[bijowo1676]

I dont understand the purpose of using 40,000 lbs of TNT (0.2 kilotons) that registers as M3.9 quake - what kind of explosive payload is it simulating?

the only thing that comes to mind, is the smallest yield settings of a modern tactical nuke B61-12

[walrus01]

I would guess that they want to simulate a percentage of the shock force of a near miss or hit from a (russian, chinese, other equivalent-tech) torpedo or naval mine without actually risking rupturing the hull. So they need a much greater weight of explosives positioned a much further distance away than if they were to actually fire a torpedo at the ship.

Or for general shake and vibration and shock force testing of the entire ship, simulating a combat environment. Unlike the shake/rattle/hydraulic ram rigs which are used to qualify a new airliner design on a structural test article, there's no other way than lots of explosives to shake/vibrate an entire Nimitz, Ford class size aircraft carrier.

[jandrewrogers]

I would guess they want a large enough explosion to generate peak acceleration of the entire ship without a local enough explosion to actually damage it. Getting enough separation to make it non-local requires a lot of explosive thanks to the inverse cube law.

If you look at e.g. seismic damage models, peak acceleration is correlated with most of the worst outcomes.

[jandrewrogers]

The structure is engineered to survive a multitude of conventional threats intact. It is testing properties of the design rather than specific weapons per se. Also, these tests are intended to be non-destructive which impacts their design.

Exercises where the US military uses decommissioned aircraft carriers and other large ships as targets are illustrative. They are basically unsinkable. You can hit them with torpedoes, bombs, missiles, etc all day. At the end of the exercise they usually have to send over a specialized demolition crew to actually scuttle the ship. Astonishingly damage resistant.

A nuke would of course do the trick but now you are playing a different game.

People chronically underestimate how difficult it is to get enough conventional explosive on target to sink a major naval vessel, even ignoring the extensive active defenses.

[mschuster91]

> People chronically underestimate how difficult it is to get enough conventional explosive on target to sink a major naval vessel, even ignoring the extensive active defenses.

American ships, certainly. Russian ships? Oh boy. The Ukrainians, a country with no navy to speak of, sunk the Russian flagship Moskva to widespread memefied acclaim, a bunch of other Black Sea assets and are now taking potshots at the shadow fleet.

[thyristan]

Well, there was that small incident that nearly sunk that ship: https://www.fbi.gov/history/cases-and-criminals/uss-cole-bom...

I'm guessing with a few more tries to get the right positioning and amount of explosives, those terrorists could blow up US ships as well as the Ukrainians do Russian ones.

[dboreham]

Falklands war shows otherwise.

[cpgxiii]

> Falklands war shows otherwise.

Well, actually, the Argentinians had no trouble delivering high explosives to UK vessels, but they did have a great deal of trouble getting those explosives to sink those vessels ... mostly because their bomb fuzes were incorrectly set or inappropriate for the delivery profile.

But on a more serious note, none of the ships sunk by air attack in the Falklands were large military vessels. The largest vessel sunk was the Atlantic Conveyor, and that was (1) a civilian cargo ship built to civilian levels of durability, and (2) it was carrying a large quantity of ammunition essentially unprotected (unlike how a large warship would carry it). Even then, the missile strike and fire did not sink the ship immediately. For the largest military vessels sunk by air attack, the two Type 42s Sheffield and Coventry were relatively small destroyers (less than half the displacement of either their USN contemporaries the Spruance/Kidd or a modern Arleigh Burke) and again there the Exocet strike and resulting fire did not sink Sheffield immediately either. The smaller Type 21 frigates lost, Antelope and Ardent, were never really meant to survive meaningful damage and yet both remained afloat overnight before sinking. For comparison, the roughly contemporary USN frigates, the Perry-class (larger in displacement than the Type 42s), survived both Exocet (Stark) and mine (Samuel B. Roberts) strikes.

(The General Belgrano was a larger military vessel lost to submarine attack with, but considering that it was a treaty-limited 44-year-old light cruiser operating unprepared for submarine attack, it is hard to draw too many conclusions about modern ship durability from its loss - and her sisters in the Brooklyn class generally survived quite a punishment in WWII.)

[jandrewrogers]

How so?

The ships sunk in the Falklands War were all less than half the displacement of a typical US Navy destroyer. The sole exception is the Belgrano, which was built in the 1930s!

The ship being tested here is ~25x the size of the largest British ship that was sunk. Generally speaking, there is a super-linear relationship between ship size and the amount of explosive required to sink it. There is mountains of empirical data on this that you are choosing to ignore.

Every military knows this. They are making a tradeoff between size, which makes the target more difficult to destroy and easier to defend, and the number of ships they can build which allows them more flexibility in force projection.

[imp0cat]

I mean, we've all seen Battleship (2012), right? ;)

[euroderf]

Burning aluminum.

[fwipsy]

Does it need to be the direct analog of any specific weapon, to be a useful test?

[IndrekR]

0.018 kilotons. Order of magnitude smaller at minimum.