diff --git a/conf/airframes/twinstar3.xml b/conf/airframes/twinstar3.xml
index 6623a4eafc..affdded8e9 100755
--- a/conf/airframes/twinstar3.xml
+++ b/conf/airframes/twinstar3.xml
@@ -35,7 +35,7 @@
     <define name="RAD_OF_IR_CONTRAST" value="0.75"/>
     <linear name="RollOfIrs" arity="2" coeff1="-1" coeff2="-1"/>
     <linear name="PitchOfIrs" arity="2" coeff1="-1" coeff2="1"/>
-    <define name="RAD_OF_IR_MAX_VALUE" value="0.0045"/>
+    <define name="RAD_OF_IR_MAX_VALUE" value="0.01"/>
     <define name="RAD_OF_IR_MIN_VALUE" value="0.00075"/>
     <define name="ADC_ROLL_NEUTRAL" value="-1026"/>
     <define name="ADC_PITCH_NEUTRAL" value="5"/>
diff --git a/sw/simulator/flightModel.ml b/sw/simulator/flightModel.ml
index 92bd34be87..1d3eda25ed 100644
--- a/sw/simulator/flightModel.ml
+++ b/sw/simulator/flightModel.ml
@@ -66,33 +66,33 @@ let g = 9.81
 module Make(A:Data.MISSION) = struct
   open Data
 
-let section = fun name ->
-  try
-    ExtXml.child A.ac.airframe ~select:(fun x -> ExtXml.attrib x "name" = name) "section"
-  with
-    Not_found ->
-      failwith (Printf.sprintf "Child 'section' with 'name=%s' expected in '%s'\n" name (Xml.to_string A.ac.airframe))
+  let section = fun name ->
+    try
+      ExtXml.child A.ac.airframe ~select:(fun x -> ExtXml.attrib x "name" = name) "section"
+    with
+      Not_found ->
+	failwith (Printf.sprintf "Child 'section' with 'name=%s' expected in '%s'\n" name (Xml.to_string A.ac.airframe))
 
 
-let simu_section = section "SIMU"
+  let simu_section = section "SIMU"
 
-let defined_value = fun sect name ->
-  try
-    (Xml.attrib (ExtXml.child sect ~select:(fun x -> ExtXml.attrib x "name" = name) "define") "value")
-  with
-    Not_found ->
-      failwith (Printf.sprintf "Child 'define' with 'name=%s' expected in '%s'\n" name (Xml.to_string sect))
+  let defined_value = fun sect name ->
+    try
+      (Xml.attrib (ExtXml.child sect ~select:(fun x -> ExtXml.attrib x "name" = name) "define") "value")
+    with
+      Not_found ->
+	failwith (Printf.sprintf "Child 'define' with 'name=%s' expected in '%s'\n" name (Xml.to_string sect))
 
-let float_value = fun section s ->  float_of_string (defined_value section s)
+  let float_value = fun section s ->  float_of_string (defined_value section s)
 
-let roll_response_factor = float_value simu_section "ROLL_RESPONSE_FACTOR"
+  let roll_response_factor = float_value simu_section "ROLL_RESPONSE_FACTOR"
 
-let yaw_response_factor = float_value simu_section "YAW_RESPONSE_FACTOR"
+  let yaw_response_factor = float_value simu_section "YAW_RESPONSE_FACTOR"
 
-let weight = float_value simu_section "WEIGHT"
+  let weight = float_value simu_section "WEIGHT"
 
-let max_phi = 0.7 (* rad *)
-let bound = fun x mi ma -> if x > ma then ma else if x < mi then mi else x
+  let max_phi = 0.7 (* rad *)
+  let bound = fun x mi ma -> if x > ma then ma else if x < mi then mi else x
 
 
 
@@ -129,14 +129,14 @@ let bound = fun x mi ma -> if x > ma then ma else if x < mi then mi else x
       Not_found ->
 	failwith (Printf.sprintf "Child 'servos' expected in '%s'\n" (Xml.to_string A.ac.airframe))
 	  
-let misc_section = section "MISC"
+  let misc_section = section "MISC"
 
-let infrared_section = section "INFRARED"
+  let infrared_section = section "INFRARED"
 
+  let nominal_airspeed = float_of_string (defined_value misc_section "NOMINAL_AIRSPEED")
 
-let nominal_airspeed = float_of_string (defined_value misc_section "NOMINAL_AIRSPEED")
-
-let ir_roll_neutral = ios (defined_value infrared_section "ADC_ROLL_NEUTRAL")
+  let adc_roll_neutral = ios (defined_value infrared_section "ADC_ROLL_NEUTRAL")
+  let roll_neutral_default = rad_of_deg (float_value infrared_section "ROLL_NEUTRAL_DEFAULT")
 
   let get_servo name =
     try
@@ -181,9 +181,9 @@ let ir_roll_neutral = ios (defined_value infrared_section "ADC_ROLL_NEUTRAL")
 	and no_aileron_left = int_attrib aileron_left "no" in
 	fun state servo ->
 	  let left = - sign_aileron_left * (servo.(no_aileron_left) - n_delta_a) in
-	(** if left <> 0 then Printf.printf "left=%d\n" (servo.(no_aileron_left) - n_delta_a); flush stdout;  **)
-	state.delta_a <- c_lda *. float left;
-	do_thrust state servo
+	  (** if left <> 0 then Printf.printf "left=%d\n" (servo.(no_aileron_left) - n_delta_a); flush stdout;  **)
+	  state.delta_a <- c_lda *. float left;
+	  do_thrust state servo
     | None, Some ailevon_left, Some ailevon_right ->
 	let c_lda = 2.5e-4 in (* phi_dot_dot from aileron *)
 
diff --git a/sw/simulator/flightModel.mli b/sw/simulator/flightModel.mli
index 117c48eeb4..70dd9b3d80 100644
--- a/sw/simulator/flightModel.mli
+++ b/sw/simulator/flightModel.mli
@@ -44,6 +44,7 @@ module Make :
       val do_servos : state -> Stdlib.us array -> unit
       val nb_servos : int
       val nominal_airspeed : float (* m/s *)
+      val roll_neutral_default : float (* rad *)
       val state_update : state -> float * float -> float -> unit
       (** [state_update state (wind_x, wind_y) dt] With m/s for wind and s for
 	 dt *)
diff --git a/sw/simulator/sim.ml b/sw/simulator/sim.ml
index f3ef0a2e82..c583c716ab 100644
--- a/sw/simulator/sim.ml
+++ b/sw/simulator/sim.ml
@@ -149,7 +149,8 @@ module Make(AircraftItl : AIRCRAFT_ITL) = struct
 		horizon_right -. horizon_left
 	      else
 		0. in
-	    let ir_left = ( (phi +. delta_ir ) *. !infrared_contrast)
+	    let phi = phi +. FM.roll_neutral_default in
+	    let ir_left = (phi +. delta_ir ) *. !infrared_contrast
 	    and ir_front = 0. in
 	    Aircraft.infrared ir_left ir_front
       with
diff --git a/sw/simulator/sitl.ml b/sw/simulator/sitl.ml
index 1eccd51a9b..be90d9f192 100644
--- a/sw/simulator/sitl.ml
+++ b/sw/simulator/sitl.ml
@@ -139,6 +139,7 @@ module Make(A:Data.MISSION) = struct
 
   external set_ir_roll : int -> unit = "set_ir_roll"
   let infrared = fun ir_left ir_front ->
+    (** ADC neutral is not taken into account in the soft sim (c.f. sim_ir.c)*)
     set_ir_roll (truncate ir_left)
 
   external use_gps_pos: int -> int -> int -> float -> float -> float -> float -> float -> bool -> unit = "sim_use_gps_pos_bytecode" "sim_use_gps_pos"