I see your issue. It only locks the steering once. You need to put your lock steering line into a loop with your code that updates the pVal. Try this instead. clearscreen. set mOrbit to 200000. set mAtmoHight to 70000. set pVal to 0. print "fasten your seatbelts!". wait 1. lock steering to UP + R(0,0,180) - R(0,pVal,0). lock throttle to 1. print "here we go...". until apoapsis > mAtmoHight { print pVal. set pVal to apoapsis / mAtmoHight * 90. [B] lock steering to UP + R(0,0,180) - R(0,pVal,0).[/B] }.