diff --git a/src/FDM/YASim/FGFDM.cpp b/src/FDM/YASim/FGFDM.cpp
index 8bcd6437f..e5e3f51f5 100644
--- a/src/FDM/YASim/FGFDM.cpp
+++ b/src/FDM/YASim/FGFDM.cpp
@@ -27,25 +27,6 @@
 
 namespace yasim {
 
-// Some conversion factors
-static const float KTS2MPS = 0.514444444444;
-static const float KMH2MPS = 1/3.6;
-static const float FT2M = 0.3048;
-static const float DEG2RAD = 0.0174532925199;
-static const float RPM2RAD = 0.10471975512;
-static const float LBS2N = 4.44822;
-static const float LBS2KG = 0.45359237;
-static const float KG2LBS = 2.2046225;
-static const float CM2GALS = 264.172037284;
-static const float HP2W = 745.700;
-static const float INHG2PA = 3386.389;
-static const float K2DEGF = 1.8;
-static const float K2DEGFOFFSET = -459.4;
-static const float CIN2CM = 1.6387064e-5;
-static const float YASIM_PI = 3.14159265358979323846;
-
-static const float NM2FTLB = (1/(LBS2N*FT2M));
-
 // Stubs, so that this can be compiled without the FlightGear
 // binary.  What's the best way to handle this?
 
diff --git a/src/FDM/YASim/FGFDM.hpp b/src/FDM/YASim/FGFDM.hpp
index c888202d2..28eabba21 100644
--- a/src/FDM/YASim/FGFDM.hpp
+++ b/src/FDM/YASim/FGFDM.hpp
@@ -4,6 +4,7 @@
 #include <simgear/xml/easyxml.hxx>
 #include <simgear/props/props.hxx>
 
+#include "yasim-common.hpp"
 #include "Airplane.hpp"
 #include "Vector.hpp"
 
diff --git a/src/FDM/YASim/YASim.cxx b/src/FDM/YASim/YASim.cxx
index f966b29e1..cfdf70d3f 100644
--- a/src/FDM/YASim/YASim.cxx
+++ b/src/FDM/YASim/YASim.cxx
@@ -15,6 +15,7 @@
 #include <Main/globals.hxx>
 #include <Main/fg_props.hxx>
 
+#include "yasim-common.hpp"
 #include "FGFDM.hpp"
 #include "Atmosphere.hpp"
 #include "Math.hpp"
@@ -34,22 +35,6 @@
 using namespace yasim;
 using std::string;
 
-static const float YASIM_PI = 3.14159265358979323846;
-static const float RAD2DEG = 180/YASIM_PI;
-static const float PI2 = YASIM_PI*2;
-static const float M2FT = 3.2808399;
-static const float FT2M = 0.3048;
-static const float MPS2KTS = 3600.0/1852.0;
-static const float INHG2PA = 3386.389;
-static const float SLUG2KG = 14.59390;
-
-#if 0 // unused constant values
-static const float RAD2RPM = 9.54929658551;
-static const float CM2GALS = 264.172037284; // gallons/cubic meter
-static const float KG2LBS = 2.20462262185;
-static const float W2HP = 1.3416e-3;
-#endif
-
 YASim::YASim(double dt) :
     _simTime(0)
 {
diff --git a/src/FDM/YASim/proptest.cpp b/src/FDM/YASim/proptest.cpp
index 29a1aeec6..c32c849e3 100644
--- a/src/FDM/YASim/proptest.cpp
+++ b/src/FDM/YASim/proptest.cpp
@@ -29,23 +29,6 @@ float fgGetFloat (const char * name, float defaultValue) { return 0; }
 double fgGetDouble (const char * name, double defaultValue) { return 0; }
 bool fgSetDouble (const char * name, double defaultValue) { return false; }
 
-static const float KTS2MPS = 0.514444444444;
-static const float RPM2RAD = 0.10471975512;
-static const float HP2W = 745.700;
-static const float FT2M = 0.3048;
-static const float N2LB = 0.224809;
-
-// static const float DEG2RAD = 0.0174532925199;
-// static const float LBS2N = 4.44822;
-// static const float LBS2KG = 0.45359237;
-// static const float KG2LBS = 2.2046225;
-// static const float CM2GALS = 264.172037284;
-// static const float INHG2PA = 3386.389;
-// static const float K2DEGF = 1.8;
-// static const float K2DEGFOFFSET = -459.4;
-// static const float CIN2CM = 1.6387064e-5;
-// static const float YASIM_PI = 3.14159265358979323846;
-
 const int COUNT = 100;
 
 int main(int argc, char** argv)
diff --git a/src/FDM/YASim/yasim-common.hpp b/src/FDM/YASim/yasim-common.hpp
new file mode 100644
index 000000000..6f2678087
--- /dev/null
+++ b/src/FDM/YASim/yasim-common.hpp
@@ -0,0 +1,34 @@
+#ifndef _YASIM_COMMON_HPP
+#define _YASIM_COMMON_HPP
+
+namespace yasim {
+  static const float YASIM_PI = 3.14159265358979323846;
+  static const float PI2 = YASIM_PI*2;
+  static const float RAD2DEG = 180/YASIM_PI;
+  static const float DEG2RAD = YASIM_PI/180;
+  static const float RPM2RAD = YASIM_PI/30;
+
+  static const float KTS2MPS = 1852.0/3600.0;
+  static const float MPS2KTS = 3600.0/1852.0;
+  static const float KMH2MPS = 1/3.6;
+
+  static const float FT2M = 0.3048;
+  static const float M2FT = 1/FT2M;
+
+  static const float LBS2N = 4.44822;
+  static const float N2LB = 1/LBS2N;
+  static const float LBS2KG = 0.45359237;
+  static const float KG2LBS = 1/LBS2KG;
+  static const float CM2GALS = 264.172037284;
+  static const float HP2W = 745.700;
+  static const float INHG2PA = 3386.389;
+  static const float K2DEGF = 1.8;
+  static const float K2DEGFOFFSET = -459.4;
+  static const float CIN2CM = 1.6387064e-5;
+  
+  static const float NM2FTLB = (1/(LBS2N*FT2M));
+  static const float SLUG2KG = 14.59390;
+    
+};
+
+#endif // ifndef _YASIM_COMMON_HPP
diff --git a/src/FDM/YASim/yasim-test.cpp b/src/FDM/YASim/yasim-test.cpp
index 25783bfa1..58efbfafe 100644
--- a/src/FDM/YASim/yasim-test.cpp
+++ b/src/FDM/YASim/yasim-test.cpp
@@ -7,6 +7,7 @@
 #include <simgear/xml/easyxml.hxx>
 #include <simgear/misc/sg_path.hxx>
 
+#include "yasim-common.hpp"
 #include "FGFDM.hpp"
 #include "Atmosphere.hpp"
 #include "RigidBody.hpp"
@@ -26,11 +27,6 @@ float fgGetFloat (const char * name, float defaultValue) { return 0; }
 double fgGetDouble (const char * name, double defaultValue = 0.0) { return 0; }
 bool fgSetDouble (const char * name, double defaultValue = 0.0) { return 0; }
 
-static const float RAD2DEG = 57.2957795131;
-static const float DEG2RAD = 0.0174532925199;
-/// knots 2 meters per second
-static const float KTS2MPS = 0.514444444444;
-
 
 enum Config 
 {