraft use, the MK 14 for submarines, and the MK 15 for destroyers. With a paltry R&D budget of about $50,000 per year, NTS was forced to take an economical approach to their development. Engineers established a common technology base based on the MK 12 torpedo. The development cycle for all three torpedoes was also simplified by using steam turbine power plants, a compressed air and alcohol combustion system, a common depth and course control system, and similar exploders. NTS managed to develop the three torpedoes for an impressive R&D cost of $200,000, less than $70,000 per torpedo. Most evaluations with the new designs were performed with exercise torpedoes to reduce costs; testing of warshot torpedoes, especially against real targets, was almost nonexistent due to the high costs involved, so the torpedos entered service almost untested.


Much more to come.

(C) Copyright 2018,  John Drain