[TorpX]

Yes, at $3.8M it is expensive, but it is a +90% sure kill; Mark 14s were expected to be launch in salvos and a 10% success rate more than acceptable...

How does torpedoing a small, uncrewed, ship at anchor prove a weapon is capable of giving 90% sure kills in battle? This sort of test strikes me as being no more serious than those done with the Mk 14's and others before WWII.

They did test the Mk.14 but with the magnetic detonator they did not test a live round and it was off the east coast the reason they did so little testing was because they wanted to keep it secret (this was in the late 30s) the problem with the mk.14 was that it went through a very limited and unrealistic testing program.Once they ran tests in Fremantle and Hawaii the submariners solved the mk.14s problems without the help of engineers.

In 1926, they did two live tests with a Magnetic Influence exploder. In the first one, the torp ran under the target without exploding, it being considered to have run too deep. When the torpedo was adjusted and fired again, it exploded under and sank the target (an obsolete sub). It should be noted that these were not production Mk 14's and Mk 6 exploders, but rather prototypes that were modified later, so these were not really "battlefield" tests of frontline weapons. Nevertheless, they were impressive enough to be considered a success.

I believe the main reason for such skimpy testing was the expense, not secrecy. Not only were the torpedos themselves very expensive, but suitable "targets" were nearly impossible to obtain. Further testing was done with test warheads, using "electric eyes" and recording devices and the like.

IMO, proving the effectiveness of the MI exploder would be almost impossible without blowing up a large number of ships. The Navy would have been much better off to focus on impact detonation, which could be tested and didn't have all the messy unknowns of MI. Verification of running depth was easily done with net shots, and testing of impact exploders can be done by dropping test warheads against steel plates and the designs analyzed afterwards. Impact forces can be calculated and this does not require live shots, or mapping magnetic forces around a ship, or adjusting for the earth's magnetic field.