"...the first memory of my childhood is that it seemed to me, when I
was in my cradle, that a kite came to me, and opened my mouth with its
tail, and struck me several times with its tail inside my lips..."
- Daedalus, Giotto, after 1334
In 1505, at the age of 53, Leonardo
recounted his earliest childhood memory of a bird coming to him in his
cradle. Throughout his life, he pursued the dream of flying. Although
he was the first person to scientifically investigate flight, he was by
no means the first or only person to think seriously about the problem.
Roger Bacon, the 13th century philosopher whose work Leonardo
greatly admired, described “a flying machine in the middle of which a
man could be seated and make an engine turn to activate artificial
wings that would beat the air like those of a bird”. During Leonardo’s
own lifetime, Giovanni Battista Danti was said to have carried out
trial flights over lake Trasimeno and eventually killed himself by
crashing into the roof of a church.
It is perhaps fitting that
a 14th century relief sculpture on the base of Giotto’s bell-tower in
Florence representing man’s creative aspirations shows the figure of
Daedulus with open wings. Deadulus, the legendary Greek flyer, also
died in the attempt.
- Flying machine - Ms B Fol 74v-75r © Leonardo3 - www.leonardo3.net
In nature's image
the 15th century, people still believed that flight could be achieved
by imitating birds. Leonardo’s designs for flying machines were based
on the conviction that the principles used by nature in its flying
creatures could be imitated and reproduced by man. He cites the kite as
a model to imitate and refers to his flying machine as a “bird”.
all the flying machines designed by Leonardo before 1500 are
ornithopters, which have flexible wings like a bird. He concentrated on
designing mechanical systems that would harness the physical power of
the pilot to sustain both man and machine in flight. While his machines
are powerful in appearance, they lack the sufficient power required for
propulsion and are far too heavy to fly.
Paris Manuscript B
Fol 74v illustrates a mechanism operated by a pilot who is in a
horizontal position in the manner of a bird, recreated as a model in
the image on the left. The pilot powers and controls the beating of the
wings with his feet by pushing on pedals that are attached to the wings
by a complex system of cables.
The wings beat up and down and
inwards in a sort of rotatory movement that imitates the flight of
birds. On the reverse of the same sheet, Leonardo illustrated a design
for a wing that would flex and beat like a bird’s wing. It was made of
cane skeletons, leather tendons, muscular springs and membranes of
starched silk and “fustian, on which will be glued feathers”.
- Ms B Fol 80r - Flying machine. Photo RMN - © René-Gabriel Ojéda
Like a bird
Leonardo also designed ”standing” ornithopters. The machine on
Manuscript B Fol 80r is a bowl-shaped airship, within which the pilot
bends and unbends to pump a piston with his head while turning
windlasses with his arms to operate four flapping wings 24 metres long.
The machine has a retractable under-carriage and entry ladder.
Its considerable weight did not deter Leonardo, who seems to have
thought he was close to success. He even contemplated a test flight!
Perhaps his awareness of the dangers deterred him. He recommended to
others that the machine be tried over a lake, with inflated wineskins
attached to the aviator to prevent him drowning.
- Ms B Fol 83v - Flying machine. Photo RMN - © Bulloz
Not a helicopter
Leonardo rarely deviated from the principle of beating wings in his
inventions. One exception is the design on Manuscript B Fol 83v for an
“aerial screw”, which has led to false claim that he invented the
helicopter. Leonardo’s invention is based on a helical screw 10 meters
in diameter and not rotary blades. But the drawing does express the
scientific principle that when the air is compressed it has density,
which was to find its application much later in the propeller or
Leonardo’s machine was supposed to lift off when rotated, but one might
well ask how the force required to achieve sufficient rotating speed
would be obtained. It is likely that his device was not for manner
flight but was intended for a public spectacle. Nonetheless, it’s nice
to think that Leonardo’s drawing may have inspired Igor Sikorsky’s
invention of the first stable, single rotor controllable helicopter,
having been reputedly shown Leonardo’s drawing by his mother.
- Otto Lilienthal - early glider, 1890s
By 1500, machines with beating wings become less dominant in Leonardo’s
studies, following the realisation that humans lacked the muscular
power of birds. His studies of birds in flight take on a new intensity
as he concentrates on the possibility of sail-flying. He correctly
identified the relationship between the centre of gravity and the
centre of pressure in a glider, he comes close to the principle on
which modern gliders are based: -
“The man in a flying machine to be free from the waist upward in order
to be able to balance himself as he does in a boat, so that his centre
of gravity and that of his machine may oscillate and change where
necessity requires, through a change in the centre of its resistance.”
One of his wing designs was used in a hang glider, made for the
television programme “Leonardo’s Dream Machines” (Channel 4, UK) and
generated more than enough lift to carry an aviator over a considerable
During the early 1890s, Lilienthal achieved the first sustained stable
flight in a glider. In his machine the pilot throws his hanging torso
and legs in the direction in which he wants to travel, thus shifting
the centre of gravity and with it the centre of pressure. According to
Leonardo’s principle the upper body controls the shift. This is a
serious error, which would have led to instability and eventually the
pilot and machine toppling over!
Leonardo’s study of flight and innovative inventions had no significant
direct impact on early flying machines, simply because his work in the
field was little known before it was published in the early 20th
century. Earlier publications of his manuscripts either omitted his
work on aeronautics altogether, or did not take it seriously. Hureau de
Villeneuve’s article in L’Aéronaute in 1874 was the first publication
that properly established Leonardo as the first to scientifically
Nonetheless, Leonardo’s observations on the flight of birds are a
valuable contribution. His study led to the observation that “as much
pressure is exerted by the object against the air as by the air against
the body”. This predates Newton’s so-called third law of motion, which
states that every action gives rise to a reaction of equal strength in
the opposite direction, by almost two hundred years.