The basics of flying a hot air balloon
Pilots do not steer hot air balloons in the same way you would steer a plane or a car. Hot air balloons are actually ‘lighter than air’ aircraft which means that they move with the wind. Like a bubble of detergent, balloons are carried by the wind and their direction is determined by the direction of airflow.
Most people are unaware that wind direction varies at different heights. The direction of the wind on the surface will not necessarily be the same as it is at say 1000 metres. By flying at different altitudes, the pilots can use different wind speeds and directions to manoeuvre the balloon to where they desire, often with extreme accuracy.
Prior to a flight, pilots will release small helium balloons to allow them to observe the wind’s direction and speed at different heights. This allows the pilots to determine the direction of flight and choose an appropriate upwind launch site based on where they would like to fly and land.
While in flight balloon pilots can control the altitude of the balloon very accurately with carefully timed blasts of the burners and, if experienced, can land within metres of their desired downwind target even if it is many kilometres away.
The fabric section of a hot air balloon is called the ‘envelope’. This is the part that most people call the balloon. It is generally made of nylon and is put together by sewing hundreds of specially cut panels together to give it the ‘tear drop’ shape. These panels are sewn to nylon load tapes that actually distribute the weight loading across the envelope so the actual load on the fabric is less than 0.5kg when flying .
LPG is used to generate heat in balloons . In ballooning circles we tend to use propane, the same gas as used in BBQ’s bottles. Autogas is an option although it tends to burn at somewhat lower pressure and is less clean. LPG is contained within the basket in 45L-62L stainless steel tanks similar in size to those seen on fork lifts.
The LPG burners are handmade from stainless steel and are designed to give maximum heat output for minimum noise. They sound like a fire-breathing dragon and can shoot flames up to 5 metres in length into the envelope .
To get lift and ‘take off’, the envelope is heated using propane burners to a temperature greater than the ambient temperature. This difference in temperature between the outside and inside of the ‘envelope’ allows the balloon to lift off the ground, just as warm smoke or embers rise from a fire. A basket full of people is quite heavy so the volume of the balloon will be based on how much weight needs to be lifted.
The balloon basket or ‘Gondola’ is made of cane or wicker. They are hand woven on to a stainless steel frame with stainless steel load bearing cables woven within the wicker to provide the strength to carry passengers and equipment.
The first humans to ever successfully fly did so in a Hot Air Balloon. In 1783, two French brothers, Joseph and Etienne Montgolfier, sons of a paper manufacturer, built a balloon (named Montgolfier) out of paper and silk. On 21 November 1783, witnessed by a crowd of 400,000 people, two French noblemen, Jean-Francois Pilatre de Rozier and Marquis D’Arlandes, took to the skies above Paris in Montgolfier.
The balloon, 13 metres in diameter, was fuelled with burning wool and straw. The men stayed aloft for 23 minutes and travelled a distance of 8 kilometres, finally landing in a field outside Paris. These two men entered the history books as the first humans to fly.
With the invention of the Aeroplane in 1903, and as people became more interested in powered flight, balloons became a less popular form of aircraft.
It was not until the 1960s, with the invention of propane burners, that Hot Air Ballooning became a more practical form of aviation.
Modern hot air ballooning
Since the 1960s, many developments in technology, materials and equipment have allowed ballooning to become one of the safest forms of modern aviation. Even with all these developments, balloons still use the same principles as those adopted by the Montgolfier brothers, 200 years ago. As the name suggests, hot air balloons are able to fly because they are filled with hot air.
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