14.3: Stability Measure
Click the folder button 'Design Computation' and click into input field
'Stability Meas. [%] l_my' to enter the desired value. Valid values lie between
-100% and +100%. A measure between 5% and 30% is common.
The bigger the stability measure, the more
senseless reacts the airplane on disturbances. This might be e.g. a gust, but
also the effectiveness of flaps and the horizontal stabilizer decreases.
The stability measure determines the distance between the aerodynamic neutral
point and the airplane's centre of gravity. Stability measures smaller 0
indicate instability; the airplane cannot be controlled by hand.
Near the input field are Up/Down-buttons located. They can be used to change
the stability measure with mouse clicks.
A click on the right mouse button pops up a menu to set the increment between 0.00001%
and 1%.
Below the input fields the button 'Start Computation' is located. If you click
this button, the Vortex-Lattice computation will start. An iteration
computation with several passes (approximate computation) starts. The program
changes stepwise the angle of attack to approximate the desired stability
measure. If the program exceeds 90° angle of attack, the computation will abort
with an error message.