manuver node execution

lib/SASCheck.ks

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+function sascheck { //returns the average exaust velocity of active engines. to convert to isp, divide by constant:g0
+	set saslist to ship:modulesnamed("ModuleSAS").
+	if saslist:length = 0 {
+		return false.
+	}
+	return true.
+}

lib/isp.ks

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+function evcalc { //returns the average exaust velocity of active engines. to convert to isp, divide by constant:g0
+	local englist is list().
+	local totalflow is 0.
+	local totalthrust is 0.
+	list engines in englist.
+	for eng in englist { 
+		if eng:ignition and not eng:flameout {
+			set totalflow to totalflow + (eng:possiblethrust /(eng:isp * constant:g0)).
+			set totalthrust to totalthrust + eng:possiblethrust.
+		}
+	}
+	if totalthrust = 0 { //avoid div by 0 later
+		return 1.
+	}
+	return (totalthrust / totalflow).
+}

loadmanprogram.ks

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+if not exists("1:/lib") {
+	createdir("1:/lib").
+}
+compile "0:/lib/isp.ks" to "1:/lib/isp.ksm".
+compile "0:/nde.ks" to "1:/nde.ksm".

nde.ks

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+//import functions
+run once "lib/isp".
+set nd to nextnode.
+
+//print out node's basic parameters - eta and deltav
+print "node in: " + round(nd:eta) + ", deltav: " + round(nd:deltav:mag).
+
+//calculate ship's max acceleration
+set maxacc to ship:availablethrust/ship:mass.
+
+// calculate exaust velocity of all active engines
+set ev to evcalc().
+set thrust to ship:availablethrust.
+set dv to nd:deltav:mag.
+//magic equasion to figure burnduration.
+set burnduration to ((ship:mass*ev)/thrust)*(1-constant:e^(-(dv/ev))).
+print "estimated burn duration: " + round(burnduration) + "s".
+
+sas off.
+set steeringmanager:maxstoppingtime to 10.
+set steeringmanager:pitchpid:kd to 2.
+set steeringmanager:yawpid:kd to 2.
+set steeringmanager:rollpid:kd to 2.
+lock steering to lookdirup(nd:deltav, sun:position). //points to node, roll so that solar panels are facing towards sun.(design craft so solar panels are pointing out of vab door and directly away from vab door.)
+// sas is better at steering craft with very little control.
+//sas on.
+//sas needs 1 tick between turning on and setting mode.
+//wait until true.
+//set sasmode to "maneuver".
+//now we need to wait until the burn vector and ship's facing are aligned
+wait until vang(nd:deltav, ship:facing:vector) < 0.25.
+
+//warp to 60 seconds before the burn, if we are more than 90 seconds away from it. otherwise, we wait.
+if nd:eta-(burnduration/2) > 90 {
+	set unwarptime to time:seconds+nd:eta-(burnduration/2)-60.
+	kuniverse:timewarp:warpto(unwarptime).
+}
+
+//give some time for our sunroll.
+wait until nd:eta <= ((burnduration/2)+55).
+
+set steeringmanager:maxstoppingtime to 2.
+set steeringmanager:pitchpid:kd to 2.
+set steeringmanager:yawpid:kd to 2.
+set steeringmanager:rollpid:kd to 2.
+//lock the steering, so we wont be chasing the manuver node.
+//points to node, roll so that solar panels are facing towards sun.(design craft so solar panels are pointing out of vab door and directly away from vab door.)
+set dir to lookdirup(nd:deltav, sun:position).
+lock steering to dir.
+
+//the ship is facing the right direction, let's wait for our burn time
+wait until nd:eta <= (burnduration/2).
+
+//we only need to lock throttle once to a certain variable in the beginning of the loop, and adjust only the variable itself inside it
+set tset to 0.
+lock throttle to tset.
+
+set done to false.
+//initial deltav
+set dv0 to nd:deltav.
+until done
+{
+	//recalculate current maxacceleration, as it changes while we burn through fuel
+	set maxacc to ship:availablethrust/ship:mass.
+
+	//throttle is 100% until there is less than 1 second of time left to burn
+	//when there is less than 1 second - decrease the throttle linearly
+	set tset to min(nd:deltav:mag/maxacc, 1).
+
+	//here's the tricky part, we need to cut the throttle as soon as our nd:deltav and initial deltav start facing opposite directions
+    //this check is done via checking the dot product of those 2 vectors
+    if vdot(dv0, nd:deltav) < 0
+    {
+        print "end burn, remain dv " + round(nd:deltav:mag,1) + "m/s, vdot: " + round(vdot(dv0, nd:deltav),1).
+        lock throttle to 0.
+        break.
+    }
+
+	//we have very little left to burn, less then 0.1m/s
+	if nd:deltav:mag < 0.1 {
+		print "finalizing burn, remain dv " + round(nd:deltav:mag,1) + "m/s, vdot: " + round(vdot(dv0, nd:deltav),1).
+		//we burn slowly until our node vector starts to drift significantly from initial vector
+		//this usually means we are on point
+		wait until vdot(dv0, nd:deltav) < 0.5.
+
+		lock throttle to 0.
+		print "end burn, remain dv " + round(nd:deltav:mag,1) + "m/s, vdot: " + round(vdot(dv0, nd:deltav),1).
+		set done to true.
+	}
+}
+unlock steering.
+unlock throttle.
+wait 1.
+
+//we no longer need the maneuver node
+remove nd.
+
+//set throttle to 0 just in case.
+set ship:control:pilotmainthrottle to 0.
+sas on.