Azothath |
What should the AC modifiers be for fast things?
a quick search of the existing threads didn't show anything similar....
There are a couple of things to consider in this problem;
1) AC is what it is moving tactically 30ft/r (1.524m/s) or less. Let's not kill the system as it is unless there is good cause.
2) baseball statistics for ability to hit a baseball moving at roughly 40m/s.
3) normal surface area of target as seen by attacker... this changes with distance. For a square area that's proportionally 1/s^2 if it moves distance s away or you can use steradians. See size charts and affect to AC. There might be a better way but this is a good place to start. Some ballistic data about targeting would be handy.
4) reaction time of a healthy human, I'll take 160millisec as a good reaction time.
5) conversion to ft/round(6sec). This is the easy part.
I did a quick scaling rule of
AC bonus = 1.8*Log(v)*(ln(v-12)/ln2), where v(m/s). Obviously at less than 10 m/s there will be function issues...
so my rough handwaving come out to be;
+1 AC for 11 m/s to 14m/s (220ft/r to 274ft/r)
base speed in double move of 110ft.
base speed Running(*4) of 55ft.
+2 AC at 14 m/s (275.6 ft/r)
base speed Running of 69ft.
+14 AC for a baseball at 40 m/s (787.4 ft/r).
+21 AC for an arrow shot from a compound bow with a speed of 75 m/s (1476.4 ft/r).
+57 AC for a rifle bullet at 1200 m/s (23622 ft/r).
I am not saying the formula is accurate, just better than a simple scalar or nothing.
Azothath |
One thing that exists are range modifiers based on weapon type. That also limits the range of the weapons.
Range: Any attack at more than this distance is penalized for range. Beyond this range, the attack takes a cumulative –2 penalty for each full range increment (or fraction thereof) of distance to the target. For example, a dagger (with a range of 10 feet) thrown at a target that is 25 feet away would incur a –4 penalty. A thrown weapon has a maximum range of five range increments. A projectile weapon can shoot to 10 range increments.
While the scale is certainly linear it could be the way to handle it based on how far you move in each round.
So if you move 110ft(range of a composite longbow) then not only is it a range modifier of -2 but +4 to AC from your speed (with a normalized base of 30, a standard "range" for movement, 110/30=3.666=3, -1 for the first range ->2, and 2*-2 =-4 or +4 to AC).
For a sling it'd be -4 (range) and still +4 to AC from speed.
it get weird if you scale the running based on the range increment of the weapon. So I used a standard speed of 30.
Azothath |
for the Range Increments style (2*(RndDwn[velocty{ft/r}/30] -1)), you can see;
+12 AC for 11 m/s(220 ft/r)
+16 AC for 14 m/s (275.6 ft/r)
+50 AC for a baseball at 40 m/s (787.4 ft/r). {no one could EVER hit a 90mph baseball}
+96 AC for an arrow shot from a compound bow with a speed of 75 m/s (1476.4 ft/r).
+1572 AC for a rifle bullet at 1200 m/s (23622 ft/r).
this implies that 60ft might be a better base, but still the baseball gets +25 to AC which is still too high IMO (given existing baseball statistics and the fact that baseball players would be Expert class).
If you jump up to running speed of 120 ft/r, you get a better number midrange. The only problem is that solid angles and surface area is changing at 1/s^2 and that argues that the AC should scale at that rate and not 1/s, where s=distance(space).