Hot air balloons represent the ingenious application of basic scientific principles, allowing these massive balloons to soar into the sky while still being directed as desired.
Famous for a long time, hot air balloons have always been considered a rather impractical mode of transportation, as few people actually need to go anywhere by hot air balloon. This is simply because their flight speed is very slow, and they heavily depend on the wind direction.
However, if you just want to enjoy the experience of floating in the air, this could be incredibly delightful. Many tourists have described flying in a hot air balloon as one of the most enjoyable and peaceful activities they have ever experienced.
Hot air balloons are considered a rather impractical mode of transportation.
How Hot Air Balloons Work
Hot air balloons operate based on a very basic scientific principle: hot air rises above cold air.
This occurs because hot air has a lower mass per unit volume compared to cold air. Specifically, 1 cubic foot of air (equivalent to 0.028 cubic meters) weighs an average of about 28 grams. However, when this air mass is heated to 37 degrees Celsius, it only weighs about 7 grams.
The envelope of a hot air balloon is typically made from nylon fabric, reinforced with ripstop material. This is the ideal material for hot air balloons due to its lightweight, sturdiness, and resistance to melting at high temperatures.
A burner is placed beneath the envelope, using propane gas stored in liquid form in cylinders located in the balloon’s basket. When the pilot ignites the burner, the flame heats the air inside the envelope. The envelope starts to expand, lifting the basket and everyone inside into the air.
How Do Pilots Control Balloons?
Controlling a hot air balloon requires skill, but generally, it is quite simple.
To increase the flame size, the pilot opens the propane valve.
To lift the balloon, the pilot turns a control knob to open the propane valve, allowing the gas to flow, creating a larger flame. This operation is quite similar to controlling a gas stove.
Additionally, many hot air balloons have a secondary propane valve control. This valve directs propane through a tube that passes through heating coils, allowing the pilot to burn liquid propane instead of gas, producing a weaker but much smoother flame compared to burning gas.
The hot air balloon also has a rope to open the vent at the top of the envelope. When the pilot pulls this rope, hot air escapes from the envelope, reducing the temperature of the hot air inside, causing the balloon to descend. If the rope is held too long, the balloon will lose altitude.
Essentially, these are the only controls on a hot air balloon. This raises an interesting question: If the pilot can only move the balloon up and down, how do they navigate from one place to another?
In the atmosphere, there are many mixed wind currents blowing in different directions and at different altitudes. To move in a specific direction, the pilot adjusts the balloon’s altitude to an appropriate level and chooses the wind direction to proceed forward.
Since wind speed usually increases as you ascend higher into the atmosphere, pilots can also control lateral speed by changing altitude.
Of course, even the most experienced pilot cannot fully control the flight path of a hot air balloon. Typically, wind conditions offer pilots very few choices, and they cannot really steer the balloon along a precise route.
In reality, it is rare to pilot a hot air balloon back to the starting point. Unlike flying an airplane, hot air ballooning largely relies on improvisation and is heavily dependent on weather conditions.
Thus, for some hot air balloons in tourist areas, there are usually tethered ropes to prevent the balloons from drifting too far from their operating zones.
The History of Hot Air Balloons
The basic idea behind hot air balloons has been around for a long time. Archimedes, one of the greatest mathematicians of ancient Greece, discovered the principle of buoyancy over 2,000 years ago, likely forming ideas about flying machines lifted by buoyancy.
In the 13th century, English scientist Roger Bacon and German philosopher Albertus Magnus proposed hypotheses about flying machines based on this principle.
In 1783, the Montgolfier brothers first experimented with this model using a hot air balloon designed similarly to those of today, but instead of using propane gas, they powered their model by burning straw, manure, and other materials.
A sheep, a duck, and a rooster were the “passengers” on the first demonstration flight of the hot air balloon on September 19, 1783, witnessed by King Louis XVI.
Two months later, Marquis Francois d’Arlandes, an infantry lieutenant, and Pilatre de Rozier, a physics professor, became the first to lift their feet off the ground.
Giffard’s hot air balloon with its first passenger in 1869. (Photo: Gettyimages).
The first successfully built motorized hot air balloon was created in 1852 in France by Henri Giffard. He developed a steam engine weighing 160 kg, enough to drive a large propeller at a speed of 110 revolutions per minute and lift the entire balloon filled with hydrogen gas for a distance of about 30 km.
Starting as a project full of potential and ambition, by 1800, hot air balloons fell out of favor, largely due to accidents leading to the death of Pilatre de Rozier when he attempted to cross the English Channel in a hot air balloon.
It wasn’t until the 1960s that traditional hot air balloons saw a revival, thanks to a man named Ed Yost and his company, Raven Industries, which transformed this idea into a sporting device. He added a propane burner system, used new envelope materials, and incorporated many important safety features.
Other companies quickly emerged as more people participated in the business. Manufacturing high-tech hot air balloons for around-the-world trips even became a “trend” among millionaires.
Over the years, designers have continually modified hot air balloons, adding new materials and safety features, as well as developing creatively shaped envelopes. Some manufacturers have increased the size of the baskets and weight capacities, allowing balloons to carry up to 20 passengers.
Nevertheless, the basic design of hot air balloons remains a modified version of Yost’s compared to the original concept of the Montgolfier brothers. This superior technology has captivated travelers around the world.
Hot air balloon tours have gradually become a multi-million dollar business, followed by balloon races and other exciting events that continue to attract large audiences and participants.
