Implement launch azimuth and refine node execution.

boot/default.ks

@@ -1,5 +1,39 @@
 CLEARSCREEN.
 print "=================== BOOTING ===================".
-switch to 0.
+
+if HOMECONNECTION:ISCONNECTED {
+    update_scripts().
+} else {
+    print "No connection to KSC: not updating scripts.".
+}
 
 print "============= BOOT SEQUENCE COMPLETE =============".
+
+
+function update_scripts {
+    // Copy all .ks-files from the archive to the CPU's internal storage.
+    
+    // Get lexicon of existing items (files/directories) and sizes on the internal storage
+    local existing is lexicon().
+    for item in CORE:VOLUME:FILES:VALUES {
+        set existing[item:NAME] to item:SIZE.
+    }
+    
+    // Check if items from the archive match those in the internal storage
+    for item in VOLUME("ARCHIVE"):FILES:VALUES {
+        local skip is false.  // kOS doesn't support the 'continue' keyword...
+        
+        if not skip and item:NAME[0] = "." set skip to true.               // skip linux hidden dirs (e.g. .git)
+        if not skip and item:ISFILE
+                    and item:EXTENSION <> "ks" set skip to true.           // skip non-script items (e.g. README.md)
+        if not skip and existing:HASKEY(item:NAME)
+                    and item:SIZE = existing[item:NAME] set skip to true.  // skip if local item is same size
+        
+        if not skip {
+            print "Copying " + item:NAME + "..".
+            COPYPATH(PATH(VOLUME("ARCHIVE")):COMBINE(item:NAME), CORE:VOLUME).
+            
+            if item:NAME = "boot" reboot.  // reboot CPU if boot/ directory was updated
+        }
+    }
+}

launch.ks

@@ -2,81 +2,124 @@ run once util.
 run once vectors.
 run once node.
 
-print "====================== LAUNCHING ======================".
 
-parameter orbit_height is 100_000.
+function launch {
-parameter pitchover_tilt is 20.
+    // Launch to orbit of provided altitude and inclination.
-parameter pitchover_altitude is 1000.
+    parameter target_orbit_altitude is 100_000.  // meters
-parameter pitchover_velocity is 100.
+    parameter target_orbit_inclination is 0.  // 0-180 degrees
+    parameter pitchover_tilt is 20.  // how many degrees to tilt at pitchover maneuver
+    parameter pitchover_altitude is 1000.  // perform pitchover at this altitude
+    parameter pitchover_velocity is 100.  // or this velocity
     
     
-// Auto-stage when the stage has no solid- and liquid fuel left
+    print "========= LAUNCHING =========".
-when (STAGE:SOLIDFUEL + STAGE:LIQUIDFUEL < 1) and STAGE:READY then {
+    print "Target orbital altitude:       " + target_orbit_altitude + "m".
-    print "STAGING (zero fuel)".
+    print "Target orbital inclination:    " + target_orbit_inclination + "°".
-    STAGE.
+    print "Pitchover tilt:                " + pitchover_tilt + "°".
-    return true.  // preserve trigger 
+    print "Pitchover at:                  " + pitchover_altitude + "m or " + pitchover_velocity + " m/s".
+    print " ".
+    
+    
+    // LAUNCH AZIMUTH
+    
+    // Since the "center" of an orbit must be at the center of gravity of the body, the latitude of the launch site establishes the minimum absolute orbital inclination.
+    // KSC is almost on the equator, so we're going to always round the latitude towards zero, and accept the inaccuracies it may introduce.
+    local launch_site_latitude is round_towards_zero(SHIP:LATITUDE).
+    local target_orbit_inclination is MAX(target_orbit_inclination, launch_site_latitude).
+    
+    // Calculate the launch azimuth; the compass heading we head for when launching to achieve orbit of desired inclination
+    local launch_azimuth is calculate_launch_azimuth(target_orbit_inclination, target_orbit_altitude, launch_site_latitude).
+    
+    // If the latitude of the launch site is negative (ship is in the southern hemisphere), launch southwards instead of northwards
+    local southwards is launch_site_latitude < 0.
+    if southwards {
+        set launch_azimuth to 180 - launch_azimuth.
     }
     
-// Automatically deploy solar panels at 0 atmosphere
+    print "Launch site latitude:          " + ROUND(SHIP:LATITUDE, 3) + "°  (~" + launch_site_latitude + "°)".
-when SHIP:DYNAMICPRESSURE = 0 then {
+    print "Available orbital inclination: " + target_orbit_inclination + "°".
-    print "Deploying solar panels (zero pressure)".
+    print "Launch azimuth:                " + ROUND(launch_azimuth, 3) + "°".
-    PANELS ON.
+    print "Launch southwards:             " + southwards.
-}
-
-// Disable engine gimbal when engine is off
-on (not THROTTLE) {  // using not to cast to boolean
-    list engines in engines_list.
-    for engine in engines_list {
-        if engine:HASGIMBAL set engine:GIMBAL:LOCK to not THROTTLE.
-    }
-    return true.  // preserve trigger
-}
     
     
-// VERTICAL CLIMB
+    print "--- VERTICAL CLIMB ---".
-
-print "VERTICAL CLIMB to " + pitchover_altitude + "m or " + pitchover_velocity + "m/s".
     SAS OFF.
     set NAVMODE to "SURFACE".
+    lock STEERING to HEADING(launch_azimuth, 90).  // roll to launch azimuth
     lock THROTTLE to 1.0.
-lock STEERING to HEADING(90,90).
+    STAGE.
     
-// Once a certain altitude is reached, a slight turn is made, called the pitchover maneuver
+    // Enable auto-stage when the maximum engine thrust changes (i.e. some engines ran out of fuel)
+    on SHIP:MAXTHRUSTAT(0) {
+        when STAGE:READY then {
+            print "STAGING".
+            STAGE.
+        }.
+        return true.  // preserve trigger
+    }
+
+    // Once a certain altitude (or velocity) is reached, a slight turn is made, called the pitchover maneuver
     wait until SHIP:ALTITUDE > pitchover_altitude
             or SHIP:VELOCITY:SURFACE:MAG > pitchover_velocity.
     
     
-// PITCHOVER MANEUVER
+    print "--- PITCHOVER ---".
+    lock STEERING to HEADING(launch_azimuth, 90-pitchover_tilt).
     
-print "PITCHOVER by " + pitchover_tilt + "°".
+    wait until actual_prograde_pitch() > pitchover_tilt.  // wait until the prograde "catches up" to our tilted heading
-lock STEERING to HEADING(90,90-pitchover_tilt).
-
-wait until actual_prograde_pitch() > pitchover_tilt.
     
     
-// GRAVITY TURN
+    print "--- GRAVITY TURN ---".
+    // TODO: the angle of the launch azimuth will not account for the fact that our compass will change as we move north/south.
+    lock STEERING to HEADING(launch_azimuth, 90-actual_prograde_pitch()).  // Follow prograde pitch to get 0 deg angle of attack, but force compass heading at launch azimuth. 
     
-print "GRAVITY TURN".
+    wait until APOAPSIS > target_orbit_altitude.
-lock STEERING to HEADING(90, 90-actual_prograde_pitch()).  // follow prograde to get 0 deg angle of attack, but force compass heading 90 (east)
-
-wait until APOAPSIS > orbit_height.
     lock THROTTLE TO 0.
-unlock STEERING.
+    unlock_control().
     
     
-// CREATE AND EXECUTE CIRCULARIZATION MANEUVER NODE
+    print "--- CIRCULARIZE ---".
-create_circularization_node().
+    print "Waiting for ship to leave the atmosphere..".
+    set KUNIVERSE:TIMEWARP:RATE to 4.
+    wait until SHIP:DYNAMICPRESSURE = 0.  // don't create maneuver node until we are out of the atmosphere - otherwise the apoapsis altitude and eta will change due to drag
+    KUNIVERSE:TIMEWARP:CANCELWARP().
+    
+    print "Deploying solar panels".
+    PANELS ON.
+    
+    // Create maneuver node that will circularize the orbit.
+    // NOTE: Potential errors in the inclination are not fixed, since we are most likely going to change our orbit, which will make the inclination change cheaper later on.
+    local node is NODE(TIME:SECONDS + ETA:APOAPSIS, 0, 0, 0).
+
+    // Burn magnitude in the prograde direction is the difference between the required velocity to acheive orbit at apoapsis altitude and our velocity at apoapsis
+    set node:PROGRADE to orbital_velocity(APOAPSIS) - VELOCITYAT(SHIP, TIME:SECONDS + ETA:APOAPSIS):ORBIT:MAG.
+    
+    add node.
     execute_node().
     
     
-// EPILOGUE
+    print "========= LAUNCH SEQUENCE COMPLETE =========".
+    unlock_control().
+}
 
-// Ensure that the throttle will be 0 when execution stops
-set SHIP:CONTROL:PILOTMAINTHROTTLE to 0.
 
-// Ensure that the player is not locked out of control.
+function calculate_launch_azimuth {
-set SHIP:CONTROL:NEUTRALIZE to true.
+    // Calculate the launch azimuth; the compass heading we head for when launching to achieve orbit of desired inclination.
-unlock STEERING.
+    // http://www.orbiterwiki.org/wiki/Launch_Azimuth
-unlock THROTTLE.
+    // https://www.princeton.edu/~stengel/MAE342Lecture4.pdf
+    parameter target_orbit_inclination.
+    parameter target_orbit_altitude.  // to compensate for the rotation of the body, we need to know the velocity of the target orbit, which is calculated from its altitude
+    parameter launch_site_latitude.
     
-print "====================== LAUNCH SEQUENCE COMPLETE ======================".
+    local inertial_azimuth is ARCSIN(COS(target_orbit_inclination) / COS(launch_site_latitude)).  // azimuth in inertial space, that is, disregarding the rotation of the body
+    
+    local equatorial_rotational_velocity is (2 * CONSTANT:PI * BODY:RADIUS) / BODY:ROTATIONPERIOD.
+    local target_orbit_velocity is orbital_velocity(target_orbit_altitude).  // velocity of target orbit
+
+    local launch_vector_x_component is target_orbit_velocity * SIN(inertial_azimuth) - equatorial_rotational_velocity * COS(launch_site_latitude).
+    local launch_vector_y_component is target_orbit_velocity * COS(inertial_azimuth).
+    return ARCTAN2(launch_vector_x_component, launch_vector_y_component).
+}
+
+
+launch(100_000, 0).

node.ks

@@ -1,72 +1,57 @@
 run once util.
 
+
+function estimated_burn_duration {
+    // Calculate estimated burn duration for a maneuver node
+    // https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation
+    // https://space.stackexchange.com/questions/27375/how-do-i-calculate-a-rockets-burn-time-from-required-velocity
+    parameter node is NEXTNODE.
+    
+    local exhaust_velocity is isp_sum() * (CONSTANT:G * KERBIN:MASS).
+    return ((SHIP:MASS * exhaust_velocity) / SHIP:MAXTHRUST) * (1 - CONSTANT:E^(-node:DELTAV:MAG/exhaust_velocity)).
+}
+
+
 function execute_node {
     parameter node is NEXTNODE.
+    parameter precision is 0.05.  // m/s delta-v
     
-    print "EXECUTE MANEUVER NODE".
+    local burn_duration is estimated_burn_duration(node).
     
-    // Calculate estimated burn time
+    print "=== EXECUTE MANEUVER NODE ===".
-    // https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation
+    print "Estimated burn duration: " + ROUND(burn_duration, 1) + "s".
-    // https://space.stackexchange.com/questions/27375/how-do-i-calculate-a-rockets-burn-time-from-required-velocity
-    local isp_sum is 0.
-    list ENGINES in engines_list.
-    for engine in engines_list {
-        if engine:STAGE = STAGE:NUMBER set ISP_sum to ISP_sum + engine:VISP.
-    }
         
-    local ve is ISP_sum * (CONSTANT:G * KERBIN:MASS).  // exhaust velocity
+    print "Aligning ship with burn vector..".
-    local burn_time is ((SHIP:MASS * ve) / SHIP:MAXTHRUST) * (1 - CONSTANT:E^(-node:BURNVECTOR:MAG/ve)).
-    
-    print "Estimated burn time: " + ROUND(burn_time).
-    
-    print "Aligning ship with burn vector".
     SAS OFF.
-    lock STEERING to node:BURNVECTOR.
+    lock STEERING to node:DELTAV.
-    wait until VANG(SHIP:FACING:VECTOR, node:BURNVECTOR) < 0.1.
+    wait until VANG(SHIP:FACING:VECTOR, node:DELTAV) < 0.1.
     
     print "Initializing warp".
-    unlock STEERING.  // TODO: Doesnt work?
+    unlock_control().
-    warp_for(MAX(0, node:ETA - (burn_time/2) - 5)).  // Warp until 5s before node
+    warp_for(MAX(0, node:ETA - (burn_duration/2) - 5)).  // warp until 5s before node
     
     print "Approaching".
-    lock STEERING to node:BURNVECTOR.
+    lock STEERING to node:DELTAV.
-    wait until node:ETA <= burn_time/2.
+    wait until node:ETA <= ROUND(burn_duration/2).
     
     print "Burn!".
     lock THROTTLE to 1.0.
     
-    //throttle is 100% until there is less than 1 second of time left to burn
+    // Decrease throttle linearly when the burn duration is less than 1 second
-    //when there is less than 1 second - decrease the throttle linearly
+    wait until estimated_burn_duration(node) <= 1.
-    // TODO: Smooth at the end
+    lock THROTTLE to MAX(0.01, estimated_burn_duration(node)).  // ensure we always finish by burning with at least 1% power
-    wait until node:DELTAV:MAG < 5.0.  // TODO
+    
+    wait until node:DELTAV:MAG < precision.
     set THROTTLE to 0.0.
     
-    print "DONE! Removing node and unlocking steering".
+    print "=== MANEUVER NODE EXECUTED ===".
+    print ROUND(node:DELTAV:MAG, 3) + "m/s delta-v remaining".
+    unlock_control().
+    wait 1.
     remove node.
-    
-    unlock STEERING.
-    unlock THROTTLE.
-    SET SHIP:CONTROL:PILOTMAINTHROTTLE TO 0.
 }
 
 
-function create_circularization_node {
+function change_slash_set_orbit {
-    // parameter where.
-    
-    print "CREATE CIRCULARIZATION NODE".
-    
-    local node is NODE(TIME:SECONDS + ETA:APOAPSIS, 0, 0, 0).
-    add node.
-
-    // Calculate required velocity to acheive orbit at altitude equal to apoapsis
-    // https://en.wikipedia.org/wiki/Orbital_speed#Mean_orbital_speed
-    local orbital_speed is SQRT((CONSTANT:G * ORBIT:BODY:MASS) / (ORBIT:BODY:RADIUS + APOAPSIS)).
-
-    // Calculate the difference between the required velocity and our velocity at apoapsis
-    set node:PROGRADE to orbital_speed - VELOCITYAT(SHIP, TIME:SECONDS + ETA:APOAPSIS):ORBIT:MAG.
-}
-
-
-function create_orbitchange_node {
     parameter what.
 }

test.ks

@@ -1,3 +0,0 @@
-print "TEST".
-
-run once vectors.

util.ks

@@ -1,11 +1,64 @@
 function warp_to {
     parameter timestamp.
     
-    KUNIVERSE:TIMEWARP:WARPTO(timestamp).  // todo: improve.
+    KUNIVERSE:TIMEWARP:WARPTO(timestamp).  // TODO: improve.
+    // wait until TIME >= timestamp. // TODO
 }
 
 function warp_for {
     parameter seconds.
-    
     return warp_to(TIME:SECONDS + seconds).
 }
+
+
+
+function isp_sum {
+    local sum is 0.
+    list ENGINES in engines_list.
+    for engine in engines_list {
+        if engine:STAGE = STAGE:NUMBER set sum to sum + engine:VACUUMISP.
+    }
+    return sum.
+}
+
+
+function round_towards_zero {
+    parameter n.
+    
+    if n < 0 return CEILING(n).
+    return FLOOR(n).
+}
+
+
+function orbital_velocity {
+    // Calculate the required velocity to acheive orbit at the provided altitude.
+    // https://en.wikipedia.org/wiki/Orbital_speed#Mean_orbital_speed
+    // http://www.orbiterwiki.org/wiki/Front_Cover_Equations
+    parameter altitude.
+    
+    return SQRT(BODY:MU / (BODY:RADIUS + altitude)).  // BODY:MU = CONSTANT:G * BODY:MASS
+}
+
+
+
+function unlock_control {
+    // Ensure that the throttle will be 0 when execution stops
+    set SHIP:CONTROL:PILOTMAINTHROTTLE to 0.
+    
+    // Ensure that the player is not locked out of control.
+    set SHIP:CONTROL:NEUTRALIZE to true.
+    unlock STEERING.
+    unlock THROTTLE.
+}
+
+
+function disable_engine_gimbal {
+    // Disable engine gimbal when engine is off
+    on (THROTTLE = 0) {
+        list ENGINES in engines_list.
+        for engine in engines_list {
+            if engine:HASGIMBAL set engine:GIMBAL:LOCK to (not THROTTLE).
+        }
+        return true.  // preserve trigger
+    }
+}