Slashdot | Fuelless Flight with Air Submarine?

Pretty cool, the following link at slashdot.org:

http://science.slashdot.org/article....23&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/vie...PACE&catId=379

Tim

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

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