Plane: fixed bad yaw rate demands in tailsitter fixed wing modes

this prevents the pilot putting in crazy yaw rate demands due to the
use of rudder stick in fixed wing modes for tailsitters while still
allowing for FBWA flat turns if the user wants them.

It uses the existing RUDD_DT_GAIN parameter for a gain scaling of yaw
rate for copter tailsitters

ArduPlane/quadplane.cpp

@@ -1248,6 +1248,14 @@ float QuadPlane::get_pilot_input_yaw_rate_cds(void) const
 
     // add in rudder input
     float max_rate = yaw_rate_max;
+    if (!in_vtol_mode() && tailsitter.enabled()) {
+        // scale by RUDD_DT_GAIN when not in a VTOL mode for
+        // tailsitters. This allows for flat turns in tailsitters for
+        // fixed wing modes if you want them, but prevents crazy yaw
+        // rate demands in fixed wing based on your preferred yaw rate
+        // when hovering
+        max_rate *= plane.g2.rudd_dt_gain * 0.01;
+    }
     if (tailsitter.enabled() &&
         tailsitter.input_type & Tailsitter::input::TAILSITTER_INPUT_BF_ROLL) {
         // must have a non-zero max yaw rate for scaling to work