Copter: AP_MotorsCoax now uses 4 servos

ArduCopter/Copter.cpp

@@ -36,7 +36,7 @@ Copter::Copter(void) :
 #elif FRAME_CONFIG == SINGLE_FRAME  // single constructor requires extra servos for flaps
     motors(g.single_servo_1, g.single_servo_2, g.single_servo_3, g.single_servo_4, MAIN_LOOP_RATE),
 #elif FRAME_CONFIG == COAX_FRAME  // single constructor requires extra servos for flaps
-    motors(g.single_servo_1, g.single_servo_2, MAIN_LOOP_RATE),
+    motors(g.single_servo_1, g.single_servo_2, g.single_servo_3, g.single_servo_4, MAIN_LOOP_RATE),
 #else
     motors(MAIN_LOOP_RATE),
 #endif

ArduCopter/Parameters.cpp

@@ -1024,6 +1024,12 @@ const AP_Param::Info Copter::var_info[] = {
     // @Group: SS2_
     // @Path: ../libraries/RC_Channel/RC_Channel.cpp
     GGROUP(single_servo_2,    "SS2_", RC_Channel),
+    // @Group: SS3_
+    // @Path: ../libraries/RC_Channel/RC_Channel.cpp
+    GGROUP(single_servo_3,    "SS3_", RC_Channel),
+    // @Group: SS4_
+    // @Path: ../libraries/RC_Channel/RC_Channel.cpp
+    GGROUP(single_servo_4,    "SS4_", RC_Channel),
     // @Group: MOT_
     // @Path: ../libraries/AP_Motors/AP_MotorsCoax.cpp
     GOBJECT(motors, "MOT_",           AP_MotorsCoax),

ArduCopter/Parameters.h

@@ -465,7 +465,7 @@ public:
 
 #if FRAME_CONFIG ==     COAX_FRAME
     // Coax copter flaps
-    RC_Channel      single_servo_1, single_servo_2; // servos for two flaps
+    RC_Channel      single_servo_1, single_servo_2, single_servo_3, single_servo_4;     // servos for four flaps
 #endif
 
     // RC channels
@@ -541,6 +541,8 @@ public:
 #if FRAME_CONFIG ==     COAX_FRAME
         single_servo_1        (CH_1),
         single_servo_2        (CH_2),
+        single_servo_3        (CH_3),
+        single_servo_4        (CH_4),
 #endif
 
         rc_1                (CH_1),