Why does "Star Fox" do a barrel roll?

The barrel roll maneuver in the "Star Fox" video game series is used to evade incoming projectiles and enemy units. A barrel roll is initiated by double-tapping the L or R buttons in the original "Star Fox" or the Z and R buttons in "Star Fox 64."

The phrase, "Do a barrel roll," is first spoken in "Star Fox 64" on Nintendo 64 by the character Peppy Hare while teaching players about evasive maneuvers and Arwing ship controls. When a barrel roll is executed in "Star Fox," the aerial maneuver that is depicted is actually called an aileron roll. The aileron roll differs from a barrel roll in that a barrel roll features changes in elevation while an aileron roll does not.