"Aileron Feel: Is Aileron Feel merely controlled by a spring -the more you turn the control column, the greater the tension on the spring? Is it that simple, unlike the elevator and rudder which have their own seperate Feel Units??"
The 747 aileron system still has it's own individual feel (and trim and centering) unit. This is located in the left hand wing gear well. The rudder, as far as I know, has no force modification other than the mechanical cam and springs arrangement. The effective output, however, is modified by the rudder ratio system.
The elevator feel system, however, looks at airspeed and stab position to generate different feel at the control column end.
Hope this is correct.
Cheers.
Q.