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Aviation History
1932
1932 - 0512.PDF
FLIGHT, MAY 27, 1932 The Ugo Antoni Variable Wing 1) Y the publication, in FLIGHT of May 13, 1932, of the articles on the Schmeidler (German) and Makhonine (French) variable-lift wings, we called attention to the work which is going on abroad in an effort to increase the speed range of aircraft. In commenting on Herr Heinze's description of the Schmeidler wing, we pointed out that an increase in chord and camber seemed a less logical way of attacking the problem than the Makhonine way of varying the span. Of the two, it would appear that the German method is the easier from a mechanical point of view, even if the resulting advan tages are smaller, so that the net gain may be as large in the one case as in the other. The possibilities of the variable-lift wing are, of course, by no means exhausted with these two systems. The Fairey variable-camber gear has been in use for many years in this country, and as the extra weight of the gear is very small, it is well worth using. Against it may be advanced the argument that, with a trailing edge flap, the amount of camber variation is limited, while the sudden break in aerofoil contour is liable to be less efficient than would be a variable-camber wing in which the rib flanges were actually bent, resulting in a smooth curvature. Such a wing will be produced in this country in the near future. It owes its inception to an Italian engineer, Signor Ugo Antoni, but is to be built by the Gloster Aircraft Co., Ltd., at their works at Hucclecote, Gloucestershire. Signor Antoni has worked on the problem of variable-lift wings for very many years, and it is of interest to record that as long ago as 1907 he took out a patent on a variable- camber wing. For various reasons Signor Antoni has not yet been able to get his latest type of wing made in Italy, although this will probably be done sooner or later. In the meantime he has arranged with the Gloster firm to construct a wing for him, and the first of these wings is to be fitted to a " Breda " monoplane for flying tests. Signor Antoni has, in his latest type of variable-camber wing, incorporated the results of many years of experi ence, and it would appear that he has evolved a system of construction which is practical from an engineering stand point, although naturally the wing will be somewhat heavier than a plain fixed wing. The principle of the Antoni variable-camber wing will be readily understood from the three photographs of a demon stration rib, which show the rib in the two extreme and intermediate positions. Briefly explained, the camber gear of the Antoni wing consists in hingeing the nose and trailing edge portions of the rib to the wing spars, with levers projecting towards the middle of the wing chord, these levers with their operating mechanism forming a sort of toggle. The rib flanges or booms continue right across the rib, and are braced to the toggle levers by short ties, so that as the leading and trailing edges are depressed by raising the toggles, the top and bottom flanges of the middle portion of the rib follow their movement and maintain a smooth rib contour. The photographs show the great degree of camber varia tion which is possible. It will be observed that the toggle lever of the trailing edge is shorter than that of the lead ing edge. This is, of course, done in order that the angular movement of the trailing edge may be greater than that of the leading edge. In this way not only is the angle of incidence increased as the camber is increased, but Signor Antoni claims that the resulting curvatures are such that no shift of the centre of pressure occurs. Obviously this is a great advantage. In the actual wing to be built by the Gloster Company only every fourth rib will be operated. Between every pair of operated ribs there will be three auxiliary ribs of lighter construction, which will automatically follow the curvature of the main or controlled ribs. This arrangement THE ANTONI VARIABLE WING : The upper photograph shows a demonstration rib in the position of minimum camber, i.e., with the lower surface flat. The lower photograph shows the maximum camber attainable, while in the central picture an intermediate camber position is illustrated. Note that incidence as well as camber is changed. (FLIGHT Photos.) 472
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