When did they decide to abandon ship's bows?

[Captain Sub]

Dear folks,

so I recently came across a picture of probably one of the last subs (post-war) that were built in ship's bow design.



I'm wondering when and why they decided to abandon that design and why they never built belly-bow subs in WW2.



kind regards,

Paul

[Raptor1]

Post-WWII submarines differed from earlier ones because they were designed to operate underwater most of the time rather than most WWII-era dive boats. The teardrop hull (Pioneered by USS Albacore) is much more hydrodynamic, allowing for greater speed and maneuverability underwater (Along with some other advantages), wheras the WWII-style design was designed to increase performance on the surface much like a normal ship.

At least, I think that's what you're talking about...

[msxyz]

The "bow" in post war subs is actually a dome containing an array of transducers. The principle is more or less the same of a sinthetic aperture antenna but this is designed to pick up sound, not radio waves.

That looks like a soviet Romeo submarine or a similar class. It has a slight, protruding bow that helps breaking the waves but it's not the main function of that bow, as it holds a U-shaped sonar array.

Basically, when submarines began spending more time underwater than surfaced, the classic bow shape (that helps seakeeping) was dropped in favour of designs that guaranted lower resistance underwater.

[TLAM Strike]

Originally Posted by msxyz

That looks like a soviet Romeo submarine or a similar class.

That is a Soviet Foxtrot class boat.

Interestingly the first modern subs (The Holland boats) used a cigar shape for greater underwater performance much like the ones today, it was Simon Lake (John Holland's competitor) who came up with the idea of a sub that was faster on the surface and had a surface ship like bow- this design philosophy became the Fleet Type Submarine. It wasn't until the 1950's with the USS Albacore that submarines returned to Holland's origional design philosophy.

(Don't take the above paragraph as disparaging of Simon Lake, he had many good ideas including the Conning Tower, Dive Planes and the Rotating/Retractable Periscope.)

When submarines were no longer required to operate and transit on the surface, the requirement for hull forms optimised for surface travel could be replaced by designs optimised for undersea travel.

As far back as the 1917 R Class of the Royal Navy it was recognized that high underwater speed required different shapes than surface seaworthyness. The R's were the first submarine hunter-killers and even if the technology was not mature enough to make them successful in that role they had some features, the bulbous bow shape in particular, that greatly improved their submerged performance relative to those boats with ship-like stems, either straight or flared.

USS Albacore (AGSS 569) is generally considered the forerunner of the teardrop shape submarine whereas the Soviet Navy retained a basic Type XXI hull form as late as the Project 641B (NATO Tango Class) introduced in the late 70's. The OP's linked photo looks to be a Project 641 (NATO Foxtrot Class) which preceded the Tango's into service. Cold War accounts of Foxtrot and Tango operations indicate that these boats spent more time surfaced than submerged so retaining a flared stem for improved seaworthyness made sense.

The first true teardrop hull in Soviet service was probably the Project 671 (NATO Victor Class) first reported from 1969 although Soviet designs had featured much smaller and very streamlined sails as far back as the Project 627 (NATO November Class) and Project 569 (NATO Echo Class) from the late 1950's and early 1960's.

For the R Class see:

http://www.battleships-cruisers.co.uk/r_class.htm

For USS Albacore see:

http://www.ussalbacore.org/

[TLAM Strike]

Originally Posted by Randomizer

As far back as the 1917 R Class of the Royal Navy it was recognized that high underwater speed required different shapes than surface seaworthyness. The R's were the first submarine hunter-killers and even if the technology was not mature enough to make them successful in that role they had some features, the bulbous bow shape in particular, that greatly improved their submerged performance relative to those boats with ship-like stems, either straight or flared.

As I said in another thread the R class boats wouldn't have look out of place in the 1950's. Go UK!

USS Albacore (AGSS 569) is generally considered the forerunner of the teardrop shape submarine whereas the Soviet Navy retained a basic Type XXI hull form as late as the Project 641B (NATO Tango Class) introduced in the late 70's. The OP's linked photo looks to be a Project 641 (NATO Foxtrot Class) which preceded the Tango's into service. Cold War accounts of Foxtrot and Tango operations indicate that these boats spent more time surfaced than submerged so retaining a flared stem for improved seaworthyness made sense.

Actually it appears they have retained the Type XXI hull style today!



Sat photo of Sarov class submarine. Note the Stern- twin screws with control surfaces much like the Whiskey. Also note the bow shape:

[msxyz]

Project 627 actually looks like a giant torpedo when it's out of the water. Its lenght far exceeds the other dimensions. Its bow, however has a proper drop shape. There aren't many shots of November class submarines in drydock, not even after the fall the USSR when they went to the scrap yard. This is the best I could find:



Notice the bulge under the bow. The first vessels in the class lacked this dome which housed a huge cylinder that is the sonar "antenna".

No wonder the XXI shape was so popular. It was designed using water tunnels, so it was extensively tested through trial and error. Possibly the most elegant offspring of this design was the Project 651 juliett

Actually it appears they have retained the Type XXI hull style today!

I think the OP was concentrating on the existance of a flared stem as opposed to actual hull form or cross-section. It would certainly be strange if the 21st Century Sarov's were optimized for surface operations and this is not at all apparent in the photo links you provide.

There are certainly advantages to not using a teardrop shaped hull if it is not required for high underwater speed.

That some Type XXI hull characteristics are still being utilized is a nice engineering example of how form follows function regardless of nationality.