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32 3. SHAPING THE BODY OF AN AIRCRAFT
the air head-on generates more and more drag. Variable sweep wings are most popular in military
aircraft (like the B-1 Lancer and the F-14 Tomcat).
To use a variable sweep in X-Plane, you can add a sweep control to the instrument panel.
Alternatively, you could assign a button or key to the “vector sweep aft” and “vector sweep forward”
controls in the Joystick and Equipment dialog box.
Figure 3.28: Variable wing sweep illustrated (thanks to Wikimedia Commons user Steelpillow for the
image)
Setting Variable Wing Dihedral
Checking the box labeled “variable dihedral” in the Airfoils dialog box (seen in Figure 3.27) will
allow you to change the angle of the wing above or below the horizontal plane in flight. This is
illustrated in Figure 3.29.
Entering a positive value here corresponds to an angle upward from horizontal (like the wings in
Figure 3.29). Likewise, entering a negative value will correspond to a downward angle. A relatively
high dihedral angle will increase the “dihedral effect” on the wings—that is, the wings’ tendency
to stabilize and level the aircraft in a roll.
Figure 3.29: Wing dihedral, the upward angle of the wings, illustrated (thanks to Wikimedia
Commons user Steelpillow for the image)
Setting Variable Wing Incidence
Checking the box labeled “variable incidence” in the Airfoils dialog box (seen in Figure 3.27) will
allow you to change the wing’s angle of attack in flight. This angle, known as the angle of incidence,
is illustrated in Figure 3.30.
Enter the maximum incidence here, in degrees. Positive values correspond to an upward angle of
the wing when viewing the aircraft from the side, while negative values correspond to a downward
angle.