Was just curious but almost every md11 I have watched land seems like they are almost fully trimmed out. Can anyone please explain this 
Credit to me for pic
I have no idea but maybe @SingaporeAirlines can help!
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http://www.pprune.org/tech-log/230596-md-11-stab-trim-vs-tocg-position-any-references-available.html
Try the second question
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If I recall correctly (IIRC) the size of the MD 11ās tail was reduced quite significantly to allow for an increased Mach cruise number and led to the reduction in the low speed handling quality of the aircraft in respect to landing performance.
Hence the tail was at the limit of authority for landing leading to the ārequirementā for a full baulked landing procedure for any ābouncedā landing.
Happy to be corrected by any MD11 drivers out there. :D
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facepalm
think ya mean pilots
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š¤¦āāļø nope he probably ment exactly what the captain said.
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that makes no sense in any of the (albeit limited) languages I know
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My uncle is a Naval Academy graduate and in his role as a Cold War era submariner he and his colleagues refer to themselves as āsub driversā. Must be an American English idiom to call operators of certain moving vehicles ādriversā in coloquial situations.
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Take @Heavydriver 's username for example. It makes sense when you are a pilot that has the weight classification as a heavy. You can now add āheavy driverā to your ever growing list of aviation vocabulary. š
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Can we get back on topic please š
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@Yuan_Tugo is a commercial pilot, so he didnāt say drivers for nothing. Heās got way more aviation knowledge than youā¦
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How does this picture tell you that itās trimmed? Iām not very educated on trim and MD-11ās.
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Look at the front of the tail itās pointed towards the ground. When they taxi after landing itās goes back to normal
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Thatās not really trim, but the elevator deflection.
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Ok so how come itās the only model to do that if thatās truly what it is
Itās not only on this model, but any model that has a stabilator. So the entire stabilizer is the elevator, instead of having a fixed horizontal stabilizer that the elevator is attached to.
Every landing will be fairly close to full elevator extension on landing. As you want to hold the nose off as long as possible. Trim is a secondary tab located on the Elevator, Rudder, Alerions that direct airflow in the opposite direction of the desired control surface input youāre trying to relieve.
So if your looking for a nose up attitude the trim control surface will actually move down forcing the elevator up, to obtain the nose up attitude.
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The issue with the Stabilator here is that the aerodynamic effect of the flying surface reduces with speed as with any other flying surface. (1/2 density * V^2 * Surface area). As the speed comes back the flying surface will have to deflect more to provide the requisite aerodynamic force. At landing speeds the control will be toward itās limits as there are no slat or flap systems on the tail to give variable geometry.
Hence by reducing the surface size of the aerodynamic component they reduce its effectiveness at lower speeds. Reducing the Vapp of the aircraft will further push the stabilator toward itās limits. In the case of the very sad MD11 crash in Narita they tried to correct the bounce below Vapp but the stabilator was already at max deflection and they had no pitch authority left.
Jammed Stab is something we practice in the sim. There are alternate controls for the pitch trim system to allow you to have pitch authority even if the tail is stuck.
Cheers
Yuan
777 āDriverā ;D
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bloody hell. i donāt need 3 people attacking me for one little mistake.
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Donāt get too worried about it, itās a common phrase in the military where pilots refer to themselves as ādriversā, e.g a āHarrier driverā or an āF15 driverā etc.
Not so common in the GA or the airline world.
Have fun.
:)
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To be fair, I wasnāt attacking you - I was just making a point. We all make mistakes, and itās okay to have someone correct you. Because we are on a forum with over 20,000 users, itās easy for multiple people to correct you about that one mistake. Iāve got nothing against you, and I apologise if I came across as āattacking.ā
I know that was off topic, but everybody makes mistakes - oh and I was just making a point ;)
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