airbusb0y
Topic Author
Posts: 9
Joined: Wed Dec 29, 2010 6:33 pm

M11 Empennage Questions

Sun Jan 02, 2011 7:43 pm

Hello a few questions about the MD11,

1. Where is the yaw damper on the MD11 exactly located?
2. What and how does the dual rudder work?
3. Does the MD11 have trim tabs on the rudder?

Does any one have a detailed empennage drawing of the MD11. I've checked Boeing's technical section, but it was just general schematics. If any one could kindly send me a picture if they have access to it.

Any info appreciated!
 
CosmicCruiser
Posts: 2049
Joined: Tue Feb 22, 2005 3:01 am

RE: M11 Empennage Questions

Mon Jan 03, 2011 5:46 pm

1. ask a mechanic

2. The upper rudder is powered by hyd sys 1 and the lower rudder hyd sys 2. each rudder consists of a forward and aft section. The aft section of the upper & lower rudders are bused to move as the forward sections.

3. yes the rudder has trim
 
wingscrubber
Posts: 806
Joined: Fri Sep 07, 2001 1:38 am

RE: M11 Empennage Questions

Wed Jan 05, 2011 3:57 am

Clarification on trim - there are no trim TABS on the MD-11, they would be useless on a hydraulically powered rudder, the trim is probably mechanical-electric input and likely works either with bias on the rudder PCU control cables or a separate screwjack input directly at the rudder at a guess. Maybe an MD-11 mech will come enlighten us shortly.

Here's an old thread on yaw dampers:
Yaw Damper... What Exactly Is It? (by GulfstreamGuy Mar 7 2004 in Tech Ops)

Here's an explanation of the 727 yaw damper:
http://www.boeing-727.com/Data/systems/infoyawdampers.html

Commercially available yaw damper, though probably not the same used on MD-11:
http://vonesh.com/pdf_files/YawDamp.pdf

Hooks up to the rudder trim to prevent dutch roll as far as I can tell...
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fr8mech
Posts: 6627
Joined: Mon Sep 26, 2005 9:00 am

RE: M11 Empennage Questions

Wed Jan 05, 2011 5:23 am

Quoting airbusb0y (Thread starter):
1. Where is the yaw damper on the MD11 exactly located?


The MD11 does not have any dedicated yaw damp components as found in other aircraft. The yaw damp system resides, basically, in the FCC's.

Quoting airbusb0y (Thread starter):
What and how does the dual rudder work?


Not sure what you're asking. The rudder is split into an upper and lower rudder. Several aircraft have this design. It provides for redundancy in the case of a single, or in some cases, a dual hydraulic failure. I'm sure there are some aerodynamic considerations, but they are beyond my level of caring.

Quoting airbusb0y (Thread starter):
Does the MD11 have trim tabs on the rudder?


No, rudder trim is achieved by changing the neutral on the rudder load and feel mechanism via an electric actuator.
When seconds count...the police are minutes away.
 
CosmicCruiser
Posts: 2049
Joined: Tue Feb 22, 2005 3:01 am

RE: M11 Empennage Questions

Wed Jan 05, 2011 2:47 pm

Quoting fr8mech (Reply 3):
The yaw damp system resides, basically, in the FCC's.

I KNEW THAT!!    Just doing some studyng and went over FCC stuff but it is a little complex.

I also must apologize at my quick abbreviated answers about the trim. I just wrote yes meaning yes we have a rudder trim knob. sorry

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