When is a Dreadnought ... [LONG]

After I commented that FASA's _Renegade Legion_ "is perhaps the only
game I have run across that is consistant in its explanation as to why both
fighters and battleships are used in large numbers," Aaron Teske asked for
more
explanation.  The following is from the essay presented in _Prefect_.

Let's start with some of the salient features of the _Renegade Legion_
universe. Specifically: * a ship moving under FTL drive can only move in
straight lines; * ships moving under FTL drive cast a spherical disruption
pattern with a
radius measured in light-years;
* the faster a ship moves, the larger its disruption pattern; * the greater
the mass of a ship, the larger its disruption pattern; * the disruption
pattern can be detected by special detection stations; * the larger a ship's
disruption pattern, the farther away it can be detected; * ships have a
limited endurance of air, food and other consumables; * FTL communications
exist, and allow system commanders to call in reinforcements; * the FTL
communication arrays are HUGE, far too large (and fragile) to be carried on a
ship.

As a result of these factors, a capital ship which wishes to make it to a
target system before its consumables run out is forced to approach at a high
speed. Between the ship's high mass and high speed, it casts a very large
disruption pattern. In turn, this large disruption pattern assures that the
ship will be spotted and its course plotted in sufficient time for the system
commander to request and recieve reinforcements from the theater reserve

maintained for exactly this purpose. Since the size of the pattern is
determined by the mass and speed of the incoming ship(s), and the speed can be
determined if the pattern is detected by multiple detection stations, the
defenders usually have a a pretty good idea of exactly what is coming in,
whereas the attacker is jumping in blind.

In other words, capital ships are for pitched battles to take systems, not
hit-and-run raids or recon.  Those jobs are left for fighters.

Fighters, on the other hand, can be carried to a system on relatively small
ships which, because of the decreased mass of the ship, have a much smaller
disruption pattern. In many instances, they can approach at a slower speed as
well, further decreasing the size of the disruption pattern [The effect of
mass and speed on the disruption pattern is such that sometimes you need to
increase speed to cut down on the warning time that they would have anyway
based on the mass of your ship; with smaller craft this isn't necessary. It's
confusing without the examples and illustrations presented in the essay;

you'll have top trust me on it (or read the essay).]

If done right, even if the system commander detects the incoming ship, he will
have insufficient time to receive reserves from his theater commander, and
will thus be forced to deal with the threat with the forces on hand. These
forces are usually smaller ships (capital ships are too precious to waste
garrisoning systems -- they are needed for the theater reserve), and
while the system commander may have more ships, they are often spread out to
cover

several possible targets. Thus, while the attacking force may be smaller than
the total defending force, the attackers may be able to achieve local
superiority. For this reason, incoming attack forces often try to obscure
their actual target until they absolutely must commit; oftentimes, the
defender won't know the actual target until some of the defending ships are
already out of interception range. The attackers conduct their strike (or
recon mission) and move towards the outer system, where their carrier (which
may be very small, i.e., corvette-sized) is waiting, having itself made
a
high-speed pass through undefended portions of the system.

The essay discusses the above in terms of a ship's "maneuver sphere", which
can be defined as a sphere encompassing all the possible final locations of a
ship after a given amount of time. The size of this sphere is determined by
the ship's maximum thrust, with the location of the sphere centered on the end
of the ship's current vector arrow. Note that since we are talking about the
volume of a sphere, the size of the sphere increases as a cube of the thrust,
i.e., a ship with a thrust of 1 has a maneuver sphere of (R^3 x pi), or in
this case, 1pi; a ship with a thrust of 4, on the other hand, has a maneuver
sphere of 64pi. In order for the defenders to guarantee an interception, their
manuever sphgere must totally encompass the attacker's maneuver shere.

Fighters have three primary roles: reconaissance raids, stopping reconaissance
raids, and hit-and-run strikes.  The first two put a premium on fighters
with higher thrust ratings, which are generally smaller. The last mission
usually calls for heavier fighters.

Thus, both capital ships and fighters have their own unique missions. Neither
is particular suited for the missions of the other, although in a general
system-wide melee involving capital ships, there is usually plenty of
work for the fighters to do as well.

Overall, the essay hangs together very well, with few inconsistencies; it
explains both the strategic and tactical implications of the technology, and
hence the significant (but different) roles of both fighters and capital

ships.  It by-and-large avoids the problems of other science fiction
games where incompatible tactical models of warfare (e.g.,
offensive-battleship-
dominance vs. offensive-carrier-strike-dominance) are forced into a
common
system, such as occurred in _Traveller_, where the Imperium had huge
numbers of fighters and fighter carriers, but fighters were fairly ineffectual
weapons compared to battleships.

BTW, now is a good time to put in a plug for one of my favorite books on this
subject, _Fleet Tactics_ by Wayne Hughes, published by the US Naval
Insitute Press. While the book is rooted firmly in the Real World(tm), it does
look at some topics which are relevant to a science fictional setting, such as
how sensors affect tactics, and when you should divide your carriers and when
you shouldn't. I'm rereading it now; it's very good.