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*****

Introduced in 1917, these were almost identical to the VI****, but had small improvements in constructions and could withstand 100 psi pressures.[16]

In submarine use (at least), in 1917 it was decided that they were to be altered to deliver:[17]

  • 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, 1917. p. 27.
  17. Annual Report of the Torpedo School, 1917. pp 25-26.

Bibliography

See Also