Good point. Having air inside must be indispensable anyway to offset the weight of the metal hull and batteries.
Michel ----- Original Message ----- From: "Robin van Spaandonk" <[EMAIL PROTECTED]> To: <vortex-l@eskimo.com> Sent: Tuesday, February 12, 2008 3:07 AM Subject: Re: [Vo]:Ambient temperature variations powered engine? (was Re: Ocean glider uses ocean heat differentials) In reply to Michel Jullian's message of Tue, 12 Feb 2008 01:26:20 +0100: Hi, [snip] >Thanks Lawrence this makes more sense, the initial BBC article and the WHOI >press release stated, wrongly it now seems, that "[the surface] heat is used >to push oil _from a bladder inside the hull to one outside_". If it's the >other way round as the WP article below suggests (oil from outside to inside >at the surface), then the outside oil bladder needs not contain anything but >oil as I am sure Robin will agree. [snip] While I do agree strictly, consider that the oil is incompressible, and hence always takes up the same volume (almost) whether inside or outside. If the oil can be pumped into the device, then that means that there must be something compressible inside the device, i.e. an air bladder. In short, it makes no difference where that bladder is, as long as it is part of the device. The reference I provided to the manufacturers web site, makes clear that there is at least one air bladder. Regards, Robin van Spaandonk The shrub is a plant.
