الموضوع: Aircraft for Amateurs
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قديم 14-07-09, 05:36 PM

  رقم المشاركة : 7
معلومات العضو
المنتصر
مشرف عام

الصورة الرمزية المنتصر

إحصائية العضو





المنتصر غير متواجد حالياً

رسالتي للجميع

افتراضي



 

Back Stick of Movement Effects





Backward stick movement forces the tail down and the nose up. This rotation occurs around the center of gravity of the airplane. Initially the airplane, even though its nose is up, is still headed in the same direction - the only thing that has changed is the angle of attack. But an increase in the angle of attack results in an increase in lift, so now the airplane starts to go up. Then, like an arrow, it points into the wind, increasing its pitch. This process continues, viewed from the cockpit as an increase in pitch, until the pilot moves the stick forward to a neutral position and stabilizes the pitch.



The temptation to think that the stick directly raises or lowers the nose is very strong, and most of the time, roughly correct. But if the stick is moved back when the airplane is very close to the stall the aircraft will not pitch up much, if at all. This back stick movement and increase in AOA will stall the wing, causing a loss of lift and acceleration downward: now the pitch moves opposite the stick movement.





The Ailerons




The ailerons are a much simpler control than the elevator. Located near the wing tips on the trailing edge of the wing, they are used in unison to change the amount of lift each wing is producing and roll the airplane.


When the pilot moves the stick side-to-side from center, the ailerons move in opposite directions. In a roll to the right (as viewed from the cockpit), the right aileron goes up and the left aileron goes down. Each aileron serves to change how that part of the wing deflects the air and thus increases or decreases the amount of lift produced by each wing. The down aileron forces the air down harder, resulting in an increase in lift and the up aileron decreases the downward force, resulting in a decrease in lift. In the case of a right roll, the decreased lift on the right side and increased lift on the left side result in a roll to the right.




Aileron Effects




Operating the ailerons causes an effect called adverse yaw. Adverse yaw is the result of an increase in drag on the wing with the down aileron, or "upgoing" wing. This wing, since it is forcing the air down harder than the "downgoing" wing and producing more lift, also produces more drag. The drag pulls the wing back and causes yaw. If this yaw is not corrected with rudder, the roll is said to be "uncoordinated."




The Rudder




The rudder is controlled by the "rudder pedals" located on the floor of the aircraft. They are both connected to the rudder so that when one or the other pedals is depressed, it moves the rudder in the desired direction. The rudder, connected to the vertical stabilizer, then starts to deflect air much like a wing, only the resulting force is to the side. This force causes a change in yaw. As mentioned earlier, the rudder is not used very often, but when it is needed (e.g., in a crosswind), its presence is appreciated.



 

 


المنتصر

يقول احد القادة القدماء وهويخاطب جنوده . ( اذا لم تكونوا مستعدين للقتال من أجل ما تروه عزيزاً عليكم , فسوف يأخذه أحد ما عاجلا أو اَجلا , واذا كنتم تفضلوا السلام على الحرية فسوف تخسرونهما معاً , واذا كنتم تفضلوا الراحة والرخاء والسلام على العدل والحرية فسوف تخسروهما جميعا ) .

   

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