okayokay, here's my conjecture...
For any Missile or Laser with corkscrew effect turned on, and $Homing set to NO, the weapon will fire at an angle which is defined by putting a nonzero number in the +Radius field of the corkscrew effect. 1.0 causes the weapon to fire about 10 degrees downward, 9.0 causes the weapon to fire straight down. Anything past 9.0 causes the weapon to fire straight downward at higher velocities. Negative numbers can be used to cause a weapon to fire upwards.
Also...
A laser with Homing set to HEAT or ASPECT will not have homing capability of any kind, but they are capable of having the real corkscrew effect, like the tornado.
that's pretty much it. If Homing is on, then the weapon can corkscrew, if homing is NO, then the weapon can fire at angles.
oh, and i made the shockwaves on my FS2 from blue to red, they look cool!