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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Fri, 22 Jun 2001 21:28:48 GMT
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Viewed:
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39 times
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In lugnet.space, Jason J. Railton writes:
> In lugnet.space, David Drew writes:
> > 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.
>
> 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 impacts as individual retarding impulses, but if you've
> got enough power to move your own mass that fast, their net effect on
> forward velocity is still going to be negligible. The only concern is their
> net effect on your orientation and course, and that's if you solve the
> problem of the actual damage caused by the impacts.
>
> The design may well be streamlined, but in a way to deflect impacts rather
> than to smooth the flow of passing fluid. Wedge-shapes rather than
> tear-shapes, since you don't have to worry about drag from a turbulent wake.
>
> I mean, it's hardly rocket science, is it? Oh, hang on...
>
> Jason J Railton
How many posts have resulted since my comment about wings in space? My
calculations say that there have been about fourty or fifty posts since my
comment about wings in space. My space craft is generally wedge shaped,
Jason, if you want to know about the design or my space craft.
Jesse Long
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Message is in Reply To:
 | | 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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