diff --git a/libraries/AP_Motors/AP_MotorsHeli.cpp b/libraries/AP_Motors/AP_MotorsHeli.cpp
index 458d639aa89d0b..9934350bf21897 100644
--- a/libraries/AP_Motors/AP_MotorsHeli.cpp
+++ b/libraries/AP_Motors/AP_MotorsHeli.cpp
@@ -623,3 +623,10 @@ float AP_MotorsHeli::get_cyclic_angle_scaler(void) const {
     return ((float)(_collective_max-_collective_min))*1e-3 * (_collective_max_deg.get() - _collective_min_deg.get()) * 2.0;
 }
 #endif
+
+// function to calculate the normalised collective position given a desired blade pitch angle (deg)
+float AP_MotorsHeli::calc_coll_from_ang(float col_ang_deg) const
+{
+    float col_norm = col_ang_deg / MAX((_collective_max_deg.get() - _collective_min_deg.get()), 1.0);
+    return constrain_float(col_norm, 0.0, 1.0);
+}
diff --git a/libraries/AP_Motors/AP_MotorsHeli.h b/libraries/AP_Motors/AP_MotorsHeli.h
index 8dc690611b95d4..03d9832f5e6b46 100644
--- a/libraries/AP_Motors/AP_MotorsHeli.h
+++ b/libraries/AP_Motors/AP_MotorsHeli.h
@@ -118,8 +118,8 @@ class AP_MotorsHeli : public AP_Motors {
     // support passing init_targets_on_arming flag to greater code
     bool init_targets_on_arming() const override { return _heliflags.init_targets_on_arming; }
 
-    // arot_man_enabled - gets contents of manual_autorotation_enabled parameter
-    bool arot_man_enabled() const { return _main_rotor.autorotation_enabled(); }
+    // rsc_arot_enabled - gets contents of manual_autorotation_enabled parameter
+    bool rsc_arot_enabled() const { return _main_rotor.autorotation_enabled(); }
 
     // helper for vehicle code to request autorotation states in the RSC.
     void set_autorotation_active(bool tf) { _main_rotor.set_autorotation_active(tf); }
@@ -135,8 +135,11 @@ class AP_MotorsHeli : public AP_Motors {
 
     // set land complete flag
     void set_land_complete(bool landed) { _heliflags.land_complete = landed; }
-	
-	//return zero lift collective position
+
+    // function to calculate the normalised collective position given a desired blade pitch angle (deg)
+    float calc_coll_from_ang(float col_ang_deg) const;
+
+    //return zero lift collective position
     float get_coll_mid() const { return _collective_zero_thrust_pct; }
 
     // enum for heli optional features