External torpedo tubes

Dear Friends,

I've been always wondering why Marine Nationale used external rotating torpedo tubes in the upper casing on their boats (as well as boats built for foreign navies i.e. Poland, Latvia). Those tubes were as far as I know never used in combat and were quite unpractical (no possibility to realod, when rotating they were causing whirls). Can anyone of you tell me what was the reason (and advantages) of installing those tubes on French-built submarines?! And why most of the external tubes was of 400 (or 450) mm diameter and not standard 550 mm?!

Any help would be greatly appreciated!


Very best regards from Warsaw,
Andrzej

PS. Feel free to answer in French - I can read some French

crolick a écrit:

Dear Friends,

I've been always wondering why Marine Nationale used external rotating torpedo tubes in the upper casing on their boats (as well as boats built for foreign navies i.e. Poland, Latvia). Those tubes were as far as I know never used in combat and were quite unpractical (no possibility to realod, when rotating they were causing whirls). Can anyone of you tell me what was the reason (and advantages) of installing those tubes on French-built submarines?! And why most of the external tubes was of 400 (or 450) mm diameter and not standard 550 mm?!
Any help would be greatly appreciated!
Very best regards from Warsaw,
Andrzej
PS. Feel free to answer in French - I can read some French

Bonjour Crolick
d'après mes connaissances :

1) Calibre de 400/450mm:
Pour les tubes externes, la marine francaise adopta les calibres 400 ou 450mm simplement car elle estima que ceux ci suffisèrent contre des navires marchands (pas besoin de forte charges explosives ou grande portée.....), et puis aussi un peux pour des raisons de couts (1 torpille de 4500mm valant moins chères qu'une torpille de 550mm)

(source de mes propos: all the worlds fighting ships 1922/1946 & magazine navire et histoire )

mais bien sur avoir 2 calibres de tubes lance torpille, cela était il vraiment une économie ? ,....je ne le crois pas

2) Le choix d'avoir des tubes externes rotatifs:
la marine francaise durant la période 1900/1940 considéra que les sous marins était des "torpilleurs sous marins", et pour cela décida d'y installer (dès que la technologie le lui permis) des lances torpilles rotatifs externes, et ce pour pouvoir eventuellement etre capable:
a) etre capable d'effectuer une attaque a la torpille en surface
b) les affuts rotatifs permettant une certaine "liberté" de tirer, un peux comme les torpilleurs

3) L'utilisation en combat:
oui tu as raison, a ma connaissance, aucun sous marins francais n'utilisa ces tubes externes en combats (1939/1945) ?

4) Le probleme du rechargement:
normal que les tubes externes ne puissent pas etre rechargés en mer, car pour rechargé un tube externe, il faut du matériel (petite grues, matériels de levage, poulies, ect....), et en mer, manoeuvré sur le pont d'un sous marins de 5 à 8 metre de large, une torpille de 700 ou 900 kg et 5 ou 8 metres de long, c'est quasiment impossible

Ces torpilles étaient destiné aux navires de commerce.
Les sous marins étant utilisés comme corsaires.


Jef

Bonjour

Petite précision de langage tout de même. J'ai buté sur le terme rotatif avant de comprendre qu'il s'agissait tout bêtement de tubes "orientables".
Les torpilles avaient peu ou pas du tout de déviation gyroscopique. Elles étaient lancées directement en direction d'un but futur.
L'idée des tubes orientables était à l'origine de permettre un lancement sur une cible, tout en conservant avec elle une route parallèle. Mais cette dispostion s'est très vite heurtéeà l'accroissement de la vitesse des cargos à moteur par rapport à la vitesse que pouvait soutenir un sous-marin de cette époque aux électriques.
A+

Hello all
and thank you for your answers

From what you have said it seems that:
(1) French Navy adopted 400/450 mm torpedoes to use them against enemy shipping due to smaller cost of those torpedoes (comparing to larger 550 mm ones) and due to larger amount of 'small' torpedoes which could be carried onboard the submarines
(2) The 'orientables' torpedo tubes (TT) were installed because it was desired to have ability to use torpedo tubes onboard submarine just like on destroyers (and be able to take a shot at any angle)

If so what were the advantages of the 'orientables' TT comparing with the traditional TT?! Since if they were introduced and mounted on all French subs it means that advantages overweighed disadvantages. And latter are quite significant. First of all 'orientables' TT were heavy (as far as I know around 5-6 tons one set of double 'orientables' TT) which decrease speed as well as range. Second of all when 'orientables' TT were supposed to be used underwater at any angle they were creating whirls which could be easily seen from the surface and could give away the position of the sub. And last but not least as far as I know the speed when firing from 'orientables' TT was limited to 5 kts, so the idea of going on parallel course to the merchant ship and fire torpedoes is simply limited only to ships slower then 5 kts!
So what were the advantages?! Or maybe it was simple solution of the problem how to 'pack' two kinds of torpedoes on one submarine and it was decided to use 'orientables' TT as the platform for the 'smaller' torpedoes?!

Andrzej


PS. I'm sorry but I do not get the part about 'orientables' TT used against submarines?! Why they were supposed to be used against submarines and in what way?!