Damage Effects of main deck mounted torpedo tubes

[oldpop2000]

I just wanted to ask the question about deck mounted torpedo tubes. In the real world this was not done on any ship above a light cruiser with exceptions, I am certain. Many British battleships removed those deck mounted torpedo tubes. Partially to free up deck space for AAA but many times to remove possible secondary explosive effect. So, if deck mounted torpedo tubes are mounted on dreadnought, will those loaded torpedo tubes cause secondary explosions or enhance an incoming shells damage without the log noting this. 

[mycophobia]

They do explode, with oxygen torpedo being especially risky. I couldn't remember if the game have a distinct message when the torpedo explodes, but not all "torpedo tube destroyed" means they will explode.

[colprice]

IIRC, the Royal Navy tested the likelihood of torpedoes suffering sympathetic explosion and concluded it unlikely. This was fed into the enquiry regarding the loss of the Hood, where the possibility was considered.
As the dive photos of be Hood show some torpedoes still in their tubes, it seems as if the chances of a TT exploring from shellfire are remote.
The experience of the Japanese with oxygen torpedoes really highlights the problems managing pure oxygen.

The argument for Battleship torpedoes relates to the concept of two fleets steaming parallel and with minimum spacing between ships. The RN estimated that about 1/3 of the battle line would be hit by torpedoes if the correct firing position could be reached. As gun ranges grew longer than torpedo ranges, the idea became obsolescent, and many BBs had their torpedo flats repurposed.
The BCs were still considered to have a torpedo role because they may still be able to achieve a firing position.

Of course, following the interest treaties, the line of battle would be significantly shorter and the practicality of "browning" shots vanished.
(See Friedman British Battleships)

The German BCs and Panzerschiffe were fitted with deck mounted TTs, intended for merchant ships..

Colin

[rimbecano]

Oct 31, 2019 13:41:08 GMT -6 oldpop2000 said:

I just wanted to ask the question about deck mounted torpedo tubes. In the real world this was not done on any ship above a light cruiser with exceptions, I am certain.

The Japanese put torpedoes on everything up to CAs by doctrine, and suffered several CA losses due to torpedo explosions, though much of this may have been due to their use of oxygen torpedoes.

The USN, OTOH, did not order very many CLs with torpedoes, and no CAs, and this, arguably, bit them a few times during the Solomons campaign.

[oldpop2000]

From "The loss of the HMS Hood by William Jurens

Detonation of Torpedoes

A number of writers, including some members of the original boards of inquiry, have speculated that it was an explosion of torpedo warheads which directly or indirectly caused the loss of the ship. The Second Board of Inquiry itself concluded that though such an event was possible, it was not a likely scenario. The board concluded:

"Evidence of eye witnesses, REPULSE, and an Officer who had recently served in HOOD leaves little room for doubt that the mantlet doors were closed. A warhead could still, however, have been detonated or exploded by a direct hit from BISMARCK'S shell. There is no direct evidence that such a hit occurred, but it may have done so on either side of the ship. If a single warhead had gone off one other, but probably not more than one, the other warhead would also have gone off. . . . Expert opinion suggested that the explosion of two warheads would produce an all round almost instantaneous flash. It would not have produced the very high column of flame of appreciable duration, which was seen by so many witnesses. Nor was the noise, reported as being heard, compatible with that of a T.N.T. detonation or explosion. The consensus of expert opinion was definitely against the characteristics of the explosion as given in evidence by eyewitnesses being that of T.N.T."70

Sir Stanley Goodall, then Director of Naval Construction, held to a dissenting opinion, however:

"If one or more shells from the 5th salvo burst in this devastated area [where fire was already burning], where there are eight torpedo heads, four each side, each containing about 500 lbs of TNT at the base of the mainmast, and if one or more of these warheads detonated, the result would be an explosion where it was actually observed. Such an explosion could break the ship's back already weakened in this neighbourhood by the earlier damage. With the force on the after bulkhead of the engine room due to the ship's speed of 28 knots and the low reserve of buoyancy of the after part of the ship, this portion would rapidly sink. The foregoing is an alternative explanation of the occurrence which is as likely as the explanation in the finding of the court."71

Sir Stanley was probably wrong. Although no formal calculations were ever done, the court had looked long and hard into the issue, and received the testimony of a number of expert witnesses. Typical of these was Capt. John Carslake, R.N., an explosives expert who testified on Friday, 29 August. After confirming that although he was not an expert on cordite explosions per se, but that he ". . . knew a fair amount" about high explosive detonations, the court subjected him to a detailed examination.

"Would a 15-in or 8-in shell striking Hood's side abreast the torpedo tubes detonate a warhead with a pistol in it?" they asked. His answer, based on trials, was "No, not unless it penetrated and detonated inside the mantlet. If it detonated outside it would not detonate the warhead." "Would a direct hit, either from a shell or a splinter detonate a warhead without a pistol in it?" the court inquired. "If the shell detonated on impact with the warhead, it would detonate the warhead. If the shell hit the warhead but did not detonate, it would not detonate the warhead . . ." When asked what would be the probable effects if the warheads detonated, he replied:

"I would expect the mantlet, the ship's side, and the forecastle deck to be nearly demolished, but that the major venting would have been as I suggested horizontal. Immediately after the explosion it is anticipated that the observer would have seen a gap in the ship's side, probably some 15 or 20 ft. radius down to the top of the 12-in belt. . . . I would expect the boat deck above the tubes also to be blown away.72

B.A. Fraser, Controller, summarized his particular objections to the torpedo scenario in a memo dated 7th July:73

"D.N.C. has raised the question of whether the above water torpedoes in 'HOOD' were responsible for the destruction of the ship. I disagree with his view, and accept the report of the Board of Inquiry for the following reasons:

from trials, a 15-in shell burst outside a torpedo tube protected by a mantlet will not detonate the torpedo.

Although a direct hit may detonate one torpedo, it is extremely unlikely that others will be countermined. In 'KHARTOM' a torpedo was fixed74 into the after galley by an air vessel bursting. The head did not detonate but it burnt to detonation in the fire after a considerable period, about 20 minutes, and in 'HOOD' the interval between the first hit and the destruction of the ship seems to have been under 3 minutes.

These descriptions are consistent with the results of other experience. To take one example, on 26 December, 1943 the destroyer U.S.S. Brownson (DD-518) was struck by a Japanese bomb which apparently detonated one or more of the 374kg torpex loaded torpedo warheads in her after quintuple torpedo mount.75 The resulting explosion removed or completely demolished all ship structure over a radius of approximately 10 meters. Fifteen minutes later, Brownson sank. Although the detonation of a torpedo tube nest could result in the sinking of a destroyer in fifteen minutes, it is clearly unlikely to have caused the loss of a battlecruiser in three. The chances of a torpedo explosion near the mainmast detonating even the closest of the ship's magazines twenty-five meters and two decks away are inconsequentially small.

As you can see, a battle cruiser such as the Hood could not sink in 3 minutes with a torpedo hit by a shell, it does not say that 18 torpedoes could not sink a dreadnought in 22 minutes if they were being struck. It does say that a direct hit would detonate one torpedo in the mantlet. But we don't know if the game uses mantlet's, do we?