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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Thu, 21 Jun 2001 01:09:04 GMT
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Viewed:
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1063 times
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On 21/6/01 5:19 AM, "William R. Ward" <bill@wards.net> wrote:
> David Drew writes:
> > On 20/6/01 5:54 AM, "William R Ward" <bill@wards.net> wrote:
> >
> > > Actually, this is false. Space is a vacuum - there is no air, only a
> > > few stray molecules of gas or cosmic dust. As a result, there is no
> > > friction and thus no need for wings or streamlined shapes on space
> > > craft. Also, there is very little gravitational pull, so the lifting
> > > power of wings is useless.
> >
> > Actually, if you're travelling at near-light velocities, the density of the
> > interstellar medium becomes high enough (especially within solar systems, so
> > I guess that would be intrastellar medium) that a streamlined shaped would
> > become essential. Even then, there would be both heavy erosion of whatever
> > impact-shielding you have, and heavy drag on the ship.
>
> That may be true, but I don't think anyone knows for sure, because we
> haven't tried going that fast yet. My spacecraft follow a very "hard
> SF" policy - no FTL travel, no artificial gravity, etc. But that's
> not to say that it's the only way...
We know it's true, since we have our nice and handy fluid mechanics
calculations. The drag experienced by a vehicle depends on a number of
factors, including surface area, drag coefficient, viscosity and density of
fluid, and the velocity of the vehicle.
Obviously, for low speeds, the drag is near zero, since density is near
zero. But get near to 3*10^8 m/s, and it becomes a whole different story.
There will probably be other effects coming in as an object approaches
relativistic velocities, which we cannot account for, but there are unlikely
to reduce the drag.
Later,
David Drew.
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Message has 2 Replies:
 | | Re: Wings [was: Re: Building big]
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| (...) Oh please. Drag calculations are only approximations for something immersed in a fluid. You're not going to get conventional boundary layer effects when you only bump into a single gas molecule every few meters. You could consider molecular (...) (23 years ago, 21-Jun-01, to lugnet.space, lugnet.loc.au)
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