Re: [ft] Orbits in Vector

>Does anyone have a system for doing on-table planets and orbits with
>vector movement?
> I'd kind of like to be able to do slingshot maneuvers and...

Actually, the so-called "slingshot" maneuver doesn't actually add much
_speed_ to an object.  It relies on the distinction between speed and
velocity, in which velocity is a speed in a particular direction,
whereas
speed just measures distance travelled over time.

Any two-dimensional motion in space can be described as two separate
motions
with respect to the sun:  one motion towards or away from the sun, and
another "left" or "right" of the sun.  When NASA uses a slingshot
around,
say, Jupiter, to "speed up" a probe, what they're doing is using
Jupiter's
mass (and angular momentum) to alter the directional vector of the
probe, so
that more of its "speed" points away from (or towards) the sun, instead
of
at a right angle to it.  Although the actual "speed" doesn't change
much,
the radial velocity (the important part when trying to escape the sun's
gravity) changes alot, as does the direction of motion.

All that said, what I'd probably do to simulate this in FT using Vector
Thrust rules is allow a close brush with a planet to alter your
direction of
motion while retaining all speed.  (The amount of "speed" gained in
falling
towards the planet is mostly lost again when leaving it, so it
essentially
cancels out for game purposes).  To make it interesting, you might limit
the
amount of direction change based on how close you brush the planet;
those
who dare to fly closer get more of a benefit, but get too close and...

Just my nickel ninety-five.

bart