From Sonic Retro
The Egg Launcher is an enemy Eggman robot faced by Sonic the Hedgehog in the day stages of Sonic Unleashed. They come in three flavours: H (horizontal), V (vertical), and H+V (horizontal + vertical), referring to the orientation of their missile armaments.
Looking a bit like distorted Egg Pawns, the Egg Launchers sport rather bulky homing missiles that can track Sonic over limited distances. The missiles continue to seek even after the robot is destroyed, so a smart move is to whack them with a homing attack before they can get off a single rocket. They reappear in Sonic Generations where they can fire missiles at Sonic in the background of the stage.
|“||Egg Launcher (H): These units fire horizontal missiles straight ahead at oncoming targets. The missile's homing feature makes them tough to dodge, but a well timed Stomp or Sonic Boost can send them flying.
Egg Launcher (V): After firing two Sonic-seeking missiles into the air, these drones are all out of ammo, left to tackle our hero with their fists.
Egg Launcher (H+V): Loaded for bear with two horizontal and vertical missiles, these units have four shots at smoking Sonic, making them a royal pain.
— Description from the Sonic Unleashed (360) bestiary, entries 011, 012, and 013