Simple FIM guidelines

Date: Mon, 4 Sep 1995 19:31:59 -0600 (MDT)
From: merrick@Rt66.com (Merrick Burkhardt)
Subject: Simple FIM guidelines


Some notes on using Fully Independent Missiles (FIMs):
 
FIMs are mentioned in BL, but we never get to see one.  The problem with
using them is how to have them behave like missiles, and not like they
are being controlled by a person.  The concentration on SIMs and
controlled missiles in BL is because the PC controlling it uses
his/her/its skill to avoid being spoofed by the target (a way to get the
players into it, IMHO).
 
Here are some guidelines for playing FIMs in BL using stuff you already
have. I need to design some FIMs from scratch, but I hate the missile
design rules :-)
 
What do they look/act like?
---------------------------
Fully independent missiles can be true "fire and forget" missiles or
they may require guidance in the form of designating the target with a
ship's own active sensors.  Regardless, at some point they achieve a
sensor lock on a target, then attempt to intercept it.  FIMs may have
sensor locks handed-off to them before or after they are launched
(depending on how they are designed). 
 
FIMs are active, passive, or, rarely, both.  Active FIMs are frequently
programmed to drift a short period of time before "pinging" their
targets.  Actives are also bigger and more expensive than passives.
Passive FIMs all home on active sensor radiation as well as the target's
EMS signature.  
 
Design:
-------
FIMs are designed as normal space missiles (what a pain :-), but they
must have some kind of a sensor installed.  A small passive sensor works
well, and in fact, many FIMs home on reflected active signals from the
firing ship since they can use the shortrange of the firing shipUs
active sensor (not double the range in this case, since their sensor
path length is not half).  
 
Sample types:
-------------
1.  PEMS FIM for ARM (anti-radiation missile) use.  Use the smallest
PEMS possible.  If it is used as an ARM then it will home on the active
signal of the target and calculate the difficulty level based on twice
the target active sensor's short range.  Once relatively close it can
home on the passive signature of the target even if it isn't active (in
this case it will use the seeker head's own passive short range). 
 
	*  Design your own, or just use the TL12 SIM in FFS.  The cost for a KKM
	version is 0.8MCr.
 
 
2.  In designated (semi-active) mode, an AEMS, Radar, or Ladar lock on
the target by the firing (or sometimes another ship or drone) is
detected by the missile, and it homes on that signal.  The Missile is
designed with a short range PEMS (or HRT) and when it attempts Lock-On
it uses the SR of the active "painting" sensor, but the range will be
the range to the designating ship, or missile---whichever is longer.  
 
	*  Design your own, or use the TL12 SIM in FFS.  The cost for a KKM
	version is 0.8MCr.
 
3.  Active Homing Missile.  This missile type has a AEMS  or RADAR
sensor.  It has a sensor lock passed off to it by the firing ship, then
goes active and homes on its target.  They are frequently used as SIMs
and controlled until near their targets so that passive locks may be
used until the point they have to go active (in an attempt to avoid
countermeasures, and to conserve fuel).  These will have to be designed
from scratch as active sensors require power and volume such that they
most likely won't be the standard 1/2ton missile size (think of the
Pheonix as an example).  These are most likely Det-Laser missiles since
their size and expense justifies improving the chance of a hit at all
costs.
 
	*  Design your own, or use the TL12 active passive drone as a
	model--you'll have to call this a det-laser or it'll never hit unless
	the target does nothing to stop it.  
 
I included notes for KKM versions in case you use them.  Remember that
KKMs will need the target's evasion gturns left over (+evasion success
DM) after the hex intercept to even have a chance of hitting, so an 8G8
missile will be easily dodged by most any military ship.
 
 
A homing missile would operate under the following rules:
---------------------------------------------------------
First premise:  Homing missiles *must* have a Lock-On to home in on a
target.
 
Second premise:  Homing missiles try to cross the present position of
their target using whatever fuel required (intercept).  (I use BR/Maydy
style movement here, BTW.  Ditch the heading wheel (except for facing)).
 
If they cannot, with a max burn, do this *this turn*, they will use the
minimum fuel required to put their future position (for the following
turn) as close to the future position of the target as possible (in any 
ambiguous situation try to put the future position of the missile *ahead* of 
the target's future position (it'd be flying a lead pursuit)).  
 
The "minimum fuel required" is further limited by the missiles
programming.  Missiles may be programmed to burn no more than say 1
gturn in the event that it cannot intercept *that turn*.  I use this all
the time to avoid problems.  A missile is normally noted, say, 12G12, in
the programmed case above it would be written 12G12 1D6 (discretionary).
The trailing 6 is the maximum number of 1gturn burns the missile can
make before it will just drift---leaving it with 6 gturns to kill a
target that drifts too close.
 
That's it for driving the missiles :-)
 
Getting a Lock and firing:
--------------------------
FIMs must have a Lock to home on their targets.  As a result, they are
usually launched with a handed off lock.  In the case of SIMs (any FIM
with commo installed is a SIM) the lock may be handed off at some point
on the missiles path after launch, or even change.  Unlike the SIM rules which 
use the crew or PCs skill as an asset, FIMs have their own assets.
 
FIMs have an Asset=(TL - 5).
 
All tasks attempted by the FIM (or SIM operating as a FIM) are done at
this asset.
 
This will make them easier to "spoof" than controlled missiles, a good
thing, I think.  To deal with this assume that if a Lock-On attempt by a
FIM fails, it may try again next turn (or even a different target this
turn).  If the Lock-On task is a Catastrophic Failure then the missile's
guidance system is totally spoofed and the missile goes ballistic (or
chases the decoy if one was used) and is useless.

-Merrick