Alternate Starship Combat Rules HD # 142.02
Date: 15-Nov-90
Roger Myhre
Odvar Solbergsvei 136
0973 Oslo 9, Norway
ABSTRACT
Variant starship combat rules. Fighters have more chance to knock out a
battleship, but only if they are in large formations. Ships or fighters
with armor-120 can now be damaged by weapons smaller than factor-T.
This is a variant to the existing starship combat rules. I'll discuss
each segment of the combat rules separately with tables. These rules provide
fighters more chance to knock out a battleship, but only if they operate in
large formations.
A fighter with factor-3 pulse lasers firing at a battleship with armor
of factor 100+ can just give up. There ins't any chance this puny craft can
make a dent in the hull. Even large formations don't have a chance.
The rules work both ways. Nothing prevents one from creating a fighter
with armor-120 except for the cost. The fighter can still have a speed of 6G
and possibly some agility depending on armament. Such an armored fighter will
be nearly indestructible. A weapon of factor T+ is required to get a critical
hit against an armor factor of 120.
To Hit. The to hit task is not changed - it works good enough as it is.
Optional: Those who hate to roll each battery may roll once for all
bearing batteries. Subtract the difficulty value to hit from the roll, and
multiply the remainder by 10%. This indicates how many batteries hit.
Example: The to hit task is Difficult, 11+. The attacker rolls 15.
(15-11) * 10% = 40% of the batteries hit.
When applying the 40% to the number of firing batteries, round up.
Penetration. The penetration task is not changed.
Optional: When using the optional to hit method discussed above, the
defender may combine the defensive batteries bearing. Find the ration of
offensive vs defensive batteries and consult the following table.
Off/Def
4:1 gives DM +3 Add the DMs given here to the attacker's
3:1 gives DM +2 task roll. Ratios which exceed 4:1 or 1:4
2:1 gives DM +1 are treated as 4:1 or 1:4 respectively.
1:1 gives DM 0
1:2 gives DM -1
1:3 gives DM -2
1:4 gives DM -3
Use the same procedure as in the to hit task to determine how many
weapons penetrated. This precedure can be used against screens, but the ratio
DM from the table above is not included.
2. Damage Point Computation
The component hit points computed during design evaluation are not used
in the current combat rules. This variant uses them.
First, we will compute the damage points each type of weapons does.
Turret mounted weapons do 10*UCP in damage. A bay weapon does 20*UCP in
damage. Spinal mounts do 100*UCP in damage.
Nuclear and anti-matter do four times the precalculated damage. Example:
a UCP-3 turret firing nuclear missiles does 120 points of damage ((3*10)*4).
Now we are going to compute how much beating each ship component before
the damage has an effect. The following examples use the Imperial Planet-class
Heavy Cruiser from Rebellion Sourcebook, using the corrected UCP available in
Clay Bush's HD 1703.
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IMPERIAL Planet Heavy Cruiser
CraftID: PLANET Heavy Cruiser, Type CA, TL15, MCr31,811(d)
Hull: 67 500/168 750, Disp=75,000, Config=2SL, Armor=50G
Unloaded= 752,149 tons. Loaded= 799,548 tons.
Power: 5 140/ 10 280, Fusion= 925,200 MW, Duration= 30/90.
Loco: 5 063/ 10 125. Manuever=2.
6 075/ 12 150. Jump=5.
Agility = 0.
Commo: RadioComm = system x3
LaserComm = system x10
MaserComm = system x3
Sensor: EMM, EMSjammer= FarOrbit x3, PassiveEMS = Interstellar x3
ActiveEMS = FarOrbit x3, NeutrinoDect = 10 kw x3
Densitometer = LowPen/250m x1, HighPen/1km x2.
ActObjScan = Routine, ActObjPin = Routine
PasObjScan = Routine, PasObjPin = Routine
PasEngScan = Simple, PasEngPin = Routine
OFF: MesonGun=J0x, PartAcc= x90, Missile=x 9 3, Blaser=xx7, Fusion=x04
Batt S 2 25 A 25 A
Dear S 2 19 8 19 8
DEF: DefDM= +8, NucDamper=9, Back-up OptNucDamper=1, MesonScrn=9
Repulsor=x90, Sandcaster = xx 7
Batt A 30
Bear 8 21
Controls: Computer Model/9fib x6, Panels= HoloLink x31,867
Special: LgHoloDisplay x28
Basic Env, basic LS, extended LS, grav plates, inertial comp.
Acomm: Crew 292 (75 x4), staterooms=292
(Bridge=16, Engrng=83, Gunnery=30, Flight=30,
Troops=75, Command=39, Steward=10, Medical=10)
FrozenWatch=164, LowBerths=164, EmerLow=233
Shuttle x3, Cutter x4, Air/Raft x4
Other: Fuel = 636,822 kliters, Cargo = 2 821 kliters.
Fuel scoops, Purification Plant (12 hour).
ObjSize = Large, EMLevel = Moderate.
Hull. To find out when the armor factor is reduced, divide the
inoperative value by the armor factor. The Planet has an inoperative hull
value of 67500 and an armor factor of 50. Each 1350 hits received reduce the
armor factor by one.
There is a snag in that craft with high armor values will drop faster
than craft with low armor value. To negate this we will reduce received with
1% per armor value above 40. Also, damage is increased with one point for each
armor value below 40.
Each time an interior hit is scored, apply half the hit damage to the
hull. If a shot penetrates armor, it will always give at least one damage
point to the hull.
Power plant. Divide the inoperative number by ten to determine how many
hits the power plant can take before before losing 10% of its output. With
5140 points, the Planet takes 514 hits before power output is reduced 10%.
For each 10% lost reduce the ship's agility by one.
When 50% of the power plant has been lost, the spinal mount is
inoperative. The ship captain chooses either to maneuver or to fire energy
weapons (not both) in a turn.
Manuever. Divide inoperative number by acceleration in G to determine
how many hits the maneuver plant can take before the maneuver G is reduced by
one. The 5063 hit points divided by 2G gives 2532 hits to reduce the rating by
one G. (The old system reduced acceleration by factors of one, two, or three.
With this system the maneuver plant will last longer.)
Jump. As maneuver.
Computer. I had trouble making damage plausible without being too
devastating. Weapons with a UCP of 1-4 give "Computer-1", UCP of 5-9 gives
"Computer-2", and UCP-A gives "Computer-3." On exceptional success reduce the
computer factor by an additional one. Radiation hits have no effect on fib
computers.
Sensors. As computer hits.
Weapons. As computer hits. If there is only one battery, reduce the
battery's UCP by the appropriate number.
Screens. As weapon hits.
Crew. One crew section is killed for each 100 damage points inflicted on
internal systems. A weapon which inflicts 80 damage points applies 40 to the
hull, and the remaining 40 kills one crew section. 120 points applied to crew
will kill two crew sections.
3. Applying Hits
Hull. For internal hits, apply 50% of the damage points to the hull. If
the weapon does 100 damage points, apply 50 to the hull.
Radiation hits. When a weapon which does radiation damage hits, apply
25% of the damage points to the radiation hit table. A factor-9 missile bay
firing nuclear missiles inflicts 720 damage points. If an internal hit is
scored, apply 360 points to the hull, 180 points to the radiation table, and
180 points to the internal explosions table.
Critical hits. Per the standard rules. When the armor factor is reduced.
Remember to reduce the hull inoperative number in the process.
4. Armor Penetration Procedure
Under the standard rules there is no hope that a low UCP weapon can
penetrate or do any kind of damage to a well-armored craft. In this variant
there is a slight chance that fighters and SDBs can dent the armor and
possibly scratch inside a battleship.
To penetrate armor:
Routine, Off=(weapon UCP/3), Def=((armor-40)/5), Confontration
Referee: Meson guns do not roll this task. If they oenetrate
configuration, they just pass through the armor and explode inside.
A natural 12 means automatic penetration of the armor. Drop fractions
when dividing weapon UCP and armor. Armor factors below 40 will give a DM in
the attcaker's favor.
5. Damage Table
Damage Table (2D)
Die Surface Interior Radiation
1 No Effect No effect No effect
2 Weapon Power plant Weapon
3 Fuel Sensor Weapon
4 Manuever Computer Crew
5 Weapon Power plant Computer
6 Manuever Crew Sensor
7 Weapon Screen Crew
8 Weapon Crew Computer
9 Fuel Sensor Weapon
10 Weapon Jump drive Weapon
11 Interior Fuel tank shatter Sensor
12 Interior Critical Crew
13 Critical Critical Critical
DMs:- 1 Weapon UCP 1-4
0 Weapon UCP 5-9
+1 Weapon UCP A+
- - 1 if black globe operating
+1 if nuclear, anti-matter, or spinal mount weapon
Spinal mounts: as per standard rules, spinal mounts get one additional roll
for each UCP factor above 9. Each roll inflicts UCP*100 damage points.
Black globes: A black globe absorbs a percentage of the damage value according
to its flicker rate. A globe on 40% flicker absorbs 40% of all damage
points before they take effect. Overload is by the standard rules.^L6. Exceptional Success
For each point achieved above the required difficulty, add 10% to the
damage points inflicted by the weapon.
Attacker rolls 13 (including DMs) for a weapon which inflicts 100 damage
points. Increase the damage points by 20% to 120 before black globe and damage
takes effect.
[CRB: I think this applies to the to hit task. I disagree with
increasing damage for each point above the difficulty throw needed. A miss
inflicts no damage. Why should most hits inflict extra damage?]
7. Optional Sensor Rules
Make all sensor tasks one level less difficult if the target is in an
adjacent hex.
Make active sensor tasks one level more difficult:
o if the target is within a gas giant,
o when attempted through a hex where a nuclear missile has exploded.
o if target uses jamming.
Neutrino detection:
o If target's EMLevel is faint, give a -1 DM to neutrino scans.
o If target's EMLevel is strong, give a +1 DM to neutrino scans.
Densitometer detection:
o If target is small, give a -1 DM to densitometer scans.
o If target is large, give a +1 DM to densitometer scans.
o Increase detection task difficulty by one level if detection is
attempted through a planet or moon with size 5+ or through a planetoid belt.
*********************
ADDENDUM, 29 July, 1990
My second draft on starship combat rules is near complete. There are
some rules I would like to get a second opinion on.
Damage record. I have made a damage record form: boxes are crossed off
when damage is taken. MegaTraveller starships tend to have large damage
numbers, so I had to make a new system for hit points for each starship
component. Two reasons: I wouldn't get space for 500,000+ boxes on one A4
page, and lower numbers are easier to calculate.
Time and distance. I plan to scale down the time and distance scale in
starship combat from 20 minutes/25000km to 4 minutes/5000km. For longer combat
turns, more damage must be given for each hit. With the reduced damage my
system does, I feel it is right to reduce the time and distance scale.
This would make some planet's occupy two hexes. Hexes adjacent to a
planet are atmosphere hexes. If a ship is out of control and heading for
planet, it will burn up in the atmosphere.
Hit and Penetrate. The most drastic changes will be the hit and
penetration tasks. I feel the task is either too difficult or too easy. So,
here is my change: I will do the tasks rolled on percentile dice (D100). Take
DMs from the tables in the Referee's Manual as usual.
To Hit:
Chance to hit: 30% * (1+(OffDM-DefDM/100))
Example: A craft with factor-9 missile bay and computer model/9 firing
at a target with a DefDM of +7 will get a hit percentage of 33%:
30% + (1+(8+9-7)/100)% = 33%
To Penetrate Defense:
Chance to penetrate: 30% (1+(OffDM-DefDM)/100)
Example: The same ship as above is attempting to penetrate a factor-9
repulsor. the defending ship has a model/9 computer. The total chance is 29%.
30% + (1+(9-9-5)/100
To Penetrate Armor:
Chance to Penetrate: 30% *(1+((Weapon UCP-(ArmorValue-40))/100)
Example: The same ship as above attempts to penetrate an armor factor of
60. The total chance is 27%.
30% * (1+ ((9-(60-40))/100)
Exceptional Success: Given when the roll is 1/10th under the required
roll. Example: if the base chance to hit is 33%, a roll of 01-03 indicates
exceptional success. A roll of 01 on the task is always treated as exceptional
success.
Fleet or Ship Tactics: Add these skill points to the attacker's
offensive DM on the hit task. Follow the standard rules for how many tactical
points can be pulled from the pool.
Firing arcs: Something that MegaTraveller ships should have is firing
arcs, but this is not possible as the design system is today.
Movement: I am inclined to make some changes in the movement rules.
First, I want to make heading changes somewhat more difficult. As in
Interceptor or Leviathan, it costs thrust points to change heading. What I
want to do is require a certain number of hexes travelled at a given velocity
before allowing a one hex side course change. How many hexes to travel may
depend on both maneuver gee and/or agility. Using this rule would make it
appropriate to limit the arc of the spinal mount to forward.
Second, I want a planet's gravitational pull to interfere with a ship's
heading, depending on a ship's velocity and a planet's size and gravity (like
in Mayday.)
I'm working hard on these rules, but I must admit that my knowledge in
this area is limited. I have not been able to come up with any easy, user-
friendly rules. If you have any good suggestions, I would like to hear them.
DAMAGE RESULTS
Fuel Tank. I'm going to change the "fuel tank shattered" to "fuel leak".
A certain amount of fuel will be lost per turn. Subsequent hits will make the
leak more severe.
Hull Inoperative. There is no effect in the standard rules (or my
variant) for an inoperative hull, when that damage level is reached. My
suggestions are:
y restrict craft to 1G
y prohibit atmosphere entry
y hull is breached
y stress severely limits heading changes
y Agility drops to zero
y may not fire spinal mount
y Craft may not be recovered. They may be launched.
y Rapid Launch Facilities are inoperative.
y Fuel leak.
I would like to have your reflections on these suggestions. If you have
any better solutions, I would like to hear them. I hope it will turn out to be
a good set of rules which make starship more interesting and realistic.