Set the default aileron trim for the JSBSim Cessna 172 to -0.055.

This is sufficient to keep the wings level in cruise at 3000 ft, 2200
RPM; the value will have to change as we make changes to the model.

Note that a stock Cessna 172 does not have an aileron-trim wheel
inside the cockpit; to set the trim, you actually bend a sheet of
metal by hand when the plane is on the ground.

Aircraft/c172-3d-set.xml

@@ -71,6 +71,7 @@ October 23 2001 John Check, fgpanels@rockfish.net
  </consumables>
 
  <controls>
+  <aileron-trim>-0.055</aileron-trim>
   <magnetos>3</magnetos>
  </controls>
 

Aircraft/c172-ifr-set.xml

@@ -55,4 +55,8 @@ October 23 2001 John Check, fgpanels@rockfish.net
    </config>
  </autopilot>
 
+ <controls>
+  <aileron-trim>-0.055</aileron-trim>
+ </controls>
+
 </PropertyList>

Aircraft/c172-set.xml

@@ -67,6 +67,7 @@ October 23 2001 John Check, fgpanels@rockfish.net
  </consumables>
 
  <controls>
+  <aileron-trim>-0.055</aileron-trim>
   <magnetos>3</magnetos>
  </controls>