Center of pressure (fluid mechanics)

The pressure point (DP ) of a body in the flow is, where can summarize all effective flow forces. It is located at the wing profile at the intersection of Luftkraftresultierenden and the chord. Its position on the profile chord depends on the curvature of the profile and the angle of attack of the wing.

With respect to the printing point, no torque acts. This is very different from the neutral point.

With curved profiles of the pressure point is typically a third of the surface and moves to the depth of the front, when the angle of incidence becomes larger. In a DP position behind the quarter point of the profile depth each angle of attack causes an upturned (nose up) torque change. Therefore arched profiles are unstable.

The pressure point is located at buoyancy profiles behind the neutral point. The distance between these two points,

Wherein the chord length, the Momentbeiwert with respect to the neutral point and the lift coefficient is.

Symmetric and certain S-bend profiles ( straight or wavy skeleton line ) are pressure- point fixed. The pressure point remains stable in these profiles in the normal angle of attack at about a quarter of the chord on the chord.

Pressure point hike

An arched wing profiles of the pressure point changes depending on the angle of its position in the flow direction. It moves along the chord, to the front, when the angle of incidence is increased. As a geometric measure of the pressure point hike applies the profile curvature and their reserve. As a dynamic measure of the pressure point hike the torque applies to the neutral point. For symmetrical airfoils is in the normal inflow of stable pressure point at the location of the neutral point and there is no pressure point hike instead.

Stability

The air force vector at the pressure point developed at fixed neutral point on the profile torque. This torque about the transverse axis ( longitudinal stability) is balanced and stabilized in steady gliding flight ( trim speed) the glider through the deep center of gravity. The same purpose is achieved, the glider through the pressure point positioning with the tailplane.

Control

To control the speed ( pitch movement about the transverse axis ), the focus is shifted horizontally in the hang glider. When the glider location of the pressure point with the wing trailing edge or the accelerator is changed horizontally and the glider with the tailplane.

Stability and control

For stability and control setting (trimming) and moving means ( taxes) of the pressure point or the center of gravity the same. The decisive factor is the geometry of the "pinch point - focus " (distance, direction).