Instructions
Find the RC plane's pushrod -- the thin, circular piece of metal that connects the servo arm to the control horn on the plane's frame.
Use your ruler to measure the push rod's length from one tip to the other.
Measure the length of the rod's curve, located at its top end.
Measure the length of the rod curve's end circle; this is the rod's width.
Measure the short, horizontal length that connects the rod's curve to its straight length; this is the rod's height.