Fw: [sfconsim-l] RE: Scale in Full Thrust

I thought this might be of interest :)

Date: 20 December 1999 21:22
Subject: [sfconsim-l] Scale in Full Thrust

>From: mccueb@mcwl.quantico.usmc.mil
>
>One of the strengths of Full Thrust is its Protean nature and the
resulting
>ability of players to adapt it to different SF settings. In large part,
this
> Protean nature results from the lack of any defined scale.
>
>At some point I got interested in adding gravitation. That was easy
enough
to
> do, even in by-hand vector movement, and resulted in a fun game with
some,
>but the strength of the gravity was pretty much arbitrarily assigned.
>(That is to say, it was inverse-square, but the product of the black
hole's
>mass and the gravitational constant G was just pulled out of the air.)
Then
my
>group played the Liberte scenario from the More Thrust book, wherein
there
is a
>planet just off one whole edge of the board. I started to wonder how
big
>planets really ought to be.
>
>So it was time to figure out what G really ought to be, which meant
deducing a
> scale for the whole game.
>
>MASS: There are some indications in the rules that 1 Mass Point is 100
tons,
>and when I did some submarine designs (that's another story), this
convention
>worked out fairly well. We will say these tons are metric tons, of 1000
>kilograms.
>
>TIME: It's a tactical game, so a turn is probably a small number of
minutes.
>Let's say, for simplicity, that it's 100 seconds.
>
>DISTANCE: Based on accelerations (8 inches/turn^2 seems to be about the
most
>anything can take), it seems as though an inch/turn^2 is probably about
1
>gravity. (Whence the upper limit of 8, beyond which people have lots of
>trouble functioning.) A gravity is (very nearly) 10 meters/sec^2, which
is
>100 kilometers/(100 sec)^2, so an inch is 100 kilometers.
>
>G: The gravitational constant is (very nearly) 2/3 x 10^(-10)
>newton-meters^2/kg^2. (That's how they write the units in Halliday and
Resnick,
> but it's really awful and an impendiment to understanding. It would be
much
>better to write the same units as meters^2 (meter/sec^2)/kg.) Anyway,
based
on
>the above translations of the mass, time, and distance units into Full
Thrust,
>G is 2/3 x 10^(-16) gravities per inch^2/mass point, where the "inches"
are
>inches of distance between the gravitating mass and the spaceship and
the
>"mass points" are the mass of the gravitating mass, in the same units
of
100
>tons in which spaceship masses are measured.
>
>THE SPEED OF LIGHT, c: The speed of light is 3 x 10^8 meters per
second,
>which is 3 x 10^5 inches per turn.
>
>Brian McCue
>

>From: mccueb@mcwl.quantico.usmc.mil
>
>Obviously, the weak link in my earlier derivation of the implicit scale
in
>Ground Zero Games's _Full Thrust_ is the assumption that turns are
about
100
>seconds long.
>
>Varying this assumption, while retaining the more solid assumption that
a
inch
>per turn per turn is one Earth gravity, leads to some interesting
effects.
>Because of the squaring, a factor-of-ten increase in the turn length
leads
to
>a factor-of-100 increase in the distance represented by an inch on the
table.
>And with time and distance varying non-proportionally, speeds (e.g.,
the
speed
>of light) change.
>
>Turn length Inch scale km/inch c	 Radii in inches
>(seconds) Meters (inches/turn) Earth Sun AU
>      100	 100,000	  100 300,000	       64 10,000
1,500,000
>    1,000	 1.E+07       10,000 30,000	      1    100	  15,000
>   10,000	 1.E+09    1,000,000   3,000	       0      1      
150
>  100,000	 1.E+11     1.00E+08	 300	       0      0        
2
>1,000,000 1.E+13     1.00E+10	    30		 0	    0	      0
>
>The thousand-second (about 15 minute) turn is, to me, at the outer edge
of
>plausiblity for a tactical game.
>
>But the longer turns have their attractions--the 10,000 second turn
makes
it
>possible (especially if your "inches" are centimeters) to get much of
the
Inner
>System on the table, as in Triplanetary, and the 100,000 second
(somewhat
less
>than  a day)turns would let you get a whole solar system on the table,
as
might
>be handy for fighting out combats that arise in Stellar Conquest or the
like.
>
>In all these cases, the speed of light remains great enough that ships
would
>not be limited by in in their knowledge of the placement of other
ships.
>In the million second (1 week) turn case, the speed of light does start
to
>come into play, and write-ahead or some other system ("play everything
double-
>blind with a referee") would need to be used.
>
>Brian McCue
>
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