NKP S2 From United States of America, joined Dec 1999, 1714 posts, RR: 7 Reply 1, posted (7 years 5 months 1 week 4 days 8 hours ago) and read 1083 times:
Easy: No hyd pressure plus the weight of the aileron Equals droop. "Fly by wire" only means control by wire ( electrically ) via computers. Hydraulics still do the "heavy lifting".
Mr.BA From Singapore, joined Sep 2000, 3423 posts, RR: 25 Reply 2, posted (7 years 5 months 1 week 4 days 6 hours ago) and read 1049 times:
Noticed that Airbuses' flight controls droop pretty easily... I mean almost all kinds of their planes have the ailerons droop or 'drop' when the hydraulics are turned off but I don't seem to notice the same trend on many Boeings. Especially for the B744s, which the control surfaces are supposedly heavier but they don't seem to droop, not even the high speed ailerons... same goes for the B767.. or so. But the B777s do have the control surfaces droop pretty easily. Is this due to the different systems that power the controls? Seem to notice that FBW can droop easier...
Starlionblue From Greenland, joined Feb 2004, 14992 posts, RR: 69 Reply 4, posted (7 years 5 months 1 week 4 days 5 hours ago) and read 1039 times:
The construction of the actual hinge and mechanism probably differs slightly from plane to plane, which would explain the differences in behavior. I don't know exactly how they are built, but a simple counterweight in the mechanism would eliminate drooping, for example.
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Ual747 From United States of America, joined Dec 1999, 7904 posts, RR: 30 Reply 5, posted (7 years 5 months 1 week 4 days 4 hours ago) and read 1028 times:
"Not really right on topic, but I have also noticed that some a/c, especially the A32x family, have their rudders blown by the wind to either side."
If you go to DFW terminal A, when there is the usual strong breeze from the south, all of AA's 777's will have their rudders looking like they are making a hard turn to the right.
UAL747
"Bangkok Tower, United 890 Heavy. Bangkok Tower, United 890 Heavy.....Okay, fine, we'll just turn 190 and Visual Our Way
320tech From Turks and Caicos Islands, joined May 2004, 479 posts, RR: 5 Reply 7, posted (7 years 5 months 1 week 4 days 3 hours ago) and read 1005 times:
What's with all the drooping aileron questions lately?
A320 series ailerons and elevators droop because pressure is not retained in the servos when hydraulics are off. There is nothing special about fly by wire that would cause it, other than the lack of cables.
Rudders on all large aircraft will displace in a strong wind. Large aircraft don't have gust locks on the rudder (not even the Dash-8), they have dampers, that protect the rudder from being slammed over.
Incidently, the newest A320 series ailerons don't droop. Not sure what's different about them, I'll see what I can find out.
The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.
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