Thruster pushes was re: FB2 preview

> On Tue, 9 Mar 1999, Wasserman, Kurt wrote:

> No offense but either of those are really good solutions.

i assume kurt intended to put an 'n' on the front of that 'either'...

> A) really tears a lot of the fun out of maneuvering and B) is just

well, if the main drive produces an exhaust which can then be vented through
any one of a number of drive ports, you'd have a justification: if you wanted
a push, you'd need to divert thrust from the main drive. likewise for reverse
thrust. think of the reverse thrust buckets some big aircraft have to use for
braking on landing.

> I am not sure about the physics of space travel. Hell, I barely

well, there's one main drive and twenty thrusters, but the main drive is much
more than 20 times bigger than a thruster...

<physics-n-maths>

it's fairly straightforward to figure out possible values for the size of
a move unit, turn and thrust point based on simple mechanics - the
1000km-15min-1m/s2 combination is, i think, the most widely accepted.
it's even possible to rationalise the slight deviation from newtonian
mechanics which has all of a ship's thrust take effect at the start the turn
in which it was made: we say ships use a short, powerful burst type of drive,
which only fires at the start of the turn. if the burst is 1/10th the
length of the turn (100s, 1m40s), then it works out that one thrust point
is 10 m/s2, which is 1 g.

however, it's a bit harder to analyse rotation. if we stuck to real physics,
then the time taken for a ship to do a particular rotation is not proportional
to the size of the rotation, but to the square root of the size. i think.

this wouldn't be all that hard to factor in to FT, actually (i think). if you
spend T thrust points on rotation, you can rotate up to T*T course points.

here's a quick table:

Thrust Change

1       1
2       4
3       9

this isn't very pretty, is it. curses. you might want to say that you can
do (T*T)/2 or (T*T)/4 instead, though.

anyway, if we work this in, then the acceleration needed (if split into two
and applied at the ends of the ship in opposite directions, a bit like certain
types of lawn sprinkler) to get one maneuver point is

a       =       (pi / 9) * r / t^2

where r is the length of the ship and t is the time used for turning.
let's say this is one-tenth of a turn (as i have suggested for the main
drive burn). if we assume a ship length of 100m, and a turn of 1000s
(16m40s), then a comes out as about one three-thousandth of a g. given
that a main drive point in the same scale is about 1 g, you see why thruster
pushes are not realistic.

qed, i believe...

</physics-n-maths>

> Each propulsion

yes. any acceleration will reach any speed (pace Einstein) given long enough.

> I find it logical (and pleasing) to imagine a ship boosting itself in
right.
> And, since this "Thruster Effect"(tm) is common to all ships using

that's certainly true. many games have thruster pushes, and no-one seems
to mind very much.

Tom