Subject:
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Re: Hypothetical design question
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Newsgroups:
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lugnet.space
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Date:
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Mon, 23 Jun 2003 13:32:25 GMT
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Viewed:
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446 times
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In lugnet.space, Sylvia Tresto wrote:
> Okay, just something I thought of while fiddling with my LEGO: An aerodynamic
> desigh is only handy in atmosphere and not necessary in space, right? I remember
> it from physics lessons and some posts in this newsgroup. But space is not a
> true vaccuum, is it? There is all sorts of stuff out there, even if it is only
> on a molecular or atomic level. So if a spaceship had a revolutionary drive
> which would allow it to travel close to lightspeed (let's stay true to Einstein
> and assume faster is no option) it should be very aerodynamic or its would
> sustain heavy damage from even the smallest of particles out there. Am I right
> or have I completely overlooked something?
>
> Love, Sylvi
Sylvi,
Aerodynamics is complex. One usually divides aerodymanic behavior into different
categories, depending on the speed of the vehicle in comparison to the speed of
the particle. If your vehicle is traveling under particle speed (the speed of
sound for air), you have subsonic, incompressible flow. A little faster, you
have transonic flow, then supersonic, then hypersonic.
Shapes that you may consider aerodynamic are typically designed for
subsonicincompressible flow situations, where the velocity of the vehicle is
about 80% or less of the Mach speed (the speed of the individual particles in
the flow), the fluid does not compress, and the fluid is considered a continous
liquid. Think a sport car, TGV train, jetliner.
Supersonic flows create aerodynamic shapes that are very thin and pointed, think
the Concorde.
Very high speed near vacuum flows react very different, you end up with
hypersonic flows, and sharp leading edges can get hot, very hot. Think of Apollo
re-entry capsules. You dnn't really have a fluid-flow, just lots and lots of
individual particles hitting the craft.
So, for a near light speed craft, anything hitting it would probably destroy it,
if it didn't have some sort of shield. I can't find the link, but there is a
page that describes very nicely what happens when an object the size of a soup
can hits a Star Destroyer at half the speed of light ( a huge explosion).
Thanks,
George
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Message has 2 Replies:
 | | Re: Hypothetical design question
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| (...) Wow, that's quite a bit more complicated than I assumed... (...) Yup, I had those in mind for vehicles which actually travel through atmosphere. (...) No thank YOU, George, for clearing some things up. What about this, taken from the SF novel (...) (21 years ago, 23-Jun-03, to lugnet.space)
| | | Re: Hypothetical design question
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| (...) Well, it's only theoretical at the moment, but scientists believe that there's such a thing as "Dark Matter". It is invisible to all modern sensing systems (including the naked eye), but it is the only explanation for certain celestial events (...) (21 years ago, 23-Jun-03, to lugnet.space)
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Message is in Reply To:
| | Hypothetical design question
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| Okay, just something I thought of while fiddling with my LEGO: An aerodynamic desigh is only handy in atmosphere and not necessary in space, right? I remember it from physics lessons and some posts in this newsgroup. But space is not a true vaccuum, (...) (21 years ago, 23-Jun-03, to lugnet.space)
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