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14.1: Angle of Attack

Click the folder button 'Design Computation' and enter the desired angle of attack into the input field 'Angle of Attack'. The dimensional unit for entered data is 'degree' [°]. Valid values lie between -90° and +90°.
In practice angles of attack of more than 10° to 20° are not reached. With these angles, especially with Reynolds numbers smaller then 1.000.000 flow separation occurs.
Near the input field are Up/Down-buttons located. They can be used to change the angle of attack with mouse clicks.
A click on the right mouse button pops up a menu to set the increment between 0.00001° and 1°.



To see the effect of this function, it is useful to select the incident flow vector button.



The pictures below shows a rectangular wing with 0° angle of attack. The X-axis of this wing is equal to the angle of attack.



Enter into input field 'Angle of Attack [°]' 10° and confirm with enter. The wing will now be pitched, X-axis of wing and incident flow vector differ.



If no actual vortex computation is present, the input fields are shaded in red. After vortex computation the background colour of input fields is white.

Below the input fields the button 'Start Computation' is located. If you click this button, the Vortex-Lattice computation will start. This computation runs twice, first with an angle of attack tightly above the selected angle, and afterwards with the selected angle. These two computations are necessary to get a stability measure.

A successful vortex computation fills the five design computation fields on the left side of the 'Design Computation' folder. You find there Design Cl, the stability measure l_my, centre of gravity (referenced to the airplane's zero-point) and the airspeed which is necessary to keep the airplane on a straight and level flight.

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