Difference between revisions of "18-in Mark IV Torpedo (UK)"

Revision as of 17:16, 30 November 2012

The 18-in R.G.F. Mark IV Torpedo was a British torpedo developed at the Royal Gun Factory in 1894 or 1895.^{[Fact Check][1]}

Development and History

In 1895, they were just about to enter service.

Particulars

The final design is extensively laid out in the Annual Report of the Torpedo School, 1895.^[2]

The construction was very similar in materials to the 14-in Mark IX torpedo.

• Diameter: 17.71 inches
• Length: 16 feet, 7.4 inches
• Weight with pistol, without air: 1,156 pounds
• Metacentric height: at least .575 inches
• C.G. distance from tip of shaft, no air: 114.175 inches
• C.G. distance from tip of shaft, 60 pounds air: 114.35 inches
• Warhead: 200 pounds wet guncotton

It carried a charge of 170 pounds, 15 ounces – the same as in the Mark III torpedo.

It had a Brotherhood engine of 3.25x3 inches.

Mean pitch of propellors was 40 inches. When charged with air, the torpedo must pass through a gauge 9 inches long and 17.725 inches internal diameter.

With pistol and charged with 60 pounds of air was ballasted and adjusted to float horizontally and upright in salt water at a density of 1.026 and 60 degree temperature. In fresh water, with pistol and no air, it had a buoyancy of 31 pounds.

The proof and passing tests were six runs when charged to 1,350 psi:

• two runs from a submerged frame at target 800 yards distant
• two runs from an A.W. tube at least four feet above the water at a target 400 yards away
• one run above water at target 800 yards away
• one run from submerged frame at target 800 yards away

The limits of deviation permitted were:

• lateral deviation from the submerged frame must be less than 12 yards either way throughout run
• from A.W. tube, lateral deviation of 8 yards at 400 yards or 24 yards at 600 yards
• deviation from set depth not to exceed +/- 18 inches

The speeds required were:

• not less than 30 knots to 600 yards and 29 knots to 800 yards in 60 degrees and warmer
• not less than 29.5 knots to 600 yards and 28.5 to 800 yards in 50-60 degrees
• at least 29 knots to 600 yards and 28 knots to 800 yards in water colder than 50 degrees

Endurance was tested in just one torpedo in a batch of twenty, after passing the above tests:

1. make six short runs from above water gun 10 feet or more above water
2. be fired from submerged frame and pass within 14 yards of target at 800 yards
3. it must then "shew no signs of weakness or distortion"

Manufacture and Use

Horsea was adjusting the first manufactured lots in 1896:^[3]

• 89 newly built torpedoes with Side Lugs made 30.47 knots at 600 yards and 29.08 knots at 750 yards in 53.1 degree water.
• 128 newly built torpedoes with Hook Brackets made 28.72 knots at 600 yards and 27.23 knots at 750 yards in 55.4 degree water.
• one short R.G.F. torpedo of unstated Mark was also tested, achieving 28.64 knots to 600 yards in 42 degree water.

Footnotes

Bibliography

See Also

• 14-in Mark IX torpedo, its contemporary