Re: Need Physics Help!

On 16 Jul 98 at 12:15, Mikko Kurki-Suonio wrote:

> On Wed, 15 Jul 1998, Richard Slattery wrote:
> 
> > Taking the 15 minute turn/1,000km per move unit scale, full thrust 
> > ships have a puny thrust of a 1/4g to 1/8g per thrust point, so 
> > gravity really sucks. <yes! I worked that pun in at last>
> 
> I can't agree. I did my campaign with 1 thrust = 1/4g (knowing that
> MU and turn length don't matter) and gravity is a minor irritation
> at best.
> 
> Consider that gravity is inversely related to the square of
> distance. Actually ON earth, it's 1g. But few spaceships fight on
> the ground.
> 
> About 6500km out, it's only 1/4g
> About 20000km out, it's 1/16g (0.25 thrust)
> 
> Geostationary orbit is, IIRC, about 30000km out.  
> 
> Moon, as we all know, is about 300 000km out, which on the solar
> system scale is still an insignificant distance.
> 
> So, gravity is only a factor if you *choose* to fight *very* close
> to a planetary body, amidst all the orbiting satellite junk
> (including weapon platforms).
> 
> If you were moving at constant acceleration of say, 0.5g from Mars
> to Venus and happened to pass within 50 000km of Earth, the impact
> on your final course is close to a rounding error.

When I said, gravity sucks, I meant, if you do manage to get /too/ 
close to something with more gravity than the earth...	a gas giant 
for example, you could be in serious trouble. Also, those ships that 
are intended to land on planets had better have good enough drives to 
manage it. If they have atmospheric streamlining, sure, they can 
glide with the bricklike quality that the space shuttle does, but 
taking off again with half a g of thrust is going to be problematic. 
Even worse, if the planet has no atmosphere for you to get lift in...

With regard to fighting near a planet... yup, I'd prefer to if I'm 
defending and it has orbiting defenses to help my fleet.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Richard Slattery	     richard@mgkc.demon.co.uk
Progress was all right. Only it went on too long. 
     James Thurber
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