From 9a09a86bb8c4dc261ac22789709b003e1fd5ff3e Mon Sep 17 00:00:00 2001
From: Jonathan Challinger <mr.challinger@gmail.com>
Date: Fri, 22 Jan 2016 10:41:19 -0800
Subject: [PATCH] AP_Motors: add AP_MOTORS_DENSITY_COMP_DISABLED option

---
 libraries/AP_Motors/AP_MotorsMulticopter.cpp | 2 ++
 libraries/AP_Motors/AP_MotorsMulticopter.h   | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/libraries/AP_Motors/AP_MotorsMulticopter.cpp b/libraries/AP_Motors/AP_MotorsMulticopter.cpp
index 3cac7c2786..6d5944d6d0 100644
--- a/libraries/AP_Motors/AP_MotorsMulticopter.cpp
+++ b/libraries/AP_Motors/AP_MotorsMulticopter.cpp
@@ -333,10 +333,12 @@ float AP_MotorsMulticopter::get_compensation_gain() const
 
     float ret = 1.0f / _lift_max;
 
+#if AP_MOTORS_DENSITY_COMP == 1
     // air density ratio is increasing in density / decreasing in altitude
     if (_air_density_ratio > 0.3f && _air_density_ratio < 1.5f) {
         ret *= 1.0f / constrain_float(_air_density_ratio,0.5f,1.25f);
     }
+#endif
     return ret;
 }
 
diff --git a/libraries/AP_Motors/AP_MotorsMulticopter.h b/libraries/AP_Motors/AP_MotorsMulticopter.h
index 65b6b4d6d2..632f8e4c90 100644
--- a/libraries/AP_Motors/AP_MotorsMulticopter.h
+++ b/libraries/AP_Motors/AP_MotorsMulticopter.h
@@ -8,6 +8,10 @@
 
 #include "AP_Motors_Class.h"
 
+#ifndef AP_MOTORS_DENSITY_COMP
+#define AP_MOTORS_DENSITY_COMP 1
+#endif
+
 #define AP_MOTORS_DEFAULT_MIN_THROTTLE  130
 #define AP_MOTORS_DEFAULT_MID_THROTTLE  500
 #define AP_MOTORS_DEFAULT_MAX_THROTTLE  1000