When the time comes to put the balloon up, the envelope is removed from the bag and laid out in a long line. The burners are attached to the uprights, and the basket is attached to the cables on the bottom of the envelope. An engine driven fan is used to inflate the envelope with cold air. When partially inflated, the air is heated by a burner and the envelope rises above the basket. With further heating, there is sufficient ‘lift’ for the balloon to fly.