From 752b8d0accaedd35a7b5efa178354a2eb5e4b659 Mon Sep 17 00:00:00 2001
From: Erik Hofman <erik@ehofman.com>
Date: Wed, 3 Jun 2015 13:55:00 +0200
Subject: [PATCH] Add the option to (properly) revert the propellers moment of
 inertia calculation

---
 src/FDM/JSBSim/models/propulsion/FGPropeller.cpp | 10 ++++++++--
 src/FDM/JSBSim/models/propulsion/FGPropeller.h   |  6 +++---
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/FDM/JSBSim/models/propulsion/FGPropeller.cpp b/src/FDM/JSBSim/models/propulsion/FGPropeller.cpp
index 7ed41d49a..6b36d5dec 100644
--- a/src/FDM/JSBSim/models/propulsion/FGPropeller.cpp
+++ b/src/FDM/JSBSim/models/propulsion/FGPropeller.cpp
@@ -45,7 +45,7 @@ using namespace std;
 
 namespace JSBSim {
 
-IDENT(IdSrc,"$Id: FGPropeller.cpp,v 1.49 2014/12/27 14:37:37 dpculp Exp $");
+IDENT(IdSrc,"$Id: FGPropeller.cpp,v 1.51 2015/04/20 12:12:49 ehofman Exp $");
 IDENT(IdHdr,ID_PROPELLER);
 
 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -79,6 +79,12 @@ FGPropeller::FGPropeller(FGFDMExec* exec, Element* prop_element, int num)
 
   if (prop_element->FindElement("ixx"))
     Ixx = prop_element->FindElementValueAsNumberConvertTo("ixx", "SLUG*FT2");
+
+  Sense_multiplier = 1.0;
+  if (prop_element->HasAttribute("version"))
+    if  (prop_element->GetAttributeValueAsNumber("version") > 1.0)
+      Sense_multiplier = -1.0;
+
   if (prop_element->FindElement("diameter"))
     Diameter = prop_element->FindElementValueAsNumberConvertTo("diameter", "FT");
   if (prop_element->FindElement("numblades"))
@@ -273,7 +279,7 @@ double FGPropeller::Calculate(double EnginePower)
   // natural axis of the engine. The transform takes place in the base class
   // FGForce::GetBodyForces() function.
 
-  vH(eX) = Ixx*omega*Sense;
+  vH(eX) = Ixx*omega*Sense*Sense_multiplier;
   vH(eY) = 0.0;
   vH(eZ) = 0.0;
 
diff --git a/src/FDM/JSBSim/models/propulsion/FGPropeller.h b/src/FDM/JSBSim/models/propulsion/FGPropeller.h
index ceb4b326a..192782411 100644
--- a/src/FDM/JSBSim/models/propulsion/FGPropeller.h
+++ b/src/FDM/JSBSim/models/propulsion/FGPropeller.h
@@ -45,7 +45,7 @@ INCLUDES
 DEFINITIONS
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
-#define ID_PROPELLER "$Id: FGPropeller.h,v 1.20 2011/10/31 14:54:41 bcoconni Exp $"
+#define ID_PROPELLER "$Id: FGPropeller.h,v 1.22 2015/04/20 11:40:45 ehofman Exp $"
 
 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 FORWARD DECLARATIONS
@@ -142,7 +142,7 @@ CLASS DOCUMENTATION
     <li>Various NACA Technical Notes and Reports</li>
     </ul>
     @author Jon S. Berndt
-    @version $Id: FGPropeller.h,v 1.20 2011/10/31 14:54:41 bcoconni Exp $
+    @version $Id: FGPropeller.h,v 1.22 2015/04/20 11:40:45 ehofman Exp $
     @see FGEngine
     @see FGThruster
 */
@@ -283,7 +283,7 @@ private:
   double MaxRPM;
   double Pitch;
   double P_Factor;
-  double Sense;
+  double Sense, Sense_multiplier;
   double Advance;
   double ExcessTorque;
   double D4;
-- 
2.39.5