How Do Hot Air Balloons Work?

Flying in a hot air balloon is very enjoyable, and the view up there is breathtaking. It’s one of the most enjoyable activities people could experience. Sometimes though, people can’t help but be curious about how these hot air balloons work.

Hot air balloons are an innovative application of fundamental scientific principles. They are based on this very fundamental scientific principle: warmer air rises over cooler air. Hot air is lighter than cool air, having less mass per unit of volume. 

One cubic foot of air weighs around 28 grams, but its weight decreases by around 7 when it’s heated by 100 degrees Fahrenheit. Each cubic foot of air in hot air balloons can lift around 7 grams, which isn’t much. So, hot air balloons are huge because they need 65,000 cubic feet of hot air to lift 1,000 pounds.

Let’s look at the different parts of a hot air balloon and know how each part plays in heating the air. But if you want to learn more about galaxies, open the given link. 

Main Parts of a Hot Air Balloon

Hot Air Balloons

Every hot air balloon has three main parts:

  • The burner for heating the air
  • The balloon envelope for sustaining the air
  • The basket carrying the passengers


For the balloon to keep on rising, you must find ways to reheat the air. A hot air balloon does this through a positioned burner under an open balloon envelope. As it cools, it can be reheated by the pilot by firing its burner.

Now, modern hot air balloons burn propane to heat the air. Propane is a substance frequently used in barbecue grills. It’s compressed in liquid form and stored in lightweight cylinders placed in the balloon basket. 

There’s an intake hose running down to the bottom of the cylinders that draws the liquid out. The propane can quickly flow through the hose to the heating coil since it’s very compressed in lightweight cylinders. 

For those wondering, the heating coil is steel tubing that coils around the burner. When the burner is started, the propane goes through a process that changes it from liquid to gas. The gas amounts to a stronger flame and more efficient consumption of fuel.

Balloon Envelope

The envelope in many modern hot air balloons is made from extensive nylon gores strengthened with sewn-in webbing. The gores extending from the envelope’s base to the crown are made up of multiple smaller panels. Due to its lightweight quality, nylon works great in balloons. 

Even if it’s lightweight, nylon has a high melting temperature and is also quite sturdy. The nylon at the envelope’s base is called a skirt. It’s coated with a special fire-resistant material that keeps the balloon from being ignited.

With buoyancy keeping it moving upward, hot air won’t be able to go out of the envelope’s hole at the bottom. The continuous firing of the fuel jets will have the balloon continue rising. Eventually, the air will become too thin that the buoyant force- equal to the weight of air displaced by the hot air balloon, won’t lift the balloon due to it being weak in an upper altitude. 

This is the reason why there’s an upper altitude limit. Larger balloon envelopes mainly have higher upper altitude limits than smaller balloons.


The basket accommodates the passengers and contains navigation equipment and propane tanks.

Wicker baskets are utilized for the passenger compartment of most hot air balloons. Wicker is not just sturdy and flexible; it’s also fairly lightweight, so it works great in hot air balloons. The wicker’s flexible quality helps with the balloon landings. 

Baskets made of more stiff material would make the passengers feel the impact force’s effect, unlike those made with wicker, which absorbs some of the force due to its flexibility.

Piloting a Balloon

two men pulling a hot air balloon, hot air balloon, field

You need skills to pilot a balloon even when the controls are simple. To lift it, pilots move a control lever that opens up the propane valve. 

It works like the knobs on gas stoves, which increases the gas flow and flame size as you turn it. The larger the flame, the faster the vertical speed of the balloon.

Hot air balloons also have an attached cord, which opens a parachute valve at the envelope’s top. When it’s pulled, the air temperature inside decreases as some hot air escapes the envelope. With this, the balloon ascents slower. 

To sink, the pilot has to keep the balloon’s valve open long enough.

Pilots can change their vertical position by moving horizontally. To move in a specific direction, pilots go up and down to the right level of altitude then go with the wind. To control the horizontal speed, pilots have to change the altitude due to the wind speed that increases as you go higher in the atmosphere.

Flying a hot air balloon isn’t like flying an airplane. The piloting is mainly improvised from time to time, so some of the hot air balloon crew stay on the ground and ride a car to follow the balloon and see where it lands. They then can collect the passengers and also the equipment.

Who Invented Hot Air Balloons?

hot air balloon on the air, a man with a camera posing on the hot air balloon

Here are some notable moments in ballooning history:

c.200 BCE: Archimedes (287–212 BCE), a Greek mathematician, describes buoyancy: things can float in fluids (gases and liquids) by displacing them until the pressure of the fluid driving up beneath them equalizes their weight. Water pressure keeps ships afloat, while air pressure keeps balloons afloat.

17th century CE: Robert Boyle (1627–1691), an Irish-born chemist, demonstrates how heated fluids grow lighter (less dense).

June 1783: Jacques-Étienne Montgolfier and Joseph-Michel Montgolfier (1740–1810 and 1745–1799), two French brothers, create the first workable hot-air balloon out of a linen envelope coated with paper. They utilize a simple fire composed of straw and wood instead of gas burners.

November 1783: In a balloon built by the Montgolfiers, two additional Frenchmen, the François Pilâtre de Rozier (1757–1785) and Marquis d’Arlandes (1742–1809), travel 9 kilometers (5.5 miles) across Paris, France. The era of human flight is here!

August 1859: For the first time, the mail is transported across the U.S. by hot-air balloon. John Wise attempts to transport a box of 123 letters from Lafayette, Indiana, to New York City but is forced to abandon his journey when he arrives at Crawfordsville, Indiana.

Aside from this informative article, we also recommend you read our post on the Top 5 Tips to Help You Chose a Telescope for Astronomy.