A blimp has many different parts. Helium fills the envelope, which gives the blimp its giant, oval shape. There are two engines that help the blimp reach speeds from 30 to 70 miles per hour. The rudder is the part of the tail that controls the blimp when it moves to the left or the right. The basket at the bottom of the blimp is called a gondola. It's a small room where passengers and pilots enjoy their ride. Some blimps have night signs and can flash messages from the sky during the night.