![]() By trapping more high pressure under the tip of the wing and low pressure on the top of the wing, the end plate increases the lift of the wing near the tip. The end plate does affect the loads on the wing in a way that may be significant structurally. They are more like fences near the tip than large surfaces and rarely protrude more than about 1/4 of the cord above or below the surface of the wing.īecause of this, the forces on the end plate are relatively small and the plate itself can be a thin flat plate rather than a more substantial structure. The end plate increases the amount of lift the wing generates at a given angle of attack and reduces the induced drag of the wing. ![]() ![]() The end plate traps some additional high pressure on the lower surface of the wing near the tip and reduces the ability of the high pressure from the bottom of the wing to bleed into the low-pressure zone on the upper surface. The overall effect of the end plate is to maintain the pressure differential between the upper and lower surface of the wing farther outboard on the wing. The end plate restricts the cross-flow near the wingtip, and this also weakens the tip vortex. It acts as a fence that opposes the spanwise flow near the tip of the wing. End PlatesĪn end plate is a thin flat plate mounted at or near the tip of the wing, perpendicular to the wing surface and parallel to the airflow. The two classes of tip devices are end plates and winglets. The trade between parasite drag due to wetted area and reduction in induced drag is a function of the flight condition of the airplane and will determine whether it is appropriate to incorporate a tip device. These devices function as barriers to the cross-flow near the wingtip or manipulate the cross-flow in the vortex itself in order to weaken the vortex and/or recover energy from the swirling flow.īoth types add wetted area to the airplane, and hence increase parasite drag at the same time as their influence on wingtip airflow reduces induced drag. There are two types of wingtip aerodynamic devices that go a step beyond a planar tip and seek to directly manipulate the cross-flow at the tip to alter the formation of the tip vortex. This month we’ll look at two types of wingtip aerodynamic devices that go a step beyond a planar tip and seek to directly manipulate the cross-flow at the tip to alter the formation of the tip vortex. Last month we saw how tip planform and shaping can affect formation of the tip vortex and the effective span of the wing. ![]() The combination of the downwash behind the wing itself and the upward flow just outboard of the tip causes the air to wrap up into a vortex that sheds aft of the tip of the wing. Just inboard of the tip the wing deflects the air downward, while outboard of the tip the air is driven upward by the pressure difference between the top and bottom of the wing. The pressure on top of the wing is lower than the pressure on bottom.Īt the wingtip, the wing disappears to the air, removing the barrier between the two pressure zones. (Photo: Leonardo Correa Luna)Ī wing produces a pressure difference between its upper and lower surface. An end plate increases the amount of lift the wing generates at a given angle of attack and reduces the induced drag of the wing.
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