Plane: added plane specific arming checks

added check for roll and pitch limits, after flyaway due to small
LIM_ROLL_CD

ArduPlane/Plane.h

@@ -104,10 +104,26 @@
 #include <AP_HAL_Empty.h>
 #include <AP_HAL_VRBRAIN.h>
 
+/*
+  a plane specific arming class
+ */
+class AP_Arming_Plane : public AP_Arming
+{
+public:
+    AP_Arming_Plane(const AP_AHRS &ahrs_ref, const AP_Baro &baro, Compass &compass,
+                    const enum HomeState &home_set, gcs_send_t_p gcs_send) :
+        AP_Arming(ahrs_ref, baro, compass, home_set, gcs_send) {}
+    bool pre_arm_checks(bool report);
+};
+
+/*
+  main APM:Plane class
+ */
 class Plane {
 public:
     friend class GCS_MAVLINK;
     friend class Parameters;
+    friend class AP_Arming_Plane;
 
     Plane(void);
     void setup();
@@ -610,7 +626,7 @@ private:
 #endif
 
     // Arming/Disarming mangement class
-    AP_Arming arming {ahrs, barometer, compass, home_is_set, 
+    AP_Arming_Plane arming {ahrs, barometer, compass, home_is_set, 
             FUNCTOR_BIND_MEMBER(&Plane::gcs_send_text_P, void, gcs_severity, const prog_char_t *)};
 
     AP_Param param_loader {var_info};

ArduPlane/arming_checks.cpp

@@ -0,0 +1,47 @@
+// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+/*
+  additional arming checks for plane
+ */
+#include "Plane.h"
+
+/*
+  additional arming checks for plane
+ */
+bool AP_Arming_Plane::pre_arm_checks(bool report)
+{
+    // call parent class checks
+    bool ret = AP_Arming::pre_arm_checks(report);
+
+    if (plane.g.roll_limit_cd < 300) {
+        if (report) {
+            gcs_send_text_P(SEVERITY_HIGH,PSTR("PreArm: LIM_ROLL_CD too small"));        
+        }
+        ret = false;        
+    }
+
+    if (plane.aparm.pitch_limit_max_cd < 300) {
+        if (report) {
+            gcs_send_text_P(SEVERITY_HIGH,PSTR("PreArm: LIM_PITCH_MAX too small"));        
+        }
+        ret = false;        
+    }
+
+    if (plane.aparm.pitch_limit_min_cd > -300) {
+        if (report) {
+            gcs_send_text_P(SEVERITY_HIGH,PSTR("PreArm: LIM_PITCH_MIN too large"));        
+        }
+        ret = false;        
+    }
+
+    if (plane.channel_throttle->get_reverse() && 
+        plane.g.throttle_fs_enabled &&
+        plane.g.throttle_fs_value < 
+        plane.channel_throttle->radio_max) {
+        if (report) {
+            gcs_send_text_P(SEVERITY_HIGH,PSTR("PreArm: invalid THR_FS_VALUE for rev throttle"));        
+        }
+        ret = false;
+    }
+
+    return ret;
+}