Leonardo da Vinci - Inventions

Leonardo designed the wings of his flying machines based on the natural shapes of the wings of flying animals, such as birds and bats. He is therefore considered the inventor of bionics, the transfer of principles from nature to technology.

Leonardo initially intended his flying machines to imitate the flapping of birds' wings. Such flying machines are called ornithopters. For this purpose he created two versions, one standing and one lying. The wings were to be moved by human muscle power via ropes, pulleys and mechanical joints. The arms were to be used as well as the legs. When Leonardo realized that sheer muscle power would not be enough, he began to design gliders.

To prevent injury in the event of a crash landing, Leonardo recommended that pilots be clothed in air bags. This was to cushion the impact from low altitudes and thus prevent serious injuries. The then novel principle of cushioning violent impacts with yielding air cushions is now known as an airbag. Airbags are used in modern cars to protect the occupants from impacts against the vehicle interior in the event of an accident.

In contrast to many of Leonardo's other inventions, one of the flying machines was probably actually built, and there was an attempted flight in 1505 when Leonardo was 53 years old. He noted it with remarkable pathos:

"For the first time, the great bird will rise from the back of the mighty swan. It will fill the whole world with wonder and all writings with its glorious deed, for the eternal glory of the nest where it was born."

With the "back of the mighty swan," he meant Swan Mountain ('Monte Ceceri'), a hill near Florence. The hill drops very steeply on one side, making it ideal for launching a glider. Today, there is a memorial stone there to commemorate Leonardo's attempts. At the foot of the hill lies the town of Fiesole.

The quote is the last sentence in the Codex Turin, Leonardo's book on bird flight. There, he succinctly summarized the principles of flight using bird flight as an example. Leonardo also wrote that he was heading to Fiesole in March 1505. Since the book includes both the dramatic announcement ("the great bird will rise") and technical drawings, it is believed that Leonardo created it in conjunction with a practical flight attempt that took place in Fiesole.

However, the attempt likely failed because the notebook ends at that point, and Leonardo does not mention flight experiments in other writings. Therefore, it is unclear whether there were further flight attempts after the (presumed) failure in Fiesole. Had the experiments been successful, Leonardo would have been the first designer of a glider, 300 years before Otto Lilienthal.

It has been said that Leonardo took the concept of the propeller from a Chinese children's toy. And indeed, the way Leonardo cites the ruler as evidence is reminiscent of a centuries-old East Asian children's toy, a bamboo dragonfly. This toy consists of a ruler-like wooden plate to which a thin stick has been nailed vertically in the center. Because at least one of the wings is tilted slightly upward, the stick can be made to rotate between the palms of the hands and take off.

Leonardo maintained good relations with international travelers, such as Benedetto Dei, who toured Europe, North Africa, and the Orient. Their stories fascinated Leonardo and he listened with interest. Therefore, there exists a description of the Caucasus by Leonardo that seems as vivid as if he had been there himself. Due to the international trade routes and stories in Leonardo's environment, it is therefore quite conceivable that he could have had knowledge of the Chinese toy.

Could Leonardo's helicopter fly?

The helicopter was never built, but it could not have flown at the time. For one thing, the weight of the wooden construction was too high, and for another, it lacked a sufficiently powerful propulsion system to allow the propeller to take off.

Apart from the materials and the drive, however, the principle of lift by means of a propeller was correctly recognized by Leonardo. A replica of the design would be a flyable helicopter with today's means (lightweight construction and electric motor). Therefore, Leonardo's sketch of the propeller is considered the first vertical take-off and landing (VTOL) aircraft ever designed.

Modern adaptations

To mark the 500th anniversary of Leonardo da Vinci's death in 2019, University of Maryland students submitted a design based on Leonardo's propeller principle to a helicopter design competition.

Instead of just one propeller, however, they used four of Leonardo's propellers connected in a square for safety reasons. In their center was the pilot's capsule. For cost reasons, they could only create a mini-drone and a 3D simulation. But the calculations were accurate and so they were able to prove that Leonardo's principle of the propeller basically works. The details can be read on the University of Maryland's website.

Directly below, Leonardo makes the sketch of the parachute and writes to it:

"If a man has over him a canopy of sealed linen, which shall be twelve cubits wide [about 6m] and twelve high, he will be able to throw himself down from any height, however great, without suffering any harm."

What was the purpose of the parachute?

Leonardo did not invent the parachute as an end in itself; it was related to his attempts at flight. Leonardo was aware that a flying machine had to have an emergency system that could save lives in the event of a crash. The idea for the parachute must have arisen from this consideration. Elsewhere, Leonardo recommends that flight tests be conducted over bodies of water so that the aircraft can still land safely in the event of a sudden descent. 

Was the parachute tested?

Leonardo only made this one casual drawing about the parachute. It is unknown whether this flying device was realized during his lifetime.

The flight capability of the drawn parachute was discussed by experts for a long time. On June 26, 2000, the Briton Adrian Nicholas dared a test jump with a parachute made of medieval materials based on this sketch. He let himself be pulled above South Africa's Kruger National Park by a hot air balloon to an altitude of 3000m. Then he released and glided to the ground in a gentle descent. However, after 5 minutes and 2200m of descent, he had to disengage and landed with an additional modern parachute he carried. Leonardo's parachute, weighing about 100kg, is almost four times heavier than modern parachutes. Had Nicholas been unfortunate enough to land, the heavy parachute could have fallen on him and injured him.

After the basic functioning of Leonardo's parachute was proven, there were numerous imitations, many of which were documented on film. Today, they give a dreamlike impression of how far ahead of his time Leonardo was.

Above the left interior

"In this way the interior is arranged".

Below

"8 men operate it, and these men also control it and pursue the enemy"

Below the right exterior view

"This is good for breaking through the ranks, but you [the infantry] have to follow". 

The tank was never built or used for war purposes. 

A peculiarity of the left representation is the crank drive. According to the illustration, the wheels, each driven by a crank, should lock against each other. The crank cannot be moved, the tank cannot drive.

Since Leonardo da Vinci sketched far more complicated gear constructions at other place, this representation mistake surprises. In the research different theories are discussed.  

• Leonardo wanted to protect the drawing from imitation. The argument is often also used as an explanation for the use of mirror writing
• Da Vinci had moral scruples and wanted that the, according to this sketch, non-functional tank could never have been used in war. Accordingly, any replica would have produced an immobile model. However, this would have been easy to recognize and fix by an experienced designer
• It may simply have been a clerical error

Functionality

Armor

What was new about Leonardo's design for armor was that the outer armor was sloped at about 30°, which increased the likelihood that enemy bullets could ricochet off the armor, which was presumably made of solid wooden planks. At the same time, the sloped armor improved the tank commander's angle of view of the immediate environment. The commander was supposed to be able to look down on the battlefield from a turret with a 360° viewing slit.

Firepower

The vehicle should be equipped with embrasures all around. There was no fear of smoke from cannons inside the tank, since muzzle-loading cannons were still used at that time, which directed the projectile along with the explosive gases out of the vehicle. 
Contrary to what is assumed in modern research, it is not clear that it should be exclusively a gun carriage. This is because cannons, bullets and powder would have made the vehicle too heavy. Also, such a vehicle would have needed far more crew than the planned 8 men. 
The drawing itself does not only show cannons. Rather, the side openings may have been openings for musket gunners. This is especially clear in the middle opening, which shows two shotgun barrels lying on top of each other. The smoke drawn by Leonardo also suggests that cannons should have been located only in the front part of the tank. 

The vehicle would have been set in motion by hand cranks connected to the wheels. By adjusting the crank speed on one side as well as the other, the vehicle could have been steered. Also novel was the idea of placing the wheels of the combat vehicle under the armor so that they were less susceptible to destruction and thus threatened maneuverability.

Leonardo writes that this machine hurled a ball the weight of a talent six stadiums. This corresponds to a ball of about 30kg over a distance of about 1.2km. 

The ancient units of measurement Leonardo mentions suggest that he did not perform the experiment himself, but refers to the experiments of Archimedes. A military use at the time of the Renaissance is not known.

The cannon has the advantage over conventional cannons in that it works without gunpowder. However, it cannot be used in the rain, which makes it unsuitable for military use. Nevertheless, the idea was taken up again by some military men in the 18th century, but these attempts did not go beyond prototypes. 

The essential insight that Leonardo gained here, however, was another. Leonardo was constantly searching for powerful sources of propulsion for his mechanical machines. The power that could be generated by emerging water vapor in a pressure vessel must have made a great impression on him. This principle was the basis for the civilian harnessing of steam by steam engines, which 200 years later heralded the industrial revolution.

In the accompanying text, Leonardo claims that the cannon was not his invention, but that of the ancient natural scientist Archimedes. However, there are no known sources that attribute the invention of a steam cannon to Archimedes.

Archimedes was not only a very important scientist, but also a resourceful engineer. He lived in the Sicilian coastal city of Syracuse. When it was besieged by the Romans for three years, his inventions inflicted devastating damage on the Roman attackers. Famous are the huge gripping arms with which he could lift and sink entire ships. According to a later tradition, Archimedes also used burning mirrors to ignite the ships of the Romans over long distances. Modern experiments have shown that Archimedes could have done this in principle with the means and knowledge of optics available at the time. Archimedes was killed when the city was taken.

Leonardo possessed some writings of Archimedes and it is obvious that he was in his tradition. Both had in common their work as war engineers. And like Archimedes, Leonardo's interests lay in mechanics, fluid mechanics and optics. However, Archimedes is not known to have been concerned with pressure of water vapor or pressure projectiles. Such an invention would certainly have been used in the long siege of Syracuse and would not have gone unmentioned in contemporary accounts. So it is quite possible that Leonardo dedicated his invention to Archimedes out of respect for the ancient scholars.

Heronsball

At this point, it should not go unmentioned that machines driven by steam pressure were already known in antiquity. Heron of Alexandria lived at the turn of time, about 200 years after Archimedes. He was a mathematician as well as an engineer and designed the Heronsball, an engine that converts the thermal energy of steam into kinetic energy (see Heronsball). It is unknown today whether Leonardo knew the principle of the Heronsball. 

Some of Leonardo's sketch sheets suggest that he conceived of a mechanically driven knight. The mechanical knight, like the wind-up car or the mechanical lion, may have been demonstrated at a courtly festival in Milan. However, it is unknown whether the mechanical knight was realized. What became known about its functioning are technical interpretations of three leaves of the Codex Atlanticus (579r, 1021r/v, 1077r). According to these, he could stand up, sit, move his arms, and turn his head. It is also possible that he was able to emit mechanically generated sounds.

It seems, then, that Leonardo used such automobiles with wind-up mechanisms primarily to entertain his aristocratic patrons at court. They were more mechanical gadgets than serious means of transportation or robots in their own right. In their time, however, such machines were marvels never seen before.

Leonardo uses for his water course the principle of buoyancy that every swimmer and boater knows, but which was scientifically established only by Archimedes. 

According to this principle, the static buoyancy of a body in a medium is as great as the weight force of the medium displaced by the body. 

In practice, this means that the shoes of Leonardo's runner must be so large that their volume balances the weight of the runner. That is, the shoes must displace about as many liters of water as the runner weighs in kg.

Example calculation: A person weighing approx. 80 kilos needs two waterproof shoes, each 20 cm high, 20 cm wide and 1 m long. Together, both shoes displace about 80 liters. 

In order to keep the volume of the shoes as small as possible and thus practical, the shoes should be precisely matched to the weight of the runner. They must be waterproof at the top so that they cannot fill up with water. The water should also be as calm as possible. The arm supports are used to maintain balance. These also have water shoes. Such a water run would then be comparable to skiing. Experienced water skiers can do without the arm supports.

As with many of Leonardo's inventions, it is unclear whether a water course was realized.

What the design lacks at this point are control devices, a drive, and an indication of exactly how the water level in the side chambers is regulated.

That Leonardo had the necessary pumps to force the water back out of the side chambers is proven by two sketches on the already known sheet with the water runner. In addition, Leonardo constructed several devices that would allow the water in the intermediate walls to be pumped out. 

So far Leonardo's submarine is able to swim, to dive and to rise again. As in the first "real" submarines, a conventional candle could serve as a light source in the dark vehicle, even if this consumed additional oxygen. Several hours would have to pass before the breathing air in the submarine would run out. In principle, a submarine could be operated with only one person, as can be seen in the example of the Turtle.

Leonardo's mental achievement becomes clearer when his submarine is compared with the first realized submarine, the US "Turtle". The already fully functional underwater vehicle was used in the American War of Independence about 250 years after Leonardo's death. Its purpose was to sink enemy ships with explosive charges.

In the principle of the diving process it does not differ from Leonardo's submarine. It has a cavity in the bottom that is filled with water when diving is required and can be emptied with pumps when the submarine is to rise again.  In addition, the Turtle has only a hand crank that uses a propeller for propulsion, plus a rudder that can be used to steer left and right.

Given Leonardo's extensive mechanical knowledge, it would be naïve to think he had no idea to steer his underwater vehicle to the left and right, or to attach a rotor with a hand crank for locomotion. Leonardo's knowledge of the rotor principle as a driving force is shown a little later in his model of the helicopter, which is in the same notebook as the submarine. The drawing of the submarine was the first (folio 11 vs folio 83).

Leonardo's sense of social responsibility is often cited here. Having a submarine fleet would certainly have meant naval supremacy at that time. No fleet could have done anything against this kind of warfare. Submarines could not be effectively countered until the beginning of the 20th century. At that time, sonar equipment began to be developed that could detect submarines underwater and then target them for bombardment. 

How it works

The diving suit consisted of a waterproof full-body suit made of leather with sewn-in glass openings for the eyes. In the drawing, the diver wears two larger weights over his shoulders to enable him to walk on the seabed. 

To be able to supply the diver with breathing air, Leonardo wanted to use an oversized snorkel. Floating on the surface of the water was a buoy made of cork, from which two breathing tubes led to the diver's head. The two tubes - one for inhaled air, the other for exhaled air - consisted of several sturdy pipes connected by elastic joints. The joints, covered with a waterproof fabric, were reinforced internally by spirally twisted wire or the like, and thus kept open so as not to be compressed by water pressure. Such a hose system, allowed the diver some freedom of movement. How exactly the valve for separating fresh and used breathing air worked is not clear from the drawing.

The diving suit, in addition to locomotion in the air, on land, and on water, now made locomotion underwater possible. But Leonardo, in addition to a civilian use, certainly thought of a military use of the submarine innovations, because on the same sheet to the right of the diver is a device for drilling into ships to sink them. Typically for Leonardo, he also gives hints to defend against this, e.g. by double ship's hulls, whereby the outer one should only serve as a shield against such attacks and was separated from the inner one by a hollow space.

Does Leonardo's diving suit work?

Leonardo's diving suit was never manufactured. Leonardo's employer, the Duke of Milan, had no direct access to the sea and so there was no need for the invention for him, if he knew about it at all. For elsewhere Leonardo notes that he had found a way to sink ships unseen, but he wished to keep this a secret because the potential uses were too devastating. Presumably he was referring to the ideas on this sheet.

The BBC made a replica of the diving suit as part of a documentary on Leonardo's inventions, and with the assistance of professional divers was able to show that the principles of Leonardo's diving suit basically worked. 

Did Leonardo invent the wetsuit?

Leonardo was not the first to design a diving suit. He collected the ideas known at the time and improved them where necessary. His technical innovations included the use of a stable tube system that could better withstand the pressure of the water. The introduction of flexible joints to the tubes to improve freedom of movement was also novel, as was the separation of breathing air by means of a valve. 

What makes Leonardo's development of the diving suit so special is that his diving suit does not stand on its own, but is part of a well thought-out system of inventions aimed at enabling the element of water to be explored in greater detail. As with the conquest of the element of air, Leonardo proceeded systematically and designed a device to walk on water, an underwater vehicle, an emergency rescue system and finally created the possibility to walk under water.