Problems with wind direction.

[Guest]

Hi allUsing aircraft that show graphic representation of wind speed and direction in the ND PSS a320 DF737 etc,I,ve noticed that I have to use rudder Input Which seems to be the reverse of what would be needed in real life.For Example Takeoff from RW 27 at Heathrow Wind reported as 195 10kts Needle on ND correctly reports wind blowing from my left to my right.Intead of using Left rudder to hold the aircraft I have to use right rudder to remain centreline??.Anyone else noticed this?.cheersJohn

[Guest]

Airplanes tend to "weather vane" into the wind, especially when on the ground. This weathervaning would require a right rudder input given the type of wind you described...

[Guest]

Hi Caveman Thanks for the reply, never heard of this effect, guess you learn something new each day.Wondering why this effect happens ?? why doesn't the aircraft move to the right when the force( wind) is being applied in that direction.While in flight this does happen, just curious why this changes on the ground as the same wind force is still being Exerted.just curious.CheersJohn

[Guest]

John,when the wind is e.g. coming from the left while taking-off,the wind will mainly "push" the vertical fin to the right,thus the aircraft's nose will go to the left,so you'll have to give right rudder to correct thisregards,Seba

[Guest]

Most aircrafts CG is about a third of the way back on the wing. So... the wind force that "pushes" the tail that stands up like a big sail has a "moment arm" associated with it that gives any force applied to the tail a multiplied turning effect on the front of the plane -- the longer the distance of the tail relative to the CG, the greater the induced force will "appear" to the plane. When the plane is flying the effect is still there although an additional effect of "getting blown off course" is also there. So... in the wind you gave the aircraft should yaw slightly to the left (depending on forward speed) and trnslate to the right as it flies through the air...

[michal 44]

>>Wondering why this effect happens ?? Becaues the center of lateral drag is behind the center of gravity.Michael J.

[Guest]

Hi allThanks for your replies, the sail analogy makes it easy to understand...nice one.Another bug hits the dust.:)Thanks guysJohn