re: Planetary Invasions

	I am forwarding the following for Steve Higginbotham....


Subject : Planetary invasions, defenses, etc.

In order for any discussion of planetary invasion to be meaningful, the extent
of the defense forces should be determined.  Using Trin ( one of those lovely
little TL15 Hi Pop worlds so beloved by the Imperium ) as an example, (and, as
usual, using Striker Rule 73, and listings of the Spinward Marches as
references) it is seen that Trin's planetary defense forces (read: Army)
should have a value of MCr 25,872,000.
Given that, for whatever arbitrary reason, we use 10% of that amount for deep
meson sites, and the associated sensors, we come up with :

           300 Factor-T meson guns,
           power plants for same (distributed in small plants throughout the
                        planetary crust, heavily ECM'ed to prevent detection)
           1,362,727 TL14 passive EMS sensor arrays (and power plants for
                        same) scattered about the planet.

By the by, don't forget the near space defense spacecraft, infantry, cavalry,
armor, and other stuff.  They'll be in there, making an invasion unpleasant
and unproductive, too.

First, let's look at the sensor platforms and meson sites.  Trin is
Terra-sized, and so has those sensor platforms scattered all over the planet
about 22km apart over the entire surface.  Each of them can spot an object
10,000 meters above the planetary surface to a range of 350+ Km.  Therefore,
each point of the planet's surface is watched over by about 1000 sensor
arrays.  As long as the enemy knocks out less than 99.9% of the sensor net,
reasonably complete coverage can be maintained over the surface.  Any ship
coming within 50,000 Km of the planet can be removed by the combined fire of
300 spinal mount weapons.  Assuming the ships are approaching orbit at 4Gs,
they will be within that range for 26 minutes (plus or minus).  Unless a WHOLE
BUNCH of EXPENDABLE ships are sent at one time, the likely result is total
loss of all ships in that range bracket.
Note also that if the attacker has 12,000 warships, and if each of them
survives to destroy 100 sensor platforms, then the sensor system will be
reduced by 88%, and will still function pretty much as well as at start.

Assume 30% of the Army budget buys guys in battledress with FGMP-15s.  Then
you have an army of (about) 57,000,000 guys with FGMPs.  Using the Rebellion
Sourcebook, you get about 25,000,000 guys like that.  VERY difficult to remove
entirely, or even significantly.  Note that the FGMP has a range of 5000
meters, more or less.  That can keep those attackers nervous, at least, as
they approach ground.

Assume another 30% in AFVs (imperial marine standard, from Striker), we get
about 4,000,000 AFVs...  Note that the main gun on an imperial marine grav APC
can punch holes (small ones, at least) in all but the heaviest battleship.
They can scrape guns off the surface of even those battleships.  Put those
things up to about 15,000 meters, and the effective range of the weapons
become 1054 Km.  Quite adequate for denying orbital space to an attacking
fleet.  Keep them on the ground, and range is 105 Km, which is more than
enough to deny use of airspace near a battlefield.


Then, there is the system defense fleet.  About 5000 "flying Knives" (stats to
follow at the end of this ramble).  Any one is a match for anything less than
a battleship/battlerider.  Any six can butcher the best battleship in the
Imperium.


now, discussion.

Assuming the classic 3-to-1 odds for a successful assault, the Imperium would
require the resources of seven similar worlds to successfully assault Trin
(note that most of a world's resources are not interstellar capable).  Note
that the spinward Marches includes THREE other worlds similar to Trin.  The
closest (Mora and Glisten) are twelve parsecs away.  Four jumps at Imperial
standard J4 (note that the route must be slightly indirect due to stellar
placement).  That is a six week trip (five if you are lucky and fast).  The
trip from the USA to France in WWI was only three weeks long.  About the same
in WWII (excluding aircraft, which could transport only a small amount of the
needed war materials).

Admittedly, the Solomani Rim, for instance, has a great many such worlds
crowded together.  It also has worlds like Terra and Muan Gwi which make Trin
look like a deserted cross-roads at midnight.  Still the same problem, just
more ships, and equipment.



As to tactical (as opposed to logistic) concerns - the "dogfight" described in
an earlier post is wonderful, except that it ignores the possibility of
"stealth" ships for reconnaissance and some combat use.  Note that a such a
vehicle will be included after the "flying Knife".  It also assumes that all
ships follow the GDW pattern of massive offense, trivial defense.  A ship with
heavy defenses and light offenses can survive a lot longer, and cause that
phase of the conflict to last that much longer.  And the longer it takes, the
worse for the attacker.  Note that the defender doesn't really need to knock
out the attacking battlewagons.  it needs to knock out the transports and
landing vehicles.  Saves a lot of wear on the nerves when you can ignore all
the tough parts of the enemy fleet.

The "mop-up" phase is another amusing idea that depends on the defender
cooperating.  It assumes that the defender's sensor nets will be destroyed at
a higher rate than the attacker's.  Assuming the defender understands, this,
he can target the attacker's sensors specifically to delay the attacker.
Remember that anything that stretches the attack out will help that long
supply line to cause the attacker problems.

Then there is the "non-existant" guerrilla phase.  Anyone out there care to
guess the most effective weapon for a guerrilla on Trin???  Assuming that a
miracle happens and all the meson sites' sensors are destroyed, the army
destroyed, the world occupied...

Gauss rifle?
FGMP?
snub pistol?

no.  Try the telephone, instead.

Assume that the control computers for the deep-meson guns include a map of the
location of every phone on the planet.  Assume that a phone used to call is
automatically located by the meson gun control system.  Pick up a phone, dial
a number that links to the meson gun control system, tell them that a cruiser
is 12 Km south of you, hang up!  the control determines the position, aims the
guns, and obliterates the cruiser.
Make sure there are a few dozen million numbers that get into the meson gun
control system (there are ten billion possible numbers in the US phone system,
not to mention the overseas connections.  Plenty to spare).  Include a million
or so numbers that require no message - call the number, and the meson guns
obliterate everything within 1000 meters of the calling phone.  The caller
dies, and so do all the enemy troops and ships near him (a good trade if you
are into that sort of thing)


Note that if planetary invasions were easy, then the five frontier wars would
have included a lot more territory changing hands.


And have any of you noticed that during the last few months all the
assumptions about planetary invasions look like Desert Storm?  Last year they
all looked like D-Day.  Strange...
Has anyone ever tried to play one out, using TCS campaign rules, or other of
your choice.  Try it about six times.  After each trial, rework the attacker
and defender to incorporate lessons learned, or new ideas.  Then, you MIGHT
have an idea of how an invasion works in MT.



And for those of you having a hard time setting up defenses for your TL10
worlds, how about the "treatymaker" (traveller model)? --

(designed using Striker laser design sequence)

   TL 10
   Type - beam
   Power input - 300,000 MW (same as type T meson gun)
   Fire control to taste
   Mount likewise
   Crew as needed (about 1 plus maintenance men)
   Mass - 19,800 Mg
   Volume - 19,800 Kl
   Price - MCr 1200 (slightly more than the T meson gun)
   Output - 75,000 MW
   Range - (effective) 150,000 Km, (long) 300,000 Km, (extreme) 1,500,000 Km
            NOTE - this range is through atmosphere.  In a vacuum, range is
                  1000 times listed.)
   Penetration - (effective) 155, (long) 147, (extreme) 137
   Hit Bonus - +2
   Signature - +18,750  (yes, it will be spotted when it fires)
   Number of Targets - 2 (per 30 second turn)

Notice that, while extreme, this weapon can punch a whole all the way through
a planetary crust, or destroy any moon nearby (it penetrates in excess of 50Km
of rock)

It can also blow a hole 450+ meters in diameter in your average battleship.
Since your average battleship is less than 1200 meters long, over 30% of the
ship would evaporate under that light.  Alas for that former Imperial
battleship.

Remarkable digression that, but I've always loved that as an example of an
EXTREMELY powerful weapon.  Consider it as a spinal mount sometime.  Makes a
nice change of pace from the meson guns.



I digressed too much.  The "flying Knife" and stealth ship will follow on
another post.


                                        Steve Higginbotham
                                         (still kibitzing)