bearfoil - in reply to
Post # 1847
RUDDER ANGLE
The acute angle between a water or airborne craft's fore-and-aft line and the current longitudinal center-line of the rudder.
The Graph likewise shows a ~4degree angle consistent with RTLU default after Law Change for the assumed speed, 272 knots.
Wrong! The graphic shows
7.9° of rudder angle at 272KCAS - the value that is "locked in" (when the flight law changed to Alternate) until slats extension, when it reverts to that available in Normal Law.
The
4.0° angle is that available at 350KCAS and beyond when in Normal Law, and would be the value "locked in" if an overspeed event had resulted in a change to Alternate or Direct Law. The
4.7° angle was included as a reference as to the angle at FL350 and M0.86 / 330KCAS.
Maximum rudder travel is therefore automatically limited as a function of aircraft KCAS to prevent structural overloading. In this respect, the "travel" is the angular deflection from the fore-and-aft line as described above. I haven't seen a schematic for the RTLU, but I suspect that a worm screw driven device creates a "feedback" position that inhibits hydraulic pressure to the operating rams beyond the set point. In this respect, the RTLU position is utilized by both port & starboard rams.
mm43