Is Volume Important Concerning Hot Air Balloons?

Understanding the physics behind the gas in hot air balloons can be confusing, since hot air makes balloons rise, how does this relate to density and volume?

Well, volume is important in hot air balloons because, without a high volume of gas, the air wouldn’t have a low density according to gas lawns, meaning the balloon would not float or would slowly sink if already in the air.

Within our guide below, we will take you through how volume relates to hot air balloons, how hot air balloons work, what hot air balloon lifts mean and buoyancy.

How Does Volume Relate To Hot Air Balloons?

To understand how volume relates to hot air balloons, we must first know what the gas law is and how it works.

The ideal gas law says that pressure times volume is equal to the number of molecules which are gas at a constant times temperature. A short equation for this is PV = nRT.

As hot air increases so do volume, so density equals mass/volume.

We can understand how volume works in hot air balloons by comparing them to helium balloons too.

• The N, R and P do not change in helium and hot air balloons, only volume and temperature.
• The decreasing temperature in a balloon will decrease the volume too.
• Density means mass divided by volume, a lower volume equals a higher density which means enough drop in volume the helium balloon could be too dense to float.

How Do Hot Air Balloons Rise?

Now we understand volume and hot air balloons, we can now understand how it makes these balloons rise into the sky through a change of air density

To begin, the density inside a hot air balloon remains the same as the outside, the air inside is then heated by the balloon’s burner which makes the density lower allowing the balloon to float up through buoyancy, this can lift the basket as well as the passengers too.

To maintain an altitude when flying the pilot has to make sure the temperature inside stays the same, a temperature change will mean that the altitude changes too.

What Does a Hot Air Balloon Lift Mean?

You can calculate the lift of a hot air balloon by knowing the temperature inside and outside of a balloon as well as the volume of the balloon.

The lift of a balloon can be worked out by the difference in the weight of heated air and the weight of the same volume of air in the surrounding temperature. For example, if a 4 person hot air balloon has a volume spec of 2,200 m3 and the ambient temperature was 10 degrees then the inside of the balloon was heated to 100-degrees it would have a lift of 662 kg.

The hotter the air inside of the balloon, the more lift it has.

What Does Buoyancy Mean?

Buoyancy is used a lot in conjunction with volume when talking about a hot air balloon, when we are talking about hot air balloons they can be positive, neutral or negatively buoyant.

For example, a positively buoyant hot air balloon means its lift is greater than the weight so will be climbing, a neutral buoyancy means the hot air balloon is level and a negatively buoyant hot air balloon will descend.

Frequently Asked Questions About Volume & Hot Air Balloons

Does a greater volume in a hot air balloon mean a greater lift? 

Yes, since a high temperature increases volume inside a hot air balloon which makes it less dense, allowing it to have a higher lift or float.

How high can a hot air balloon go? 

Most hot air balloons fly to a height of 3000 feet but there is a world record of them flying up to 69,850 feet although this is not safe.

Can a hot air balloon become too heavy? 

Yes, most hot air balloons have a weight limit of 1000 pounds, but the weight they can carry also depends on the size of the basket and weather conditions.

Who invented the hot air balloon? 

The hot air balloon and its physics were invented in 1783 by the Montgolfier brothers, it flew for around 15 minutes and its passengers were a duck, sheep and a rooster.

Do hot air balloons use convection? 

Yes, hot air balloons do use the process of convection since the warm air gets pushed up inside of the balloon while the cold air gets pushed out, this turn helps the balloon to float up.

What happens if the air inside a hot air balloon becomes cooler?

If the air inside of the hot air balloon becomes cooler then it will start to descend since this air is denser, pilots often let hot air out when they want to land the balloon or change height.

Last Words

Overall, volume is very important when flying a hot air balloon, a high volume inside a hot air balloon is caused by a warm temperature inside from the burner in the hot air balloon, this, in turn, reduces the density of the balloon, helping it lift and float.

To make a hot air balloon descend, the temperature will be reduced by letting hot air out which will lower the volume, therefore increasing the air density causing it to lower in altitude.