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RE: [PSUBS-MAILIST] Reserved buoyancy
Erik
My humble apologies, physicist ouch, well far more educated than I am
I have a formula slighly deverent to calculate volume πR²L calculate volume of a sperre 4/3πR³ not that it will work with end caps tough.
Enjoy
MG
-----Original Message-----
From: Erik Muller [mailto:emuller@naic.edu]
Sent: 11 March 2004 03:09
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Reserved buoyancy
Grrrr..
Marius,
I KNOW the principals involved!, I am a physicist!
Displacement is totally decoupled from the TYPE of the fluid, it is the
boyant force which is different and which is dependant on the density!
There just seemed to be a typo in Carsens original post where there was
a 'm^3' where I would have expected 'kg'!
humph. I might seem like it sometimes.. but I like to think I am not
excessively thick ALL the time...!
sigh.
But thanks for that fun experiment, I will show my neice.
EM.
Greeff, Marius (M) wrote:
>I posted a photo of this on moki.
>
>Regards,
>Marius
>
>-----Original Message-----
>From: Greeff, Marius (M)
>Sent: 11 March 2004 07:39
>To: personal_submersibles@psubs.org
>Subject: RE: [PSUBS-MAILIST] Reserved buoyancy
>
>Thanks Carsten,
>The mid section where my conning tower is located is 21mm thick steel,
>grade of steel I am not sure of so drop testing will be no1 on list of
>tests. This already with the first section of coning tower displaces
>close to 1 m3 and weighs 660Kg. This section is 1.35m long. Adding the
>rest of the hull and conning tower will take it to 1.85 m3. Here I will
>use 1/4" thick steel where view ports will be placed. I would like my
>buoyancy correct on paper to cancel out any other parts still to come
>like the motors and battery pods. I will ammend my design to a point
>where it will work before I make another hasty buy.
>
>PS. Erik Muller, fun experiment: raw egg floats in salt water and sinks
>in fresh water.
>
>Kind regards,
>Marius
>
>-----Original Message-----
>From: Carsten Standfuss [mailto:MerlinSub@t-online.de]
>Sent: 10 March 2004 10:35
>To: personal_submersibles@psubs.org
>Subject: Re: [PSUBS-MAILIST] Reserved buoyancy
>
>Yes thats right - the body displace stil the same 1cm of something.
>But the density of something is different - and there with on a planet
>with constant gravitation - the lift force - bouancy.
>
>A sub of a volume of excat 1 m3 and a weight of 1 t or 1000 kg
>in freshwater with a density of 1,0 will just be in dive trim.
>It displace excat 1000 kg of water.
>
>Saltwater has an higher density = about 1,025 t per m3 (or 1025 kg)
>So you can build the sub 0,025 t or 25 kg heavier and it will be still
>dive trim.
>
>Put your 1m3 sub in mercury with a density of 13,595 t per m3
>and you have to add 12,595 t of lead or something into your sub before
>it dive.
>
>If you dive with a 1m3 and 1 t heavy sub in petrol tank to inspect a big
>oil raffinere from Shell.. it will sunk strait to the bottom of the tank
>-> Petrol = 0,68 -0,75 t per m3 means negative lift of 0,25-0,32 t
>
>Real sample :
>
>Euronauts weight is about 57 ts.
>Baltic sea has about 1,000 t per m3 density.
>North Sea has about 1,025 t per m3 density.
>
>If I leave the baltic on dive station via the Kategatt way -
>the lift of the water will increase of 1,025 x 57 = to 58.425 t
>and the boat will be force on the surface with a lift of 1,425 t - the
>weight of a Kittredge size sub..
>
>It is a bad idear to dive with a militar high sea sub from the South
>Atlantic into the Amazonas river delta in dived condition..
>A 8000 ts boats "lost" about 195 ts of lift -> bouancy ;-)
>
>Sorry about my poor english language.. Carsten
>
>Erik Muller schrieb:
>
>
>>Hello Carsten,
>>I am just following up on that calc.
>>I am unclear why the displacement is different for salt and fresh
>>
>>
>water.
>
>
>>I know that the boyant force will be different, but surely if I put a
>>1cm cube of metal into a cup of liquid, I still displace 1cm,
>>
>>
>regardless
>
>
>>of anything else disolved., Do you mean to write that the boyant force
>>is 1 5323 kg (i.e. rather than m^3) in fresh and 1 5706 kg in sea?
>>Thanks Carsten,
>>EM.
>>
>>Carsten Standfuss wrote:
>>
>>
>>
>>>Show us the general weight calculation of your boat here..
>>>
>>>I estimate that :
>>>
>>>A.1) Estimate bouancy calculation :
>>>
>>>0,921 by 0,921 x 3,1415/4 x 2,3 m = 1,5323 m3 displacement in
>>>
>>>
>freshwater
>
>
>>>(1,5706 in seawater) without endcaps and outside displacement parts.
>>>
>>>B.1) Estimate weight calculation :
>>>
>>>hmm...
>>>Which tickness has the pipe ? Mild steel or stainless ?
>>>
>>>regards Carsten
>>>
>>>
>>>Steven Mills schrieb:
>>>
>>>
>>>
>>>
>>>>Ouch ! Marius,
>>>>
>>>>What grade and standard of steel did you get?
>>>>
>>>>--Steve
>>>>
>>>>On Wed, 10 Mar 2004 15:58:33 +0200 "Greeff, Marius (M)"
>>>><Marius.Greeff@sasol.com> writes:
>>>>
>>>>
>>>>
>>>>
>>>>>Howdy,
>>>>>I think I bought the wrong piece of steel to start my pressure hull
>>>>>with. I end up calculating about 700kg buoyancy reserved on the
>>>>>design before motors, batteries and all the rest are added. I wish
>>>>>to get this right before I buy the rest of the steel needed to
>>>>>build. My design have the hull already 2.3m long and a diameter of
>>>>>921mm(36").
>>>>>
>>>>>Kind Regards
>>>>>Marius
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
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