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Re: [PSUBS-MAILIST] Ducting

I notice that Wislicenus' treatise on waterjet propulsion is now available for free download from: 
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD775620&Location=U2&doc=GetTRDoc.pdf
It's a pretty ugly copy, but it's free, unlike the much cleaner copies that I sell. Go to "search technical reports" on the same site and search "water jet" or "waterjet." I notice that several more reports are now available for downloading, but I haven't had time to grab them yet. 

Best,
Marc

Archivale catalog: http://www.archivale.com/catalog
Ducted fans: http://massflow.archivale.com/
Polymath weblog: http://www.archivale.com/weblog
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On 11/21/2010 11:20 AM, JimToddPsub@aol.com wrote:

Frank,
I saw one design that ducted the water flow from the underside of the
sub through a channel to twin thrusters at the rear just inside the
fairing. The arrangement looked really neat, however the thrusters
didn't articulate at all so all maneuvering was left to the rudders and
dive planes. The ultimate seems to be Cliff's jet-drive which does
articulate.
I'm trying to keep it as simple and clean as possible. Right now I'm
expecting to have a single, fully articulated Kort thruster at the rear,
but that could raise issues of torque roll. Hopefully the model process
and the full-scale mockup (and the critiques) will help resolve that. I
might end up going with dual thrusters.
By the way, are you going to update your profile?
Jim
In a message dated 11/20/2010 12:46:02 P.M. Central Standard Time,
ShellyDalg@aol.com writes:

    In a message dated 11/20/2010 10:37:23 A.M. Eastern Standard Time,
    JimToddPsub@aol.com writes:

        eliminate the possibility of snagging on something as much as
        possible, and a Kort is part of that.

    I imagine there is some loss of efficiency but I have seen a few
    thruster designs where the props and motors are enclosed inside a
    "fairing" and water flow is "ducted" to the props. This eliminates
    entanglement issues but again, probably would slow the boat a bit.
    As an example, think of the props on the James Bond Car that was a
    submarine. It was a Lotus I think but the props were visible at the
    back end and water going TO the props went through a grille type
    plate below the vehicle.
    That vehicle was actually built and was a working "wet ambient" sub
    where the pilot wore scuba gear. Of course, in the movie it was
    portrayed as a "dry 1 ATM. sub"
    Still, it was an early inspiration to me.
    Frank D.




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