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Flight Surface Authority

Videns From Argentina, joined Mar 2004, 133 posts, RR: 0
Posted (8 years 7 months 3 weeks 1 day 23 hours ago) and read 1575 times:

What are the speeds at which flight surfaces start having an effect on an aircraft?
eg: when an airplane is taxiing, none of the flight surfaces have any effect on what the airplane does...
Any flight surface/aircraft combination info appreciated...

Travel? Why would i travel if I can watch it on TV?

3 replies: All unread, jump to last

Woodreau From United States of America, joined Sep 2001, 890 posts, RR: 7
Reply 1, posted (8 years 7 months 3 weeks 1 day 22 hours ago) and read 1471 times:

I think it depends on the airfoil design.

There are gliders when sitting on the ground, hooked up for aerotow, the ailerons are fully effective and can be used to keep it upright when a good 5-10kt breeze blows across wings.

Good judgement comes from experience. Experience comes from surviving bad judgement.

WILCO737 From Greenland, joined Jun 2004, 8473 posts, RR: 78
Reply 2, posted (8 years 7 months 3 weeks 1 day 18 hours ago) and read 1437 times:

AIRLINERS.NET CREW
HEAD MODERATOR

hi Videns,

during take off roll u use the rudder pedals to keep the aircraft on the centerline. This happens because the nose wheel is connected to the rudder pedals and you have a steering angle of about 3.5° in each direction! At about 60-80 kts the rudder on the tail is effective that you can hold the aircraft on the centerline only with the aerodynamic forces of the rudder! So, you can say at about 60-80 kts the filght controls become effective...

WILCO737

It it's not Boeing, I am not going.

FredT From United Kingdom, joined Feb 2002, 2184 posts, RR: 26
Reply 3, posted (8 years 7 months 3 weeks 1 day 10 hours ago) and read 1386 times:

They don't become effective at one defined airspeed. They are effective in proportion to the dynamic pressure, which is proportional to the airspeed squared. At a very small airspeed, they are effective but perhaps not effective enough to control the aircraft, depending on what you do. At twice that airspeed, they are four times as effective... which might just be enough.

It is like asking "at which temperature does cold water turn into warm water". There's no answer as it all depends on what you are trying to use it for!

Regards,
Fred

I thought I was doing good trying to avoid those airport hotels... and look at me now.