Wednesday, January 11, 2012

Flight without Engines

Nearly all of us are used to flying around the country, and indeed the world, in the amazing modern aircraft that are such triumphs of engineering and with the modern jet engine making it all possible. 

But there is another stream of engineering considerably older, that achieves flight without the use of engines, and this has produced a number of fascinating machines throughout the years.

In ancient times many attempts at flight were made using various contraptions with men leaping from cliffs using frantically flapping wings or rudimentary gliders, with the results often being fatal.

Early attempt at flight using eagles wings – these experiments often ended in disaster. Image from Wikipedia Commons – click to enlarge.

However there are existing reports that men flew in primitive gliders as long ago as the 11th century, with the English Benedictine Monk Eilmer reported as having glided for some 200 metres in his winged machine in about 1005. 

But the first properly documented human ascent using a machine was a tethered hot air balloon that lifted Etienne Montgolfier from the ground at Faubourg Saint Antoine, in France, on October 17th 1783. 

Reproduction of the Montgolfier balloon that produced the first successful human ascent in 1783. Image from Wikipedia Commons - click to enlarge.

This was the forerunner of the engineless hot air balloons that are still used up to the present day, particularly for tourist joy riding.

Kites, which are a form of tethered aircraft, were also used to lift people from the ground, possibly in quite ancient times. 

The Australian engineer, Lawrence Hargrave, lifted himself some 5 metres from the ground at Stanwell Park in NSW in 1894 using a train of 6 box kites acting in tandem. 

Hargrave used a chain of box kites to lift himself off the ground at Stanwell Park in 1894. Image from Wikipedia Commons – click to enlarge.

In 1866, the Polish carpenter Jan Wnek built and piloted a glider that was launched from the top of a local church tower. He successfully flew into the valley below on several occasions and this was the forerunner of ever more sophisticated aircraft that are now widely used as a popular type of recreation. As far as aerodynamics is concerned, the modern glider is the ultimate in flying without engines.

A modern high performance glider constructed of fibreglass. Image form Wikipedia Commons - click to enlarge.

Particularly fascinating examples of engineless flying machines arose from a prize offered to the first individual who could fly a figure eight course of 1 mile (1.6 km) powered entirely by human means. This prize, of $100,000, was finally won by the American engineer Paul Macready who designed the Gossamer Condor in 1977, using a pedal powered configuration. 

Another more substantial challenge was proposed – to design and construct the first human powered aircraft to cross the English Channel, and this incredible feat was also achieved by a Macready designed machine, the Gossamer Albatross in 1979.

This pedal powered aircraft crossed the Channel in just under 3 hours at an average altitude of 1.5 m (5 feet). For amazing footage of this historic event see

The Gossamer Albatross in flight, 1979. Image from Wikipedia Commons – click to enlarge.

The spectacular evolution of the so-called “hang glider” has also produced a fascinating variant of engineless flight. One of the main pioneers of hang gliding was Otto Lilienthal, a German aviation pioneer who succeeded in producing and flying a hang glider back in the 1890’s. Tragically he was later killed when his glider stalled in flight and he fell to his death.

Otto Lilienthal in flight from a hill - circa 1890.
Image from Wikipedia Commons - click to enlarge.

The modern hang glider, the result of continuous developments of Lilienthal’s work over the last 100 years, incorporates increased knowledge of avionics and evolving hi tech materials and has become a fabulous engineless flying machine.

It consists of a rigid aluminium frame upon which is mounted a flexible fabric wing and harness that holds the pilot.

It can be foot launched, simply by jumping off an elevation, or launched by towing behind a winch or boat. Depending on the skill of the pilot, and the prevailing conditions, modern hang gliders can soar for prolonged periods of time, reach heights above 5000 metres and travel for hundreds of kilometres across country.

A high performance hang glider in flight. Image from Wikipedia Commons – click to enlarge.

A close relation to the hang glider is the paraglider – a type of hybrid cross between a paraglider and parachute. Unlike the hang glider, this aircraft has no rigid primary structure but consists of a flexible fabric wing to which a harness is attached that supports the pilot. This aircraft is normally foot launched and extended flights over hundreds of kilometres at altitudes of several thousand metres are routinely attained through skilful use of atmospheric conditions.

A paraglider high above the ground. Image from Wikipedia Commons – click to enlarge.

Over the last 30 years or so there has been a proliferation of engineless flight vehicles, all made possible by increased knowledge of aerodynamics and the invention of lighter and stronger materials.

An interesting speculation concerns the antiquity of engineless aircraft. The balloonist Julian Nott raised the possibility that hot air balloons could have been by the Peruvian Nazca people of 1500 years ago to help them design their large ground motifs that depict spiders, monkeys, fish, sharks and various lines, some of which are plainly visible from space.

The Nazca ground motif depicting a monkey – image from Wikipedia Commons – click to enlarge.

As mentioned above, primitive gliders could have been in use in the 11th century and kites that lifted people off the ground were within range of the technology of the ancient Chinese. Also the use of bamboo and silk was well known to the Chinese of ancient times. Could a hang glider be built from these materials? Both are light and strong and it raises the possibility that devices such as these could have been built long ago but not recorded.

Therefore, engineless flight in its various forms could theoretically have been performed long before we currently understand and this is an area of speculation being investigated by various historians.

One of the most extraordinary forms of engineless flight was developed in the 1990's called a wingsuit. This consists of fabric stretched between the arms and legs to create a wing like structure. The wearer leaps off a cliff and is able to glide at high speed for considerable distances before deploying a parachute for landing.

Two wingsuit fliers in action
image from Wikipedia Commons – click to enlarge.

Some truly incredible footage was shot by Jeb Corliss carrying a camera during his wingsuit flight showing the high speeds achieved during flights of this nature. See it here

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