ArduPlane: add QRTL always as Q_RTL_MODE option

ArduPlane/mode_rtl.cpp

@@ -108,11 +108,17 @@ void ModeRTL::navigate()
 
 // Switch to QRTL if enabled and within radius
 bool ModeRTL::switch_QRTL(bool check_loiter_target)
-{
-    if (!plane.quadplane.available() || (plane.quadplane.rtl_mode != QuadPlane::RTL_MODE::SWITCH_QRTL)) {
+{ 
+    if (!plane.quadplane.available() || ((plane.quadplane.rtl_mode != QuadPlane::RTL_MODE::SWITCH_QRTL) && (plane.quadplane.rtl_mode != QuadPlane::RTL_MODE::QRTL_ALWAYS))) {  
         return false;
     }
 
+   // if Q_RTL_MODE is QRTL always, then immediately switch to QRTL mode
+   if (plane.quadplane.rtl_mode == QuadPlane::RTL_MODE::QRTL_ALWAYS) {
+       plane.set_mode(plane.mode_qrtl, ModeReason::QRTL_INSTEAD_OF_RTL);
+       return true;
+   }
+
     uint16_t qrtl_radius = abs(plane.g.rtl_radius);
     if (qrtl_radius == 0) {
         qrtl_radius = abs(plane.aparm.loiter_radius);

ArduPlane/quadplane.cpp

@@ -195,8 +195,8 @@ const AP_Param::GroupInfo QuadPlane::var_info[] = {
 
     // @Param: RTL_MODE
     // @DisplayName: VTOL RTL mode
-    // @Description: If this is set to 1 then an RTL will change to QRTL when within RTL_RADIUS meters of the RTL destination, VTOL approach: vehicle will RTL at RTL alt and circle with a radius of Q_FW_LND_APR_RAD down to Q_RLT_ALT and then transission into the wind and QRTL, see 'AUTO VTOL Landing'
-    // @Values: 0:Disabled,1:Enabled,2:VTOL approach
+    // @Description: If this is set to 1 then an RTL will change to QRTL when within RTL_RADIUS meters of the RTL destination, VTOL approach: vehicle will RTL at RTL alt and circle with a radius of Q_FW_LND_APR_RAD down to Q_RLT_ALT and then transission into the wind and QRTL, see 'AUTO VTOL Landing', QRTL Always: do a QRTL instead of RTL
+    // @Values: 0:Disabled,1:Enabled,2:VTOL approach,3:QRTL Always
     // @User: Standard
     AP_GROUPINFO("RTL_MODE", 36, QuadPlane, rtl_mode, 0),
 

ArduPlane/quadplane.h

@@ -362,6 +362,7 @@ private:
         NONE,
         SWITCH_QRTL,
         VTOL_APPROACH_QRTL,
+        QRTL_ALWAYS,
     };
 
     // control if a VTOL GUIDED will be used