Subject:
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Re: Wings [was: Re: Building big]
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Newsgroups:
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lugnet.space, lugnet.loc.au
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Date:
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Sat, 23 Jun 2001 02:28:16 GMT
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Viewed:
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1640 times
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In lugnet.space, David Drew writes:
> Hi.
> I can't remember the density of space off the top of my head, but let's say
> it's somewhere near the 1 molecule per 3m^3 like you suggest. If a vehicle
> is travelling near the speed of light (3*10^8 m/s), then the ship is hitting
> in the vicinity of 1*10^8 molecules per second per metre^2 of frontal
> surface area!
>
> I can't be bothered working out how many molecules of nitrogen and oxygen
> fill a 1m^3 box of air, but I think it can become clear that when travelling
> at near-relativistic velocities, the flow of molecules over the surface of a
> spaceship can become more than high enough to qualify it as a 'fluid', and
> thus impose the problems of drag and turbulence suggested.
Hmmm, this is pretty interesting (in an aero-geek way). I can't
remember Avogadro's number so I won't work out the numbers, either.
I suspect this would become a whole different branch of "fluid"
dynamics compared to what we deal with today. Because the particle
density is so very tiny, the whole concept for viscosity of this
"fluid" becomes pretty messed up. Practically speaking I don't
believe there would be any communcication between the particles
like in fluids we encounter today. Because of that there might not
be any fluid shear to develop to form anything like boundary layers,
in the conventional sense. Relative to the ship the particles may
appear to be approaching as a "fluid", but relative to each other
the particles are still horribly distant and "non-interacting".
Hey, maybe I can use this for my new masters thesis topic---I
change it every 3 months or so :]
Of course we have to start throwing relativity at it now too, which
is waaay beyond my area. The last pure physics we dealt with involved
calculating whether a ladder leaning on a wall would slip out from
under the monkey sitting it :] Oh, and something about "electricity"
or some whacky nonsense like that ;]
Anyhow, at those speeds I can agree that drag would be caused by
the impacting particles (if not a nuclear reaction <G>). But
I think they would be a form of "impact drag", with transfer of
momentum between the particle and ship. I'm not so sure any kind
of "flow drag" would develop in the conventional sense. I have
trouble thinking about what happens when one single particle
crashes into gazillions hurtling along in close formation. Does
it just "stick"??
I'll develop some theories and publish the book by Monday :]
KDJ
_______________________________________
LUGNETer #203, Windsor, Ontario, Canada
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Message has 1 Reply:
 | | Re: Wings [was: Re: Building big]
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| (...) 6.022 x 10^23. Get computin'! ;) (...) Bwaaa! I know how that goes. As long as the money is coming, why finish it? ;) (...) An electric ladder or an electric monkey? (...) Sometimes it tries to pass through. If nothing else it would, I'd (...) (23 years ago, 23-Jun-01, to lugnet.space, lugnet.loc.au)
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Message is in Reply To:
| | Re: Wings [was: Re: Building big]
|
| Hi. I can't remember the density of space off the top of my head, but let's say it's somewhere near the 1 molecule per 3m^3 like you suggest. If a vehicle is travelling near the speed of light (3*10^8 m/s), then the ship is hitting in the vicinity (...) (23 years ago, 22-Jun-01, to lugnet.space, lugnet.loc.au)
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