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Published on 29 Jul 2013 | over 3 years ago

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"1930s test conducted at NASA Langley Research Center's 6 by 19 inch Transonic Tunnel during its NACA era."

Public domain film from NASA, slightly cropped to remove uneven edges, with the aspect ratio corrected, and mild video noise reduction applied.
The film was silent. I have added music created by myself using the Reaper Digital Audio Workstation and the Proteus VX VST instrument plugin.


In aeronautics and aeronautical engineering, camber is the asymmetry between the top and the bottom surfaces of an aerofoil. An aerofoil that is not cambered is called a symmetric aerofoil. The benefits of camber, in contrast to symmetric aerofoils, were discovered and first utilized by Sir George Cayley in the early 19th century...


Camber is usually designed into an aerofoil to increase the maximum lift coefficient. This minimises the stalling speed of aircraft using the aerofoil. Aircraft with wings based on cambered aerofoils usually have lower stalling speeds than similar aircraft with wings based on symmetric aerofoils.

An aircraft designer may also reduce the camber of the outboard section of the wings to increase the critical angle of attack (stall angle) at the wing tips. When the wing approaches the stall angle this will ensure that the wing root stalls before the tip, giving the aircraft resistance to spinning and maintaining aileron effectiveness close to the stall.

Some recent designs use negative camber. One such design is called the supercritical aerofoil. It is used for near-supersonic flight, and produces a higher lift to drag ratio at near supersonic flight than traditional aerofoils. Supercritical aerofoils employ a flattened upper surface, highly cambered (curved) aft section, and greater leading edge radius as compared to traditional aerofoil shapes. These changes delay the onset of wave drag...


Flaps are hinged surfaces mounted on the trailing edges of the wings of a fixed-wing aircraft to reduce the speed at which an aircraft can be safely flown and to increase the angle of descent for landing. They shorten takeoff and landing distances. Flaps do this by lowering the stall speed and increasing the drag.

Extending flaps increases the camber or curvature of the wing, raising the maximum lift coefficient—or the lift a wing can generate. This allows the aircraft to generate as much lift but at a lower speed, reducing the stalling speed of the aircraft, or the minimum speed at which the aircraft will maintain flight. Extending flaps increases drag which can be beneficial during approach and landing because it slows the aircraft. On some aircraft, a useful side effect of flap deployment is a decrease in aircraft pitch angle which improves the pilot's view of the runway over the nose of the aircraft during landing. However the flaps may also cause pitch-up, depending on the type of flap and the location of the wing.

There are many different types of flaps used...

The Fowler, Fairey-Youngman and Gouge types of flap increase the planform area of the wing in addition to changing the camber. The larger lifting surface reduces wing loading and allows the aircraft to generate the required lift at a lower speed and reduces stalling speed...


A leading edge slot is a fixed aerodynamic feature of the wing of some aircraft to reduce the stall speed and promote good low-speed handling qualities. A leading edge slot is a span-wise gap in each wing, allowing air to flow from below the wing to its upper surface. In this manner they allow flight at higher angles of attack and thus reduce the stall speed...

Purpose and development

At an angle of attack above about 15° many airfoils enter the stall. Modification of such an airfoil with a fixed leading edge slot can increase the stalling angle to between 22° and 25°.

Slots were first developed by Handley Page in 1919 and the first aircraft to fly with them was the experimental H.P.17, a modified Airco DH.9A. The first aircraft fitted with controllable slots was the Handley Page H.P.20. Licensing the design became one of Handley Page's major sources of income in the 1920s.

Similar, but retractable, leading edge devices are called slats. When the slat opens, it creates a slot between the slat and the remainder of the wing; retracted, the drag is reduced.

A fixed leading edge slot can increase the maximum lift coefficient of an airfoil section by 40%. In conjunction with a slat, the increase in maximum lift coefficient can be 50% or even 60%...

Unlike trailing edge flaps, leading edge slots do not increase the lift coefficient at zero angle of attack since they do not alter the camber.

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