Merge pull request #623 from danielenriquez59/develop

Address issue #620
suavecode · Nov 6, 2022 · d1299d0 · d1299d0
2 parents dc46e12 + d0cdc76
commit d1299d0
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Showing 2 changed files with 7 additions and 5 deletions.
diff --git a/trunk/SUAVE/Analyses/Stability/Fidelity_Zero.py b/trunk/SUAVE/Analyses/Stability/Fidelity_Zero.py
@@ -185,7 +185,8 @@ def __call__(self,conditions):
 
             # Derivative of pitching moment with respect to pitch rate
             l_t                    = geometry.wings['horizontal_stabilizer'].origin[0][0] + geometry.wings['horizontal_stabilizer'].aerodynamic_center[0] - geometry.wings['main_wing'].origin[0][0] - geometry.wings['main_wing'].aerodynamic_center[0] #Need to check this is the length of the horizontal tail moment arm       
-            stability.static.Cm_q  = Supporting_Functions.cm_q(conditions.lift_curve_slope, l_t,mac) # Need to check Cm_i versus Cm_alpha
+            vht                    = geometry.wings['horizontal_stabilizer'].areas.reference * l_t / (geometry.reference_area*geometry.wings['main_wing'].chords.mean_aerodynamic)
+            stability.static.Cm_q  = Supporting_Functions.cm_q(conditions.lift_curve_slope, vht, l_t,mac) # Need to check Cm_i versus Cm_alpha
 
             # Derivative of pitching rate with respect to d(alpha)/d(t)
             stability.static.Cm_alpha_dot = Supporting_Functions.cm_alphadot(stability.static.Cm_alpha, geometry.wings['horizontal_stabilizer'].ep_alpha, l_t, mac) # Need to check Cm_i versus Cm_alpha

diff --git a/.../Flight_Dynamics/Dynamic_Stability/Full_Linearized_Equations/Supporting_Functions/cm_q.py b/.../Flight_Dynamics/Dynamic_Stability/Full_Linearized_Equations/Supporting_Functions/cm_q.py
@@ -3,13 +3,14 @@
 # 
 # Created:  Jun 2014, A. Wendorff
 # Modified: Jan 2016, E. Botero
+# Modified: Nov 2022, D. Enriquez
 
 # ----------------------------------------------------------------------
 #   Method
 # ----------------------------------------------------------------------
 
 ## @ingroup Methods-Flight_Dynamics-Dynamic_Stability-Full_Linearized_Equations-Supporting_Functions
-def cm_q(cm_i, l_t, mac):
+def cm_q(cla, vht, l_t, mac):
     """ This calculates the damping in pitch coefficient        
 
     Assumptions:
@@ -30,6 +31,6 @@ def cm_q(cm_i, l_t, mac):
     Properties Used:
     N/A           
     """
-    cm_q = 2. * 1.1 * cm_i * l_t / mac 
-
-    return cm_q
+    cm_q = -2. * l_t / mac * vht * cla
+    cm_q = cm_q * 1.1 # factor to account for fuselage contribution
+    return cm_q