A gore is the fabric strip running from the top to the bottom of a hot-air balloon envelope.
A balloon envelope is assembled from many long, tapered sections of fabric. Each section is called a gore, and the gores are sewn together to create the balloon’s curved shape. The number and geometry of the gores vary according to the envelope’s design and size.
Modern envelopes commonly use lightweight ripstop nylon or polyester fabric, with stronger materials and tapes reinforcing stress-bearing areas. The lower portion near the burner is exposed to particularly high temperatures and receives additional protection.
“Gore” is sometimes confused with “panel.” A panel may refer more generally to a piece of fabric, while a gore is a specific longitudinal section used in constructing a roughly spherical or teardrop-shaped envelope.