Re: FT Taskforce and Fleet Actions

*blink*

I'm not quite sure I follow your view of physics...

>> I'm not sure I agree with this radiant energy inefficient drive /
>> only way to drive a machine is to light stuff on fire crud.
>
>     Not quite correct. What I'm saying is that I'm assuming a 
>reaction drive (ie a drive that operates in accordance with Newton's 
>3rd law of action / reaction -- in order to accelerate forward, you 
>HAVE to toss something else back). Any other drive violates 
>conservation of momentum, conservation of angular momentum, and 
>conservation of energy. I prefer not to introduce that unless I have 
>to.

1.  Why assume a reaction drive?  You have alien species (I've seen zero
exclusion and lots of all encompassing statements here) that use
"grav-drives."	While I don't recall fluff ever mentioning one way or
another, its a dead bet they aren't talking about reaction drives... 
Not
if a ship can change course without changing facing or using a duct
porting
or multi-directional porting.  

2.  No, other drives, that are not reaction drives (in the classic
sense,
specifically the one you're using, "heating of a reaction mass and
expelling it out opposite to the direction you want to go) don't violate
physics.  Ion drives (no real appriecable heat, "coherent" and single
directional exhaust), thier cousin the Laser drive (Man-Kzin wars, first
book, IIRC first story, is a wonderful example, as well as a really
solid
read), pulsed fusion drives (long one to explain, but coupled with
charged
particle fuel and magnetic "shielding" can be finely tuned such that all
expulsion is coherently directed, and given the D-He^3 reaction all by
products have zero residual radioactivity... theoretically.  Check out
Project Orion, IIRC), then there's the grail of drives, the antimatter
drive:	The end result are gamma rays, but during the process, the
creation
and vector the rays will have can be controlled such that all radiation
can
be coherently focused into one strait line vector (no "backlash," and
unless you're directly in the line of these rays, no detection).  This
is
also been termed the photon drive (not for "light" but the real
definition,
discreet packets of energy).  I'll discuss the vacuum energy drive
later.



>
>> While I'll admit, solar sails aren't as useful out of system, or in
>> bound, they are an example of a difference.
>
>     They're also VERY easy to detect. How does a solar sail work? By 
>reflecting sunlight. That means it's a) as big as you can make it, 
>and b) as reflective as you can make it. This means that it's VERY 
>easy to detect (as much so as a high-thrust reaction drive? maybe 
>not, but still dead easy for any nation that can build telescopes 
>with today's technology).
>

1.  They do not just use light.  They use the solar wind which is
radiation, yes, but particles as well.	

2.  Given a proper "deflection" angle such that the angle of reflection
is
not directed at the sensor, you won't see it.  Practical experiment. 
Take
a mirror, and a flashlight in a darkened room (recommend some
"navigational" light be used to avoid harm).  Place the mirror at arms
length (in hand) pointed directly back at your eyes.  Take the flash
light,
point it at the mirror, such that it is directly at or below eye level
but
does not impede your sight.  Turn flash light on.  Now, after you've
blinded yourself, twist the mirror in any direction.  Note how the light
no
longer stings your eyes.  Not how just a slight tilt is all that is
needed.
 True, a slightly tilted solar sail will not let you travel directly
towards an object if you keep the sail angle constant.	It's up to the
reader to go learn basic sailing, specifically the word Tacking. [sp?]

As to your points A and B.  A.	The size affects the acceleration.  If
you
don't mind smaller acceleration, you can use a smaller sail.  B.  See
point
2.  Further, reflection of light is NOT reflection of particles, or
higher
radiation.  Either of which is preferable to light.  Higher energy
radiation imparts more speed per area of sail.	Particles provide higher
mass, thus more potential energy (yes it's kinetic in a manner, but it
can
also be argued, relative, that it is moving at slower speeds).	

>> However, assuming a fission/fusion drive (take your pick, either are
>> likely to be dirty) and a ship headed IN bound, with the right
>> shielding (Absolutely necessary to some extent just to protect the
>> crew) why would there be _any_ emmisions heading towards the
>> system?  Last I checked EM radiation doesn't bend around corners
>> without help or special very narrow appatures (and I would not
>> qualify an SDN's main engine cone to be a narrow appature).
>
>     Because the drive plume itself emits EM radiation. A drive is 
>efficient in direct proportion to the temperature of the reaction 
>mass emmitted. This means that a high-temperature exhaust mass allows 
>you to go farther for the same fuel. For high-thrust you want to 
>reduce the temperature somewhat from the optimum, but you still want 
>a VERY hot reaction mass to allow you to get up to any reasonable 
>speed without needing far too much fuel.

The drive plume only emits radiation if, and only if, it has the energy
to
do so.	There are other factors, all of which can be reduced to a level
underneath the cosmic static, such that they are undetectable.	

Why this would be done-
Inefficiency.  Any energy NOT used to propel the craft in the direction
it
wants, is wasted.  Heat, light, etc, are all _by-products_, undesirable
at
that, of a burning reaction engine.  Idly, the only energy you want
expelled is the kinetic force applied to allow you to thrust.  Thus, if
a
plume is hot (radiation or heat), it's inefficent.  Now, there are
reasons
why you may accept this inefficency (hot implies more energy, thus more
thrust), true, but that doesn't mean in 10 years, much less hundreds,
that
we won't have solved this inefficiency.  Specifically, there are
theoretical models already being looked at that do solve various parts
of
this inefficiency.

To disabuse you of a false notion, heated/burning reaction engines are
the
_least_ efficient model of engine we know of.  They just happen to be
easiest/cheapest to use currently.

>     This means that your drive plume is also expanding after it 
>leaves your ship (at a velocity roughly proportional to its 
>temperature). This means that the drive plume will be emmitting 
>strongly (for any realistic high-thrust reaction drive, the 
>emmissions will be up in the x-ray regions probably) and those 
>emmissions will be coming from a plume that's probably several light-
>seconds in length (definitely in the tens of thousands of kilometers) 
>and at least a few hundred km in diameter. If your ship will occlude 
>THAT, the defenders are screwed whether they detect it or not.

Expansion does NOT equal emmision.  As I pointed out early, a compressed
gas system (assuming a non heated non irradiated gas) is the counter to
your declaritive.

I never said the ship would occuled the plume, only the reaction that
causes the plume.

>     Also, of course, you have to slow down eventually. At the half 
>way point, actually. Once you do, your drive plume is pointing right 
>at the place you're heading for. Even easier to detect.

Point well taken.  But not necessarily true for all values of "engine"
or
drive plume.  Again, a compressed gas is the counter example.  (I know,
I
over use this one, but it fits well, is a simple mechanic using simple
physics, and is doable _now_, not just theoretical)

>     I hate to bring in another list, but the rough consensus on 
>sfconsim-l (backed up by an astronomer, also the person who wrote 
>the "definitive sensor rules" for Traveller's FFS2(?), Bruce 
>Macintosh), is that a high-thrust, high-efficiency reaction drive 
>would be naked-eye visible out probably to the asteroid belt (even 
>with the ship in the way) and detectable by telescope significantly 
>beyond Pluto's orbit (for reference: today's telescopes would allow 
>us to detect the drive plume from the Space Shuttle's main engines as 
>far out as Pluto, and its manuvering thrusters as far out as the 
>asteroid belt).
>

If you hate to do it, then don't.  Specifically, I'm not on the list,
and
so I have no reason to beleive anything posted of it or about it.  I've
not
read or had the chance to "check-out" the so called astronomer to verify
that the person is who they say they are, and really does know what they
are speaking of.  And given the nature of the net, this is a
necessity...
To many people pose as something they are not out there.

Next...  An astronomer is NOT a rocket scientist.  (sorry, had to be
said)
And someone who writes Sci-Fi is no more likely an expert on science
(much
less a particular branch) than the next joe who walks by me.

A high-efficiency drive of TODAY may be, but of tomorrow?  I'll again
point
out the by-products of light and how inefficient that is.

>> How about magnetic shielding that already goes on?  Shielding that
>> contains plasma's?  Ones that can theoretically hold point
>>-anomalies (not sure that's the proper vocabulary for a tiny black
>> hole)?
>
>     I'm not sure what you mean by this.
>

Magnetic shielding (used today) can contain and control a plasma, it can
be
used to simply hold, or to duct/vent it in a desired direction.  It can
completely shield the emmisions of the plasma.	Any and all emmissions.  

>> However, if you insist that it does, why not use compressed gas?
>> Gaussian marble throwing?  Both throw stuff, but neither emits
>> anything really detectable beyond a very small bit of space...
>
>     Compressed gas: at what temperature? If it's at a high 
>temperature, it'll BE a drive plume (thus detectable). If at low 
>temperature, then you will need incredible tankage volumes to have 
>ANY delta v (required by laws of physics, not technological 
>assumptions, unless you can create this 'compressed gas' from a 
>vacuum).

Gas != plasma.	2 completely different states of matter, thank you.

You missed one of the fundamentals of gasses...  PRESSURE.  (Thus the
term
compressed)

Given tough enough containers, amazing preasures can be had.  Given that
(in another thread) we've spoken about the hulls of these craft
withstanding nukes, is it to hard to imagine a container that can
withstand
amazing pressures by todays standards?

*shrug*  There's a bunch of math and basic physics here, that I really
don't want to get into, but it can be done.

A compressor only requires energy to run.  Hydrogen is loosly abundant
in
space.	(space is not empty)  An excercise for the reader: lookup
Bussard
Ram-Scoop engine.

On a separate path, but relevant in reply to your above paragraph:
The vacuum energy drive:
Without going into the quantum physics of it, let me state this, and let
the reader do the research (and headache):
Quantum theory and General Relativity both show that a vacuum has a very
large positive value of energy per unit volume.
Richard Feynman estimated two billion tons per cubic centimeter.  Based
on
the Casimir Effect, Richard showed that a small amount of energy could
be
produced from vacuum energy.  Others, such as Harold Puthoff, have
theorized (but not proven) that much larger amounts can be produced. 
Check
out "All the Colors of the Vacuum" by Charles Sheffield, or Arthur
Clarke's
"The Songs of Distant Earth" for sci-fi examples.  (By use of sci-fi,
I'm
talking hard sci, with fi built around facts, not fluff, which is hard
fi,
with pseudo sci)

>     Gaussian marbles are even less efficient. To get even a 
>100km/sec velocity out of them (with a mass driver tube of a mere 1km 
>in length), with 99.999% efficient mass drivers, they'll emerge from 
>the barrel with a temperature in the thousands of degrees (inductive 
>heating). The strain on your railgun will also be considerable. And 
>the thrust produced not all that much. I can do the math on this one, 
>if you'd like (the others are a bit advanced to try without my 
>reference books).

Efficient how?	In acceleration?  true.  In by-products?  Depends.
Inductive heating can be controlled, thus allowing lower force
acceleration.  But it's still viable.

You're welcome to do the math.	I've seen it.  However, I'd like to
point
out that current tests have shown a effective jet velocity (EJV) of up
to 8
km/sec.  This is almost double what is currently used to day for
chemical
burning, liquid oxygen/liquid hydrogen (LOX), which has an EJV of
slightly
more than 4 km/sec.

That's without superconductors.

>
>> Basically, I'm trying to understand how a species who invents
>> hyperdrive, gravity control, "shields," can't think of a way to
>> hide thier emissions.  Specifically, a species that's shown just
>> how creative it can be when waging war on itself...	One that
>> already knows the military value of being sneaky.
>
>     The big reason is these pesky little things called the laws of 
>physics. Unfortunately, they place limits on how well you can do 
>things.

They're wonderful things.  And if you want to talk about them, I'm happy
to.  Specifically in regards to space flight, in relation to today, near
future, or far future.	However, I do request that you bone up on said
physics, especially recent practical/applied physics in regards to the
subject.

>     The other big reason is that space is an INCREDIBLY sensor-
>friendly environment. If the detectors and the countermeasures are at 
>the same technology level, or even close, you can't hide. Sensor 
>ranges will vastly exceed weapons ranges unless you assume an 
>incredible advance in stealth with no advance in sensors (and 
>probably break a few laws of physics while you're at it).

This is a totally different arguement, to which I STRONGLY disagree.

Space is very very very very sensor unfriendly.  Though size alone, the
problems are astronomical... (Had to use the pun!)  

As a 2 part excercise for the reader...  Part A: Given X distance from
target Y, what size linear/circular wall/plate is necessary to block
(occlude?  Damn, I need to invest in dictionaries instead of physics
books)
view of any sort of object Z (at point X) by target Y, given that the
plate
is impenatrable to view.
Hint: easy answer, assuming no angle, is: diameter of object Z.
Part B: given a "plume" that stretches length A behind object Z, what,
if
any, changes are necessary to Part A's answer.
Hint: easy answer, to follow Part A: diameter equal to the greatest
diamter
of plume. 
(for ease of math, question was stated where answers in 2D or 3D will be
accepted)

Anyway, enough for tonight.  My question still stands.