charlie im failing to understand the need for any weight when you have all the air pressure against it? wouldnt more area above that weight be better?
The area of a control surface forward of the hinge serves a different purpose than the added weight.
The area provides an aerodynamic assistance that sets the amount of force you need to apply to the controls to provide a desired "feel".
The weight is there to reduce or eliminate the dynamic movement of a hinged surface that is induced by air loads which is far beyond a humans control, "flutter we call it"
Aerodynamic,
By adding more area forward of the hinge on a rudder will reduce the effort, or call it force your feet, or toes need to apply to get the desired surface movement.
Each designer and aircraft's mission will utilize a different aerodynamic ratio, But an example, the ailerons will generally be ¼-½ the force the elevators need while the rudder will take 5-7 times that effort to get the intended movement. These forces are all determined from the humans dynamics.
The weight,
A Cub with it's flat surfaces and metal to metal hinges are not prone to developing "flutter".
An aircraft with airfoil shaped surfaces and where all my controls are mounted with ball bearings can be very prone to "flutter".
What happens here is the surfaces center of pressure will vary from where the hingeline is. And as you vary the camber in the surface from control movement this center of pressure changes fore-aft on each side of the surface. As such there are allot of interesting dynamics going on which the one thing the industry has determined is you balance the weight of the movable surface along the hingeline you will reduce the chance of a dynamic oscillation.
Engineers in the industry might choose a partial balance in some applications but is is common on the rudder which is generally a symmetrical shape to aim for the surface to be balanced right along the hinge. Aka a 100% balance which is my goal.
