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View Full Version : Split Rudder 74, 777 and why not airbus.


Sticky Fingers
6th Aug 2012, 19:48
Hey Everyone,

I'm hoping someone can clarify as to why the 777 and 74 both have a split rudder but not the 330 or 340's?

Furthermore with regards to the split rudder, what sort of authority does the lower rudder have over the upper half. Does the yaw damper in the cruise control the lower section of the spit rudder to preserve tail life?

t6 sparky
6th Aug 2012, 22:45
The 777 doesn't have a split rudder.

NSEU
7th Aug 2012, 00:36
747: Because it can?

I guess having four hydraulic systems allows the 747/744 to control each rudder with different pairs of hydraulic systems (redundancy). The upper and lower rudders move in unison, however (under normal circumstances).

The 744 Rudder Ratio System reduces the movement of both rudders at higher speeds (by the same amount) for a given manual pedal input. The Yaw Damper System (acting independently) would factor in airspeed and things like the number of IRUs and ADCs available.

Rgds
NSEU

MarkerInbound
7th Aug 2012, 01:24
Because Boeing wanted it that way and Airbus didn't.

The 727 also has upper and lower rudders. Both the 727 and 747 have yaw dampers on both. On the 727 the lower rudder has more throw when the flaps are not up. On the 747 the rudder ratio control varys the throw of both rudders as the speed changs.

Sticky Fingers
7th Aug 2012, 07:36
Ok I can see where my mistake went with the 777. Thanks, you saved my ar$e there.


Photos: Boeing 777-206/ER Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/KLM---Royal/Boeing-777-206-ER/0742885/&sid=e3a902466a2220fbdfaa49845771a946)


Excuse if the question sounds a bit pathetic, but would the 74's lower and upper rudder sizes have something to do with the moment arm?

SMOC
7th Aug 2012, 08:09
Size!

747s and A380s have split rudders anything smaller is single. (Unless it's simply archaic)

dixi188
7th Aug 2012, 20:04
DC-10 and MD-11 have split rudder and the Vickers VC-10 has three rudders.