Hot Air Balloon Book: Build and Launch Kongming Lanterns, Solar Tetroons, and More
impossible One of the stories about Zhuge Liang tells how he invented the hot air balloon Zhuge Liang and his troops were occupying the town of Pingyang when his enemy Sima Yi sur rounded it and began a siege hoping to force the famous Zhuge Liang to surrender Sima Yi s troops had occupied the land all around the town and watched carefully for messengers leaving the town So there was no way for Zhuge Liang to send a signal to his allies for help Zhuge Liang noticed that the wind was blowing toward his allies so he asked for a special large lantern to be made with no hole in the top and a wax burner held in the bottom He painted a message onto the side of the lantern and carried it up to a tower on the town wall He lit the burner and released the lantern which floated away in the wind toward his allies Sima Yi s troops below could only watch as the lantern passed overhead carrying a message that asked for help Sure enough Zhuge Liang's allies saw the message rode to Pingyang and rescued Zhuge Liang and his troops Apart from this legend there is no historical evi dence that Zhuge Liang invented the hot air balloon One writer suggested that the Kongming lantern might have been invented by a Chinese lantern maker and then named after the famously clever Zhuge Liang perhaps because it looks a lot like the little square hat Zhuge Liang always used to wear Sadly even this explanation is unlikely as there are
no written descriptions of paper hot air balloons in China before 1783 Italy Francesco Lana was born in 1631 in Brescia Lom bardy an area in the north of modern Italy He became a Jesuit priest and like many Jesuits was encouraged to study so that he could become a teacher Eventually he became a professor of mathe matics and physics at Brescia and while he was teaching there he learned about Otto Von Guericke's experiments at Regensburg and Magdeburg in 1654 Von Guericke had shown that two copper hemi spheres 20 inches 50 cm in diameter could be held together by pumping out the air from the space between them The atmospheric pressure outside the hemispheres was so great that once all the air had been pumped out two teams of eight horses could not pull them apart Lana was fascinated by the experiment but he was particularly interested in the new and more effi cient vacuum pump Von Guericke had invented Lana calculated the weight that must have been lost from the pair of copper hemispheres when the air was pumped out If a sphere could be made from thin enough material then the weight of the air removed from inside the sphere by this new pump might actu ally be greater than the weight of the sphere itself This should make the sphere float in the
Lana's airboat In 1663 Lana designed a lighter than air ship the details of which he later published in 1670 in his book Prodomo This design used four large floating copper spheres from which a boat is suspended The boat had a sail and hull as Lana intended it to be propelled by the wind and steered much as a boat on the sea Lana never tried to build his airboat and of course there would have been practical problems if he had To make the airboat fly I estimate that the copper skin of the big spheres would have to be less than 0 004 inches 0 1 mm thick This is about the thickness of a human hair and only about four times the thickness of household aluminum foil At this thickness the sphere would collapse under its own
weight even before you tried to pump out any air Portugal and Brazil Bartholomeu Lourenco de Gusmao was born in Sao Paolo Brazil in 1685 At that time Brazil was a part of the Portuguese empire so when it became clear that Gusmão was a brilliant student and had quickly outgrown the opportunities for study in Brazil it was natural that he should travel all the way to Portugal to study at the University of Coimbra At Coimbra he studied mathematics physics chemistry astronomy and philology the language of literature It must have been during these studies that Gusmão discov ered the work of Francesco Lana and Gusmao began to develop Lana's ideas for flying machines Gusmão knew that Lana's copper spheres would not be practical but his early attempts at designing a flying machine used equally strange devices to lift the boat such as powerful magnets U Gusmão's magnetic airboat Passarola
