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Aviation History
1924
1924 - 0044.PDF
THE MAGNAN MONOPLANE GLIDER: General arrangement drawings. The "fin area" of the forward portion of the fuselage is very considerable, although of rounded, section, and altogether the machine does not look reassuring from the point of view of directional stability It would seem that the designer has attempted to copy the outward shape of a bird without taking into consideration that the range and numher of movements of which a bird's wing is capable enable it to carry out with perfect safety manoeuvres which a machine outwardly resembling the bird but lacking its adaptability could not hope to imitate. Constructional Features Constructionally no less than aerodynamically the Magnan glider is somewhat unusual. The monoplane wing has but a single spar, of box section and built of wood. The construc tion of this spar must have presented considerable difficulties, as there are two fairly sharp bends in each spar, one a few feet out from the body, where the horizontal cahane meets the spar, and another (this in a horizontal plane) a few feet from the tip. where the spar tip is swept forward to meet the straight leading edge. The ribs have top and bottom flanges of ash, the lower flange, which runs from leading to trailing edge, being screwed and glued to the lower face of the spar. The top flange stops short of the trailing edge, about one-third of the chord from it, and is so attached to the lower flange and to the spar that it can slide a short distance in a fore- and-aft direction, thus allowing the trailing edge to flex. The details of the arrangement are not available, but we under stand that they constitute a patent. Near the wing tips the ribs slope outwards, and also they are so mounted on the spar as to give a pronounced " wash-out " to the wing. Lateral control is by warping, but instead of the warp causing a change of angle without sensible change in camber, in the Magnan monoplane both angle of incidence and camber are altered. It would appear that the force on the control column necessary to produce the required amount of warp must be very considerable. The fabric covering is applied in a special way, which is claimed to prevent wrinkling when the wing is being warped. The fuselage is of egg-shape section, and is built up of formers alternating sloping back and forward, thus forming a series of Vees as seen in side view. To these formers are attached four main longerons and a great number of stringers, and wire bracing is employed for stiffening the structure against torsion. (The Vee formation of the formers plus the four longerons already provide a structure stable under plain bending loads.) The fuselage is fabric covered except at the extreme nose and stern. The tail is of more or less orthodox design, but is supported m a BRITISH STANDARD METHOD FOR THE DETER MINATION OF VISCOSITY IN ABSOLUTE UNITS (B.E.S.A. Publication No. 18S—1923) THE object of this specification is to provide an accurate yet simple and commercially applicable method for the deter mination of viscosity of a liquid in C.G.S. (centimetre-gramme- second) units. The specification includes standard dimen sions for U-tube, co-axial bulb and falling sphere viscometers, 44 on a duralumin cone bolted to the rear bulkhead of the fuselage proper. A simple undercarriage consisting of two wheels carried on a duralumin axle is fitted, the axle being sprung by rubber cords anchored inside the lower portion of the fuselage. The pilot's seat is mounted on longitudinal rails, somewhat like the sliding seat in a boat, and for fore-and-aft control he can alter the position of the centre of gravity by sliding the seat along. The ordinary controls are of the usual type. The manner in which it is hoped to carry out gust soaring with the Magnan glider is as follows. The machine will be launched from a cliff on the coast, and will glide into the wind until fairly low over the sea. It is assumed that gusts will be present, and that these occur at such intervals as to enable the pilot "to manoeuvre the machine in the manner required to extract energy from the fluctuations in the wind. During a gust the pilo't will pull back the stick, and if necessary shift his seat back so as to bring the tail down quickly. As the gust dies down he will push the stick forward and slide his seat forward at the same time so as to avoid stalling the machine. During a lull it will be the pilot's endeavour to glide forward with the minimum loss of height, i.e., at the best gliding angle for the particular conditions. As soon as he feels another gust rising he will again elevate, and so the cycle is continued with alternate elevations and depressions. Dr. .Magnan considers that another method would be to glide down-wind during the lulls and up-wind during the gusts, but that it is doubtful if the machine could be manoeuvred quickly enough to make this form of gust- soaring feasible. Some preliminary tests over land have been made with the machine, piloted by Canivet, and these are stated to have indicated that the machine should, under suitable conditions, be capable of taking advantage of a gusty wind. The main characteristics of the Magnan Monoplane, known as the " Tvpe Marin M.2," are as follows : Length o.a., 4 -95 m. (16 ft. 3 ins.) ; span, 11-5 m. (37 ft. 9 ins.) ; chord (root), 1 -3 m. (4 ft. 3 ins.) ; wing area, 10 -25 sq. m. (110 sq. ft.) ; weight of wing, 60 kgs. (132 lbs.) ; weight per sq. ft. of wing, 1 -2 lbs. ; weight of machine (empty) 130 kgs. (286 lbs.) ; weight in flying trim, 200 kgs. (440 lbs.) ; wing loading, 19 kgs./sq. m. (4 lb./sq. ft.). As alighting on the sea will be one of the normal functions of the machine, the fuselage and wings have been made watertight, the opening for the wheel axle being bulkheaded off from the rest of the fuselage. The wing loading, it will be seen, is fairly heavy, and the structural weight appears to be greater than usual in gliders. Probably this is due, mainly, to the wing construction. Actual tests over the sea will be looked forward to with interest. H H and the standard liquids recommended for their calibration. The use and calibration of the instruments are described in detail, also the method for determining the viscosity of opaque liquids by means of the Lidstone Viscometer, and by the adaptation of the tube and falling sphere viscometers. Copies of this publication (No. 188—1923) are obtainable from the B.E.S.A., Publications Dept., 28, Victoria Street, S.W. 1.
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