It was done on some aircraft, though. Marc Archivale catalog: http://www.archivale.com/catalog Polymath weblog: http://www.archivale.com/weblog Translation services: http://www.proz.com/profile/639380 Ducted fans: http://massflow.archivale.com/ On 9/26/2010 9:43 PM, MerlinSub@t-online.de wrote:
Make a single screw design but with two counter rotating props. Like a torpedo or a japanes A-class midget sub. Than apply each props to an undepedable engine or power source. Or better make two gears that way that engine one feed prop 1 or/and prop 2 and engine/drive 2 can do the same. That way you have the high efficency drive and two undepedable drive trains. Funny obviously nobody ever did this.. vbr Carsten "Marc de Piolenc"<piolenc@archivale.com> schrieb: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 Archivale catalog: http://www.archivale.com/catalog Polymath weblog: http://www.archivale.com/weblog Translation services: http://www.proz.com/profile/639380 Ducted fans: http://massflow.archivale.com/ 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************************************************************************ ************************************************************************ ************************************************************************ The personal submersibles mailing list complies with the US Federal CAN-SPAM Act of 2003. Your email address appears in our database because either you, or someone you know, requested you receive messages from our organization. If you want to be removed from this mailing list simply click on the link below or send a blank email message to: removeme-personal_submersibles@psubs.org Removal of your email address from this mailing list occurs by an automated process and should be complete within five minutes of our server receiving your request. PSUBS.ORG PO Box 53 Weare, NH 03281 603-529-1100 ************************************************************************ ************************************************************************ ************************************************************************************************************************************************ ************************************************************************ ************************************************************************ The personal submersibles mailing list complies with the US Federal CAN-SPAM Act of 2003. Your email address appears in our database because either you, or someone you know, requested you receive messages from our organization. If you want to be removed from this mailing list simply click on the link below or send a blank email message to: removeme-personal_submersibles@psubs.org Removal of your email address from this mailing list occurs by an automated process and should be complete within five minutes of our server receiving your request. PSUBS.ORG PO Box 53 Weare, NH 03281 603-529-1100 ************************************************************************ ************************************************************************ ************************************************************************
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