The Heavycopter (unofficial name) is a miniboss in the NES port of Double Dragon II: The Revenge. It is an armed green military helicopter with a turret mounted on its front that is piloted by the Black Shadow Warriors.
The Heavycopter is encountered immediately after the player reaches the top of the third building in Mission 2. It makes its introduction by raiding the place, showering it with a barrage of bullets fired from its frontal mounted turret, leaving little space for the player to take cover. The only way to stay safe from its projectiles is by positioning below the aircraft itself, out of the turret's firing range. An experienced player who knows about its attack patterns should be able to take shelter immediately by climbing the building's drainage pipe until the helicopter appears, wait for its first barrage to pass below and then immediately climb down and remain on the right side of the platform, forcing the vessel to enter its second phase.
When the Heavycopter reaches the middle of the screen, it will remain hovering in place, open the hatch on its side and start releasing several Black Shadow Warriors to ambush the player, which include: two Lindas, two Williamses and two Right Arms. Dealing with all of these enemies in such a constrained space may prove difficult, but if the player remains on the platform below, these thugs can be taken down easily by receiving them with hurricane kicks while they're climbing down the pipe; or, if preferred, immediately receive them with a hurricane kick as they're trying to climb out the aircraft. After all the enemies have been defeated, the helicopter will fly away.