A translational braking device for a projectile on its trajectory. The device has at least two air brakes made in the form of flaps that are moved in a plane perpendicular to the axis of the projectile to increase the aerodynamic drag of the projectile. Each flap has at least two closed grooves, extending essentially parallel to a direction that is perpendicular to the axis of the projectile, each groove cooperating with a rod that is fixed with respect to the projectile.