Slashdot | Fuelless Flight with Air Submarine?

[Tim Schoenfelder]

Pretty cool, the following link at slashdot.org:

http://science.slashdot.org/article.pl?sid=04/02/27/1837223&mode=thread
<http://science.slashdot.org/article.pl?sid=04/02/27/1837223&mode=thread>

reads as follows:

*from the in-this-house,-we-obey-the-laws-of-thermodynamics dept.*
An anonymous reader writes /"Using the same physics principles as
submarines, a new company is planning a fuelless air ship
<http://www.fuellessflight.com/>. Recent advances in ultra light and
strong materials are making this concept a practical reality
<http://www.machinedesign.com/ASP/viewSelectedArticle.asp?strArticleId=56635&strSite=MDSite&Screen=AEROSPACE&catId=379>."/
There's no question that changes in buoyancy can be used to propel a
vehicle
<http://science.slashdot.org/article.pl?sid=03/11/24/0438213&tid=126>,
but "fuelless" is going to be tricky.

The original article above at slashdot references the an article from
Machine Design Magazine as described below...

http://www.machinedesign.com/ASP/viewSelectedArticle.asp?strArticleId=56635&strSite=MDSite&Screen=AEROSPACE&catId=379

Tim

[David O]

Tim Schoenfelder > wrote:

>Pretty cool, the following link at slashdot.org:

What Robert Hunter proposes is a perpetual motion machine. Put
simply, it won't work. He will find this out when he tests his theory
with his submarine version. Now, if he relies on internal energy that
slowly gets depleted (such as batteries), or external energy sources
such as solar power or thermal lift for his glider, then it's another
ball-o-wax. From my cursory reading, however, that is not what he
proposes.

As for his submarine, in a frictionless world a submarine could
descend and ascend in perpetual cycles by adjusting internal volume
(water ballast) while expending zero net energy per cycle. In the
real world, however, friction losses get added to the energy equation.
It doesn't matter how efficient Mr. Hunter's wizmo-gizmo turbo
generators are, their efficiency will always be less than one. His
generators will therefore generate less energy then they extract from
the buoyancy cycle. Additionally, the ballast pumping mechanism will
have an efficiency of less than one, the sub will lose energy to
friction while moving through the medium, etc. His glider concept is
similarly flawed.

David "party pooper" O -- http://www.AirplaneZone.com

[Richard Lamb]

David O wrote:
>
> Tim Schoenfelder > wrote:
>
> >Pretty cool, the following link at slashdot.org:
>
> What Robert Hunter proposes is a perpetual motion machine. Put
> simply, it won't work. He will find this out when he tests his theory
> with his submarine version. Now, if he relies on internal energy that
> slowly gets depleted (such as batteries), or external energy sources
> such as solar power or thermal lift for his glider, then it's another
> ball-o-wax. From my cursory reading, however, that is not what he
> proposes.
>
> As for his submarine, in a frictionless world a submarine could
> descend and ascend in perpetual cycles by adjusting internal volume
> (water ballast) while expending zero net energy per cycle.

I was with you - up to here.

In order to rise, something has to force the water out of the ballast
tanks. That would likely be high pressure air.

That's a LOT of energy expended per cycle.


My ex wife is a chemestry professor.
She often advised her students that two weeks in the lab
will save three days in the library - every time.

So true...

Richard

> In the
> real world, however, friction losses get added to the energy equation.
> It doesn't matter how efficient Mr. Hunter's wizmo-gizmo turbo
> generators are, their efficiency will always be less than one. His
> generators will therefore generate less energy then they extract from
> the buoyancy cycle. Additionally, the ballast pumping mechanism will
> have an efficiency of less than one, the sub will lose energy to
> friction while moving through the medium, etc. His glider concept is
> similarly flawed.
>
> David "party pooper" O -- http://www.AirplaneZone.com