Submarine design from scratch

I would agree, but there is this Wassenaar thing...

 

I would whole heartedly second that.

 

So, on wet submarines, how do you deal with the mass of the water?

 

I can see it's a touchy subject with you and yours, but I wasn't
trying to be argumentative or abusive.
I'm also wondering why you are blaming Joubert personally. DSTO could
easily have restricted the publication of his report but chose not to.
They are sensitive to the dissemination of information but obviously didn't
think it important enough to do so.

Personally, I'd be more concerned with drones dispersing biological agents
than a lone anarchist with the money and wherewithal to build a
fleet of subs hellbent on causing murder and mayhem. There's a huge gap
between seeing the plans of systems on a sub and being able to build many
of them, Colombian drug cartels notwithstanding.

I still wonder whether that's more or less than what the "good guys" are
trying against the "bad guys".

We are in agreement there. All you need now is to keep some of those pesky
old Russians from selling plans and expertise to the highest bidders.

 

I think JE is letting his professional knowledge of the subject drive somethings he cannot discuss openly with you guys....

Just a hunch.

 

Or, he is screamingly over paranoid .... IMHO.

 

You have to track it seperately. Submarine dynamics are comprised of 3 parts. The real mass, the entrained water mass, and the added mass. See this thread. http://www.boatdesign.net/forums/stability/submarine-roll-45427.html and this one http://www.boatdesign.net/forums/design-software/added-mass-31800.html.

 

I am talking about the total mass. If the submarine is flooded, then there will be several tons of water to accelerate, maneuver and stop.

 

Yes that is correct, which is why for a HPV envelope volumne should be as small as possible. But on the other hand, maximum speed is limited by only by drag, not the mass. So there is a real tradeoff based how long you have to accelerate. SUBHUMAN II set her speed record in accelerating a 2 MT mass from a standing start to speed in 50m ( 1/2 the length of the Arctec Model basin in Escondido, CA) as opposed to the 200m that OMER had in the DTMB model basin. FWIW, my data collected during the trials showed the SH II was still accelerating when she cleared the end of the speed trap (60m down tank)...Max speed ~ 5.5 knots...not bad for one guy breathing through a small tube in a water filled coffin.

 

I would think a fish would have a mass similar to the water in which it lives, being mostly water itself. Some of them are quite swift, so the more similar the vessel is to a fish the greater would be its efficiency of movement through the medium if my conjecture is correct.

 

A complex matter, I'd say.
Fish are not simple objects with fixed shape and surface finish. Their movement through the water involves some pretty complex unsteady hydrodynamics, where large eddy structures are produced and used for the propulsion by the whole fish body, not just tail. Their skin has a modifiable geometry and surface roughness too, and produce very slippery mucus.
A combination of all of these characteristics contributes to the propulsion of fish and to decrease their hydrodynamic resistance.
It is still a largely unexplored field subject to studies. For the time being, and as far as I know, we are able to mimic and to put into good use just a small number of these features - like skin patterning for decrease of frictional resistance, hull shaping for minimum pressure drag, or even the fish-like propulsion.
Check this out: https://www.youtube.com/watch?v=AURgJQ5gOSg
Cheers

 

That, I must say, is pretty cool!

 

Yeah, those robo-fish really are cool.

I wonder what are they like with some olive oil, garlic, parsley, white wine and a wedge of lemon.

 

Too chewy, most likely.