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Old 10-November-2008, 02:24 AM
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cran cran is offline
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Originally Posted by pzkpfw View Post
I see your point. Thanks. ...was mixing bouancy with floating.

(i.e. that an object in a more dense medium still "feels lighter" even if fully immersed. Doh! e.g. Water tanks used to train crews for space-walks!)

I guess I need to try to calculate the density of a Dragonfly, compare to the density of air; and then with the density of air at higher pressures... that would provide a % improvement in natural bouancy. A lunch-time "project".

{But would the more-dense air create more drag and thus make it harder to move?}
not sure - the best modern analogy would be to ask some of the deep sea critters whether it's harder to swim ...

Quote:
[
What I was thinking about, was arguements about whether a sinking ship would ever go down far enough that it hit water at such a high pressure that it stops sinking. Turns out "no". As long as the ship is denser than the water, it will keep sinking, and it always is. (The twist was apparently that at high enough pressure the water would turn into ice - and that would stop the ship sinking... but it wouldn't occur on Earth.).

]
one of the design concepts incorporated into the Titanic* (and, I believe, submarines) was water-tight compartments within the structure - a ship (or sub) sinks because water displaces air - if the air cannot be displaced, then sinking will only continue until the total of air and container reaches equilibrium with the water [edit: that should be total of remaining air ... and it only holds true if it doesn't hit the seafloor first ] ...

*of course, it didn't work on the Titanic ...

back to your dragonfly - if, within its structure, there are locations to trap air (pockets, sacs, whatever), and that air can be warmed with respect to the outside air ...?
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