Re: Summarry of the momentum wars and idea.

[KellySt@aol.com]

>> Besides not treating momentum as a vector quantity, people are
>> making the mistake of thinking that lateral loading of the sail
>> assembly is a magical sink for momentum or energy.  The error is
>> in thinking that stress on a static structure absorbs energy or
>> momentum continuously over time.  If the sail does not move
>> relative to the ship, then it cannot absorb or dissipate momentum
>> separately from the ship.  It cannot absorb momentum if it does
>> not move, because momentum means motion.  ----


(??!)  <sigh>
Thats like the old argument that if a tractor is pushing against a wall its
doing no work, since the wall isn't accelerated.  The sail is getting a
thrust that is perpendicular to the surface of reflection.  If you want to
describe the portion of the thrust that isn't accelerating the ship as
invalid, enjoy.  But when you start to mutter things like:

>> ---as long as the sail does not fall apart or the support 
>> members do not break, no more energy is dissipated into 
>> loading of the sail structure.

We have a problem.  

A considerable amount of energy will be continuously loaded and (hopefully)
disapated by the sail cross webbing.  If we don't consider it, and make sure
the structure can disapate it, the cross cables will melt under the energy
they have to disapate under this lateral thrust load.

One very consistent problem in LIT over the last year has been a very limited
interest in the engineering realities of a situation, and to much fondness
for endless equation wars.

Kelly