SUBSIM Radio Room Forums - It is not the length but the girth in torpedoes

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- - It is not the length but the girth in torpedoes (https://www.subsim.com/radioroom/showthread.php?t=133847)

I think almost all decisions like this in weaponry are based on best punch for size. In the case of torpedoes the propulsion system limitations of the time also had to play a role I would think, as well as what size a torpedo human beings could maneuver around to load them, but I'm betting the neccessary warhead size dictated much of the torpedo's size.

The U.S. used .50 guns on most fighters until the jet came along. Then it was discovered the projectile wouldn't travel fast enough or make up for the increased drag at the increased speeds of jet fighters in combat so they went to 20mm. In weaponry and war in general the overiding idea is always what delivers the neccessary destructive power at the least cost, both financial and weight (or any physical charactistic) while allowing for a decent amount of ordnance to be delivered. i.e. one huge torpedo can only sink one ship IF you get a hit. Better to use torpedoes that are just large enough to penetrate a ships hull but still allow you to carry as many as possible. The same tradeoff for infantry weapons. Why don't they all carry .60 machine guns? Why does the M16 shoot .22 rounds? Why not .12 or .60? For those who have had calculus the value is called the limit. A value you approach from both sides. Not too small, not too large. There is a best size for a given job. She said. LOL

My two cents.

Gibbons

I think Platypus hit the nail on the head and that generally, torpedo diameters are what they are because that is what they are. I do not know a lot about the hydro-dynamic properties of torpedoes but have taught artillery ammunition and ballistics for many years and a lot of things such as gun calibres, for example just are what they are. Attempts to find hard and fast reasons only lead to contradictions and frustration, but rest assured there are frequently engineering or manufacturing considerations that may not be obvious to an outsider. Early Whitehead models were roughly 14", which grew to 17", then 18" then 21" and finally 24" with only minor variations seemingly regardless of country of manufacture. The nature is similar to that of artillery pieces, naval or land that are roughly standardized in calibre (in this case the mean outside diameter of a typical projectile measured at the borroulet).

There are no specific ballistic reasons why the vast majority of tubed guns fall into specific calibre groups, they just do. Some examples
3", 75mm, 76.2mm, 77mm
3.7",85mm, 88mm, 90mm
4", 102mm, 105mm
5", 128mm, 130mm
6", 150mm, 152mm, 155mm
And so on... with the caveat that there are exceptions and oddities some of which may even have seen considerable service.

Note that 21" torpedoes seems to provide a good balance of managability, warhead wieght and internal volume for engine, fuel and guidance systems. Increasing diameter increases payload and provides more usable interior space but increase handling problems, reduces the number that can be carried on a given displacement and increase the size of the holes that need to be cut into the pressure hull to accomodate the launch tubes. Any weapons system design is a matter of compromises the fact that 21"/533mm is so common indicates that this diameter generally allows for an effective torpedo.

Think I ran over my $0.02 limit. Sorry to ramble on...

Good Hunting

Answer about 21 inch diameter torpedoes

Hi. I can perhaps cast a little light on the subject. The reason for UK and US torpedoes having diameters of 18", 21", and 24" seems clear if written in feet and inches: those sizes are 1ft 6in (1.5ft), 1ft 9in (1.75ft), and 2ft diameter. The answer to the final question quoted below is presumably that, just like Goldilocks and the Three Bears, 1ft 6in diameter was too small, 2ft was too big, and 1ft 9in turned out to be just right for submarines. Apologies if this is a glimpse of the obvious.

According to WP the G7 was a WW1 torpedo used by U-boats.

Quote:

Originally Posted by Platapus (Post 833865)

I think I may have found half the answer.

My original question was actually two separate but related questions

1. Why did Japan, Britain, Germany and United States all use torpedoes with the same diameter (533mm/21”)?

2. Why was 533mm/21” chosen?

The answer for the first question is that Japan, Britain, United States, Germany and Italy were all in cahoots with Robert Whitehead’s through his and other related companies.

Stabilimento Tecnico di Fiume (and its many incarnations)
Schwartzkopff (later known as Berliner. Maschineubau A.G.)

both were developers of Whitehood’s designs. They all had dealings with Japan, Britain, Germany and Italy. Representatives from all countries interacted with each other.

In 1908 as Whitehead moved toward 533mm/21” torpedoes, it is understandable that the other distributors would follow suite.

The Whitehead Mk VIII was the first UK developed 533mm/21” submarine torpedo. Its design dates back to 1925.

Germany’s G7a was their first 533mm/21” submarine torpedo designed in 1930. The G7a is an oddity as it was a follow on to the ship launched G7. The G7 was 500mm/19.7” in diameter. Why the G7a needed the extra 1.3” is still a puzzler.

Italy developed the W270/533.4x7.2 Velosa in 1935. Japan was especially interested in the design of the Italian W270/533.4x7.2 Velosa torpedo and copied some of the components.

Japan was using Whitehead designs for their 21” Type 43 ship launched torpedo in 1910. In October 1917, the Japanese Navy decided to move toward the 533mm/21” design for their submarines. The 533mm Type 92 was designed in 1934 and used designed from the G7a.

The United States is an oddity. The relationship between Whitehead and the United States Navy was stormy at best.

Even though the Whitehead torpedoes were successful and widely sold, from 1870-1900, the United States Navy concentrated on other non-whitehead designs.

Lay, Barber, Ericsson, Lay-Haight, Sims-Edison, Cunningham, Howell were all designs evaluated and used by the United States Navy with the Howell design having the most usage.

In 1891, the United States Navy contracted with the Bliss corporation to build the Whitehead Mk 1 ship launched torpedo. This started the short relationship between the United States Navy and Whitehead. This also started a longer relationship between Bliss and Whitehead in the joint development/improvement of torpedo designs.
By 1901, the last Whitehead torpedo, the Mk 5 was contracted for use in the United States Navy. It was an 18” ship launched torpedo.

In 1904, the United States contracted with the Bliss-Leavitt corporation to build their Mk 1 21” ship launched torpedo. This started a long history of USN - Bliss-Leavitt contracts.

Starting with the Mk-X 21” torpedo in 1917, the design and production of future was under the auspices of the United States Naval Torpedo Station in Newport with few exceptions.

The United States Navy decided on 21” as a standard diameter for ship launched and submarine launched torpedoes in 1917 with the commissioning of the USS Caldwell (DD-69) that was designed to fire the new Bliss-Leavitt Mk-8 21” torpedo. One of the few exceptions to this was the Mk-27 19” torpedo developed in 1943.

So we have somewhat of and explanation as to why the United States used 21” torpedoes. Command decision in 1917.

We also have an explanation as to why Britain, Japan, Italy, and Germany used torpedoes of the same diameter -- they shared designs and variations in designs with the Whitehead designs.

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.

First post and you resurrect a 2 1/2 year old thread-talk about rising from the dead. :D
Oh well, I think we've all stepped in that trap before.

Welcome aboard! :salute:

:)

Well, if he happens to be a subject matter expert it would be a shame not to share that knowledge.

Personally I don't care how old a thread is. Necrothreading is fine by me. Just as long as it isn't about SPAM.

Quote:

Originally Posted by Pisces (Post 1539638)

Agreed and it did add more detailed information on the subject.

Welcome Aboard Giles http://www.psionguild.org/forums/ima...es/welcome.gif