@lazyglobal off.
wait until ship:unpacked.
lock throttle to 1.0.

local booster is ship:partstagged("booster")[0].
local sustainer is ship:partstagged("sustainer")[0].

from {local countdown is 3.} until countdown = 0 step {set countdown to countdown - 1.} do {
    hudtext( "..." + countdown, 1, 2, 15, yellow, false).
    wait 1.
}

// Launch!
stage.

// Drop Booster
wait until stage:ready.
wait until sustainer:thrust > booster:thrust.
stage.

// Drop payload & arm chute
wait until stage:ready.
wait until ship:verticalspeed < 0.
stage.