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Steve Reichmuth gave a good explaination as to why the x-tail hasn't been adopted by the US.
The main one being the requirement of electronic mixing of controls- although he stated that it's possible to mechanically mix an x-tail, so that arguement is largely irrelevant.
I guess the same principles apply for British boats too- cruciform arrangment.
It's also been pointed out that the x-tail is more suited to shallower and smaller waters where the maneuverability is better appreciated.
Maybe the design brief doesn't stipulate the need for a boat that can turn on a sixpence?
Am I missing something here?
The Seawolf and Virginias, for example, are highly automated and computer controlled. So, does that not kinda squelch the electronic control thing, since almost everything is nowdays?
On a combat submarine , I would want every edge I could have.
If it would make my boat turn quicker, I would want it! If an occasion arose where I had to sit on the bottom or slip in shallows, the advantage of the X-tail would be there.
Maybe I am looking for tactical disadvantages.
I can not really see any.
I seem to remember reading something somewhere that the U.S. decided to not use X-tails because they were considered to be too prone to allowing sudden changes in depth well below operating/crush depth when operating at high speeds......
Yes, it was handed down by ADMIRAL HYMAN RICKOVER (aka, God himself) Specifically, one of the designs for the ConForm sub had an X-tail. And, the ConForm design competed with Rickover's 688 class design, which had his new, higher SHP reactor. So, although ConForm had many innovative & neat features, it was going to employ the tried & true S5W as a powerplant, and Rickover wanted the new S5G to be built. Hence, ConForm (and the X-tail) died in favor of the 688 (a design with serious compromises). Rickover also had a huge distrust of computer controls in submarines. The original Seawolf design had an X-tail, but that too died. As time goes by, the Rickover influence will wane to some degree, and maybe we will see X-tails.
Not exactly politics, just the very strong dominant influence of Rickover over the US submarine program. There was an X-tail on Albacore in Phase III & IV, so the technology is well established in the US Navy. Among other advantages, X-talis make it a lot easier to bottom the boat without damagin the rudder. However, to do it right, you would use computer mixing of the controls, and Rickover believed in a high degree of manual control in his submarine designs. He did not wnat computers in the loop, and was not enamored of Conalog and Squire, which were merely computer controlled navigational tools for the helmsman. That influence persists to this day. Remember, the 688s were designed in the late 1960-early 1970's, the Seawolf class in the early 1980's. Again, going forward, we may see the advantages of X-tails. We may also see a return of turbo-electric drive (e.g. in later versions of the Virginia class) and other innovations.
There must be more a technical than a philosophical reason to this.
Notice that no big and long sub has a X tail design but only "coastal" subs do (yeah I know the Walrus are not small but compared to US or Russian SSNs....).
I do not have the answer but I can't believe USA, Russia, UK or France have not yet built a X tail just because they have not shaken the old basements of the sub building tradition.
Tom has a good point. Thanks.
Antoine has one too. Wonder what it is? The Russians sure as heck did not have Rickover. Although they did a lot of quanity over quality, they were not afraid to take a chance on design. Alfa-case in point.
Tight turning (at high speeds) which the x-sterns afford can create indiscrete knuckles or turbulence which enemy sonars could detect in the deep ocean ('blue water'). A cruciform stern arrangement will provide just as effective a turning moment in simpler fashion at those speeds. Tight turns in shallow or more restricted waters with more background sonar noise and clutter makes the same tight turning provided by an X-stern more welcome and handy. The X-stern provides more effective turning at lower silent speeds in those restricted water ways.
Was not ever 'political' directly, more along the line of practicality. Rickover was an engineer that embraced the 'Kiss' principle. Keep it simple. During WWII, young Rickover (hard to imagine Rickover was ever young once...lol) in the Navy's Bureau of Ships was responsible for powerful electrical propulsion systems, and general ship repair in wartime. It likely influenced Rickover in bias toward not elegant design concepts, so much as elegant simplicity.
Now that likely a higher percentage of submarine operations occur in shallower coastal 'littoral' areas, X-sterns should be reconsidered along with other systems at a designers disposal. However, how many early new submarine design concepts ever pass over that designers desk in the future working for the US Navy? New American submarine designs tend to be long production runs over several decades, and this new engineering is not exported overseas directly, now this is political, also one of security considerations. It is also simply all American designs are exclusively nuclear powered. By contrast the Germans primarily are very successful designing and tailoring their excellent designs as exports to not a single customer, but many varied Navies and their strategic needs. Also shorter production runs. New technology is always added though regardless of short or long production lines. An American submarine designer might have a very different set of design issues to deal with working for a simular German firm. If X-sterns appear in the USN, it might be for a small to medium sized special coastal operations submarine. Another possibility is one off designs in the long line of future Virginia class SSN's, if 'smart' duct pump jet shrouds does not mature. Smart shrouds may likely be the way it could go, all things considered. Also, many new concepts, unmanned remote vehicles and such concepts now eliminate the need of a large submarine needing to risk working in shallower water and risk detection, and the turning systems that would require. Many options.
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