Fix all hardcoded values to the parachute area.

tests/TestExternalReactions.py

@@ -23,6 +23,12 @@
 
 from JSBSim_utils import JSBSimTestCase, CreateFDM, RunTest, CopyAircraftDef
 
+def getParachuteArea(tree):
+    parachute_area = 1.0
+    for value in tree.getroot().findall('external_reactions/force/function/product/value'):
+        parachute_area *= float(value.text)
+    return parachute_area
+
 class TestExternalReactions(JSBSimTestCase):
     def getLeverArm(self, fdm, name):
         lax = (fdm['external_reactions/'+name+'/location-x-in']
@@ -52,9 +58,12 @@ def test_wind_frame(self):
         self.assertAlmostEqual(fdm['external_reactions/parachute/y'], 0.0)
         self.assertAlmostEqual(fdm['external_reactions/parachute/z'], 0.0)
 
+        tree, _, _ = CopyAircraftDef(script_path, self.sandbox)
+        parachute_area = getParachuteArea(tree)
+
         while fdm.run():
             Tw2b = fdm.get_auxiliary().get_Tw2b()
-            mag = fdm['aero/qbar-psf'] * fdm['fcs/parachute_reef_pos_norm']*10000.0
+            mag = fdm['aero/qbar-psf'] * fdm['fcs/parachute_reef_pos_norm']*parachute_area
             f = Tw2b * np.mat([-1.0, 0.0, 0.0]).T * mag
             self.assertAlmostEqual(fdm['forces/fbx-external-lbs'], f[0, 0])
             self.assertAlmostEqual(fdm['forces/fby-external-lbs'], f[1, 0])
@@ -227,11 +236,7 @@ def test_moment(self):
         self.assertAlmostEqual(fdm['external_reactions/parachute/n'], mDir[2])
 
         fdm['external_reactions/parachute/magnitude-lbsft'] = -3.5
-
-        # Compute the parachute_area
-        parachute_area = 1.0
-        for value in extReact_element.findall('force/function/product/value'):
-            parachute_area *= float(value.text)
+        parachute_area = getParachuteArea(tree)
 
         while fdm.run():
             Tw2b = fdm.get_auxiliary().get_Tw2b()