[PSUBS-MAILIST] Water jets

[Graham Bayliss via Personal_Submersibles]

Hi Marc de Piolenc

I agree whole heartedly there is nothing inefficient about a water jet just
point it one way and add power and you will end up going the other way as
they say a=b= push. I will carry on with this and have a working craft at
the end to enjoy.

Graham



-----Original Message-----
From: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org]
On Behalf Of Marc de Piolenc via Personal_Submersibles
Sent: 26 October 2014 14:11
To: Personal Submersibles General Discussion
Subject: [PSUBS-MAILIST] Water jets

There is nothing inherently inefficient about waterjets. There are
commercial fast ferries using them and getting very good thrust per
horsepower - better than any supercavitating propeller could do at the same
speed, certainly.

Lousy design will of course produce poor results, and jets are much less
amenable to rule-of-thumb construction than open propellers. But whether it
is "well known" or not, good design will produce good results.

Marc de Piolenc

On 10/26/2014 8:41 PM, hank pronk via Personal_Submersibles wrote:
>
> Graham,
> In the world of marine jet drive it is well known that jet drive takes two
times the horse power to do the same job.  Jet drive is well suited to a
craft that needs a shallow draft.  I think you will find it very complicated
to control and it will be very inefficient. I have been down this road, I
love the concept but abandoned it.  If you go forward may I suggest you
start with a jet drive.  It is not a simple part to replicate.  The impeller
tolerances are critical.  I have a jet unit on the shelf I could donate to
your project.  The jet is from a jet ski. I would consider a single rear
motor on a full gimbal.
> Hank --------------------------------------------
> On Sun, 10/26/14, Graham Bayliss via Personal_Submersibles
<personal_submersibles at psubs.org> wrote:
>
>   Subject: [PSUBS-MAILIST] (no subject)
>   To: "'Personal Submersibles General Discussion'"
<personal_submersibles at psubs.org>
>   Received: Sunday, October 26, 2014, 7:39 AM
>
>   #yiv9417249292
>   #yiv9417249292 --
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>   #yiv9417249292  Hi   I am near the end of my build
>   of my k350 and have started to look at new designs I am
>   interested in building a flyer sub and have come up with a
>   design which will include a vectored motor drive this will
>   enable my flyer to hover and stop where ever I want. I have
>   designed a motor unit which will drive a fan type propeller
>   as an intake this will force water to the rear of the unit
>    where it is compressed  then it is forced into ducting
>   which will take  the water to four nozzles on the side of
>   the craft. The nozzles are able to turn three hundred and
>   sixty degrees  both side are independent of one another so
>   rolls will be achievable. The reason for a vectored motor is
>   you only need one motor source and one power pack this will
>   ease the maintenance and increase the enjoyment of using
>   your sub. I am interested in the clubs thought of this kind
>   of design.  Graham
>
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