Subject:
|
Re: Wings [was: Re: Building big]
|
Newsgroups:
|
lugnet.space, lugnet.loc.au
|
Date:
|
Mon, 25 Jun 2001 10:38:02 GMT
|
Reply-To:
|
SSGORE@SUPERONLINE.saynotospamCOM
|
Viewed:
|
174 times
|
| |
|
|
David Drew wrote:
>
> 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.
>
> later,
> David Drew.
No, it's not..:-) At STP (Standard temperature and pressure, 1atm and
273K if IIRC), only 22.4 lt. of any gas would have 6.022x10^23
molecules. Your number given above is quite negligible when compared to
this I think. You must consider individual attitudes of the molecules in
your case (microscopic approach), rather than their behavior as a whole
as a fluid (macroscopic approach), since there is nothing like you could
mention as a fluid in that case, and continuum model is pretty not
working, which is the most basic thing in fluid mechanics. I might be
wrong about the numbers, it was 12 years ago, but the idea is quite true
I think.
The main problem when traveling through space at such high velocities is
the wear caused by the inter-whatever dust particles that impacting your
ship at similar velocities.
Selçuk
> ----- Original Message -----
> From: "Jason J. Railton" <j.j.railton@cwcom.net>
>
> 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.
|
|
Message has 1 Reply:
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 (...) (25 years ago, 22-Jun-01, to lugnet.space, lugnet.loc.au)
|
34 Messages in This Thread:
 
 
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
This Message and its Replies on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
