Adding rudder control to HITL standard VTOL fixed-wing

Hi there,

I was try to add rudder control to the HIL standard VTOL airframe, but it did not work. The following steps were what I have done, I edited the standard_vtol_hitl.sdf file.

At the rudder plugin, I added the <control_joint_name>

  <plugin name="rudder" filename="">
  <cp>-0.5 0 0.05</cp>
  <forward>1 0 0</forward>
  <upward>0 1 0</upward>

Then in the channel, I added the channel for rudder with input_index of 8:

      <channel name="rudder">

However, when I run the HIL, the rudder control is not performed when I input yaw control on my joystick. I have tried to change the input_index to 7, then I think it works, however I would lost my elevator control which also has input_index of 7.

I am wondering if I did any step wrong or I missed any step.
Thanks in advance!