The autonomous Rotorcraft Sniper System (ARSS) is based on the Vigilante 502 unmanned helicopter which is a much modified version of the commercially available Ultrasport 496 which is an ultralight class kit helicopter. Powered by a 115 hp 4 cylinder turbocharged Rotax engine the 1,100 pounds (500kg) UAV can fly at 117 knots (135 mph / 216 kph) for up to 9 hours with a ceiling of 13,000 feet (4,000 m). The Vigilante can carry up to 380 lb (172 kg) of payload which is enough for a medium caliber machine gun, a shotgun or in this case a sniper gun. The autopilot is based on a 266Mhz Pentium PC-104 industrial computer that gets it bearings using GPS, radar altimeter and magnetometer. Communication with the ground is via RF digital modems at 115kbps and has a 20 mile range. Mounted onto this UAV is a lightweight gun turret developed by Space Dynamics Laboratory. The turret carries a .338 Lapua Magnum rifle and a situational awareness camera plus a scope with cameras attached that provides two levels of zoom. Control of the rifle is via a laptop computer with a Xbox 360 gaming controller used for aiming and firing.