GB474065A - Improvements in or relating to surfaces adapted to be displaced in a fluid medium - Google Patents

Abstract

474,065. Deformable aerofoils and hydrofoils. FAUVEL, C., and COLTEL, H. Jan. 17, 1936, No. 1640. Void. Convention date, Jan. 17, 1935. [Classes 4 and 113 (ii)] The Specification is concerned with aerofoils and hydrofoils which are capable of being deformed in correspondence with changes in angle of attack in such manner that the centre of pressure remains constant. The camber of the surfaces may be made variable by an elastic construction, by the provision of leading and/or trailing edge flaps, by the provision of a number of such flaps, Fig. 3, or by split flaps for instance as shown in Fig. 18. The flaps may be controlled through a relay by devices measuring the angle of incidence of the wings or the speed of the craft. Other controlling instruments stated to be applicable are gyroscopes, accelerometers, altimeters, statoscopes, engine speed indicators, or generally any automatic piloting device. Alternatively, the movable surfaces may be coupled to the elevator controls and themselves in some circumstances act as control surfaces, for instance, trailing edge flaps may be differentially operable for lateral control. In one such arrangement, Fig. 5, a wing A has three flaps B<10>, B", B<12>, and B<20>, B<21>, B<22> on either side of the plane of symmetry which are differentially adjustable to different degrees. External aerofoil ailerons such as 3, Fig. 6, may be pivoted at the centre of pressure or be provided with flaps adjustable to maintain a stationary centre of pressure at any adjusted angle. Fig. 8 shows an arrangement particularly for tailless aircraft in which the chord e of flaps B, B<10>, B<20> is at any point a fixed fraction of the chord D of the wing at that point. The plan form of the wing is such that the locus of points disposed at a distance d from the leading edge which is a constant fraction of the chord D at that point, for instance, between 25 and 30 per cent, is a straight line passing through the centre of gravity of the aircraft. In a tandem wing aircraft, Fig. 10, a forward wing A is pivotally mounted and has a controllable flap B or two slotted wings A, Fig. 21, are both pivotally mounted. Adjustable surfaces controlled in the manner set forth above may be provided on control surfaces,' gyroplane blades, or hydrovanes.