sas off.

set RADAR_GROUND_HEIGHT to 1.8. //Set this too high and you get negative sqrt and crash.
                                //Set this too low and you slam into the ground.
set DESCENT_SPEED to 3. // fudgey number. higher is faster
set JET_SPOOL_TIME to 3. // aproximate number of seconds the jet spools.
set SURFACE_SHEAR_CAP to 40. //how many meters per second before we just lock to 45 degrees
                             //higher means less aggressive reactions to sideways movement.

set pt to TIME:SECONDS. //previous time
set pv to 0. //previous velocity

until false {
	wait 0.1.
	CLEARSCREEN.
	set surfaceShear to vxcl(up:forevector, velocity:surface).
	if surfaceShear:MAG > SURFACE_SHEAR_CAP { SET surfaceShear:MAG to SURFACE_SHEAR_CAP. }
	set desiredVelocity to -sqrt(alt:radar-RADAR_GROUND_HEIGHT)*DESCENT_SPEED.
	set velocityChange to desiredVelocity-ship:verticalspeed.

	set dt to TIME:SECONDS - pt.
	set dv to ((velocityChange - pv)/dt)*JET_SPOOL_TIME.

	set baseThrottle to (ship:mass*9.87/ship:maxthrust).
	set adjustmentThrottle to (velocityChange+dv)/3.

	print "Target Descent Speed: " + round(desiredVelocity, 2).
	print "Diff From Target    : " + round(velocityChange, 2).
	print "Diff Rate Of Change : " + round(dv, 2).
	print "Surface Shear Speed : " + round(surfaceShear:mag, 2).
	print "Neutral Throttle    : " + round(baseThrottle, 2).
	print "Adjustment Throttle : " + round(adjustmentThrottle, 2).

	lock throttle to adjustmentThrottle + baseThrottle + surfaceShear:mag/SURFACE_SHEAR_CAP.
	lock steering to lookdirup(up:forevector*SURFACE_SHEAR_CAP-surfaceShear, facing:topvector).

	set pt to TIME:SECONDS.
	set pv to velocityChange.
}