Landing Burn

// Landing Burn

// Configuration
set radarOffset to 27.977.                                  // Measure "alt:radar" of the vehicle when landed

// Physics
lock trueRadar to alt:radar - radarOffset.                  // Distance from the bottom of vehicle to the ground
lock g to constant:g * body:mass / body:radius^2.           // Gravitational acceleration
lock maxDecel to (ship:availablethrust / ship:mass) - g.    // Maximum achievable deceleration of the vehicle
lock stopDist to ship:verticalspeed^2 / (2 * maxDecel).     // Distance to kill all the velocity
lock idealThrottle to stopDist / trueRadar.                 // Hoverslam throttling setting
lock impactTime to trueRadar / abs(ship:verticalspeed).     // Time to impact with the current velocity

// State variables
set burnStarted to 0.                                       // 1 if landing burn has started

clearscreen.

wait until ship:verticalspeed < -1.
    print "Preparing for landing burn...".
    rcs on.
    brakes on.
    lock steering to srfretrograde.

wait until trueRadar < stopDist.
    print "Landing burn has begun!".
    set burnStarted to 1.
    lock throttle to idealThrottle.

wait until burnStarted = 1.
    until impactTime < 4.
        print "Deploying landing legs...".
        gear on.

wait until ship:verticalspeed > -0.01.
    print "Landed!".
    set ship:control:pilotmainthrottle to 0.
    wait 5.
    rcs off.
    sas off.
    brakes off.