Russia has developed one, apparently.
Or have they?

http://www.bbc.com/news/world-europe-34797252

Yep.
Also the Russians have had high-speed (~200 knot) torpedoes for some time now.
Shkval

makes sense

it creeps up to a port undetected and then explodes

to make it more effective you need to have one that pops the warhead out of the water 200m or so and then explodes

the americans most likely have something similar and the russians are just letting them know they have them too just in case they decided to think they can do something silly

nuclear weapons are a posturing weapon

why bother doing all this when you can plant a bomb in a building and let it sit there?

no 4 minute warning

the americans were lax in their security and allowed people building the bomb to wander the world and hand over nuclear secrets to their masters

its not true that another country could have worked all this out, its difficult and expensive to build nuclear weapons

by restricting nuclear physics to domestic students that had been vetted they could have kept the genie in the bottle

the russians knew how to build bombs because they had been handed all the secrets of the bomb by fuchs (and by my reckoning another spy in the ranks that was never caught)

Spiny Norman said:

Yep.
Also the Russians have had high-speed (~200 knot) torpedoes for some time now.
Shkval

Interesting, thanks.

Spiny Norman said:

Yep.
Also the Russians have had high-speed (~200 knot) torpedoes for some time now.
Shkval

Hold on a moment. Cruise missiles are slow. So are ordinary torpedos. What makes this one different? Terrain following?

mollwollfumble said:

Spiny Norman said:

Yep.
Also the Russians have had high-speed (~200 knot) torpedoes for some time now.
Shkval

Hold on a moment. Cruise missiles are slow. So are ordinary torpedos. What makes this one different? Terrain following?

I would say it was a way to sneak into a major city and detonate

the cruise missile could silently be released miles from the port then perhaps take advantage of the tides and current to quietly slide into an enemy port / city

the Russians tend to make knock offs of American gear and sometimes vice versa

it’s smaller than a sub

the screw could turn relatively slowly without creating tell tale noise

if the missile had small wings it can move forward by diving and moving to
the surface – an underwater glider – these are virtually noiseless

mollwollfumble said:

Spiny Norman said:

Yep.
Also the Russians have had high-speed (~200 knot) torpedoes for some time now.
Shkval

Hold on a moment. Cruise missiles are slow. So are ordinary torpedos. What makes this one different? Terrain following?

Isnt that the torpedo that has a bubble of air around it as it moves through the water?

CrazyNeutrino said:

mollwollfumble said:

Spiny Norman said:

Yep.
Also the Russians have had high-speed (~200 knot) torpedoes for some time now.
Shkval

Hold on a moment. Cruise missiles are slow. So are ordinary torpedos. What makes this one different? Terrain following?

Isnt that the torpedo that has a bubble of air around it as it moves through the water?

Yes. The big advantage is a sub could approach quite close and then this high-speed torpedo could be launched. There would be little response time after detection (if detected) and a method to stop it is problematic. For an airborne cruise missile you have a number of intercept or barrier systems (e.g. CWIS, other point defence weapons) but a high-speed torpedo has no real opposition except for torpedo nets (or similar).