Re: FT: FB2 Preview - Obi Wan Tuffley

On Sun, 7 Mar 1999, Oerjan Ohlson wrote:

> Jon T. wrote:
> 
> > >Vector Movement Modification Proposal:
> > >Main Drive thrust and Thruster Pushes must be executed together;
they
> > >may not be separated by a Facing Change.
> > >
> > >  This is to avoid events such as: a Thrust 6 ship uses a Main
Drive 6
> 
> > > burn in direction 12; rotates to heading 3; and uses its two
> remaining 
> > >Thruster points to Push to port; its total movement in direction 12
> has 
> > > therefore been 8 instead of 6.  Next turn it could perform the
same 
> > > steps in reverse order, to end facing direction 12 again.
> > 
> > Hmmm, an interesting thought, and one that I can see the rationale
> > behind... what does anyone else think?
> 
> Mikko for one would be overjoyed to see it <g>
> 
> It is simple and reasonably realistic. It can be made more realistic,
but
> then it's not simple any more :-/

the trouble is, a ship's turning ability is not proportional to its
linear
acceleration ability; longer (ie bigger) ships turn more slowly. i think
a
ship twice as long turns one quarter as fast (ie, takes 4 times longer)
but don't quote me on that. thus, a linear scale between angular and
linear acceleration is somewhat incorrect. still, as has been noted,
this
is a game.

> I'd drop the restriction on using only one rotation, though (IIRC,
using
> the "common" FT2 scale it'd take a Thrust-2 ship approx. 1 minute to
do a
> 180-degree facing change - assuming the hull structure is up to it, of
> course, since the shear stresses would be fairly big <g> - and that
> leaves quite a lot of time in a 15- or 20-minute turn <g>).

well, the mechanics as they stand suggest that ships apply thrust in one
big push at the start of the turn; this is why, when you apply thrust to
go, say, from speed 6 to speed 10, you move 10 units over the turn, not
8.
now, 1 Mu = 1000 km, 1 Tu = 1000 s (= 16'40") gives 1 Th = 1 m/s2, or,
say, 10 m/s2 applied for 100 s at the start of the turn. thus ships will
be built with accelerations on the order of a few gravities in mind.
however, thrust (when the engine is at the back) produces compressive
stress, whereas spinning produces shear and tension stress. building
hulls
from concrete is thus probably a bad idea.

Tom