From ef2898f25ce04ce6440c8f4723e92cacd8a6dd14 Mon Sep 17 00:00:00 2001
From: Colin Douglas Howell <colin.d.howell@gmail.com>
Date: Fri, 4 Apr 2014 23:05:23 -0700
Subject: [PATCH] Corrected fix for issue 1423 (YASim miscomputes incidence
 rotation of force vector)

I got the sign wrong in my previous fix, causing the vector to be rotated the
wrong way. See my latest comments in issue 1423. Sorry about that.
---
 src/FDM/YASim/Surface.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/FDM/YASim/Surface.cpp b/src/FDM/YASim/Surface.cpp
index 2baa42baa..25d8da489 100644
--- a/src/FDM/YASim/Surface.cpp
+++ b/src/FDM/YASim/Surface.cpp
@@ -228,7 +228,7 @@ void Surface::calcForce(float* v, float rho, float* out, float* torque)
     // coordinates. Since out[] is now the force vector and is
     // roughly parallel with Z, the small-angle approximation
     // must change its X component.
-    out[0] -= incidence * out[2];
+    out[0] += incidence * out[2];
 
     // Convert back to external coordinates
     Math::tmul33(_orient, out, out);