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Rudder Pedals

There are two pairs of rudder pedals: one each for the commander and pilot. The commander's and pilot's rudder pedals are mechanically linked so that movement on one side moves the other side. When a pedal is depressed, it moves a mechanical input arm in a rudder pedal transducer assembly. Each RPTA contains three transducers-channels 1, 2 and 3-and generates an electrical signal proportional to the rudder pedal deflection. An artificial feel is provided in the rudder pedal assemblies.

The rudder pedals command orbiter rotation about the yaw axis by positioning the rudder during atmospheric flight. In atmospheric flight, flight control software performs automatic turn coordination; thus the rudder pedals are not used until the wings are level before touchdown.

The RPTA SOP converts the selected left and right commands from volts to degrees; selects the largest of the left and right commands for output to flight control software after applying a dead band; and if redundancy management declares an RPTA bad, sets that RPTA to zero.

The rudder pedals can be adjusted 3.25 inches forward or aft from the neutral position in 0.81-inch increments (nine positions). The breakout force is 10 pounds. A pedal force of 70 pounds is required to depress a pedal to its maximum forward or aft position.

The rudder pedals provide two additional functions unrelated to software after touchdown. Rudder pedal deflections provide nose wheel steering, and depressing the upper portion of the pedals by applying toe pressure provides braking. Differential braking may be used for nose wheel steering.

The commander's RPTA is powered when the flt cntlr on/off switch on panel F7 is positioned to on . The pilot's RPTA is powered when the flt cntlr on/off switch on panel F8 is positioned to on .

The RPTA contractor is Honeywell Inc., Clearwater, Fla.

Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 04/07/2002
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