Leonardo was master of mechanical principles. He utilised leverage and cantilevering, pulleys, cranks, gears, including angle gears and rack and pinion gears; parallel linkage, momentum, centripetal force and the aerofoil.
Because Leonardo's inventions date from an era before the issue of patents, it is impossible to say with any certainty how many or even which of his inventions passed into general and practical use, and thereby had impact over the lives of many people. Among those inventions that are credited with passing into general practical use are the strut bridge, the automated bobbin winder, the machine for testing the tensile strength of wire and the lens-grinding machine pictured at right.
In the lens-grinding machine, the hand rotation of the grinding wheel operates an angle-gear, which rotates a shaft, turning a geared dish in which sits the glass or crystal to be ground. A single action rotates both surfaces at a fixed speed ratio determined by the gear.
Bridges and hydraulics
Leonardo's study of the motion of water led him to design machinery that utilised its force.
Among his projects in Florence was one to divert the course of the Arno, in order to flood Pisa. Fortunately, this was too costly to be carried out. He also surveyed Venice and came up with a plan to create a movable dyke for the city's protection against invaders.
In 1502, Leonardo produced a drawing of a single span 240 m (720-foot) bridge as part of a civil engineering project for Ottoman Sultan Beyazid II of Istanbul. The bridge was intended to span an inlet at the mouth of the Bosphorus known as the Golden Horn. Beyazid did not pursue the project, because he believed that such a construction was impossible. Leonardo's vision was resurrected in 2001 when a smaller bridge based on his design was constructed in Norway. On 17 May 2006, the Turkish government decided to construct Leonardo's bridge to span the Golden Horn.
War machines
In Leonardo's notebooks there is an array of war machines which includes a tank to be propelled by two men powering crank shafts. Although the drawing itself looks quite finished, the mechanics were apparently not fully developed because, if built as drawn, the tank, with a lot of effort, might be made to rotate on the spot, but would never progress in a forward direction. In a BBC documentary, a military team built the machine and found it not working, until they changed only one of the gears. It is believed that Da Vinci deliberately left this error in the design, in order to prevent it from being put to practice by unauthorized people.
Another machine, propelled by horses with a pillion rider, carries in front of it four scythes mounted on a revolving gear, turned by a shaft driven by the wheels of a cart behind the horses.
Leonardo's notebooks also show cannons which he claimed "to hurl small stones like a storm with the smoke of these causing great terror to the enemy, and great loss and confusion."
He also designed an enormous crossbow. Following his detailed drawing, one was constructed by the British Army, but could not be made to fire successfully.
Leonardo was the first to sketch the wheel-lock musket c. 1500 AD (the precedent of the flintlock musket which first appeared in Europe by 1547), although the Chinese of the earlier 14th century had used a flintlock 'steel wheel' in order to detonate land mines.
Flight
The desire to fly is expressed in the many studies and drawings. His later journals contain a detailed study of the flight of birds and several different designs for wings based in structure upon those of bats which he described as being less heavy because of the impenetrable nature of the membrane. On January 3, 1496 he unsuccessfully tested a flying machine he had constructed.
One design that he produced shows a helicopter to be lifted by a rotor powered by four men. It would not have worked since the body of the craft itself would have rotated in the opposite direction to the rotor.
While he designed a number of man powered flying machines with mechanical wings that flapped, he also designed a parachute and a light hang glider which could have flown.
No comments:
Post a Comment