From 8ec622d49763f192e02b75ae487074d3916e6cfc Mon Sep 17 00:00:00 2001
From: Serkan Mazlum <74418302+serkanMzlm@users.noreply.github.com>
Date: Wed, 13 Dec 2023 21:29:21 +0300
Subject: [PATCH 1/2] Fix incorrect light direction in  tunnel.sdf example
 (#2264)

The light on top of the vehicle was facing the wrong direction

---------

Signed-off-by: Serkan Mazlum <74418302+serkanMzlm@users.noreply.github.com>
---
 examples/worlds/tunnel.sdf | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/worlds/tunnel.sdf b/examples/worlds/tunnel.sdf
index a902e40f03..91c069437a 100644
--- a/examples/worlds/tunnel.sdf
+++ b/examples/worlds/tunnel.sdf
@@ -1165,7 +1165,7 @@
                     <outer_angle>1.1</outer_angle>
                     <falloff>1</falloff>
                 </spot>
-                <direction>0 -1 0</direction>
+                <direction>0 0 -1</direction>
                 <cast_shadows>1</cast_shadows>
             </light>
         <sensor name="camera" type="camera">

From 4eb94843a198e177dfff195e7ac0d3ff6af26eee Mon Sep 17 00:00:00 2001
From: Arjo Chakravarty <arjoc@intrinsic.ai>
Date: Wed, 27 Dec 2023 15:17:44 +0800
Subject: [PATCH 2/2] Default CMA in LiftDrag pluginto zero (#2272)

* Default CMA in LiftDrag pluginto zero

The changes in #2189 have caused a regression for our upstream users.
This fix disables moment calculations by defaulting Cma to zero. It
should help mitigate some of the regression. There is also an [ongoing
discussion](https://github.com/gazebosim/gz-sim/pull/2189#issuecomment-1866589946) as to whether the cos term should be cos^2 or cos.

Signed-off-by: Arjo Chakravarty <arjoc@intrinsic.ai>

* remove cos change to address one problem at a time

Signed-off-by: Arjo Chakravarty <arjoc@intrinsic.ai>

---------

Signed-off-by: Arjo Chakravarty <arjoc@intrinsic.ai>
---
 src/systems/lift_drag/LiftDrag.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/systems/lift_drag/LiftDrag.cc b/src/systems/lift_drag/LiftDrag.cc
index cd58c9f22c..b16766e6a0 100644
--- a/src/systems/lift_drag/LiftDrag.cc
+++ b/src/systems/lift_drag/LiftDrag.cc
@@ -74,7 +74,7 @@ class gz::sim::systems::LiftDragPrivate
   /// \brief Coefficient of Moment / alpha slope.
   /// Moment = C_M * q * S
   /// where q (dynamic pressure) = 0.5 * rho * v^2
-  public: double cma = 0.01;
+  public: double cma = 0.0;
 
   /// \brief angle of attach when airfoil stalls
   public: double alphaStall = GZ_PI_2;