Swap signs of the twist and incidence values to match the

documentation and author expectations.  Positive just wants to mean
"up", no matter what the axis conventions have to say.

diff --git a/src/FDM/YASim/FGFDM.cpp b/src/FDM/YASim/FGFDM.cpp
index 3bf8c80792673a3803dcf3b8c2655e8d6e87d78e..9fdbecd611d3059f3a1722e382bddc323ee30fc2 100644 (file)
--- a/src/FDM/YASim/FGFDM.cpp
+++ b/src/FDM/YASim/FGFDM.cpp
@@ -583,8 +583,12 @@ Wing* FGFDM::parseWing(XMLAttributes* a, const char* type)
     w->setTaper(attrf(a, "taper", 1));
     w->setDihedral(attrf(a, "dihedral", defDihed) * DEG2RAD);
     w->setCamber(attrf(a, "camber", 0));
-    w->setIncidence(attrf(a, "incidence", 0) * DEG2RAD);
-    w->setTwist(attrf(a, "twist", 0) * DEG2RAD);
+
+    // These come in with positive indicating positive AoA, but the
+    // internals expect a rotation about the left-pointing Y axis, so
+    // invert the sign.
+    w->setIncidence(attrf(a, "incidence", 0) * DEG2RAD * -1);
+    w->setTwist(attrf(a, "twist", 0) * DEG2RAD * -1);
 
     // The 70% is a magic number that sorta kinda seems to match known
     // throttle settings to approach speed.