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Prof. W.J.Griethuysen, University College, London, on 27 November 2001
Joint Meeting with the Institute of Physics,
S. W. Branch
The first submarine of the Royal Navy, HMS Holland, was launched in 1901 so it is appropriate to review progress since that time today. The rate of technical change has, as would be expected, been spasmodic, with most development work in anticipation of or during wars.
Indeed, the first ship to be sunk by a submersible craft, in 1864, was the USS Housatonic during the American Civil War, sunk by the CSS Hunley, which was driven by man-power and carried an explosive charge on a probe, and which, having previously sunk twice, also sank in harbour, with the loss of all hands, after returning from this attack. Earlier, in 1776, Bushnell's Turtle, effectively a submersible barrel, attacked HMS Eagle in New York.
All these early vessels were `submersibles' rather than `submarines' i.e. they moved on the surface and only submerged during an attack. As will be seen, modern submarines move underwater faster than they do on the surface, but that is a recent development. To submerge, water is taken
submerged for 3 days, patrolling at 4 knots.
The Trafalgar class is 5200 tons, 85m (280 ft.) long, with a speed of `over 25 knots' and a crew of 130. These have been modified to carry missiles.
The latest development is in the propulsion system: the AIP (Air Independent Propulsion) submarine is designed to provide for submerged patrols of a few weeks duration at low speed by the use of fuel cells to provide electricity, instead of batteries. These have an output of 150 300 kW instead of 3 5 MW as required for high speed, but are very quiet. The reason for the changes is the new role assigned to submarines now. The emphasis is on communication and detection rather than hunting. The latest class under development, the Astute, is even larger than the Traflagar.
Questions were asked about the lessons submarine designers might have learnt from fish, as aircraft designers did from birds. The difference in the density of the medium, water vs. air, made study of animals less useful but whales are remarkably similar in shape to the `tear-drop' submarines.
Russian submarines have double hulls and bulkheads dividing them into compartments, which is an advantage in case of grounding in shallow water.
The major source of noise from a submarine is the transmission of engine noise and the propulsor; prevention of cavitation by a propellor is essential.
Lead/acid batteries are still used; newer types have problems and the future probably lies with fuel cells.