Air travel is so commonplace and so essential to the modern world it is hard to believe the first successful, powered flight came little more than a century ago.

Air travel is so commonplace and so essential to the modern world it is hard to believe the first successful, powered flight came little more than a century ago.

Leonardo da Vinci studied the mechanics of flight as early as the 15th century, but it took two bicycle repairmen to achieve it in 1903.

The quest for human flight began in earnest with the hot air balloon, invented and successfully tested by two French brothers, Joseph and Jacques Montgolfier (1740–1810 and 1745–1799), in 1783.

That was followed quickly by airships using balloons filled with hydrogen.

Pioneers of winged aircraft tried to mirror the way birds achieve flight – by flapping.

A bird generates both power and lift with its wings, but copying that proved impossible.

In 1799, English physicist George Cayley (1773–1857) realised the way forward would be to separate the power from the lift.

He worked out the basics of aerodynamics: how a wing moving through the air generates a lifting force. All that was needed then was a source of power to push the aeroplane through the air.

Cayley drew designs for aeroplanes with all the basic features of modern aircraft.

For most of the 19th century, the steam engine was the only power source available.

People tried in vain to design a Cayley-style aeroplane with a steam engine connected to a propeller.

The problem was that a steam engine with enough power made the plane too heavy.

Englishman John Stringfellow (1799–1883) did build a steam-powered flying machine that made a short flight in 1848.

But the most successful flights of the 19th century were with unpowered gliders.

The most famous glider pilot was German Otto Lilienthal (1848–1896) who flew with great control for long periods, much as a modern hang glider does.

Between 1891 and his death in a gliding accident, Lilienthal made more than 2,000 successful flights.

The invention of the internal combustion engine, powerful but light, brought the dream of powered flight closer.

Several people began working on designs.

Two were Ohio brothers Wilbur and Orville Wright (1867–1912 and 1871–1948), skilled engineers who turned their attentions to flight around 1896 after a decade building and fixing bicycles.

They built their own engine and propeller to power a plane based on Lilienthal’s gliders.

The ‘Flyer’ was tested in the gusty open spaces of Kill Devil Hills near Kitty Hawk, North Carolina.

It had a 12-metre (39ft) wingspan and weighed 340 kg (750lb) including the pilot.

Orville went up first – and his 12-second flight put him in the history books.

By 1905, the Wrights improved their plane and were able to fly as long as the fuel lasted.

Progress in flight was rapid in the next 20 years, with the military advantages of aircraft being quickly realised during World War One.

The first airlines began carrying passengers across oceans and continents in the 1920s.

Aeroplanes played a huge role in World War Two, and it was during that war the first jet engines were used. Afterwards, the aviation industry expanded, opening up the world to leisure and business travellers.

Now, just over 100 years since Orville Wright first took to the skies, air passengers take around four billion flights a year.