FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1914
1914 - 0511.PDF
MAY 15, 1914. wing loses its velocity, unless this is prevented by the movement of a vertically pivoted tail. In the absence of a vertically pivoted tail the loss of velocity of the wing whose angle of incidence is increased, causes it to lose its support, and it descends while the other rises. Thus the vertically pivoted tail is proved to be necessary if lateral equilibrium is to b; preserved by the warping of the wings. The absence in a bird of the vertically pivoted tail proves that warping of the wings is not the method employed by a bird to preserve lateral equilibrium. " The method by which a bird preserves its lateral equilibrium, and steers to right or left, is a beautiful method of flight. If a soar ing bird is making a straight flight with its wings transversely in the horizontal and it wishes to steer to one side, it rocks its wings about a fore and aft axis by pulling one wing down and allowing the other to rise. It is able to do this because the centre of gravity of a bird is below its centre of support, and a pendulum thus exists. The force which this pendulum exerts if shifted from the natural position in which it hangs, provides a fulcrum in mid-air from which the wings can be rocked. Since the mass of the pendulum is con siderable its inertia also helps in providing a fulcrum. When the wings are rocked out of the horizontal their lift has a component force pulling to one side of the line of flight. Now, when a body which is moving in a straight line is acted on by a constant force at right angles thereto, the body describes a circle. Therefore when the bird has rocked its wings it describes a circle. "It must be remembered that this beautifully balanced flight takes place without any attention on the part of the bird except that it controls the elevation (according to whether it wishes to ascend or descend or fly horizontally during the turn) and rocks its wings to tha extent which it considers necessary to make a circle of the desired diameter. In fact the bird possesses a method of flight which takes care of itself and is controlled by two movements. The difficulty which caused Wilbur and Orville Wright to abandon this beautiful method of flight adopted by the bird was that con siderable power is required to rock the whole surface of the wings in the manner of the bird. "A soaring bird has sufficient power to rock the whole wing surface quickly, since it employs for this purpose its strong flying muscles, but the pilot of an aeroplane has not sufficient power for this purpose. Thus the Wright brothers abandoned the perfect method of flight of the bird in favour of warping wings and a vertically pivoted tail, because with this latter method the pilot can preserve lateral equilibrium without having to exert so much power. Less power is required to warp or to control the ailerons than to rock the whole wing surface in the manner of a bird. The choice between one or the other of these methods of preserving lateral equilibrium is a choice between the perfect flight of the bird, which, however, has the disadvantage of requiring considerable power on the part of the pilot, and the method of preserving lateral equilibrium by controlling the angle of incidence of the wing tips, or the angle of incidence of the supplementary surfaces, a method which has the advantage of requiring small power on the part of the pilot, but which causes an excess of resistance on the surface which has the greater angle of incidence, and thus necessitates the vertically pivoted tail with its consequent disadvantages. " It remains to examine whether it is not possible to invent a method of preserving lateral equilibrium, which requires small power on the part of the pilot, and which does not increase the resistance of one side of the machine and thus does not necessitate the use of a vertically pivoted movable tail. " In the machine described, a supplementary aeroplane surface pos;essing a lifting effect is situated above the main aeroplane, and f/OCHT] Three-quarter front view of chassis and nacelle of the Watson No. 3, showing slots in main planes through which the pilot raises his legs when lying down inside the nacelle. is attached to an upward extension of the frame of the machine. This supplementary surface can be rocked about a tore and aft axis with the exertion of small power on the part of the pilot,' and when thus rocked it gives rise to a component side force similar to the side pull of the wings of a bird when they are rocked. This side pull is exerted on the upward extension of the frame of the machine, and thu-s controls the ' list' of the frame of the machine in the same way as a bird controls its 'list.' The main aeroplane is rigid with the frame, so that the rocking of the upper plane controls the rock of the main plane. The torque about the fore and aft axis of the machine depends on the distance between the centre of gravity of the machine, and the upper part of the upward extension of the frame where the supplementary aeroplane surface is situated. This surface may be of small area, and may still exert a sufficient torque about the fore and aft axis of the machine, if the upward extension of the frame is sufficiently long. It must be remembered that the pressure on the upper rocking wing is always balanced about the axle on which it rocks, so that the rocking does not require great power on the part of the pilot. On the other hand when wings are warped, the wing with the Watson No. 2 In flight at Errol, Perthshire, 1912, Watson Nc. 2, 1912, showing balancing plane in operaticn. 5" C 2
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
