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Re: I might have an answer
Posted by: Rob Hoole ()
Date: April 11, 2008 08:35AM

Thomas Horton Wrote:
-------------------------------------------------------
<snip>
> What is still unanswered is why did Whitehead,
> Bliss-Leavitt, and Schwartzkopff all decide around
> 1920 to change to the 533mm/21” design in the
> first place?
>
> There had to be a reason.

Hello Thomas,

For what it's worth, this extract is taken from pp 102-104 of 'The Torpedomen - HMS Vernon's Story 1872-1986' by Rear Admiral Nicho Poland CB CBE:

"The Naval Staff's requirements for new and improved torpedoes led to the reconstitution in 1920 of the Torpedo Design Committee. Formed in 1887 it had last reported in 1904. The new committee was made up of representatives of the Director of Torpedoes and Mining, the Director of the Torpedo Division, the Director of Armament Supply, the Captain of Vernon, the Superintendent Royal Naval Torpedo Factory, the Superintendent of Torpedo Experiments and the Chief Inspector of Naval Ordnance. It was required by its terms of reference to clarify the staff requirements, co-ordinate experiments and prevent overlapping. In meeting these responsibilities it was authorised to co-opt the assistance of the Admiral (Submarines), Captain-in-Charge Coastal Motor Boats and the Air Officer Commanding Coastal Area, all key torpedo users.

When the committee first met on 15 September 1920 the newest weapon in the Royal Navy's torpedo armoury was the 21-inch Mk V introduced in 1918. This torpedo had been designed to satisfy demands from sea for a torpedo capable of 29 knots for 15,000 yards and of being fired from existing surface tubes. It had been designed with negative buoyancy at ranges below 7,000 yards and was considered to be unsatisfactory for use in peacetime because practice runs were usually carried out at ranges of less than this figure; torpedoes would therefore be lost. The Committee directed that future designs should combine greater ranges with positive buoyancy. There were also considerable stocks of 21-inch Mk II* and IV* torpedoes. These were used by the latest submarines, which were equipped with tubes of this calibre. Work was already in hand to improve the ranges and speed settings of these older weapons.

Inevitably, thoughts turned to radical proposals to achieve the vastly increased ranges and speeds of torpedoes which were demanded. The first experiment involved the 'mocking up' of a 21-inch Mk IV* torpedo to a diameter of 26 inches from which data was obtained for the design of torpedoes of larger diameters than hitherto. As a result of these trials it was decided to proceed with the construction of experimental 24.5-inch torpedoes for use in the new battleships Nelson and Rodney.

An increase in size alone could not produce the torpedo improvements required and experiments began in great secrecy to produce new and improved forms of propulsion. Experiments were carried out to increase the ratio of fuel to air but this only resulted in a deposit of soot in the generator. Attention then turned to the quality of the air supply. The air vessel of the heater torpedo accounted for one third of the total weight of the weapon, but the air it contained was made up of only 21 per cent oxygen. The obvious answer to these problems was to increase the amount of oxygen and to find a more volatile fuel. Experiments were begun at Vernon in the early 1920s.

By 1926 the development of the 24.5-inch torpedo had reached the stage of manufacture. During November and December 1926 the Mk I underwent a series of trials from the destroyer Vanoc in the Clyde. A year later, when this giant enriched air torpedo was issued to Nelson, the concept of the 'big' torpedoes was no longer popular as their massive weight made them difficult to handle and unsuitable for use with collision heads. Hence only a limited number were manufactured for use in the battleships Nelson and Rodney.

In parallel with the enriched air fuelled torpedoes an examination was made of the use of hydrogen peroxide as a low pressure oxidant. It was, however, the use of enriched air which continued to find favour. Such was the secrecy which surrounded these trials that they were not reported in the Vernon Annual Reports until they were well advanced. By then, the enriched air 21-inch torpedo had completed its acceptance trials and was designated the 21-inch Mk VII. Sea trials were carried out in 1928 in the new cruisers Berwick, Suffolk, Australia and Canberra (the other three 'Kent' Class ships carried Mk V torpedoes with specially strengthened tails to cope with the ships' high freeboard). The Mk VII operated satisfactorily and in 1928 was accepted into service being issued to later eight-inch cruisers. Like the 24.5-inch MK Is, the 21-inch Mk VIIs were not outfitted with collision heads and, therefore, were not run to hit in the practice mode.

The Mk VII also shared the unpopularity of the larger enriched air weapon. Enriched air was a dangerously unstable substance and if it came in contact with oil it could explode with disastrous results; the torpedoes used an alcohol/ water mix as fuel. The Mk VII's length of 25.5 feet made it difficult to handle and many a torpedoman's finger or toe were lost in the necessarily spotlessly clean torpedo workshops of 'County' class cruisers. But it was the constant need to avoid contact between the enriched air and 'torpoil' lubricant which made it so unpopular. Furthermore, the air vessels were subject to rapid corrosion. On the credit side, the use of enriched air provided a trackless wake, a valuable improvement over the conventional torpedo which it outperformed. At 33 knots the 21-inch Mk VII had a range of 16,000 yards.

The unpopularity of enriched air was not shared by all users. Shortly after the outbreak of war in 1939, Rodney's Torpedo Officer found that the oxygen making plant, which was used to manufacture enriched air for the torpedoes, had fallen into disuse. He persuaded a young Reserve Engineer officer to overhaul the plant and make it work. Thereafter, Rodney's oxygen plant was able to supply all her torpedo requirements as well as pure oxygen for medical and other purposes throughout the fleet at Scapa Flow. Early in the war the Mk VIIs in the British heavy cruisers were converted to run on natural air and shale oil which lowered their range to 5,700 yards at 35 knots. Canberra seems to have retained enriched air Mk VIIs until she was sunk in 1942 and Australia until she lost her tubes in a wartime refit.

Although the Royal Navy became disenchanted with enriched air, the Japanese, basing themselves on an erroneous report that the British had made the same move, went a stage further and developed a pure oxygen torpedo. Despite a series of fatal explosions they developed the world's most powerful and advanced torpedo. Known as the Type-93, 'Long Lance', its existence came as a great shock to the Allies during the Second World War. The Type-93 was a 24-inch torpedo, 30 feet in length: it carried a warhead of over 1,000 lbs of explosive,had neutral buoyancy and could be set at 49 knots for 24,000 yards and 36 knots for 43,000 yards.

Britain's torpedo designers had to look elsewhere for higher performance and better reliability. The obsolescent submarine torpedoes could not, in their opinion, be replaced with anything so inherently dangerous as the 21-inch Mk VII. The best alternative was the burner cycle semi-internal combus¬tion torpedo engine. This was a four cylinder radial fed with air from the main vessel. As before, fuel (initially shale oil, later paraffin) was burned in the air before it entered the engine but most of the oxygen was retained to be burned within the cylinders as more fuel was injected into them. Ignition was spontaneous as in a diesel engine and exhaust gases were ejected through ports in the piston crown and cylinder liner into a hollow propellor shaft.

The new submarine torpedo appeared as the Type G and it had a five knot advantage over the MK IV at 5,000 yards. So was born the 21-inch Mk VIII, easy to maintain, rugged and reliable, and destined to remain in service for over half a century. Its success derived from the basic excellence of the engine which gave it good development potential. The initial Mk VIII had a range of 5,000 yards at 40 knots and appeared in 1927; it went into service in the 'P' class submarines in 1930-31. A surface-launched burner-cycle torpedo was also developed as the Type-J to be fitted first to the new 6-inch gun light cruisers and then to the new destroyer flotillas from the 'D' class onwards. It entered service as the Mk IX in 1930; its range was 13,500 yards at 30 knots and 10,500 yards at 35."

Best wishes,

Rob Hoole
(www.mcdoa.org.uk)

Options: ReplyQuote


Subject Written By Posted
Simuliar diamaters in different country's torpedoes Thomas Horton 04/01/2008 12:51PM
Re: Simuliar diamaters in different country's torpedoes ROBERT M. 04/02/2008 04:46AM
Re: Simuliar diamaters in different country's torpedoes ThomasHorton 04/02/2008 02:48PM
Re: Similar diamaters in different country's torpedoes ROBERT M. 04/03/2008 03:52AM
Re: Similar diamaters in different country's torpedoes ROBERT M. 04/03/2008 03:52AM
Re: Similar diamaters in different country's torpedoes ROBERT M. 04/03/2008 03:52AM
Re: Similar diamaters in different country's torpedoes ThomasHorton 04/03/2008 04:16PM
Re: Similar diamaters in different country's torpedoes ROBERT M. 04/06/2008 05:34AM
Re: Similar diamaters in different country's torpedoes ThomasHorton 04/07/2008 01:13PM
Re: Similar diamaters in different country's torpedoes ROBERT M. 04/08/2008 03:51AM
Re: Similar diamaters in different country's torpedoes ThomasHorton 04/08/2008 11:13PM
Re: Simuliar diamaters in different country's torpedoes Rainer 04/08/2008 01:19PM
Re: Simuliar diamaters in different country's torpedoes ROBERT M. 04/09/2008 06:12AM
Re: Simuliar diamaters in different country's torpedoes Bruce Dennis 04/09/2008 07:25AM
I might have an answer ThomasHorton 04/10/2008 02:03AM
Re: I might have an answer ROBERT M. 04/10/2008 08:00AM
Re: I might have an answer ThomasHorton 04/10/2008 03:24PM
Re: I might have an answer ROBERT M. 04/11/2008 06:55AM
Re: I might have an answer ThomasHorton 04/11/2008 01:59PM
Re: I might have an answer ROBERT M. 04/12/2008 12:43PM
Re: I might have an answer Richard Uno 04/10/2008 02:50PM
Re: I might have an answer ThomasHorton 04/10/2008 03:28PM
Re: I might have an answer Richard Uno 04/10/2008 03:53PM
Re: I might have an answer Rob Hoole 04/11/2008 08:35AM
Re: I might have an answer ThomasHorton 04/11/2008 02:02PM


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