Within the series of events "24h avec... Léonard de Vinci" produced by the Auditorium of the Louvre Museum in Paris, the first of which was dedicated to Leonardo da Vinci, Pascal Brioist, history professor at the University of Tours, gave a lecture entitled "L’œil de l’oiseau : les extraordinaires machines de Léonard de Vinci" (The eye of the bird: Leonardo da Vinci's extraordinary machines). The conference was focused on the theme of flight in Leonardo's studies, presenting some recent achievements of the study group ArtesMechanicae: two new interpretations of the Loenardo’s parachute and glider, and some replicas of surveying instruments.
The two gliding "flying machines" are the result of a strict philological interpretation of the manuscripts aimed at avoiding improper integrations that would make such machines work using technologies not known at the time; a trend which often in the past led to mistakes many exegetes of Leonardo’s technology. Gliding, which, as known, was the culmination of Leonardo’s failure with mechanical flight studies, was already evoked by other engineers form late15th century. The idea of falling being slowed down by a sail is clearly shown in the anonymous manuscript largely derived from Taccola and Francesco di Giorgio - 34113 ADD - today at the British Library (c. 200v). In 16th century flight was still not possible and the only chance to jump with a parachute was from heights of about 30-40 meters, like the tops of common towers in urban centers or from the top of a hill. So a parachute should have been built with a rigid structure which would keep the sail open before the jump as the falling time would not have been long enough to open the sail itself and slow down the descent before landing. This new reading of Leonardo’s drawing in the light of this consideration has led to an alternative interpretation of some details.
According to Leonardo’s description the parachute had to be a pyramid made of waxed flax (pannolino intasato) with a square base about 7 meters wide, and same height. Leonardo uses the term "pavilion" to indicate the parachute itself; this has lead to the design of a self-standing structure and not a sail held open by air pressure as in modern parachutes. In the drawing, though just sketched and very small, there are elements to make an assumption about the structure. The double line in the middle, drawn between the human figure and the parachute, may suggest a rigid pole starting from the character’s harness and ending at the cusp of the pyramid, keeping it opened. The few - but clear - lines drawn on the human figure seem to outline the contours of a harness attached to the pelvis and the chest of the character, reminding somewhat the one of the "pianoviola" (Codex Atlanticus, f. 93r), which was taken here as a model. To the four corners of the square base frame are fixed as many strings ending on the central pole near the character's hands. The design is unfortunately not clear making uneasy to understand if the strings are tied to the pole or whether the "pilot" can operate them to tilt the sail and thereby controlling the descent trajectory of the parachute. In the model the ropes have been anchored around the pole that supports the opened pavilion - the easiest solution - as if it was a huge umbrella.
The glider too is a device which brakes the fall with a sail but unlike the parachute its descent is guided by the pilot. The device conceived and drawn by Leonardo is characterized by a singular profile that seem reproduce the zoomorphic aspect of a green shield bug (palomena prasina) or most likely the shape of a leaf. The note beside the picture clarifies that the glider is designed to flight with the most tapered side forwards. The pilot is standing on a sort of trapezium that he uses to control the roll thanks to the two ropes fixed to the traversal beam of the sail. A hand driven lever mounted on the vertical beam regulates the pitch. In the drawing is totally absent any device to control the yaw. On the same sheet of the Madrid Codex there also is the famous "flying sphere", to be built - Leonardo says - using reeds and sendal (very thin drape mostly of silk). According to Leonardo’s notes, the glider must be built "of the same nature", with the same materials. At first glance it may seem a quite refined drawing, but it actually contains many very uncertain details. Among these the most difficult to interpret is the area which should accommodate the pilot: despite its position is clearly pointed by Leonardo, the drawing does not show any evident structure suitable to host it.
The roll is controlled by two ropes fixed to the ends of a short transverse axis. This one is anchored orthogonally to the central longitudinal axis of the sail, through a joint which evidently has a limited rigidity. Having the two ropes being directly fixed to the outer edges of the sail structure would have been much easier and more effective.
At the lower end of the vertical beam which hosts the controls, the drawing shows a large and very clear facing down arc of a circle. To date no convincing assumptions have been made on the interpretation of this sign.