FR2780026A1 - Articulated airframe for ultra-light glider - Google Patents

Abstract

The articulated airframe enables the transmission of an oscillating movement to the wings of the glider. It is composed of a horizontal triangular chassis (1) on which two oscillating frames, the seat frame (2) and the pilot's footrest frame (3), are articulated. Oscillatory movement of these frames is transmitted to the wings by a double antagonistic compass system (6). The lift of the wings during flight is balanced by springs (7,8) connecting the frames to the chassis. When the wings are high the glider is nose down and when they are down the glider is nose up. The rolling direction is assured by the handlebar (9), articulated on the footrest frame, controlling by cables the trailing edge of the wing tips.

Description

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  The present invention relates to a device for using physical force

  an ultra-light glider pilot, in order to increase the speed of this glider.

  The ultra-light gliders have reached a high level of performance. They fly, as their name suggests, in "gliding flight", that is to say that their wings are fixed. All the birds practice this flight in which they are more or less efficient. But all the birds also practice the flight "rowed". By giving their wings an up and down oscillation, and by varying the incidence of their wings during this oscillation, they increase their

  speed, and therefore their possibility of evolution.

  The device according to the invention makes it possible to achieve this movement for gliders

ultra-light.

  This device, called "articulated motor cell", is composed of a horizontal frame in the shape of an isosceles triangle. The pilot's seat is supported by a frame hinged to this chassis. We will call this part of the cell the "seat frame". The articulation which connects the seat frame to the chassis allows the seat to swing back and forth over a distance of approximately 50 cm. The pilot rests his feet on a frame articulated in the same way, in front of the seat frame. We will call this frame the "footrest frame". A

  system for blocking the movement of these frames makes it possible to stiffen the chassis assembly-

frames, if necessary.

  The device according to the invention has been developed to operate with windsurf sails as wings. Their dimensions, structure, profile, and the compromise they achieve between rigidity and flexibility, make these objects perfectly suitable for serious experimentation with the process according to the invention. Wings more specifically

  developed for use according to the invention are of course conceivable.

  The sailboard sails, to be transformed into sails that can be used according to the invention, have each been provided with a frame making it possible to articulate them to the frame of the airframe, by two hinges, so that the tip of the wing can oscillate up and down. Each wing frame is provided with an anchor point for transmitting

  the forces generating and regulating the oscillation.

  A system of double antagonistic compasses (equivalent to a deformable parallelogram) connects the anchor point of each wing to anchor points provided on the seat and the footrest of the airframe. The junction is made by ball joints, allowing a

  complex movement. When the pilot extends his legs, the seat frame and the frame

  feet move away from one another, the points of the compass connected to the anchoring points of the wings approach each other, and the wings are pulled down. Conversely, when

  the pilot folds up his legs, the wings go up.

  When the glider is on the ground, the wings, not supported by the lift, lower, driven by their weight. Conversely, when the glider is in flight, the wings rise "in abutment", pulled by the lift, and retained at the hinges by the weight of the airframe and the pilot. The effort required to get out of the abutment is very important, especially since the inertia of the wings is itself very important (they are of the order of 5 meters in span each). In order to solve this problem, a system of springs, attached to the chassis and the frames tends to separate them from each other. It is possible to use springs in tension or in compression. The springs will be chosen, mounted and adjusted so that, during the "free" gliding flight, that is to say without the pilot's efforts, and without blocking the frames, the wings are balanced, the oscillation stabilized substantially at a third higher than its total amplitude. With such a system, a very measured effort by the pilot makes it possible to initiate an oscillation. The glider will be set "neutral", that is to say neither pricking nor nose-up, in this position (the wings at the upper third of their oscillation). When the wings are raised to the maximum, the pilot himself is advanced as far as possible in the airframe, the glider becomes biting, which facilitates the movement of descent of the wings. Conversely, when the wings are fully lowered, the pilot is in full extension, his center of gravity is

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  retracted to the maximum, the glider becomes nose-up, which facilitates the ascent movement

wings.

  A propulsive wing must have a flexible, deformable or "elastic" trailing edge, particularly at the wing tip. During the oscillation cycle, the wing tip travels the greatest distance, and therefore stirs the largest volume of air. This is where the most efficient transformation of the wing's oscillatory movement into propulsive force takes place.The trailing edge must be supported by the exhaust air flow when descending of the wing, but also on the ascent (if this ascent is dynamic, and not completely passive). The profile of the trailing edge of the wing must flex flexibly with each change of direction (vertical) of the wing during the oscillation. The pilot must be able to act on this part of the wing to regulate and modulate its movements, essential for propulsion. The rider will act by traction and release on the wing tip profile slats, via a sheathed cable, such as a bicycle brake cable. These cables, one for each wing, will be connected to a handlebar articulated on the footrest frame. They will be adjusted so as to be in permanent tension during the flight. The two branches of the handlebars are normally integral, as it is on a bicycle for example. The pilot acts by rotation of this handlebar around its axis (the footrest frame). Such rotation induces

  additional traction on one of the cables, therefore lowers the trailing edge at one end.

  wing, and simultaneously, releases the tension of the other cable, inducing the rise of the trailing edge of the other wing. This action of rotation of the handlebars brings about the turning of

  the aircraft, and therefore its roll control.

  However, the two arms of the handlebars can be separated, for example by a notched device. When the two branches of the handlebars are separated, the pilot can obtain either the raising or the simultaneous lowering of the two trailing edges of the ends

  of wings. It thus acts on the pitch of the aircraft when the wings are fixed (in gliding flight).

  During the oscillation of the wings, this pulling or raising action of the two trailing edges of the wing tips allows it to modulate and optimize the propulsive action generated by the oscillation.

  The accompanying drawings illustrate the invention.

  Figure I shows the cell in plan.

  Figure 2 shows the cell in side view.

  Figure 3 shows the cell viewed from the front.

  Figure 4 shows the plan of a wing frame.

  With reference to these drawings, the device comprises a frame (1) supporting the frame-

  seat (2) and the footrest frame (3), articulated on the chassis so that it can oscillate back and forth. The wing frame allows the articulation of the wing to the cell frame by two hinges (4), and the transmission of forces by an anchor point (5). A system of double antagonistic compasses (6), or deformable parallelogram, transmits to the wings the oscillation of the seat and footrest frames driven by the pilot. A system of springs in traction (7) or in compression (8) balances the wings in flight. A handlebar articulated on the footrest frame controls cables acting by traction on the trailing edges of

wing tips.

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Claims (4)

  1) Articulated driving cell for an ultra-light glider with propelling or "swinging" wings, characterized in that it consists of a horizontal chassis of triangular shape which is suspended by articulations a seat frame and a footrest frame, on which takes place the pilot, and which can oscillate back and forth when the pilot bends or extends the legs, these oscillating frames being connected to the wings by a system of double antagonistic compasses (or deformable parallelogram) allowing the lowering of the wings when the frames are spaced from each other, and the raising of the wings when the frames are close to each other.   2) Device according to claim 1 characterized in that springs attached to the frame and the oscillating frames separate these oscillating frames so that in gliding flight (without pilot efforts), the wings are substantially stabilized   to the upper third of their oscillation.   3) Device according to any one of the preceding claims, characterized in   the roll direction is effected by a handlebar articulated on the footrest frame and connected by cables to the trailing edges of each wing tip, thus allowing the rotation of the handlebars to raise the trailing edge at one end wing, while lowering the other.   4) Device according to claim 3 characterized in that the handlebars are articulated in the middle, thus making it possible to raise or lower simultaneously the trailing edges of the two wing tips, thus providing pitch control when the   wings are fixed, or a modulation of motor skills during the oscillation of the wings.