Middleton Plotter

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The Middleton Plotter was a torpedo control device conceived by Lieutenant (T) J. R. Middleton of H.M.S. Hercules.[1]

Design and Operation

Its goal was to automatically indicate when to fire, without requiring calculations to find the bearing rate or to then find the deflection. It consisted of a telescope or periscope which would be trained to stay on the target by a hand crank. A worm gear would read this angle and then use a disc-and-roller variable speed drive set to the bearing rate being applied. A gyrocompass receiver would act through a differential to remove own ship's yaw. A mechanical calculator would then take the total deflection and subtract out the portion of the deflection attributable to own ship's motion only. The operation was by entering the speed of torpedo, speed of own ship and mean range to the target and then work the handcrank to keep the scope on the target. When two electrical contacts touched, it was time to fire the torpedo.[2]

The process of subtracting the deflection component attributable to own ship's movement from the total deflection yields the Torpedo Deflection, although it is not termed such in these early references. Perhaps the described ease of obtaining the torpedo deflection in this manner was part of the impetus that would eventually result in the British abandonment of the Torpedo Director in favour of the Torpedo Deflection Sight, which only required the torpedo deflection to derive the director angle for firing.


After promising preliminary tests, in 1913, two sets of equipment were ordered from Elliott Brothers. In 1914, one was being "hastened" to sea for testing in Iron Duke, which had been fitted for the trial. It was acknowledged that there was so much work going on that broader trials in other ships were unlikely.[3]

Rice's Torpedo Automatic Sight was viewed as a contingent system to be developed in case Middleton's proved unsatisfactory. It would perhaps be tested in Marlborough or Ajax.[4]

By the end of 1915, one of two sets of the equipment was still under construction. While there were plans to see one trialled in Iron Duke,[5] the extreme cost of the first delivered unit prompted the decision to drop the project. The first and possibly only unit created was allocated to Vernon.[6]

I have not been able to find clear reference to dates and ships that received this system or later developments.

See Also


  1. Annual Report of the Torpedo School, 1913. p. 30.
  2. Annual Report of the Torpedo School, 1913. p. 30. The editor does not find this explanation sufficient to understand its design.
  3. Annual Report of the Torpedo School, 1914. p. 36.
  4. Annual Report of the Torpedo School, 1914. p. 36.
  5. Annual Report of the Torpedo School, 1915. p. 36.
  6. Annual Report of the Torpedo School, 1915. p. 60.


  • H.M.S. Vernon. (Feb 1914) Annual Report of the Torpedo School, 1913, with Appendix (Wireless Telegraphy). Copy 42 at The National Archives. ADM 189/33.
  • H.M.S. Vernon. (Jan 1916) Annual Report of the Torpedo School, 1915. C.B. 1166. Copy 1025 at The National Archives. ADM 189/35.