A hot air balloon flies thanks to Archimedes’ principle: air heated by the burner inside the envelope becomes less dense than the air outside and generates upward thrust. The pilot controls the altitude by increasing or decreasing the burner flame, while the direction of travel depends entirely on the air currents at altitude.
From the ashes of the fireplace to the sky: a brief history of hot air ballooning
There is something almost poetic about the origin of the hot air balloon. According to tradition, it was while watching the ashes rising in the chimney that brothers Joseph-Michel and Jacques-Étienne Montgolfier had the insight that would change the history of flight. It was 1783, and that November, for the first time in history, two people flew over Paris in a hot-air balloon, reaching nearly 1,000 meters in altitude and covering several kilometers in about 25 minutes. From that day on, the world never stopped looking up in wonder.
In Italy, one of the protagonists of this story was Count Paolo Andreani, who replicated the Montgolfier feat in the garden of his villa near Milan, becoming the first Italian to perform a balloon flight. A thin thread, then, links Lombardy to the world history of hot air ballooning-a thread that reaches to the present day.
It was not until the 1950s that American Ed Yost revolutionized the modern concept of the hot air balloon, developing the propane burner system that still forms the basis of every balloon today. Since then, the technology has refined enormously, but the physical principle has remained the same: it is still hot air that lifts men and women into the sky.
How a hot air balloon works: the physical principle explained in a simple way
To really understand how a hot air balloon works, you don’t need to be a physicist. Just start with an everyday observation: hot air rises. We see it in the steam rising from a cup of tea, we feel it when we open the oven. In physics, this phenomenon is explained by Archimedes’ law, which states that a body immersed in a fluid receives an upward thrust equal to the weight of the fluid it displaces.
The atmosphere is a fluid, just like water. When the hot air balloon’s burner heats the air inside the envelope, the air molecules move faster, expand and become less dense than the cold air around them. The envelope, now filled with lighter air, receives a net upward thrust. If this buoyancy exceeds the total weight of the system – envelope, gondola, passengers and equipment – the balloon rises.
Altitude control is done directly: the more the pilot opens the burner valve and heats the air, the higher the balloon rises. Less heat, air gradually cooling, hot air balloon descending. To speed up the descent, the pilot can also open a valve at the top of the envelope to vent some of the hot air.
Why the hot air balloon does not head sideways
This is the question everyone asks at least once. The answer is as simple as it is fascinating: the hot air balloon has no motors or rudders. It cannot choose its horizontal direction. It moves where the wind takes it, with a naturalness that is part of the very charm of the experience. The experienced pilot knows, however, that air currents change direction at different altitudes.
As you climb or descend in altitude, you can intercept currents blowing in slightly different directions, allowing you to roughly orient your flight path. This ability to “read” the wind, combined with a thorough knowledge of local meteorology, is one of the elements that distinguishes an experienced pilot from a novice.
It is not about absolute precision, and that is part of the magic of the experience. Hot air ballooning is a journey that relies on nature, not a transfer from point A to point B. It is an experience of conscious surrender, of trusting the wind and the pilot’s skills.
The three basic components of a hot air balloon
A modern hot air balloon is a precise engineering system composed of three main elements that work in perfect synergy. Understanding how it is made is the first step in appreciating how sophisticated this apparent simplicity is.
The envelope: the balloon that captures heat
The envelope is the most visible and iconic part of the hot air balloon. It is not a simple sphere of fabric: it is an engineered structure composed of long slices of precision-cut crisscrossed nylon stitched together, reinforced by load belts that run from the base to the top and distribute stresses evenly.
Temperatures inside an in-flight enclosure can reach 120 degrees Celsius, but the nylon used has a melting point well above 200 degrees, providing ample safety margins. The lower part of the casing, the so-called “throat,” is the opening through which the burner pushes hot air upward.
Instead, at the top of the envelope is a vent panel, controlled by the pilot via a rope: when it is opened, some of the hot air escapes and the balloon loses altitude. An enclosure for commercial use can hold 2,000 to 8,000 cubic meters of air – to give an idea, medium-sized models comfortably accommodate 4 to 12 passengers.
AERONORD AEROSTATI ‘s hot air balloons are made of the latest materials, ensuring optimal performance in terms of thermal efficiency and durability. Want to find out from aboard how the burner’s heat feels overhead? Explore our hot air balloon flights.
The burner: the beating heart of the system
The burner is, in effect, the engine of the hot air balloon. It runs on liquid propane gas and is contained in steel or aluminum or sometimes titanium aeronautical cylinders housed inside the gondola.
When the pilot actuates the valve, the propane reaches a coil where it returns to a gaseous state due to heat, mixes with air, and is ignited by an ever-burning pilot flame. The result is a powerful flame capable of rapidly heating the air inside the casing.
Modern burners are usually dual-two independent systems for redundancy and safety-and can be precisely oriented by a gimbal that allows the pilot to direct the flame exactly to the center of the throat.
The amount of propane consumed depends on flight conditions, envelope size, and outside temperature. A well-calibrated burner, in the hands of an experienced pilot, can maintain a stable altitude with short, controlled ignitions, optimizing consumption and ensuring a smooth descent at the end of the flight.
The gondola: where excitement meets safety
The gondola-the basket where passengers and pilot board-is traditionally made of woven wicker. This is not a purely aesthetic choice: wicker offers an extraordinary balance between lightness, strength and flexibility. During landing, when the gondola hits the ground with some speed, the wicker absorbs some of the impact, protecting the passengers. In addition to wicker there are, of course, other metal materials that make it solid and strong.
Modern gondolas are designed to accommodate passengers in interior compartments, the larger ones separated from the pilot area, with handles to hold on to and walls high enough to provide stability even for those who suffer from vertigo.
The propane cylinders are fixed inside the gondola, the burner is mounted on a metal frame above the gondola itself, and the whole structure is connected to the enclosure by high-strength steel cables.
How to fly in a hot air balloon: from sunrise to sunset, the rhythm of the sky
One of the most surprising aspects of flying for the first time in a hot air balloon is the serenity of the experience. There is no engine noise, no perceptible turbulence, no feeling of speed that we are used to in airplanes. There is only the silence of the sky, interrupted by the flame of the burner and the spectacle of the landscape unfolding on the horizon.
When flying: the coolest hours of the day
Hot air balloon flights take place almost exclusively during the cooler hours of the day: at dawn, in the early morning hours, or in the late afternoon, towards sunset. This choice is neither random nor purely aesthetic, although the light during those hours makes the flight even more spectacular. The reason is physical and safety.
In the middle hours of the day, the sun heats the ground, which in turn warms the low air, creating turbulent thermal updrafts that make it difficult to control the balloon’s altitude. In the early morning and sunset, however, the atmosphere is more stable, the wind is generally light, and conditions are ideal for smooth and safe flight.
Another important factor is the temperature difference between the inside and outside of the envelope. During cooler hours, the outside air is cooler and the burner has to work less to maintain the heat differential needed for uplift.
The flight is therefore more efficient and more controllable. In addition, if the envelope is overheated too much, it is likely to be ruined. Lift and flight capacity are also affected if the temperature difference between outside and inside air is limited. In cooler seasons or locations, these issues are alleviated and one can fly even in the middle hours of the day.
Is it cold in a hot air balloon? The truth about heat at altitude
One of the most frequently asked questions by first-time visitors to the experience is:is it cold in a hot air balloon? The answer is less obvious than you might think, and it depends on where you are in the gondola. At altitude, the outside air temperature drops as you ascend-about 2 degrees Celsius for every 300 meters of elevation gain-and on a cool day you will certainly feel some biting air.
However, the burner, which is located immediately above the gondola, radiates considerable heat downward, which warms the passengers during each ignition. The result, for many, is a pleasant alternation: a slight cool breeze from outside and the enveloping warmth of the burner starting at regular intervals.
We always recommend dressing in layers, with comfortable clothing and closed shoes. Technical mountain clothing is not necessary, but a light jacket is always a good idea, especially for sunrise flights. What no one tells you is that once at altitude, you completely forget about the cold-the thrill of flying takes over everything else. Have questions about how to prepare for your first flight? Contact our team-we are here to help you with any questions.
The duration of the flight and landing
A hot air balloon flight typically takes about an hour, although the total duration of the experience-from inflating the balloon to landing to the final breakfast-typically extends between three and four hours. Inflating the envelope takes about 20 to 30 minutes: first a fan is used to fill the balloon with cold air, then a burner is turned on to heat it and straighten the balloon.
Landing is a very technical moment of flight. The pilot chooses a level area, gradually reduces the heat, and brings the hot air balloon gently down to the ground. The ground crew–the crew that follows the flight in a vehicle–intervenes to help the pilot disassemble the hot air balloon and take the passengers to their car or to the breakfast or aperitif place.
Weather as a flight partner
The wind is the sole “engine” of balloon direction, so the weather is not just a variable to be monitored-it is a true partner in flight. Experienced pilots read charts and weather reports as carefully as a sailor studies the sea.
Winds that are too strong or erratic, the presence of thunderstorms nearby, fog or reduced visibility-these are all conditions that lead to flight cancellation, without exception. For this reason, balloon flights do not have fixed routes. The landing point varies from time to time based on wind conditions, and the ground crew constantly follows the balloon to be ready to land in any suitable area. This flexibility is not a limitation: it is a guarantee that you fly only when you can fly well.
FAQ – Frequently asked questions about balloon operation and flight
- How does a hot air balloon go up and down?The balloon rises when the burner heats the air inside the envelope, making it less dense than the air outside. It descends when the air cools naturally or when the pilot opens the release valve, called a parachute, located at the top of the envelope to vent some of the hot air. The pilot manages the altitude precisely by adjusting the duration and intensity of burner ignitions.
- Why do balloon flights take place early in the morning or at sunset?Because in the middle hours of the day, the sun warms the ground, which in turn warms the air near the ground, creating thermal updrafts and turbulence that make it difficult to control the balloon. In the cool morning and late afternoon hours, the atmosphere is much more stable, the wind is generally light and steady, and conditions are ideal for safe and enjoyable flight. In addition, the hot air balloon must be filled with warmer air than the air outside to fly, and in the middle hours of the day this is often not possible.
- Is it cold in a hot air balloon when you are at altitude?The temperature decreases with altitude, so on a cool day you may feel some biting air. However, the burner radiates heat downward during each ignition, creating a warmer microclimate inside the gondola. In general, it is recommended to dress in layers with comfortable clothing. For most flights at standard altitudes (200-400 meters), the temperature is well tolerable and the excitement of the view makes you forget any feeling of cold.
- Can a hot air balloon change direction during flight?Not strictly speaking. The hot air balloon has no motors or horizontal direction controls-it moves by following air currents. The pilot can influence the path indirectly by changing altitude, where currents can blow in different directions. This dependence on wind is a key feature of the balloon, distinguishing it from airships, which have their own propulsion instead.