Re: [GZG] A new vector movement system

On Thu, Dec 11, 2008 at 7:28 AM, Ken Hall <khall39@yahoo.com> wrote:
> I am in general agreement with Robert. Seems to me that it's more
> parsimonious to "flip the ship" using thrusters and use the main drive
to
> change the movement vector. Even naval architects working with naval
> construction budgets have to save mass where possible, or else we
could just
> take Doc Smith to the logical limit and drive our planets around the
galaxy.
> ;-)
>
> The shiphandling requirements would be trivial, but would also give
officers
> something to grade junior officers on beyond spit and polish.
>
> Best,
> Ken
> --- On Thu, 12/11/08, Robert N Bryett <rbryett@gmail.com> wrote:
>
> From: Robert N Bryett <rbryett@gmail.com>
> Subject: Re: [GZG] A new vector movement system
> To: gzg-l@vermouth.csua.berkeley.edu
> Date: Thursday, December 11, 2008, 1:25 AM
>
>  From a realism point of view, I'm dubious about the
> "Retro-thruster"
> idea. It seems to be a refinement of the "Thruster Push" mechanic
> from FT2.5 vector, which I've never liked.
>
> We house-rule "thruster-pushes" out of the existing FT vector system,
>
> and only allow thrusters to pivot the ship. All changes to the
> overall trajectory of the ship require the use of the main engines.
> This house-rule reflects the fact that extremely large, powerful and
> heavy engines would be required to achieve significant accelerations
> to spaceships massing hundreds or thousands of tonnes with any
> reasonably foreseeable technology. The standard FT vector rules have
> the ships' manoeuvring thrusters deliver half the acceleration as the
> main engines, which seems improbable.
>
> The proposed rules at least restricts the thruster-push to operating
> as "retro-rockets". This is good. However, it still implies a pretty
>
> huge engine in the nose of the ship, capable of delivering half the
> thrust of the main engine. A T6 frigate for example would have a T3
> retro-engine for example. That sounds as if we should apply the
> "blind-sector" rule (assuming we're playing it) to the nose of
> the
> ship as well as the tail.
>
> A second, half-size, retro-engine would be wasted mass for some
> ships. A fast courier for example would probably be better off
> ditching it to achieve better acceleration from its main engine.
> IMHO, it's a bit dubious to just handwave it with no mass allowance
> in the design system. By the way, given that the retro-engine thrust
> is half main-engine thrust rounded down, how would you handle a T1
> battle-station?
>
> In the above remarks, I'm assuming that we're talking about
> spaceships propelled by reaction engines. If you have in mind some
> exotic reactionless drive (voodoo priests sacrificing chickens in the
> engine room for example), all realism bets are off...
>
> Best regards, Robert Bryett
>
> On 10/12/2008, at 22:11 , Hugh Fisher wrote:
>
>> I'm trying to design a new set of vector movement rules for Full
>> Thrust that increase the realism without too much extra hassle.
>
>
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Retro-thrusters that would work with some tweaking:

Main thrust is produced by reaction drives with a balanced ring of
thrusters with some freedom of movement, at the extreme rear of the
vessel.  One of the mobility restrictions is the nozzles can be
pointed no further than 120 degrees from dead astern, to prevent
thrust efflux from impinging on the hull.  The angular limit was a
compromise between safety, providing the maximum feasible
retro-thrust, and ship handling characteristics.  A long, spindly ship
could rotate the nozzles even further, but would be hard to pivot and
harder to protect against incoming weapons fire.  Even at the small
forward angle of 30 degrees ahead of the beam, the main engines,
running at full, would be able to apply a reverse thrust that is 50% (
cosine 60 degrees) of the forward thrust.  Other purposes of the
thruster mobility are rebalancing the thrust ring following damage,
high-rate pivotting, and adjustments of the hyperspace insertion
vector during acceleration to insertion velocity.

Game effects:  No thruster pushes.  Pivotting takes away thrust
available to change velocity.  Each point of retrothrust costs double
against total thrust points.

Sigh-- If my ability to write a story was even the equal of my ability
to spew technobabble, I would write more of them.

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