How many actuators does the F-35 have for each primary control surface like rudder, stabilator or aileron? And is it active/active or active/standby?
Just one per control surface. Though the airplane is unique with using a single Electro-Hydrostatic Actuator (EHA) per control surface as opposed to a centralized hydraulics system.
https://www.f35.com/in-depth/detail/up-in-the-air-understanding-the-f-35-air-vehicle
I don’t know what you mean by active/standby but the surface actuators are commanded by inputs from the flight control computers, which respond as needed to stick and rudder inputs from the pilot to achieve a desired aircraft reaction to a control input.
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1$\begingroup$ When there are two actuators per surface, active-active means that both are commanded and energized; if one malfunctions, you may have force fight. Active-standby means that only one is active at a time; if one malfunctions, the other one takes over while the first one is de-energized. The downside is there is a time lag between the takeover and your surface may run away during that time. $\endgroup$ – JZYL Dec 16 '19 at 14:49