[Date Prev][Date Next]
[Chronological]
[Thread]
[Top]
Re: [PSUBS-MAILIST] Pressure air drive.
I think that would work only in circumstances of consant force.
Unfortunately the faster you go, the more force therefore the mosr air
needed. I thinkt hat CA is a good idea, but the 73 minutes is kinda
pushing it, isn't it?
Carl
Pierre Poulin wrote:
>
> The math is simple:
>
> one tank of 220 cubic foot. divided by 3cubic foot/minute = 73 minutes of
> non-stop full throttle operation. So air reserve doesn't seem like an issue
> to me.
>
> My question is more the 25000 rpm and 0.6 HP. Would that be enough for
> moving my 1092 lbs ambient sub? And there is also the propeller design
> consideration (which I'm no expert)
>
> So, What do you think about RPM and HP?
>
> Pierre
>
> >From: Coalbunny <coalbunny@vcn.com>
> >Reply-To: personal_submersibles@psubs.org
> >To: personal_submersibles@psubs.org
> >Subject: Re: [PSUBS-MAILIST] Pressure air drive.
> >Date: Wed, 08 Jan 2003 16:52:29 -0700
> >
> >And that would explain why WW2 torps had a range of less than a mile.
> >NOW I understand.
> >Thanks Jay!
> >Carl
> >
> >
> >jbarlow@bjservices.ca wrote:
> > >
> > > 3 cubic feet per min at 90 psi
> > >
> > > If air is ideal gas then P1 x V1 = P2 x V2
> > >
> > > 3000 psi X .353 ft3 = 90 psi x V2
> > >
> > > V2 = 11.76 ft3 @ 90 psi
> > >
> > > 11.76 / 6 = 1.96 min.
> > >
> > > The volume gets worse by the head of water (15 psi per 32 feet) and also
> > > the motors lose power as then can't fully expand the air back to
> > > atmospheric to regain the stored energy. You could overcome this by
> > > feeding the motor ever increasing pressure air (measured inside your
> >boat)
> > > as you dove deeper. that is regulating it down less, to regain the
> >power
> > > loss, but that again would shorten your range. 320 feet is about 150
> >psi
> > > so now you need to feed the motors 90 + 150 = 140 psi to get .6 hp and
> >the
> > > 1.96 minutes becomes 1.26 minutes. Based on the 10 litre scuba bottle.
> > > Obviously one would need bottled gas cylinders.
> > >
> > > about 1.5 min per 10 litre bottle @ 10 atm. depth.
> > >
> > > Still a sound concept. If you have to use shop air (easy and cheap
> > > compressors) then i think it is not workable. If you have access to
> > > 3000-4000 psi compressors then it should work fine for short duration
> >use.
> > > For an occasional use would be great as it has no shelf life.
> > >
> > > Jay.
> > >
> > >
> > > MerlinSub@t-online.de
> > > (Carsten Standfuss) To:
> >personal_submersibles@psubs.org
> > > Sent by: cc:
> > > owner-personal_submersible Subject: Re:
> >[PSUBS-MAILIST] Pressure air drive.
> > > s@psubs.org
> > >
> > >
> > > 08/01/2003 10:47 AM
> > > Please respond to
> > > personal_submersibles
> > >
> > >
> > >
> > > Pierre Poulin schrieb:
> > > >
> > > > Hi,
> > > >
> > > > I've check some air grinders that could be transformed into motor.
> > > >
> > > > Free speed: 25000 rpm
> > > > - Operation pressure: 90 psi
> > > > - 0.6 HP
> > > > - Air consumption: 3 cfm
> > > > - Weight: 1.5 lb
> > > >
> > > > What do you think about that?
> > > >
> > > > Pierre
> > > >
> > >
> > > Hmm.. 3 cfm means cubif -foot- minute ?
> > > than it is
> > > are equal (sorry I think in metric..)
> > > to 3 x 0,3048 x 0,3048 x 0,3048 m = 3 x 0,028 m3 or 84 Liter
> > >
> > > if we estimate that the boat need two engines of 0,6 hp we need
> > > 2 x 84 liter = 168 Liter a minute.
> > >
> > > A normal scuba bottle has 10 Liters at 225 bars = 2250 Liters
> > > air and run the drive just 2250/168 = 13 Minutes
> > >
> > > A yard size bootle for weld gas has 50 liter and is 1,5 m (4,9 feet)
> > > high with a diameter of 280 mm (11 inch) runs about
> > > 5 times longer = 65 minutes..
> > >
> > > Two tanks of 50 Liters gives you 2 hours and 10 minutes..
> > > Not so bad - Batterys has to be replace after some years -
> > > pressure bottles not - and a 50 Liter industrial one is about
> > > 300 Dollar new and maybe cost the half if you purchase a used one.
> > >
> > > Problems:
> > > - to get an engine made from seawater resistant material
> > > - the noise ? -> no fish around the boat
> > > - the air bubbles all the time ? -> no fish around the boat
> > >
> > > Most problem is maybe that high pressure scuba compressor
> > > is mcuh more expensive than a battery charger.. :-(
> > > But for peoples which are allready scuba divers - and have allready
> > > a compressor - a solution.
> > >
> > > Carsten
> >
> >--
> >"You delight not in a city's seven or seventy wonders, but in an answer
> >it gives to a question of yours, or the question it asks you, forcing
> >you to answer, like Thebes through the mouth of the Sphinx." -- Kublai
> >Khan
>
> _________________________________________________________________
> MSN Search, le moteur de recherche qui pense comme vous !
> http://search.msn.fr/worldwide.asp
--
"You delight not in a city's seven or seventy wonders, but in an answer
it gives to a question of yours, or the question it asks you, forcing
you to answer, like Thebes through the mouth of the Sphinx." -- Kublai
Khan