Hot air balloons are fascinating to see floating through the air on a clear day. Have you ever wondered how they are made?
Hot air balloons these days are constructed of two main parts: an envelope or what is called a gas bag and a basket or what is called a gondola. Since the envelope has to be protected from tearing it is usually made of a nylon that is designed not to rip. Other materials such as polyester may be used to make the envelope. A fire proof material has to be used to make the bottom part of the envelope so that it does not catch fire. This material is called Nomex and is resistant to fire which is important since the burner will be producing flame. The basket part of the hot air balloon is constructed of a type of cane called Palambang or sometimes Kooboo cane is used along with willow or rattan. These materials are all flexible, tough and lightweight. This allows the basket to vary in size from small to quite large. The willow or rattan is woven through the frame of the basket which is made of the cane.
The envelope has various cords and load tapes attached to it to help balance and share the load. The fabric that makes up the envelope also has a coating of a type of sealant which is usually of polyurethane. This is also made to withstand the UV light so it has an added UV inhibitor to help prevent the material being worn down by exposure to the sun. The envelope is made of separate sections or panels of material. This is done to reduce stress on the material. Balloons usually are of one of two shapes: rounded or teardrop. The basket is attached to the envelope by means of strong stainless steel wires and other rigid supports. In some cases the envelope has a load ring that is attached to the envelope and to which the basket and burner can be attached.
There are two main types of baskets that are used in modern day hot air balloons. These two types of basket are known as the T-partition or the open plan. The T-partition is when the basket is divided into two sections. In this plan the pilot and passengers are separated by a divider in the basket. The open plan has no such divider and people can move about freely. The advantage of the T-partition is it is easier to keep the weight properly distributed. The base of the basket is constructed out of plywood.
The heated air that causes the balloon to lift is produced from a hydrocarbon gas burner that is attached at the top of the basket. The gas burner is a propane burner that has at least two fuel tanks, sometimes more. The burner has a pressure gauge and a valve. The pressure gauge shows the pressure of the gas and indicates how much power is available, while the valve controls how much fuel the burning is using.