Location of Torpedo Blast

[dominic contrada]

Most historians agree, based on Walther Schweiger's war diary that the torpedo struck the Lusitania in the area below the bridge which places the point of entry at the forward coal bunker. But consider this: Schweiger no doubt based his observation on the location of the water spout which resulted from the blast. But we must take into account Lusitania's forward speed. If we assume that the water spout took 1-2 seconds to reach maximum effect, the Lusitania's speed at 18 knots means that it is possible that the torpedo actually struck some 60 feet FORWARD of the coal bunker, at the juncture of the bunker and the cargo hold.

 

[Michael H. Standart]

>>the Lusitania's speed at 18 knots means that it is possible that the torpedo actually struck some 60 feet FORWARD of the coal bunker, at the juncture of the bunker and the cargo hold.<<

Actually, it doesn't. Torpedo shots are an interception where the weapon is aimed to where the ship is *expected* to be when they come into contact. As quickly as a warheads explosive charge expands on detonation, the effect would, for all practical intents and purposes be instantaneous. In other words, what you see is actually what you get.

 

[Samuel Halpern]

Michael, I think you missed Dominic's point. When the shot goes off it sends a volume of water upward directly over the point where the detonation ocurred. When it reaches its peak height would be a second or two after the detonation. During that time the ship is still moving forward. If the observer remembers the position of that spout when it reached its peak relative to the profile of the ship behind it, then that point would be centered behind the actual spot of the detonation on the hull since the hull had moved forward while the spout was rising to its peak.

 

[Michael H. Standart]

>>When the shot goes off it sends a volume of water upward directly over the point where the detonation ocurred.<<

Quite right. It does. Unfortunately, I don't think he's ever seen explosives going off at sea or has any idea just how quickly that water column goes up. I have and I do. The water column would have gone so high and so quickly, that the time lag is scarcely even worth mentioning.

 

[Samuel Halpern]

We are talking about 1 or 2 seconds here, not minutes. The issue is pinpointing the precise point of contact. That could be a little difficult especially on a moving ship seen from a periscope. The water column goes up quickly but seems to settle down a bit slower. It's hard to see anything behind it for a few seconds afterward. Best bet is to remember what you saw last as the column goes up. I've seen a hit taken from a periscope camera, and it can be quite impressive. The best I've found of what a torpedo hit looks like on the web is here: http://diodon349.com/Torpedoman/Mk48_Torpedo_images/Mk48-all.jpg. The target was stationary and the torpedo was set to go off under the hull. It was hit just aft of the funnel. This is not quite the same as what happened to the Luci, but you can still get an idea of what it is like.

 

[Noel F. Jones]

Frame No.4 looks as if it ought to precede frame No.3. No.4 looks to me like a developing plume, not a collapsing one.

That notwithstanding, we need to know the time between frames if we are to derive anything useful.

As we know, water being virtually incompressible the only way for that displaced by an underwater explosion (or indeed by a moving object such as a ship) is up.

Given the density of water and the resultant inertia, the time elapsing between the incipient plume and its eventual full development should be notionally measurable for a detonation of given power. However, in practicality it may devolve upon empirical data such as observation and photographic analysis.

Given the conditions obtaining at the time and the limitations upon the observing of the event via the periscope of a U-boat operating under combat conditons, Dominic Contrada may have a valid point.

The matter is further complexed by the assertion that a secondary explosion took place attributable to some peculiar condition of the target (explosives on board).

Noel

 

[Michael H. Standart]

>>This is not quite the same as what happened to the Luci, but you can still get an idea of what it is like.<<

I've seen that one and worse, and in moving film too. Seeing something like that is enough to make any Navyman respect the potency of these weapons. That's one of the reasons that navies have tried to develop decoy systems. None of those systems have ever been tested in actual combat but I sure *hope* they work.

>>Given the conditions obtaining at the time and the limitations upon the observing of the event via the periscope of a U-boat operating under combat conditons, Dominic Contrada may have a valid point. <<

Perhaps.

>>Given the density of water and the resultant inertia, the time elapsing between the incipient plume and its eventual full development should be notionally measurable for a detonation of given power.<<

Okay. Might as well take a look at that if we can. What was the explosive filler used in that particular model of torpedo and what are it's characteristics? It might help if we knew the expansion volocity of the stuff. I doubt it was in the same league as C-4, which I understand has an expansion volocity of 36,000 feet per second, but it would still pack quite a punch. Figure that out and we may have some basis to see how far the ship could travel from the intial detonation to the time the plume reached it's full hight.

>>The matter is further complexed by the assertion that a secondary explosion took place attributable to some peculiar condition of the target (explosives on board). <<

And therein lies a sticky problem. The munitions the Lusitania was carrying isn't exactly a state secret and nobody made a really special effort to cover that up after the ship left New York. Mostly it consisted of some small arms ammunition, some Gun Cotton...which needs to be well confined to make for a really powerful explosion...some unfilled artillary shells and...if I recall correctly...some detonators. It doesn't appear as if anything was being carried in sufficiant quantities to make for a really big explosion. If it was, I would have to wonder why it is that the region of the cargo holds shows no apprieciable evidence of such an event.