Channelwing
When Channelwing (German channel airfoil, wing channel, tube wings ) is one of Willard Ray Custer developed in the 1920s wing configuration. The most important part of the wing consists of an open-ended tube half in the center of the motor is suspended. The thrust propellers ( pressure screw ) is located on the rear side of the channel and thus of the wing.
Development
1925 observed the flight interested Willard Custer, as a full barn roof lifted by a storm and carried through the air. Since the wind is not under construction had been able to access, Custer concluded that the high wind speed was above the ridge causes a strong pull upward. His studies of this phenomenon eventually led in 1928 to the first models of a new wing design in the form of semi- tubular channel wings instead of the usual wings. Custer had patented this design in 1929. He further developed the semi- tubular channel Wings and so was on November 12, 1942 for the first time start the CCW -1 ( Custer Channel Wing 1). Custer built more aircraft, most recently the CCW -5, which was produced in small series from 1964.
Principle of operation
Custer described in summary first, that for the lift of an airplane wing, the speed is not responsible, with the wing moves through the air, but the speed of the air passing over the wing: "It's the speed of air, not the airspeed "( It is the velocity of the air, not the velocity in the air).
A support surface does expressed greatly simplified by the fact that the air above the support surface has a lower pressure than the air below the support surface. Thus the aircraft is " sucked" so to speak up. The pressure difference produced during conventional airfoil by the camber of the wing and the angle ( of inclination of the supporting surface for the air flow ). This results in a deflection of the air downwards, which creates lift on the principle of momentum conservation.
Conventional aircraft must only reach a certain speed until the air sufficiently fast flows and the wings can generate lift for a flight sufficient.
Custers channel wing, the air is accelerated in a stable beam backward by the rotating propeller. A propeller on the suction side tried according to the theory of the potential from all sides evenly to suck air. But since this is not possible in a wing channel through the underlying support surface, a strong negative pressure, and thereby lift is generated in the channel to the supporting surface. The speed of the aircraft is in this case secondary. The plane is thus capable STOL (short takeoff and landing ).
Outlook: applications and limits
The concept was so far not been a great breakthrough, although Channelwing - flight devices should theoretically have the ability to vertical flight. Custer could experimentally demonstrate the tremendous boost. Since the rudder but did not respond in the state, needed all built aircraft a short takeoff run until the rudder worked (example: 61 meters at the CCW 1, 20 meters at the CCW -2). None of the aircraft was designed for pure vertical flight, the slightest departure speed was 20 miles / hour (32 km / h). Thus be used as a bush flyer would be conceivable. With a few changes and a vertical flight would be possible.
Custer examined the flight characteristics of both pure channel - wing as well as Channel Wings with additional, external, short faces, as shown in the graph above. The design worked well at low speeds. At higher speeds, however, there were at high rotational speeds of the propeller to vibrations of the wings, which was also transmitted to the cell and led to a strong noise. Under long-term exposure, there was also the risk of structural fatigue fractures.
Another serious disadvantage of Channelwing is that the buoyancy depends directly on the propeller performance. This means, among other things, that the buoyancy on the approach ( with derated engine power) decreases rapidly. Therefore, in this concept are good short take-off associated with poor short- landing characteristics.
There are currently two CCW aircraft. The CCW -1 is located in the Smithsonian National Air and Space Museum in Suitland, Maryland. The CCW -5 is the Mid-Atlantic Air Museum in Pennsylvania, issued.