Copter: fix heli pos-hold run-up-complete issue

ArduCopter/control_poshold.cpp

@@ -75,6 +75,13 @@ static struct {
 // poshold_init - initialise PosHold controller
 bool Copter::poshold_init(bool ignore_checks)
 {
+#if FRAME_CONFIG == HELI_FRAME
+    // do not allow helis to enter Pos Hold if the Rotor Runup is not complete
+    if (!ignore_checks && !motors.rotor_runup_complete()){
+        return false;
+    }
+#endif
+
     // fail to initialise PosHold mode if no GPS lock
     if (!position_ok() && !ignore_checks) {
         return false;
@@ -165,7 +172,12 @@ void Copter::poshold_run()
         takeoff_get_climb_rates(target_climb_rate, takeoff_climb_rate);
 
         // check for take-off
+#if FRAME_CONFIG == HELI_FRAME
+        // helicopters are held on the ground until rotor speed runup has finished
+        if (ap.land_complete && (takeoff_state.running || (target_climb_rate > 0.0f && motors.rotor_runup_complete()))) {
+#else
         if (ap.land_complete && (takeoff_state.running || target_climb_rate > 0.0f)) {
+#endif
             if (!takeoff_state.running) {
                 takeoff_timer_start(constrain_float(g.pilot_takeoff_alt,0.0f,1000.0f));
             }