To add to the question here:
http://www.pprune.org/military-aviat...ml#post8556721 about the two STO Throttle positions here is some other info about dem rollyposts.
Powering the Lightning II April 2012 Chris Kjelgaard
"...According to Jones, the roll posts themselves are variable-area nozzles which are situated in the lower part of each inner wing section and act to provide roll control for the F-35B while it is in hover mode. In order to do this, the roll-post ducts direct bypass air from the engine to the roll posts, which drive the air out through the bottom of each wing. In the F-35B, 3,700lb (16.46kN) of thrust in the form of bypass air is directed out to the two roll posts while hovering.
Each roll-post assembly features a pair of flap-type doors in the bottom of the wing, controlled by the FADEC. Jones says these titanium doors are controlled by rotary actuators which allow fully variable opening, providing a degree of thrust variability and directionality so that the pilot can control roll while hovering. He says Lockheed Martin’s original X-35 concept demonstrator featured doors between the engine casing and the roll-post ducts which could be closed when the aircraft was not hovering, but in production aircraft there are no such doors and bypass airflow is constantly sent to the ducts. The only way to control roll-post thrust is via the flap-doors in the bottom of the wing...."
http://militaryrussia.ru/forum/downl...e.php?id=28256 (PDF 14Mb)