18-in Mark VII Torpedo (UK)

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18-in R.G.F. Mark VII Torpedo[1]
18-in R.G.F. Mark VII* Torpedo (bottom)[2]

The 18-in R.G.F. Mark VII Torpedo was a British torpedo developed at the Royal Gun Factory and first ordered for service in 1908 in its VII* variant.[Fact Check]

Unlike the Mark VI torpedoes, there were heater torpedoes by nature, and so are never qualified by a "H.".

Development and History

Ovalling gear was being trialled at sea in 1917.[3]

Particulars

It was hoped that these might deliver more than 41 knots, but depth-keeping issues observed above 43 knots caused them to be rated at lower speed.[4] Its overall length including 4.5-in long pistol was 17 feet, 7.4 inches (see Plate).[5]

In its Mark VIII S.L. version, it achieved 29-31 knots to 5,500 yards and 40.5-41.5 to 3,00 yards.

Manufacture and Use

Mark VII

The raw Mark VII torpedo was first ordered in 1910-1911; oddly, this is after the Mark VII* and Mark VII** variants in 1908-1909. More careful reading is required.

In submarine use (at least), in 1917 it was decided that they were to be altered to deliver:[6]

  • 35 knots to 4,500 yards
  • 29 knots to 6,000 yards

Mark VII*

Forty S.L. torpedoes were ordered in 1908-1909, but were somehow only reported the following year.[7]

These contained more fuel and water but less air than the raw Mark VII, yielding an increase in range, at least under the low speed setting: 29-31 knots to 6,500 yards and 40.5-41.5 over 3,000 yards.[8]

In submarine use (at least), in 1917 it was decided that they were to be altered to deliver:[9]

  • 35 knots to 4,500 yards
  • 29 knots to 6,500 yards

Mark VII**

Some 53 Hook Bracket and 143 Side Lug specimens were ordered or given heaters in 1908-1909 – the source needs to be read more carefully.[Citation needed]

In 1914, however, these are referred to as "new" torpedoes, with rectified threads throughout, B2 generators and air vessel pressures increased to 2,200 psi to deliver 29 knots to 7,00 yards.[10]

In submarine use (at least), in 1917 it was decided that they were to be altered to deliver:[11]

  • 35 knots to 5,000 yards
  • 29 knots to 7,000 yards

Conversion of Marks VII** to VII***** to E.R. 3 was undertaken in 1917, but by year's end, only 21 had been converted.

Mark VII***

Introduced in 1914, these combined some additional small improvements to those of the VII**.[12]

In submarine use (at least), in 1917 it was decided that they were to be altered to deliver:[13]

  • 35 knots to 5,000 yards
  • 29 knots to 7,000 yards

Mark VII****

Introduced in 1916, these had interchangeable warheads with earlier Mark VII torpedoes and combined some 18 additional small improvements to those of the VII***, including:[14]

  • Tail of H.B. 1/S.L. 1 type
  • Wider gyroscope rudders
  • strengthening rings in afterbody

In submarine use (at least), in 1917 it was decided that they were to be altered to deliver:[15]

  • 35 knots to 5,000 yards
  • 29 knots to 7,000 yards

Mark VII*****

Depth-taking Test from submarine launch[16]

Introduced in 1917, these were almost identical to the VI****, but had small improvements in constructions and could withstand 100 psi pressures.[17]

In submarine use (at least), in 1917 it was decided that they were to be altered to deliver:[18]

  • 35 knots to 5,000 yards
  • 29 knots to 7,000 yards

Footnotes

  1. ↑ Annual Report of the Torpedo School, 1908. Plate 12.
  2. ↑ Annual Report of the Torpedo School, 1909. Plate 2.
  3. ↑ Annual Report of the Torpedo School, 1917. p. 25.
  4. ↑ Annual Report of the Torpedo School, 1909. p. 12.
  5. ↑ Annual Report of the Torpedo School, 1908. p. 18.
  6. ↑ Annual Report of the Torpedo School, 1917. pp 25-26.
  7. ↑ Annual Report of the Torpedo School, 1909. p. 7.
  8. ↑ Annual Report of the Torpedo School, 1909. pp. 11-2.
  9. ↑ Annual Report of the Torpedo School, 1917. pp 25-26.
  10. ↑ Annual Report of the Torpedo School, 1914. p. 8.
  11. ↑ Annual Report of the Torpedo School, 1917. pp 25-26.
  12. ↑ Annual Report of the Torpedo School, 1914. p. 8.
  13. ↑ Annual Report of the Torpedo School, 1917. pp 25-26.
  14. ↑ Annual Report of the Torpedo School, 1916. p. 39.
  15. ↑ Annual Report of the Torpedo School, 1917. pp 25-26.
  16. ↑ Annual Report of the Torpedo School, 1918. Plate 76.
  17. ↑ Annual Report of the Torpedo School, 1917. p. 27.
  18. ↑ Annual Report of the Torpedo School, 1917. pp 25-26.

Bibliography

See Also

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