Defence Q&A About Hull Design of the Astute Class Submarine, the chine?

Nilgiri

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Would like to start discuss or take you thought about "New Tech at future/present SUBS"

Please have look front/nose of uk new Subs. Look how squere it is -> "ACTIVE DEFLECTION"!?


View attachment 31885

Yes, everyone has been jumping up and down at the norwegian 212 CD recently....as to what the hydrodynamics are like (flow noise, depth maintenance resistance, maneuverability envelopes etc etc) with chine geometry.

British buddy of mine simply said: well we've been doing it for years, so it cant be that bad....

The Chine/facetting is larger evolving way to robustly counter developments in MIMO arrays. One would think its pros are outweighing the cons by some measure, especially if you have larger well hedged naval force structure around it (much like how stealth and SEAD work in spear point for the larger Airforce spear).
 

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Would like to start discuss or take you thought about "New Tech at future/present SUBS"

Please have look front/nose of uk new Subs. Look how squere it is -> "ACTIVE DEFLECTION"!?


View attachment 31885
The red square is just bow sonar (bow sonar's shell more correctly).

a957-isehnnk4888356.jpgbow_sonar_array_inside_Akula-I_Improved _Project_971I_SSN_2.jpg
 
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Ecderha

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Love this post. I live in Cumbria, very proud the subs are built here. Even though I live at the opposite end of the county to Barrow. Also what is active deflection?
To defeat active sonar, submarines can experiment with HULL SHAPES and COATING that improve the absorption or deflection of sound waves.

In above Picture both are Already Applied
 

Ecderha

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As far I understood this uk sub/s Nose shape is called "Teardrop hull with square nose".

Quote: "A teardrop hull is a submarine hull design which emphasizes submerged performance over surfaced performance. It was somewhat commonly used in the early stages of submarine development, but was gradually abandoned in the early 20th century in favour of designs optimized for high performance on the surface as a result of changes in operational doctrine"

Why uk back to "teardrop hull"? But they combine NEW shape -> "square nose"
The Square nose Actually is split to half and half. I mean look sub nose and on front it is visible that top half and botom half have diffrent shape and purpse !?
 

Ecderha

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I will "bombard" you with more info which I am trying to get.
So


What is the deal with this new shape?
What is this and apparently this is the new hotness for "ACTIVE EVASION".
Very similer to Stealth submarine Idea -> The round submarine hall (the Albacore shape) is the Worst desgins for active reflecting, because at some point of curve is pointing right back to the tansmitter back to the source.

With the new design "pyramid like" you don't have that weakness (or at lease you have to be so close to sub).
So the purpose of these Angles is to make the SOUND bounce the active ping that hits the submarine, according to this "naval architect design" that this shape will bounce that SOUND UP to "the surface and from the surface it will be bounced back to Bottom" and This WILL REPEAT NUMBER of TIMES depending on range before it gets back to "the ACTIVE TRANSMITTER"

Disadvantage:
This is NOT good design for the presure HALL there are going to be WEAK points Anytime you have a "JOINT".
Overcome:
So to overcome above disadvantage they use this new design AS "Cover- outer HALL" like a dual hole submarine.
 

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On other navy forums there are some discussions about how uk, germany and norway "all figured out this new shape and developed it and now they building it"
and the BIG surprise surprise is that THEY DID NOT SHARE this with us americans (Ally, friend).


Now/at present uk building new shaped sub and us americans was analysing it frist results are that they will cut/stop
building numbers for us american "new tech" "new designed sub Virginia".

It is seems that us americans lost so much time and bilions of money at the moment they are pissed off (from uk, germans, and norway allies :) ) that they hidded this.

"Even there are commens from Ex militaries like they saying HOW the f.. THEY DARE to do/ hide this from us americans".

It is look like The ADVANTAGE of this new discovery is big/huge
 

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Yes, everyone has been jumping up and down at the norwegian 212 CD recently....as to what the hydrodynamics are like (flow noise, depth maintenance resistance, maneuverability envelopes etc etc) with chine geometry.

British buddy of mine simply said: well we've been doing it for years, so it cant be that bad....

The Chine/facetting is larger evolving way to robustly counter developments in MIMO arrays. One would think its pros are outweighing the cons by some measure, especially if you have larger well hedged naval force structure around it (much like how stealth and SEAD work in spear point for the larger Airforce spear).
I think pure forward-going hydrodynamics does not have the meaning they have had in the past.

Would like to start discuss or take you thought about "New Tech at future/present SUBS"

Please have look front/nose of uk new Subs. Look how squere it is -> "ACTIVE DEFLECTION"!?


View attachment 31885
That "unusual" hull form could be related to many factors in my opinion:

- they have developed a new material for coating on the outer shell that can not be curved in two-ways as of now especially on the bow-section.
- they intentionally reduce number of joints on the nose by applying such a chine at a single place, remarkably increasing efficiency of sonar by eliminating the losses-noises due to the "joints", yet this reason is weak because the chine is not present on the rest of the hull.
- something related with maneuvering to increase efficiency or the noises emerging while maneuvering underwater due to the vortices, the bow creates a shedding during the maneuvers that may affect the stability.
- reducing target echo strength from a direction by applying a single-flat surface (yet unlike the airplanes, here the whole structure's elasticity comes to importance, whole structure may respond to the sonar waves), again because of the matter 2, the rest of the hull is circular thus lesslikely.
- Especially the 212CD makes it more visible, the support volume between of the hull increases,however here, may allow larger sonar to be mounted

The chine is a risky business especially transition from chine to C2 continuity, thus probably they have needed to reach a certain stage in hydrodynamics before applying that on the hulls.

Why US does not apply that? Maybe their hulls are long enough to have sufficient support volume especially on the bow section, they have no troubles in construction of a seamless-cover on the sonar section, they are more advanced in anechoic surface coating allowing them to not mind about flat-surfaces?

One more thing to notice, the chine on Type212 is continuous through the hull, thus that one is more related to target strength, hull wake on propeller and additional support volumes with stealthiness on the surface.

It is still tear-drop, with a chine.
 

Nilgiri

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Yes, everyone has been jumping up and down at the norwegian 212 CD recently....as to what the hydrodynamics are like (flow noise, depth maintenance resistance, maneuverability envelopes etc etc) with chine geometry.

British buddy of mine simply said: well we've been doing it for years, so it cant be that bad....

The Chine/facetting is larger evolving way to robustly counter developments in MIMO arrays. One would think its pros are outweighing the cons by some measure, especially if you have larger well hedged naval force structure around it (much like how stealth and SEAD work in spear point for the larger Airforce spear).

I would like to clarify I was talking about the chine/facetting overall, rather than the snub nosed sonar arrangement:

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Astute is only a chine at the front (like the trafalgar and vanguard classes - both of which members can take closer look at)

But like the vanguard, a more blended form of it continues (like if you fillet the chine a bit in mid section etc) through the entire outer hull to a degree (i.e you get overall planar form on upward facing hull than a conventional curve would)

It's actually more pronounced on the vanguard if you look closely though some of that is influenced by the SLBM compartment as well.

i.e Astute and Vanguard have top hull facetting but without the chine per se. Probably a compromise to reduce some of the cons of a distinct chine (found on 212 CD).

212 CD on the other hand continues a distinct chine all along the length.

A look into earlier facetting project by skunkworks and current evolving trend of it:


The 212 CD will arguably be the first large macro scale version of it (a full fledged chine all along the length..i.e full complete facetting)....though more gentle facetting can be said to be used by British already.


I think pure forward-going hydrodynamics does not have the meaning they have had in the past.


That "unusual" hull form could be related to many factors in my opinion:

- they have developed a new material for coating on the outer shell that can not be curved in two-ways as of now especially on the bow-section.
- they intentionally reduce number of joints on the nose by applying such a chine at a single place, remarkably increasing efficiency of sonar by eliminating the losses-noises due to the "joints", yet this reason is weak because the chine is not present on the rest of the hull.
- something related with maneuvering to increase efficiency or the noises emerging while maneuvering underwater due to the vortices, the bow creates a shedding during the maneuvers that may affect the stability.
- reducing target echo strength from a direction by applying a single-flat surface (yet unlike the airplanes, here the whole structure's elasticity comes to importance, whole structure may respond to the sonar waves), again because of the matter 2, the rest of the hull is circular thus lesslikely.
- Especially the 212CD makes it more visible, the support volume between of the hull increases,however here, may allow larger sonar to be mounted

The chine is a risky business especially transition from chine to C2 continuity, thus probably they have needed to reach a certain stage in hydrodynamics before applying that on the hulls.

Why US does not apply that? Maybe their hulls are long enough to have sufficient support volume especially on the bow section, they have no troubles in construction of a seamless-cover on the sonar section, they are more advanced in anechoic surface coating allowing them to not mind about flat-surfaces?

One more thing to notice, the chine on Type212 is continuous through the hull, thus that one is more related to target strength, hull wake on propeller and additional support volumes with stealthiness on the surface.

It is still tear-drop, with a chine.

Really interesting....
 
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