diff --git a/src/fieldSources/basicSource/rotorDiskSource/rotorDiskSource.C b/src/fieldSources/basicSource/rotorDiskSource/rotorDiskSource.C
index e6381c543b85a280753e53e67f3ae812e09a6c85..20161147df03ba270214f9ca43515fa7d9415a3f 100644
--- a/src/fieldSources/basicSource/rotorDiskSource/rotorDiskSource.C
+++ b/src/fieldSources/basicSource/rotorDiskSource/rotorDiskSource.C
@@ -446,15 +446,15 @@ Foam::rotorDiskSource::rotorDiskSource
     inletVelocity_(vector::zero),
     tipEffect_(1.0),
     flap_(),
-    trim_(trimModel::New(*this, coeffs_)),
-    blade_(coeffs_.subDict("blade")),
-    profiles_(coeffs_.subDict("profiles")),
     x_(cells_.size(), vector::zero),
     R_(cells_.size(), I),
     invR_(cells_.size(), I),
     area_(cells_.size(), 0.0),
     coordSys_(false),
-    rMax_(0.0)
+    rMax_(0.0),
+    trim_(trimModel::New(*this, coeffs_)),
+    blade_(coeffs_.subDict("blade")),
+    profiles_(coeffs_.subDict("profiles"))
 {
     read(dict);
 }
@@ -521,9 +521,16 @@ void Foam::rotorDiskSource::calculate
             scalar invDr = 0.0;
             blade_.interpolate(radius, twist, chord, i1, i2, invDr);
 
+            // flip geometric angle if blade is spinning in reverse (clockwise)
+            scalar alphaGeom = alphag[i] + twist;
+            if (omega_ < 0)
+            {
+                alphaGeom = mathematical::pi - alphaGeom;
+            }
+
             // effective angle of attack
             scalar alphaEff =
-                mathematical::pi + atan2(Uc.z(), Uc.y()) - (alphag[i] + twist);
+                mathematical::pi + atan2(Uc.z(), Uc.y()) - alphaGeom;
 
             if (alphaEff > mathematical::pi)
             {
diff --git a/src/fieldSources/basicSource/rotorDiskSource/rotorDiskSource.H b/src/fieldSources/basicSource/rotorDiskSource/rotorDiskSource.H
index 2df09f9f7bb3224df9f5afebcffad5fd08dec50e..8e26425e10799c90efeb69da689bce5ad51fabaf 100644
--- a/src/fieldSources/basicSource/rotorDiskSource/rotorDiskSource.H
+++ b/src/fieldSources/basicSource/rotorDiskSource/rotorDiskSource.H
@@ -149,6 +149,7 @@ protected:
         word rhoName_;
 
         //- Rotational speed [rad/s]
+        //  Positive anti-clockwise when looking along -ve lift direction
         scalar omega_;
 
         //- Number of blades
@@ -167,15 +168,6 @@ protected:
         //- Blade flap coefficients [rad/s]
         flapData flap_;
 
-        //- Trim model
-        autoPtr<trimModel> trim_;
-
-        //- Blade data
-        bladeModel blade_;
-
-        //- Profile data
-        profileModelList profiles_;
-
         //- Cell centre positions in local rotor frame
         //  (Cylindrical r, theta, z)
         List<point> x_;
@@ -195,6 +187,15 @@ protected:
         //- Maximum radius
         scalar rMax_;
 
+        //- Trim model
+        autoPtr<trimModel> trim_;
+
+        //- Blade data
+        bladeModel blade_;
+
+        //- Profile data
+        profileModelList profiles_;
+
 
     // Protected Member Functions