diff --git a/boot/rocket.ks b/boot/rocket.ks
index 1a1b969..43a0472 100644
--- a/boot/rocket.ks
+++ b/boot/rocket.ks
@@ -2,7 +2,8 @@
 
 // Install software.
 compile "0:/os/rocketos" to "1:/boot/rocketos".
-compile "0:/lib/guidance" to "1:/lib/guidance".
+compile "0:/lib/navigation" to "1:/lib/navigation".
+compile "0:/lib/throttle" to "1:/lib/throttle".
 compile "0:/launch" to "1:/launch".
 
 // Set OS to boot and restart.
diff --git a/launch.ks b/launch.ks
index e912f82..4e7f7d5 100644
--- a/launch.ks
+++ b/launch.ks
@@ -1,7 +1,10 @@
-run once "lib/guidance".
+run once "lib/throttle".
+run once "lib/navigation".
 
-local APOAPSIS_TARGET is 80000.
-local GRAVITY_TURN_START is 5000.
+parameter APOAPSIS_TARGET is 80000.
+parameter GRAVITY_TURN_START is 8000.
+parameter GRAVITY_PITCH is 75.
+parameter INITIAL_PITCH is 85.
 SensorCheck().
 
 // Configure subsystems.
@@ -13,9 +16,8 @@ SAS off.
 print "Initiating automated launch sequence".
 from { local x is 5. } until x = 0 step { set x to x - 1. } do {
   print "..." + x.
-  wait 1.
+  wait 0.5.
 }
-print "Launching".
 
 // throttle controls
 when TWR() > 1.5 then {
@@ -30,26 +32,55 @@ when TWR() > 1.5 then {
 
 // Main ascent control.
 lock THROTTLE to 1.0.
-lock STEERING to heading(90,90,-90).
+lock STEERING to heading(90,90,270).
 stage.
 
+// // DEBUG
+// until false {
+//   lock STEERING to heading(90,90,-90).
+//   wait 3.
+//   lock STEERING to SHIP:SRFPROGRADE.
+//   wait 3.
+// }
+
 wait until SHIP:ALTITUDE > 200.
-lock STEERING to heading(90, 85, -90).
+lock STEERING to heading(90, GRAVITY_PITCH, 270).
 
 wait until SHIP:ALTITUDE > GRAVITY_TURN_START.
-print "Beginning gravity turn".
+
+print "Pitching for gravity turn".
+
+// Perform initial pitch...
+lock STEERING to heading(90, GRAVITY_PITCH, 270).
+// Wait until we have rotated to that pitch...
+wait until vectorangle(
+  SHIP:FACING:FOREVECTOR,
+  STEERINGMANAGER:TARGET:FOREVECTOR)
+  < 0.5.
+// then wait until Prograde catches up.
+wait until vectorangle(
+  SHIP:SRFPROGRADE:FOREVECTOR,
+  STEERINGMANAGER:TARGET:FOREVECTOR)
+  < 0.5.
+
+print "Locking to prograde".
+
 until SHIP:ORBIT:APOAPSIS > 80000 {
-  local adjustedPrograde is SHIP:ORBIT:PROGRADE * NORTH.
-  local angle is max(30, adjustedPrograde:pitch).
-  print "Adjusted Prograde = " + adjustedPrograde.
-  print "Angle = " + angle.
-  lock STEERING to heading(90, angle, -90).
+  // todo: we may need different values for bodies other than Kerbin.
+  local newHeading is lookdirup(SHIP:SRFPROGRADE:FOREVECTOR,
+    heading(90, 0, 270):TOPVECTOR).
+  if GetPitch(newHeading:FOREVECTOR) < 40 {
+    set newHeading to heading(90, 40, 270).
+  }
+  lock STEERING to newHeading.
   wait 0.001.
 }
 
 print "Releasing controls. Good luck, Kerman!".
-set THROTTLE to 0.0.
+lock THROTTLE to 0.0.
+wait 0.001.
 unlock THROTTLE.
 unlock STEERING.
+SAS on.
 wait 5.
 CORE:PART:GETMODULE("kOSProcessor"):DOEVENT("Close Terminal").
diff --git a/lib/navigation.ks b/lib/navigation.ks
new file mode 100644
index 0000000..45b7519
--- /dev/null
+++ b/lib/navigation.ks
@@ -0,0 +1,6 @@
+@lazyglobal off.
+
+function GetPitch {
+  parameter v is SHIP:FACING:FOREVECTOR.
+  return 90 - vectorangle(SHIP:UP:FOREVECTOR, v).
+}
diff --git a/lib/guidance.ks b/lib/throttle.ks
similarity index 100%
rename from lib/guidance.ks
rename to lib/throttle.ks
diff --git a/os/rocketos.ks b/os/rocketos.ks
index 9b6f667..71393ab 100644
--- a/os/rocketos.ks
+++ b/os/rocketos.ks
@@ -1,13 +1,36 @@
 function launchButtonPressed {
-  run "launch".
+run "launch"(
+  targetApo:TEXT:ToNumber(),
+  gravTurnStart:TEXT:ToNumber(),
+  initialPitch:TEXT:ToNumber()
+  ).
 }
 
 // Button panel
 local interface is gui(200).
+set interface:X to 150.
+set interface:Y to 900.
 
 // Launch button
-local launchButton is interface:addbutton("Launch").
+local hBox is interface:AddHBox().
+hBox:AddLabel("Initial Pitch").
+local initialPitch is hBox:AddTextField("85").
+
+local hBox is interface:AddHBox().
+hBox:AddLabel("Gravity Turn @").
+local gravTurnStart is hBox:AddTextField("8000").
+
+local hBox is interface:AddHBox().
+hBox:AddLabel("Gravity Pitch").
+local gravPitch is hBox:AddTextField("75").
+
+local hBox is interface:AddHBox().
+hBox:AddLabel("Target Apoapsis").
+local targetApo is hBox:AddTextField("80000").
+
+local launchButton is interface:AddButton("Launch").
 set launchButton:onClick to launchButtonPressed@.
+
 interface:show().
 
 wait until false.