The shape of a submarine

[anoopsaxena76]

Hi,
My question is perhaps very basic. I tried to figure it out by google but did not have much success.

Why are the submarines shaped the way they are? The tear shaped hull giving way to the cigar shaped one?

Thanks,
Anoop.

 

[amalakas]

I don't think the tear drop design has been abandoned, i could be wrong, but i think it simply evolved.

Essentially it is about fluid dynamics, the water resistance and how it flows around the submarine are the main factors.. well that and acoustics as well...

 

[anoopsaxena76]

Fluid dynamics part is what the information on the net said. I am not sure about the acoustics part. I mean, I do not know well enough to comment anything.

But on fluid dynamics, I would assume a tear shaped one would provide better performance than the cigar shaped one.

Regards,
Anoop.

 

[amalakas]

well i think pretty much the submarine is still a tear drop shape today still ..

your cigar shape is simply an elongated tear drop..

acoustics have to do with how much noise the hull makes while going through water...

 

[gubbi]

Can anyone throw a light on the shape of a submarine and how it influences its role? I read somewhere that form the shape of the sub, one can deduce its capabilities and hence the real picture of INS Arihant is such a closely guarded secret! We dont have a full real picture of INS Arihant yet!

 

[anoopsaxena76]

Well.. how different would it be from aerodynamics point of view?

A fighter jet's airframe versus a Boeing / Airbus passenger plane.

Sorry I was not specific. I do understand the acoustics and the role of a propeller and it's acoustic signature. What I meant was that I am not sure how the hull contributes to reducing it.

For example, the new Akula class accommodates extra space to quieten the noise.

Regards,
Anoop.

 

[500]

Hi,
My question is perhaps very basic. I tried to figure it out by google but did not have much success.

Why are the submarines shaped the way they are? The tear shaped hull giving way to the cigar shaped one?

Thanks,
Anoop.

Russian and US subs have different design:

In US subs sonar takes the whole bow, while torpedos are in the middle.

http://www.globalsecurity.org/military/systems/ship/images/ssn-688-cut-away2.gif

In Russian subs sonar is on lower deck of the bow and torpedos on upper:

http://www.deepstorm.ru/DeepStorm.files/45-92/nts/671RTM/671rtm.gif

Another difference is that US subs have single hul while Russian - double hull. Thats why Russian Subs are more fat, drop like and US more long, cigar shaped.

 

[Materialistic]

I think I can answer you on this one. Since its all about fluid dynamics. So the dominating factor is friction as well as turbulence.

The question is that why front is fat and back is more slim. Like a tear drop!!

The thing is all the moving objects need a smooth surface so they can easily cut through the medium which here is Water. This is general perception and half of the story.

When an object passes through a fluid then its like both of them travelling opposite to each other. In one direction its the object and the fluid in the opposite one.

And if we suppose its the submarine in stationary condition and it is water which is flowing (from face of submarine to the back). Then flow of water will be just like as if its flowing through a pipe and any turbulence at the rear end would resemble a blockage on the other end of the pipe. Which would eventually lead to the friction all the way to the front of the object and forming a turbulence and acting as a wall.

So to keep the flow of fluid straight and avoiding turbulance in flow even behind the submarine's rear end. Its shape should go narrower to the least possible size.

If the back suddenly ends like a block then it leaves a vacuum behind between the water molecules flowing above and below the sub. So that distance should be kept minimum so that water molecules above and below the sub should merge with each other without causing turbulence and sudden vacuum. Otherwise the water moving from front will reach the back end it will be facing friction because of turbulence to go through causing same thing that i mentioned above in bold.

So, it should be Just like an interchange bringing in additional traffic to the highway parallel to the direction of highway itself or the flow of traffic.

I Hope this helps!!

 

[Donatello]

Actually, if you look at all the classes of Subs during and since the cold war, they primarily determined by their funtion.

Hunker Killer SSKs are more sleek and cigar shaped.

Ballistic missile SSBNs are more flat at the top to accommodate the missiles.

You cannot just generalize them.

Just like jet fighters, some have delta shaped wings and some normal swept back.

Doesn't mean one is better than the other. Different functions maybe, yes?