[PSUBS-MAILIST] Group Help Request
Marc de Piolenc
piolenc at archivale.com
Tue Oct 29 10:34:47 EDT 2013
Forgot the hovercraft question.
Typical hovercraft ducts use a plywood former that coincides with the
plane of the propeller. The rest of the shroud extends forward and
rearward of that former or hoop. Only the hoop has to be a perfect fit,
and that can be guaranteed by struts running from a bearing on the
propeller shaft itself. The rest of the shroud has larger - sometimes
much larger - tolerances. Mind you, air is 800 times less dense than
water, so the two jobs are not of comparable difficulty. Working in
water is much more demanding, both because of smaller tolerances and
because of the need to provide for cavitation.
Marc
On 10/29/2013 8:54 PM, Joe Perkel wrote:
> Marc,
>
> What other build processes can you recommend? Intake diameter of nozzle exceeds capability of 3d process and cost issues.
>
> How do hovercraft builders (hobbyists) maintain an accurate profile on such large ducts?
>
> Joe
>
> Sent from my overpriced
> iPhone
>
> On Oct 29, 2013, at 7:59 AM, Marc de Piolenc <piolenc at archivale.com> wrote:
>
>> A Kort nozzle is a ducted propeller - known by the name of the inventor of that particular application.
>>
>> Marc
>>
>> On 10/29/2013 4:08 AM, Joe Perkel wrote:
>>> Yes Carsten, very hopeful moneywise!
>>> But, I wonder if this is a shrouded/ducted prop as opposed to an
>>> accurate Kort Nozzle. But, perhaps it may not matter in the end if all
>>> one wants is a prop guard.
>>> I am going to see what different configurations of the Kort Nozzle bring
>>> in terms of material cost.
>>> Joe
>>>
>>> *From:* "MerlinSub at t-online.de" <MerlinSub at t-online.de>
>>> *To:* Personal Submersibles General Discussion
>>> <personal_submersibles at psubs.org>
>>> *Sent:* Monday, October 28, 2013 3:19 PM
>>> *Subject:* Re: [PSUBS-MAILIST] Group Help Request
>>>
>>> http://www.aliexpress.com/item/Brand-New-300W-Motor-Powered-Sea-Scooter-Underwater-propeller-Diving-Assistant/336556698.html
>>>
>>> Inside Diameter of the Kortnozzle is 250mm or 9,84 something inch.
>>>
>>> Protection grid forward and aft are just fix with clips.
>>>
>>> vbr Carsten
>>>
>>>
>>>
>>> Alec,
>>>
>>> Don't count it out just yet, I went to Gavin via the link you
>>> provided and had an epiphany! Note well the inside surface vs the
>>> outside surface of that Kort nozzle!!
>>>
>>> The model I quoted was solid material!!
>>>
>>> I know what I'm doing tonight!
>>>
>>> Joe
>>>
>>> Sent from Yahoo! Mail for iPad
>>>
>>>
>>> *From: *Alec Smyth <alecsmyth at gmail.com>;
>>> *To: *Personal Submersibles General Discussion
>>> <personal_submersibles at psubs.org>;
>>> *Subject: *Re: [PSUBS-MAILIST] Group Help Request
>>> *Sent: *Mon, Oct 28, 2013 5:28:50 PM
>>>
>>> Sounds like David has just saved me the work of taking a 101 apart
>>> and measuring it, thanks! As for the 101 prop size, it's 11"
>>> diameter. Before you go off spending $760 on a nozzle, you might
>>> want to look up these folks: http://www.gavinscooters.com/ I
>>> can't help notice Emile used a Gavin, and it looks like Gavin
>>> Scooters, Inc. is right in your neighborhood.
>>>
>>> Best,
>>>
>>> Alec
>>>
>>>
>>> On Mon, Oct 28, 2013 at 12:43 PM, Joe Perkel
>>> <josephperkel at yahoo.com> wrote:
>>>
>>> David,
>>> Thats spectacular, thanks!
>>> Joe
>>>
>>> *From:* David Colombo <seaquestor at gmail.com>
>>>
>>> *To:* Personal Submersibles General Discussion
>>> <personal_submersibles at psubs.org>
>>> *Sent:* Monday, October 28, 2013 12:12 PM
>>>
>>> *Subject:* Re: [PSUBS-MAILIST] Group Help Request
>>>
>>> Hey Joe,
>>> I will send you my cad files on the Minkota 101 Saltwater. I
>>> have measured my new 101s and weed 2 prop. I have also worked
>>> out the Marin 37 Kort nozzel design and attachment to the
>>> thruster for use on the SeaQuestor project. I will be most
>>> likely sending it to my fiberglass fabricator who will cut the
>>> assembly in foam on their 5 axis cnc, ready for a fiberglass
>>> overlay.
>>>
>>>
>>> Best Regards,
>>> David Colombo
>>>
>>> 804 College Ave
>>> Santa Rosa, CA. 95404
>>> (707) 536-1424
>>> http://www.seaquestor.com/
>>>
>>>
>>>
>>> On Mon, Oct 28, 2013 at 8:03 AM, <jimtoddpsub at aol.com> wrote:
>>>
>>> Joe,
>>> Since you asked: http://en.wikipedia.org/wiki/Cast_urethanes
>>> Jim
>>> -----Original Message-----
>>> From: Joe Perkel <josephperkel at yahoo.com>
>>> To: Personal Submersibles General Discussion
>>> <personal_submersibles at psubs.org>
>>> Sent: Mon, Oct 28, 2013 9:54 am
>>> Subject: Re: [PSUBS-MAILIST] Group Help Request
>>>
>>> Ok gentlemen first round of quotes for a Marin 19A Nozzle
>>> only in ABS plastic (White) for a 6" prop and not accounting
>>> for prop clearance is $760. This is using FDM process.
>>> Same nozzle in cast urethane,.. $ 3,700,.. what is cast
>>> urethane? Dont want it anyway!!!
>>> I need to know the exact diameter of a Weedless wedge 2 prop
>>> for a 4" motor in order to get the quote exact.
>>> Joe
>>>
>>> *From:* hank pronk <hanker_20032000 at yahoo.ca>
>>> *To:* Personal Submersibles General Discussion
>>> <personal_submersibles at psubs.org>
>>> *Sent:* Monday, October 28, 2013 10:28 AM
>>> *Subject:* Re: [PSUBS-MAILIST] Group Help Request
>>>
>>> Scott,
>>> I use weights from a weight lifting set, the steel ones.
>>> They could go outside on a peg so to speak. The only
>>> problem is you want them at the bottom of the sub. That
>>> means hauling the sub unless you want to get wet. Maybe a
>>> slide system. I thought the same thing to put the air
>>> outside, that would kill my sleek and slippery-ness. :-)
>>> Hank
>>>
>>> *From:* swaters <swaters at waters-ks.com>
>>> *To:* Personal Submersibles General Discussion
>>> <personal_submersibles at psubs.org>
>>> *Sent:* Monday, October 28, 2013 7:46:30 AM
>>> *Subject:* Re: [PSUBS-MAILIST] Group Help Request
>>> Hatch closure from both sides deffenetly a good one. I would
>>> say adjustable exterior weights. I hate the idea on chucking
>>> weights on the floor and then sitting on them. I am torn
>>> between that and moving the hp air tanks to the exterior to
>>> allow alot more room on the inside.
>>> Thanks,
>>> Scott Waters
>>>
>>>
>>>
>>>
>>>
>>> Sent from my U.S. Cellular© Smartphone
>>> hank pronk <hanker_20032000 at yahoo.ca> wrote:
>>> Joe,
>>> Why don't you take a vote on what the best improvement
>>> would be for a k sub or alike. My vote would be for a hatch
>>> closure from both sides.
>>> Hank
>>>
>>> *From:* Joe Perkel <josephperkel at yahoo.com>
>>> *To:* "personal_submersibles at psubs.org"
>>> <personal_submersibles at psubs.org>
>>> *Sent:* Monday, October 28, 2013 5:41:42 AM
>>> *Subject:* Re: [PSUBS-MAILIST] Group Help Request
>>> I just love the world in which we live! Look what I found
>>> while waiting to take my daughter to school,..
>>> http://www.quickparts.com/QuickQuote.aspx
>>>
>>> Isn't that just the coolest thing! The Star Trek
>>> synthesizer in the real world.
>>>
>>> Joe
>>>
>>> Sent from Yahoo! Mail for iPad
>>>
>>> *From: *Marc de Piolenc <piolenc at archivale.com>; *To:
>>> *<personal_submersibles at psubs.org>; *Subject: *Re:
>>> [PSUBS-MAILIST] Group Help Request *Sent: *Mon, Oct 28, 2013
>>> 10:46:58 AM
>>> Never thought much about doing it at small scale.
>>>
>>> I suppose I would set up something like a wood lathe or a
>>> potter's wheel
>>> and work in some very soft material like low-density foam.
>>> Once I had
>>> the shape that I wanted, I suppose one could pour a mold
>>> around the
>>> master, melt or dissolve out the pattern and cast the final
>>> part in some
>>> suitable plastic, or even in aluminum if you were ambitious.
>>>
>>> 3D printing seems like the ultimate way to do it, though -
>>> the accuracy
>>> available is already better than what we would need, and if
>>> the inital
>>> results are not perfect, making changes and printing out
>>> another
>>> prototype is very quick.
>>>
>>> Marc
>>>
>>> On 10/28/2013 6:13 PM, Joe Perkel wrote:
>>> > How can a home builder maintain that contour 360 Deg out
>>> of "X" material?
>>> >
>>> > Joe
>>> >
>>> > Sent from my overpriced
>>> > iPhone
>>> >
>>> > On Oct 28, 2013, at 2:57 AM, Marc de Piolenc
>>> <piolenc at archivale.com> wrote:
>>> >
>>> >> Quick clarification: a properly contoured Kort nozzle,
>>> MARRIED TO A MATCHING PROPELLER, will increase static and
>>> low-speed thrust. Of course it won't increase power,
>>> since that comes from your motor. If you just put a shroud
>>> around your existing prop, you will be disappointed, and a
>>> shroud that doesn't do the job is overpriced unless
>>> it's free! Key ingredients for success:
>>> >>
>>> >> Prop matched to the shroud
>>> >> Shroud matched to the speed and thrust requirement of
>>> the vehicle
>>> >> Motor matched to the resulting prop
>>> >>
>>> >> Marc
>>> >>
>>> >> On 10/28/2013 8:33 AM, Jon Wallace wrote:
>>> >>>
>>> >>> What is the cost of having a true Kort nozzle machined
>>> by a CNC? I think
>>> >>> a 30% improvement in thrust for $30 would be great but
>>> I suspect
>>> >>> machining a Kort is going to equate to many hundreds of
>>> dollars, if not
>>> >>> reaching beyond a thousand. When I look at the Snoopy
>>> underwater videos
>>> >>> it is difficult to imagine a kort nozzle really making
>>> any difference in
>>> >>> the operational experience given that the motors are
>>> operating very
>>> >>> slowly and pushing Snoopy around at about 2 knots
>>> (estimated). The
>>> >>> props are designed for power, but that's what we
>>> want underwater. True,
>>> >>> a kort nozzle would increase that power but what is the
>>> return on the
>>> >>> cost? In other words, on a road with a speed limit of
>>> 30mph and no
>>> >>> passing zones it doesn't matter whether you have a
>>> 1.6 liter or 5.4
>>> >>> liter engine under the hood does it?
>>> >> --
>>> >> Archivale catalog: http://www.archivale.com/catalog
>>> >> Polymath weblog: http://www.archivale.com/weblog
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>>> >>
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>>> >
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>>>
>>> --
>>>
>>> Carsten Standfuß
>>> Dipl.Ing.Schiffbau @ Meerestechnik
>>> Heinrich Reck Str.12A
>>> 18211 Admannshagen
>>>
>>> 0172 8464 420
>>> WWW.Euronaut.org
>>> Carsten at euronaut.org
>>>
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>>
>> --
>> Archivale catalog: http://www.archivale.com/catalog
>> Polymath weblog: http://www.archivale.com/weblog
>> Translations (ProZ profile): http://www.proz.com/profile/639380
>> Translations (BeWords profile): http://www.bewords.com/Marc-dePiolenc
>> Ducted fans: http://massflow.archivale.com/
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>
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