COMBAT SYSTEM v 0.1
damage results
This is an attempt to make a combat mechanic that is easy and quick in
play based on the MegaTraveller task system while giving reasonably realistic
results. I hope to include both penetration and damage from MT weapon stats yet
keeping the quickness of the Azhanti High Lightning mechanic.
Another desired result is the ability to use a simple model for unimportant
npc's while having a better, more detailed model for players while keeping
reduction in abilities from wounding similar.
In order to attain the quickness of AHL, I will be basing this mechanic
partly on the AHL damage table. Ordinarily, on a hit, penetration is added and
armor is subtracted from 2d6 and indexed into a chart of possible outcomes.
However, in order to satisfy my requirement that the better one rolls,
the better the damage will by, I instead replace the 2d6 with the amount that
the hit roll was beaten and a single d6. With this, better rolls equal better
results in inflicting combat damage onto the enemy and still have a measure of
randomness. The 1d6 is needed because in MT, the 'hit' roll would have to be
beaten by an average of '7' otherwise to get similar results as in AHL.
This 1d6 could also be used as a hit location die for instances of
partial armor, or for called aimed shots..aka, 'sniping'. By making a called
shot, the task increases a step in difficulty, but if successful, the player may
place the 1d6 to any value or hit location that he wishes.
Code:
1d6 hit location
6 head
5 chest
4 abdomen
3 leg
2 arm
1 scratch
1d6+dice roll-task number+penetration-armor
Code:
less than 4 no effect
4 thru 7 minor wound
8 thru 11 major wound
12 or more death
As this gives similar results to AHL, I wished to include MT's damage
information into the mix. I feel that the interplay between penetration and
damage is what gives weapons their uniqueness. It is a guess on mine that
somehow, the number on AHL's chart might correspond with a damage multiplier.
The amount of damage caused is the product of the damage chart number times the
weapon's damage number.
In order to figure this out, I had to first find the manner in which AHL
is converted to CT combat. This information is available in Striker which uses
the same basic system as AHL. I then figured the correlation between the AHL's
'minor/major' damage and dice damage. In Striker, minor damage is 3d6 and major
damage is 6d6 in Classic Traveller terms.
The following chart can be constructed.
Code:
(damagemultiplier)
1 no effect .5
2 no effect 1
3 no effect 1.5
4 minor 2
5 minor 2.5
6 minor 3d6 3
7 minor 3.5
8 major 4
9 major 4.5
10 major 5
11 major 5.5
12 death 6d6 6
In this case, I purposefully placed the 6d6 at 'death' for the following
reason. It allows for a simple linear relationship between the dice damage and
the damage chart number. The damage chart number divided by 2 becomes dice
damage. I figured that 6d6 could very well be a 'death' outcome as that is the
same number of dice used in character generation to determine a PC's stats.
While I am no statistician, it appears to me that this results gives a slightly
better than 50% of causing an average PC's death.
Another nice coincidence is that this damage chart number divided by 2
can also be 'damage' used with life points in regular MT combat.
This brings me closer to my goal.
Naturally, having every weapon rated with a single damage value is
simplistic and workable, but 'bland'. Different weapons have different
characteristics and it'd be good to be able to show this in the game.
With Fire,Fusion and Steel, players can design their own weapons.
Although it uses a completely different method for combat ( TNE ), weapons are
built using real terms such as muzzle velocity. The supplement Guns,Guns,Guns
uses the same terms in addition to giving more detail in some areas. In GGG,
ammunition is 'built' and bullet mass is considered, which FFS lumps in with
total ammunition mass ( bullet, shell and casing ).
This is an important distinction as I will be using bullet momentum for
damage instead of muzzle energy. A series of comments in a thread on COTI
concerning old west weapons and the differences between large caliber, 'heavy'
bullets at lower velocity compared to small caliber bullets at high velocity.
Given that penetration is related to muzzle energy per unit area, for a
given muzzle energy, a smaller caliber would always rated better. I felt that
this did not show the heavy calibers correctly.
Starting with muzzle energy, I needed to find a simple way to find the
bullet's momentum.
me=.5*m*v^2
v= sqrt(me/2m)
this can be substituted into the equation for momentum.
momentum=m*v
substituting sqrt(me/2m) into 'v', we get
momentum = sqrt(2*m*me)
What needed to be done was to figure the proper ratios to use to make
it fit the modified AHL damage table and dice.
Picking a weapon that I had official details for, the tech13 7mm ACR
from FFS ( me=4800, m=.008kg) and compared it to a similar weapon from MT. With
a pen=3 and dam=3 in MT, I set it alongside the 3d6 on the table and using
information about me and ( from GGG) bullet mass ( density of lead ), I set the
following where momentum is proportional to the number of dice damage. Using
values for me and bullet mass from the example rifle, solving for 'X' will give
me the equation for damage which when multiplied by the damage multiplier in my
table, will give me total dice damage to the target.
me is in joules
m is in kg
1 = X * sqrt(momentum)
1 = X * (2*me*m)^.25
X= 1/3
dam=((2*me*m)^.25)/3
Now we have everything we need to convert guns, or any kinetic based
attack/accident into MT terms.
Here is my conversion data from a long time ago
Weapon stats;
penetration=((Me/(b^2*.7854))^.25)/4 round down
damage= ((Me*mass *2)^.25)/3 round to nearest
1/10 *
( for use with my AHL damage table variant)
attenuation=sqrt(50*bullet_mass/b^2)/2+1.25 round to nearest
bullet_vol=b^3*(.785*(Q-1)-.262)/1000 cm^3
bullet_mass=sg*bullet_vol grams
muzzle_velocity=sqrt(Me*21630/bullet_mass)/3.28 m/s
Me=muzzle energy in joules
b=weapon bore in millimeters
Q= length/width ratio of bullet ( 1=sphere,2=pistol bullet,3=rifle
bullet..etc..10=sabot penetrator )
if sabot penetrator is used with l/w=10, then b= diameter of
penetrator...not of barrel
sg= specific gravity of bullet material
take this info from armor material lists in tonnes/m^3
melee blade weapons figure pen using a contact area of 1 cm^2 ( no reason except
it gives number that are close to what guns,guns,guns gives ) for swinging attacks
perhaps a quarter of this for stabbing attacks?...weapon x-section for blunt attacks
I'll work it out better in a future post
*With smaller weapons, often the differences are small, so I keep one decimal
place. With small numbers, its often easy to multiply quickly with the single
digit numbers often taken from the chart and with big numbers, it can probably
be ignored.
This is the basis for my kinetic energy damage. It can be very detailed
and yet offers 3 steps of increasing simplicity.
1 AHL style 'minor/major/death' damage
2 MT style points damage with a lifepoints
3 Simple straight dice damage
4 Detailed damage that takes bullets caliber and mass into
consideration.
One good thing about this system is that it could conceivably be used to
figure ANY damage from kinetic impact...melee weapons or falls from height, or
hit by vehicles, etc. All thats needed is information about energy, mass and
momentum and common sense with DM on the damage table.
For melee weapons ( which would be 'built' using a design sequence like
FFS yet simpler ). The essentials are mass, length and type. ( to be detailed in
another paper )
Energy would come from combatant's strength and time spent
swinging/putting energy into the attack. This time could be in seconds or AP's
or whatever logical time step you wish. I base swing energy of T. McInnis' <sp>
way of figuring 'powerplant' power for rowers in boats. In that system, a
normal human can output 63 watts ( IIRC), so in order to make the math easy, I
assume 70 and at str=7, this gives a reasonable ratio of 10 watts per str or 10j
per sec per str point. By using joules/sec, I can figure joules energy in a
swing for 1 second of swinging. If I set an AP in my combat variant to be 1 sec,
then figuring melee attack energy is simple. Joules energy and weapon's area at
impact ( spear tip, axe blade, club, etc. ), we can know penetration. With mass
and energy known, momentum for damage can be found. We can then use these as
dm's for the modified AHL table.
Falling damage can be found by finding the body momentum at impact.
Assume no penetration. For the 1d6, use it if the body falls out of control, or
'0' if jumping down from a height ( controlled landing ).
To find momentum, first find potential energy of body. This should be the energy
with which the victim impacts.
PE=m*g*h. m=body's mass
g=local g's in m/sec^2
h=distance of fall
substitute into the equation.
dam= ((2*g*h*m^2)^.25)/3 this assumes a straight drop without
horizontal velocity added
This actually give slightly more damage than MT's rule concerning 8d6
anytime someone falls more than 9m automatically. However, if jumping down in a
controlled fashion, the amount that you beat the success roll becomes a
dm...negative in this case for AVOIDING damage. Conversely, a failed roll then
becomes the +dm causing more damage. Armor continues to count as a -dm.
The same idea applies to damage from being hit be a bus or other
vehicle. Figure energy, possible penetration and momentum, Use that information
to find base damage to be multiplied by the table's damage multiplier.
So what happens if dm's cause the damage table number to be less than zero?
Its possible that 1d6+dice rolled-success#+penetration-armor comes to
less than zero, and yet the base damage number is high enough to warrant damage
being taken even when the armor is not penetrated. An example of this might be a
tech-7 100mm recoilless rifle hitting battledress with a HE round ( based on MT
numbers for this )...or making a successful roll upon jumping off a 2nd story
balcony to the ground. The table needs to be extended into negative numbers.
On this table, 1 represents a damage multiplier of .5, but we need to go
lower. A model that should work is from MT's danger space damage... half the
damage for every step below 1. The table then looks as follows. Now its possible
to be shot while wearing body armor, have no penetration, yet get a whopping big
bruise at the point of impact.
Code:
1d6+dm's_________AHL______________CT_______________multiplier____
... ...
-6 1/128
-4 1/64
-3 1/32
-2 1/16
-1 1/8
0 1/4
1 no effect .5
2 no effect 1
3 no effect 1.5
4 minor 2
5 minor 2.5
6 minor 3d6 3
7 minor 3.5
8 major 4
9 major 4.5
10 major 5
11 major 5.5
12 death 6d6 6
13 6.5
14 7
... ... ... ...
1d6+#rolled-success#-armor+pen
(#rolled-success# gives a positive dm equal to amount the success roll
was beaten by)
for CAUSING damage, if failed, you don't enter the table; the amount the
success roll was missed gives an indication of how far the shot missed
If the roll was to AVOID damage ( falling or jumping down where player can be
hurt even on a success, but less than if failed ), then add the amount the roll
was MISSED by for damage caused by failure and subtract the amount the roll for
success was beaten by.
failure causes more damage and success causes less damage.
Knockback
Because we know how much momentum the bullet,etc, has, when we know how
much the target masses, we can figure knockback easily. While the values will
end up being greater than experience suggests, knockback won't have much affect
on soft targets like squishy humans. Against hard targets is another matter.
Humans in battledress or other hard armors can be knocked down by an attack, and
they will be knocked down if the attack's momentum is large enough ( say, as in
being hit by a bus, wrecking ball or a 12-pounder in the chest....maybe even
with a sledge hammer.) I'll have to investigate this a bit to find out how much
is necessary to cause a human to fall down or stumble even.
okay...I need to learn how to make pretty charts/tables
can someone tell me how please?
I'm getting closer at least
I think the equation in guns,guns,guns is bad
if pen is proportional to energy per area, how come its dv calc does not seem to reflect that?
maybe I'm missing something
I changed it a bit to calc MT's pen