Re: [FT] DDs and DHs inspired by WW2 types

----- Original Message -----
From: <stiltman@teleport.com>
To: <gzg-l@CSUA.Berkeley.EDU>
Sent: Tuesday, August 29, 2000 4:52 PM
Subject: Re: [FT] DDs and DHs inspired by WW2 types

> > On Tue, 29 August 2000, devans@uneb.edu wrote:
> > > I'm
> > > just not sure that at some point, long and somewhat pointy hulls
for
high
> > > thrust vehicles might not still be the most effective, perhaps to
keep
the
> > > weight centered on the thrust line.
>
> > The problem with a pointy ship is that it would take more force to
spin
it
> >around and to stop it spinning than if it was round. The old
conservation
of
> >angular momentum thing comes into play. A long pointy ship will
simply
NOT
> >spin as quickly as a round ship.
>
> Why not?  With nothing resisting it, a long pointy ship could put its
thrusters
> further out from the center of gravity without having to give up that
much
in
> terms of total mass to spin.	I'd think that, if anything, a long
pointy
ship
> would spin faster than a round one on account of simple leverage of
thrust.
>

For a given amount of thrust, the long, pointy vessel will not spin as
quickly about its center of mass as a more compact vessel.  While the
long
vessel's thrusters would be working with a longer moment-arm (I'm
assuming
that's what you meant when refering to "leverage"), the angular momentum
that it would have to overcome to get the ship spinning should be
greater as
well.  Furthermore, the vesse's structural members would have to have
the
additional strength to handle the spinning as well.

The way I see it, the globe ships would be better for maneuvering, but
the
additional structural support they would need since so much mass would
be
off-center from the thrust-line of the engines would make them a little
less
efficient for straight-line acceleration.  A lightly built pointy vessel
would be more efficient (in terms of mass needed for structural support)
to
handle straith-line acceleration, but would be less maneuverable due to
structural weakness for forces not in the "keel's" direction.  Of
course,
you could build a more heavily built pointy one, but that would then no
longer have the advantages of the pointy design (lightly built but still
able to handle high acceleration) and you'd really end up with the worst
of
both worlds.

It has been a loooooong time since I had my Dynamics of Rigid Bodies and
Deformables classes, but the above sounds right.

> On the other hand, I'm no great hand at physics, so it could be that
I've
> simply got a bad case of cranio-rectal inversion here, too...
> --
> =-=-=-=-=-=-=-=
>  The Stilt Man		stiltman@teleport.com
>    http://www.teleport.com/~stiltman/stiltman.html
>    < We are Microsoft Borg '98.  Lower your expectations and	  >
>    < surrender your money.  Antitrust law is irrelevant.	  >
>    < Competition is irrelevant.  We will add your financial and >
>    < technological distinctiveness to our own.  Your software   >
>    < will adapt to service ours.  Resistance is futile.	  >
>