face hinge moments due to deflection of the 
surface. 
The servo tad shown in figure 4.18 utilizes a 
horn which has no direct connection to the 
control surface and is free to pivot about the 
hinge axis. However, a linkage connects this 
free horn to the tab surface. Thus, the control 
system simply deflects the tab and the resulting 
hinge moments deflect the control surface.