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<DIV>A quick weigh-n on water jets. Years ago (many) I talked to the pilots of
the Cousteau “Puce de Mer” (Sea Fleas) And the famous ‘SP 350, Diving Saucer’
about the efficiency of their water jet propulsion units. They confirmed that
they were very ‘weak’ in a comedic way . . .they had a phrase in French which
made the two Sea Flea pilots break out laughing – my trusty translator also
laughed and then tried to keep a straight face as he said “they are saying that
the things that you ask about are not strong enough to “ pull a penis out of a
bucket of lard”!</DIV>
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style='FONT-SIZE: small; TEXT-DECORATION: none; FONT-FAMILY: "Calibri"; FONT-WEIGHT: normal; COLOR: #000000; FONT-STYLE: normal; DISPLAY: inline'>
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<DIV><FONT size=3 face=Calibri>Some years later we tried a high volume water
pump coupled with a duct engineered to work most efficiently with the pump. We
hooked it up to a fixed pad eye inside our large test tank and used a
spring scale to determine the bollard pull. Our froggie friends were quite
right: using a conventional prop powered with exactly the same horsepower
gave a large increase in bollard pull.</FONT></DIV>
<DIV style="BACKGROUND: #f5f5f5">
<DIV style="font-color: black"><B>From:</B> <A
title=personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">Alan James via
Personal_Submersibles</A> </DIV>
<DIV><B>Sent:</B> Sunday, October 26, 2014 9:30 PM</DIV>
<DIV><B>To:</B> <A title=personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">Personal Submersibles General
Discussion</A> </DIV>
<DIV><B>Subject:</B> Re: [PSUBS-MAILIST] Water jets</DIV></DIV></DIV>
<DIV> </DIV></DIV>
<DIV
style='FONT-SIZE: small; TEXT-DECORATION: none; FONT-FAMILY: "Calibri"; FONT-WEIGHT: normal; COLOR: #000000; FONT-STYLE: normal; DISPLAY: inline'>
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style="FONT-SIZE: 16px; FONT-FAMILY: helveticaneue, helvetica neue, helvetica, arial, lucida grande, sans-serif; COLOR: #000; BACKGROUND-COLOR: #fff">
<DIV id=yui_3_16_0_1_1414376814794_30654 dir=ltr><SPAN>Marc,</SPAN></DIV>
<DIV id=yui_3_16_0_1_1414376814794_30654 dir=ltr><SPAN>didn't want to have to
Google again.</SPAN></DIV>
<DIV id=yui_3_16_0_1_1414376814794_30654 dir=ltr>Wiki.....<SPAN
id=yui_3_16_0_1_1414376814794_31084
style="FONT-SIZE: 14px; FONT-FAMILY: sans-serif; COLOR: rgb(37,37,37); LINE-HEIGHT: 22px">
Classic prop-drives are generally more efficient and economical at low speeds,
up to about 20 knots (37 km/h; 23 mph), but as boat speed increases beyond this,
the extra </SPAN><A title="Hull (watercraft)"
style="FONT-SIZE: 14px; TEXT-DECORATION: none; FONT-FAMILY: sans-serif; BACKGROUND-IMAGE: none; COLOR: rgb(11,0,128); LINE-HEIGHT: 22px; BACKGROUND-COLOR: rgb(255,255,255)"
href="http://en.wikipedia.org/wiki/Hull_(watercraft)">hull</A><SPAN
style="FONT-SIZE: 14px; FONT-FAMILY: sans-serif; COLOR: rgb(37,37,37); LINE-HEIGHT: 22px">
resistance generated by struts, </SPAN><A title=Rudder
style="FONT-SIZE: 14px; TEXT-DECORATION: none; FONT-FAMILY: sans-serif; BACKGROUND-IMAGE: none; COLOR: rgb(11,0,128); LINE-HEIGHT: 22px; BACKGROUND-COLOR: rgb(255,255,255)"
href="http://en.wikipedia.org/wiki/Rudder">rudders</A><SPAN
id=yui_3_16_0_1_1414376814794_30668
style="FONT-SIZE: 14px; FONT-FAMILY: sans-serif; COLOR: rgb(37,37,37); LINE-HEIGHT: 22px">,
shafts (etc.) means waterjets are more efficient in the 20-50 knot range (up to
90 km/h; 60 mph). </SPAN></DIV>
<DIV id=yui_3_16_0_1_1414376814794_30654 dir=ltr><SPAN
style="FONT-SIZE: 14px; FONT-FAMILY: sans-serif; COLOR: rgb(37,37,37); LINE-HEIGHT: 22px">Alan</SPAN></DIV>
<DIV id=yui_3_16_0_1_1414376814794_30654 dir=ltr> </DIV>
<DIV> </DIV>
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style="FONT-SIZE: 16px; FONT-FAMILY: helveticaneue, helvetica neue, helvetica, arial, lucida grande, sans-serif">
<DIV id=yui_3_16_0_1_1414376814794_30657
style="FONT-SIZE: 16px; FONT-FAMILY: helveticaneue, helvetica neue, helvetica, arial, lucida grande, sans-serif">
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<HR id=yui_3_16_0_1_1414376814794_30660 SIZE=1>
<FONT id=yui_3_16_0_1_1414376814794_30659 size=2 face=Arial><B><SPAN
style="FONT-WEIGHT: bold">From:</SPAN></B> Marc de Piolenc via
Personal_Submersibles <personal_submersibles@psubs.org><BR><B><SPAN
style="FONT-WEIGHT: bold">To:</SPAN></B> Personal Submersibles General
Discussion <personal_submersibles@psubs.org> <BR><B><SPAN
style="FONT-WEIGHT: bold">Sent:</SPAN></B> Monday, October 27, 2014 1:24
PM<BR><B><SPAN style="FONT-WEIGHT: bold">Subject:</SPAN></B> Re: [PSUBS-MAILIST]
Water jets<BR></FONT></DIV>
<DIV id=yui_3_16_0_1_1414376814794_30669 class=y_msg_container><BR>A blythe
generalization that is essentially meaningless.<BR clear=none><BR clear=none>As
Pazmany used to say: poot some nombers to it!<BR clear=none><BR
clear=none>Marc<BR clear=none><BR clear=none>On 10/27/2014 3:50 AM, Alan James
via Personal_Submersibles wrote:<BR clear=none><BR clear=none>> Also I did a
bit of research on jet propulsion a couple of weeks back<BR clear=none>>
& what I read said it was inefficient compared to conventional
propulsion.<BR clear=none>> Alan<BR clear=none>><BR clear=none>>
------------------------------------------------------------------------<BR
clear=none>> *From:* Alec Smyth via Personal_Submersibles<BR clear=none>>
<<A href="mailto:personal_submersibles@psubs.org" shape=rect
ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR
clear=none>> *To:* Personal Submersibles General Discussion<BR
clear=none>> <<A href="mailto:personal_submersibles@psubs.org" shape=rect
ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR
clear=none>> *Sent:* Monday, October 27, 2014 8:11 AM<BR clear=none>>
*Subject:* Re: [PSUBS-MAILIST] Water jets<BR clear=none>><BR clear=none>>
I don't think water jets are necessarily inefficient, but if there is<BR
clear=none>> considerable piping around of the water before it exits through
the<BR clear=none>> jets, that's what I was referring to. However, even that
was not meant<BR clear=none>> as criticism, it is just a normal trade-off. It
is surely less efficient<BR clear=none>> than a conventional direct-coupled
prop, but you also get<BR clear=none>> entanglement-resistance and
maneuverability.<BR clear=none>><BR clear=none>><BR clear=none>><BR
clear=none>> On Sun, Oct 26, 2014 at 10:11 AM, Marc de Piolenc via<BR
clear=none>> Personal_Submersibles <<A
href="mailto:personal_submersibles@psubs.org" shape=rect
ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A><BR
clear=none>> <mailto:<A href="mailto:personal_submersibles@psubs.org"
shape=rect
ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>>>
wrote:<BR clear=none>><BR clear=none>> There is nothing
inherently inefficient about waterjets. There are<BR
clear=none>> commercial fast ferries using them and getting
very good thrust per<BR clear=none>> horsepower - better
than any supercavitating propeller could do at<BR
clear=none>> the same speed, certainly.<BR
clear=none>><BR clear=none>> Lousy design will of course
produce poor results, and jets are much<BR clear=none>>
less amenable to rule-of-thumb construction than open propellers.<BR
clear=none>> But whether it is "well known" or not, good
design will produce good<BR clear=none>> results.<BR
clear=none>><BR clear=none>> Marc de Piolenc<BR
clear=none>><BR clear=none>> On 10/26/2014 8:41 PM, hank
pronk via Personal_Submersibles wrote:<BR clear=none>><BR clear=none>><BR
clear=none>> Graham,<BR
clear=none>> In the world of marine
jet drive it is well known that jet drive<BR
clear=none>> takes two times the
horse power to do the same job. Jet drive<BR
clear=none>> is well suited to a
craft that needs a shallow draft. I think<BR
clear=none>> you will find it very
complicated to control and it will be very<BR
clear=none>> inefficient. I have
been down this road, I love the concept but<BR
clear=none>> abandoned it. If
you go forward may I suggest you start with a<BR
clear=none>> jet drive. It is
not a simple part to replicate. The impeller<BR
clear=none>> tolerances are
critical. I have a jet unit on the shelf I could<BR
clear=none>> donate to your
project. The jet is from a jet ski. I would<BR
clear=none>> consider a single rear
motor on a full gimbal.<BR
clear=none>> Hank
------------------------------__--------------<BR
clear=none>> On Sun, 10/26/14,
Graham Bayliss via Personal_Submersibles<BR
clear=none>> <<A
href="mailto:personal_submersibles@psubs.__org" shape=rect
ymailto="mailto:personal_submersibles@psubs.__org">personal_submersibles@psubs.__org</A><BR
clear=none>> <mailto:<A
href="mailto:personal_submersibles@psubs.org" shape=rect
ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>>>
wrote:<BR clear=none>><BR
clear=none>>
Subject: [PSUBS-MAILIST] (no subject)<BR
clear=none>>
To: "'Personal Submersibles General Discussion'"<BR
clear=none>> <<A
href="mailto:personal_submersibles@psubs.__org" shape=rect
ymailto="mailto:personal_submersibles@psubs.__org">personal_submersibles@psubs.__org</A><BR
clear=none>> <mailto:<A
href="mailto:personal_submersibles@psubs.org" shape=rect
ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>>><BR
clear=none>>
Received: Sunday, October 26, 2014, 7:39 AM<BR clear=none>><BR
clear=none>>
#yiv9417249292<BR
clear=none>>
#yiv9417249292 --<BR clear=none>><BR
clear=none>>
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#yiv9417249292 Hi I am near the end of my build<BR
clear=none>>
of my k350 and have started to look at new designs I am<BR
clear=none>>
interested in building a flyer sub and have come up with a<BR
clear=none>>
design which will include a vectored motor drive this will<BR
clear=none>>
enable my flyer to hover and stop where ever I want. I have<BR
clear=none>>
designed a motor unit which will drive a fan type propeller<BR
clear=none>>
as an intake this will force water to the rear of the unit<BR
clear=none>>
where it is compressed then it is forced into ducting<BR
clear=none>>
which will take the water to four nozzles on the side of<BR
clear=none>>
the craft. The nozzles are able to turn three hundred and<BR
clear=none>>
sixty degrees both side are independent of one another so<BR
clear=none>>
rolls will be achievable. The reason for a vectored motor is<BR
clear=none>>
you only need one motor source and one power pack this will<BR
clear=none>>
ease the maintenance and increase the enjoyment of using<BR
clear=none>>
your sub. I am interested in the clubs thought of this kind<BR
clear=none>>
of design. Graham<BR clear=none>><BR
clear=none>>
-----Inline Attachment Follows-----<BR clear=none>><BR
clear=none>>
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clear=none>> Archivale catalog: <A
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target=_blank>http://www.archivale.com/__catalog</A><BR
clear=none>> <<A href="http://www.archivale.com/catalog"
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clear=none>> Polymath weblog: <A
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clear=none>> <<A href="http://www.archivale.com/weblog"
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clear=none>> Translations (ProZ profile): <A
href="http://www.proz.com/profile/__639380" shape=rect
target=_blank>http://www.proz.com/profile/__639380</A><BR
clear=none>> <<A
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clear=none>> Translations (BeWords profile):<BR
clear=none>> <A
href="http://www.bewords.com/Marc-__dePiolenc" shape=rect
target=_blank>http://www.bewords.com/Marc-__dePiolenc</A><BR
clear=none>> <<A
href="http://www.bewords.com/Marc-dePiolenc" shape=rect
target=_blank>http://www.bewords.com/Marc-dePiolenc</A>><BR
clear=none>> Ducted fans: <A
href="http://massflow.archivale.com/" shape=rect
target=_blank>http://massflow.archivale.com/</A><BR
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clear=none>><BR clear=none><BR clear=none>-- <BR clear=none>Archivale
catalog: <A href="http://www.archivale.com/catalog" shape=rect
target=_blank>http://www.archivale.com/catalog</A><BR clear=none>Polymath
weblog: <A href="http://www.archivale.com/weblog" shape=rect
target=_blank>http://www.archivale.com/weblog</A><BR clear=none>Translations
(ProZ profile): <A href="http://www.proz.com/profile/639380" shape=rect
target=_blank>http://www.proz.com/profile/639380</A><BR clear=none>Translations
(BeWords profile): <A href="http://www.bewords.com/Marc-dePiolenc" shape=rect
target=_blank>http://www.bewords.com/Marc-dePiolenc</A><BR clear=none>Ducted
fans: <A href="http://massflow.archivale.com/" shape=rect
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