// This script will launch a rocket into a circular orbit around Kerbin
// It assumes the rocket has at least two stages and a fairing
// It also assumes the rocket has the following mods installed:
// KRPC, KOS, KOS-StockCamera, KOS-Scansat, KOS-EVA, KOS-Career, QuickStart

// Set the desired apoapsis and inclination of the orbit
set target_apo to 200000. // in meters
set target_inc to 0. // in degrees

// Set the launch time (optional)
set launch_time to "10:00:00". // in 00:00:05 format

// Set the maximum thrust-to-weight ratio (optional)
set max_twr to 1.5.

// Initialize some variables
set stage_number to stage:number.
set stage_liquidfuel to stage:liquidfuel.
set throttle to 1.
set steering to 90.

// Wait for the launch time (optional)
if launch_time <> "" {
    print "Waiting for launch time: " + launch_time.
    wait until time:seconds = time:seconds(launch_time).
}

// Activate the first stage and lock the steering to east
print "Liftoff!".
stage.
lock steering to heading(steering, 90).

// Main ascent loop
until apoapsis > target_apo or stage_number = 0 {

    // Throttle down if twr is too high
    if ship:maxthrust / ship:mass > max_twr {
        set throttle to max_twr * ship:mass / ship:maxthrust.
    }

    // Throttle up if twr is too low
    if ship:maxthrust / ship:mass < max_twr * 0.9 {
        set throttle to 1.
    }

    // Stage when out of liquid fuel
    if stage_liquidfuel = 0 {
        print "Staging.".
        stage.
        set stage_number to stage:number.
        set stage_liquidfuel to stage:liquidfuel.
    }

    // Jettison fairing when above 70 km
    if altitude > 70000 and ship:fairing {
        print "Jettisoning fairing.".
        ship:fairing:jettison().
    }

    // Adjust steering based on altitude and velocity
    if altitude < 10000 {
        // Stay vertical until 10 km
        set steering to 90.
    } else if altitude < 40000 {
        // Gradually pitch down until 40 km
        set steering to 90 - (altitude - 10000) / 1000.
    } else {
        // Follow prograde until apoapsis
        set steering to velocity:orbit.
    }

    // Lock steering to the desired direction
    lock steering to heading(steering, 90 - target_inc * sin(longitude)).
}

// Cut off engines and coast to apoapsis
print "Coasting to apoapsis.".
set throttle to 0.

// Circularize at apoapsis
print "Circularizing.".
lock steering to prograde.
wait until eta:apoapsis < 30.
set throttle to 1.
wait until periapsis > target_apo - 1000.
set throttle to 0.

// Print orbital parameters and end the script
print "Orbit achieved.".
print "Apoapsis: " + round(apoapsis) + " m.".
print "Periapsis: " + round(periapsis) + " m.".
print "Inclination: " + round(inclination) + " deg.".
print "End of script.".