L.Opdyke French Aeroplanes Before the Great War (Schiffer)

Журнал Flight

Flight, December 30, 1911.

PARIS AERO SHOW.

Roger Sommer.

ROGER SOMMER was represented at the Salon by two machines, a monoplane and a biplane, the latter constructed throughout of steel. The biplane should really be termed a double monoplane, for the cellular method of bracing the main planes has disappeared in favour of the system originated by Breguet. Balancing laterally is effected by the rotation around the front spar, of the extensions of the top plane. Its chassis, supported by six steel tubes, is composed of a pair of wheels mounted on a common axle, which latter is flexibly attached by means of stout rubber bands to the short steel tubes uniting the steel chassis struts. One peculiarity about this landing gear, which is directly descended from the original Henry Farman conception, is that the radius rods have disappeared. Elevation and depression of the machine is controlled by a small monoplane surface, measuring about 2 ft. span by 1 ft. chord, supported on steel outriggers about 8 ft. in advance of the main plane, which surface works in conjunction with a flap hinged to the rear of the lifting tail. Its diminutive size makes one wonder if this surface is of any use at all as an elevator, and the only apparent advantage of the system is that the outriggers form a good point from which to brace the main planes against drift strains.
The main planes, which are double-surfaced with leaf-green fabric, for the purpose of rendering them invisible when close to the ground, are tested before they leave the works to withstand a strain of four times that they are ever likely to be called upon to bear in normal flight.

Principal dimensions, &c. :-

Biplane-
Length 30 ft.
Span 40 ft.
Area 330 sq. ft.
Weight 640 lbs.
Speed 56 m.p.h.
Motor 50-h.p. Gnome.
Price L840


Flight, January 27, 1912.

THE SOMMER ALL-STEEL BIPLANE.

   FOR quite a long time after Sommer gave up his business as felt manufacturer, and entered the arena of aeroplane construction, it cannot be said that his productions earned any great name for excellence of general finish.
   Nevertheless they were, indeed, practical vehicles, as his list of successes prove.
   That the life of an aeroplane in those days was reckoned as not being much longer than two months is, perhaps, some excuse for his not devoting a great amount of attention to the point of finish. Today, however, engines are indefinitely more reliable, pilots have gained greater experience, and design generally has advanced, and concurrent with the increased length of life that these factors produce comes the desirability for higher-class detail workmanship.
   Roger Sommer, indeed, has not lagged behind in this respect, and for the excellence that his new all-steel biplane exhibits as regards its general design, its detail work, and its standard of finish, we can forgive him much of the crudeness that characterised his earlier models.
   Comparing his latest biplane with his former ones, it is noticeable that the cellular method of bracing the main planes has been discarded in favour of that originated by Breguet. The two main planes, unequal in span, are each built about a single boom of steel tubing passing through their respective approximated centres of pressure. These booms are separated by four steel stanchions arranged in a single row, and trussed together by stranded steel cable. In order to avoid the tendency for the booms to twist at the points to which the vertical stanchions are applied, these latter are made double, being each constructed from two parallel tubes of different diameters united by short lengths of the same material welded thereto. The planes are double-surfaced with green-rubbered fabric.
   For the maintenance of lateral stability, the extensions of the top plane are so constructed that they can pivot about their main booms, and so take different angles of incidence, according to the discretion of the pilot.
   They are interconnected, so that an increase in the angle of incidence of one is accompanied by an equal decrease in the angle of incidence of the other. In normal flight they both are incident to he relative wind at the same angle as the remainder of the top surface, and thus constitute purely sustaining planes. By virtue of the simplicity of this system of bracing, the supporting surfaces can readily be dismantled for transport from place to place, a feature that is being devoted an ever-increasing amount of attention among French constructors.
   The tail consists of a fixed cambered monoplane surface mounted some distance behind the main planes on a pair of outriggers made solely from steel tubing. Behind this fixed surface is hinged a flap, which is connected to the front elevator and to the pilot's lever, and whereby the attitude of the machine in flight is governed. Two vertical rudders immediately beneath the tail provide the means of steering laterally. They are operated in the customary way by means of a pivoted foot lever.
   The engine bed is formed by two tubular beams, representing the sides, united by cross-members of steel tubing, the whole being rigidly braced by steel wire. At its rear is mounted the 50-h.p. Gnome motor, direct coupled to an Integrate propeller. Two seats are provided, that for the pilot being about 2 feet in advance of the main planes, that for the passenger being in the same vertical plane as the centre of gravity. The chassis is quite an interesting feature, in that it is illustrative of the latest phase in the metamorphosis of the original Farman-type of landing gear. In common with other machines at the Paris salon, the skids have been entirely suppressed, and in this case a short piece of steel tubing, to which the common axle uniting the two landing wheels are flexibly strappd by rubber cord, is all that remains to remind one of their former existence.
   On each side the chassis is supported by one main tube and two subsidiary ones, the main one proceeding from the base of one of the central cellule stanchions, the two smaller ones being directly attached to the engine bed.
   Radius-rods are no longer provided, and the axle itself is not trussed, as formerly, to enable it to withstand the tendency for it to bend by virtue of the overhang of the wheels. Now a pair of simple tension wires are provided to limit the amount of possible flexion of the axle.
   Mounted in advance of the pilot's seat, on a pair of single tubular outriggers, is a pivoting monoplane surface, roughly elliptical in shape, which is connected to the control lever, and which presumably is intended to act as a forward elevator. As such, however, it really must be of little use, by comparison with the superior area and leverage of the rear-elevating flap. Indeed, the only apparent reason for its presence there is that it forms a constantly visible indicator of the attitude of the machine, and that its outriggers constitute a very convenient point from which to brace the main planes against drift strains.
   Weighing 638 lbs., the machine has been designed to lift a useful load of 500 lbs., and maintain a speed of 60 miles an hour.


Flight, November 16, 1912.

THE PARIS AERO SALON.

Sommer.

   SOMMER is showing two machines - a 75-h.p. Renault engine biplane and a 50-h.p. Gnome-engine monoplane. In neither case, we regret to say, do the machines show any advance on the types that were shown twelve months ago. For the biplane, a good deal of steel is used in its construction, although not nearly to the same extent as was evident in the extremely neat and promising biplane with the single bank of struts between the planes, that Sommer exhibited on his stand last year. The skeletons of the main planes, the tail and the front elevator, and the strutting of the cellule are of wood. The tail outriggers, elevator outriggers and chassis are of steel tubing. Sommer has abandoned his original idea of mounting his pair of landing wheels on a long common axle. In his new form of chassis each wheel is sprung from a pair of supports in such a manner that if the machine landed in any sort of a side wind, they could do nothing but collapse. From one of each pair of supports on either side of the machine, long curved tubular skids extend forward to meet the front elevator. They, too, seem of little use, for the steel tube must be insufficiently solid to avoid a smash should the machine land nose down, a contingency for which skids of this type were originally designed.
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