L.Opdyke French Aeroplanes Before the Great War (Schiffer)
Deleted by request of (c)Schiffer Publishing
De Beer
The third and fourth designs by the Belgian designer de Beer were built in France by Ratmanoff, a design firm in its own right and builder of the Normale propellers. The de Beer monoplanes were among the most complicated of the pre-War period. He wanted to vary the incidence of the mainplanes to control the speed, but he realized that the stability of his machine varied more or less with the angle of attack of the wings, and so he built different sets of wings with different airfoils, searching for the unique section which would have its lift in the center regardless of angle of attack.
Type 3: In his effort to provide a fully stable aeroplane, de Beer settled on a rather conventional-appearing monoplane, with rectangular wings and rectangular fabric-covered fuselage, small rudder and triangular tailplane with rectangular elevator set forward of the rudder on the sides of the fuselage. Through a complex control system the pilot could vary the angle of attack from +3° to +18°; by pushing the stick sideways he could vary the incidence differentially to serve instead of ailerons; the same stick controlled the elevators. The wings were not locked and could turn freely on their axes in gusts of wind.
Type 4: This 2-seater was similar to Type 3 with simpler undercarriage, slightly enlarged tail surfaces, and better finish. Current reports mentioned a weakness of the airframe.
(Span: 9.8 m; length; 7.35 m; low speed: 40 kmh; high speed: 115 kmh; optimum speed: 70 kmh; 80 hp Anzani)
At the same time that Type 4 was built, Ratmanoff produced a 2-seat trainer, quite similar, which may also have been a de Beer design.
Журнал Flight
Flight, January 17, 1914.
THE PARIS AERO SALON - 1913.
RATMANOFF AND DE BEER.
On the Ratmanoff stand were to be seen two monoplanes, one of which was a Ratmanoff school type monoplane.
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The other machine exhibited on this stand has been built by Mons. Ratmanoff to the designs of M. De Beer, and is chiefly interesting on account of the provision made for altering the angle of incidence while the machine is in flight. It is driven by an 80 h.p. Ansani engine, mounted on overhung bearings in the front portion of the fuselage. This is of rectangular section, and built up in the usual way of four longerons of ash, connected by struts and cross-members of spruce. The chassis is of a very simple type, and consists of two pairs of ash struts carrying on their lower extremities two very short skids, from which is slung by means of rubber shock absorbers the single tubular axle of the two wheels.
Inside the fuselage is the pilot's seat, from where he controls the machine by means of the control lever shown in one of the accompanying sketches. The main planes pivot round the front spar, which consists of a steel tube running right through from tip to tip, and is mounted on the fuselage. The two rear spars project slightly inside the fuselage covering, where they are secured to the system of control levers by which the angle of incidence is altered. By pulling the control lever back, the angle of incidence is increased, thus giving greater lift and causing the machine to climb, while a forward movement of the column decreases the angle of incidence, thereby causing it to descend. A side to side movement increases the angle of incidence of one wing and decreases the angle of incidence of the other, so that this operation takes the place of the warp. The elevator is connected up to the control lever, and works in conjunction with the main planes.
One point in the construction of this arrangement is open to criticism: the two rear spars are simply cut off just inside the fuselage covering, and no provision has been made for taking the compression due to the drift, which consequently has to be taken entirely by the bracing cables of the front spar. Otherwise the system appears to be quite good, although the desired object might be obtained in a somewhat simpler way.
