Control Surfaces

Control surfaces and flaps may be simulated using the option buttons and slider bars. Gaps that will exist in a real world airfoil are not modeled.

The various hinge location values will be enabled or disabled as appropriate for the hinge type as described below. The values may also be entered manually. Left click over the numeric value and a text box will open, type the desired value, close the window, and the value will be updated.


Simple hinge: The simple hinge model places the hinge on the top surface, the bottom surface, or mid-way between the surfaces. The hinge location is shown by a small blue circle. Coordinate points are automatically added and removed as necessary. Additional points are placed along a circular arc whose center is located at the hinge point and is tangent to the opposite surface

Frise hinge: The characteristic of a Frise hinge is that a portion of the control surface will extend below the bottom surface of the airfoil when the trailing edge is deflected upwards. This is used to help control adverse yaw. Frise ailerons may have a hinge located on the upper surface, the lower surface, or at some point below the chord line. The hinge location is shown by a small blue circle.

In the case of a top-surface Frise hinge, a front break point (on the lower surface) must be specified. As the location of the front break point is moved forwards, the amount of discontinuity on the lower surface increases.

In the other cases, the front break point is located on the circle whose center is at the hinge axis and is tangent at the upper surface.

Flap: Points are added as necessary along a circular arc with its center at the hinge location and tangent to the surfaces.