Plane: Make radio trim optional at ground start.

ArduPlane/Parameters.h

@@ -132,6 +132,7 @@ public:
         k_param_stall_prevention,
         k_param_optflow,
         k_param_cli_enabled,
+        k_param_trim_rc_at_start,
 
         // 100: Arming parameters
         k_param_arming = 100,
@@ -332,6 +333,8 @@ public:
 
     AP_Int8  rtl_autoland;
 
+    AP_Int8  trim_rc_at_start;
+
     // Feed-forward gains
     //
     AP_Float kff_rudder_mix;

ArduPlane/Parameters.pde

@@ -923,6 +923,13 @@ const AP_Param::Info var_info[] PROGMEM = {
     // @User: Standard
     GSCALAR(rtl_autoland,         "RTL_AUTOLAND",   0),
 
+    // @Param: RC_TRIM_AT_START
+    // @DisplayNmae: RC Trims auto set at start.
+    // @Description: Automatically set roll/pitch trim from Tx at ground start. This makes the assumption that the RC transmitter has not been altered since trims were last captured.
+    // @Values: 0:Disable,1:Enable
+    // @User: Standard
+    GSCALAR(trim_rc_at_start,     "TRIM_RC_AT_START",    1), 
+
     // barometer ground calibration. The GND_ prefix is chosen for
     // compatibility with previous releases of ArduPlane
     // @Group: GND_

ArduPlane/system.pde

@@ -261,7 +261,9 @@ static void startup_ground(void)
 
     // read the radio to set trims
     // ---------------------------
-    trim_radio();               // This was commented out as a HACK.  Why?  I don't find a problem.
+    if (g.trim_rc_at_start != 0) {
+        trim_radio();
+    }
 
     // Save the settings for in-air restart
     // ------------------------------------