Re: [PSUBS-MAILIST] Twin screw vs single screw

[Marc de Piolenc <piolenc@archivale.com>]

A single, central screw is definitely going to win the efficiency 
contest; a single screw centered in an (almost) axially symmetrical wake 
will have much higher propulsive efficiency than any other configuration 
- see "wake-adapted propeller" or "wake-immersed propeller."
I was wondering only about operational considerations, as touched on by 
another poster. Things like redudancy, being able to maneuver in tight 
places by going ahead on one shaft and astern on the other, etc.

Best,
Marc

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On 9/26/2010 7:46 PM, JimToddPsub@aol.com wrote:
> Marc,
> During the development of the USS Albacore in the 50s (not to be
> confused with the WWII sub of the same name), they did extensive
> hydrodynamic and wind tunnel including twin-screw vs single screw
> design. Single screw was the winner and became the standard ever after.
> The Albacore was primarily a test bed and was most noted for being the
> first with the tear drop shaped hull which also became the standard. The
> Albacore is now a museum near Jon's stomping grounds in Portsmouth, New
> Hampshire.
> The only subsequent military sub I'm aware of with twin screws is the
> Soviet Typhoon class, but that sucker has twin parallel main pressure
> hulls as well and a beam of 75 feet!
> Jim T
> In a message dated 9/25/2010 10:52:34 P.M. Central Daylight Time,
> piolenc@archivale.com writes:
>
>     Interesting. I wonder if subsequent operational experience confirmed
>     Kittredge and company in their condemnation of single screws, or not.
>
>     Marc



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