Plane: make TECS the default speed/height controller

ArduPlane/ArduPlane.pde

@@ -802,7 +802,9 @@ static void fast_loop()
  */
 static void update_speed_height(void)
 {
-    if (g.alt_control_algorithm == ALT_CONTROL_TECS && auto_throttle_mode && !throttle_suppressed) 
+    if ((g.alt_control_algorithm == ALT_CONTROL_TECS ||
+         g.alt_control_algorithm == ALT_CONTROL_DEFAULT) &&
+        auto_throttle_mode && !throttle_suppressed) 
     {
 	    // Call TECS 50Hz update
         SpdHgt_Controller->update_50hz(relative_altitude());
@@ -1279,7 +1281,7 @@ static void update_alt()
     //	add_altitude_data(millis() / 100, g_gps->altitude / 10);
 
     // Update the speed & height controller states
-    if (g.alt_control_algorithm == ALT_CONTROL_TECS &&
+    if ((g.alt_control_algorithm == ALT_CONTROL_TECS || g.alt_control_algorithm == ALT_CONTROL_DEFAULT) &&
         auto_throttle_mode && !throttle_suppressed) {
         SpdHgt_Controller->update_pitch_throttle(target_altitude_cm - home.alt + (int32_t(g.alt_offset)*100), 
                                                  target_airspeed_cm,

ArduPlane/Attitude.pde

@@ -360,7 +360,7 @@ static void calc_throttle()
         return;
     }
 
-    if (g.alt_control_algorithm == ALT_CONTROL_TECS) {
+    if (g.alt_control_algorithm == ALT_CONTROL_TECS || g.alt_control_algorithm == ALT_CONTROL_DEFAULT) {
         channel_throttle->servo_out = SpdHgt_Controller->get_throttle_demand();
     } else if (!alt_control_airspeed()) {
         int16_t throttle_target = aparm.throttle_cruise + throttle_nudge;
@@ -427,7 +427,7 @@ static void calc_nav_pitch()
 {
     // Calculate the Pitch of the plane
     // --------------------------------
-    if (g.alt_control_algorithm == ALT_CONTROL_TECS) {
+    if (g.alt_control_algorithm == ALT_CONTROL_TECS || g.alt_control_algorithm == ALT_CONTROL_DEFAULT) {
         nav_pitch_cd = SpdHgt_Controller->get_pitch_demand();
     } else if (alt_control_airspeed()) {
         nav_pitch_cd = -g.pidNavPitchAirspeed.get_pid(airspeed_error_cm);
@@ -887,5 +887,5 @@ static void demo_servos(uint8_t i)
 // return true if we should use airspeed for altitude/throttle control
 static bool alt_control_airspeed(void)
 {
-    return airspeed.use() && g.alt_control_algorithm == ALT_CONTROL_DEFAULT;
+    return airspeed.use() && g.alt_control_algorithm == ALT_CONTROL_AIRSPEED;
 }

ArduPlane/Parameters.pde

@@ -163,8 +163,8 @@ const AP_Param::Info var_info[] PROGMEM = {
 
     // @Param: ALT_CTRL_ALG
     // @DisplayName: Altitude control algorithm
-    // @Description: This sets what algorithm will be used for altitude control. The default is to select the algorithm based on whether airspeed is enabled. If you set it to 1, then the airspeed based algorithm won't be used for altitude control, but airspeed can be used for other flight control functions. Setting it to 2 selects the new 'TECS' (total energy control system) altitude control, which works both with and without airspeed
-    // @Values: 0:Default Method,1:non-airspeed,2:TECS
+    // @Description: This sets what algorithm will be used for altitude control. The default is zero, which selects the most appropriate algorithm for your airframe. Currently the default is to use TECS (total energy control system). If you set it to 1 then you will get the old (deprecated) non-airspeed based algorithm. If you set it to 3 then you will get the old (deprecated) airspeed based algorithm. Setting it to 2 selects the new 'TECS' (total energy control system) altitude control, which currently is equivalent to setting 0. Note that TECS is able to handle aircraft both with and without an airspeed sensor.
+    // @Values: 0:Automatic,1:non-airspeed(deprecated),2:TECS,3:airspeed(deprecated)
     // @User: Advanced
     GSCALAR(alt_control_algorithm, "ALT_CTRL_ALG",    ALT_CONTROL_DEFAULT),
 

ArduPlane/defines.h

@@ -255,7 +255,8 @@ enum log_messages {
 enum {
     ALT_CONTROL_DEFAULT      = 0,
     ALT_CONTROL_NON_AIRSPEED = 1,
-    ALT_CONTROL_TECS         = 2
+    ALT_CONTROL_TECS         = 2,
+    ALT_CONTROL_AIRSPEED     = 3
 };
 
 // attitude controller choice