Also involved with the Navy VTOL UAV demonstrations in 1998, the "Vigilante" began as an optionally piloted vehicle (OPV) that could be flown in three modes: manned, remote pilot, or intelligent autopilot/mission control system. Developed jointly by SAIC (Science Applications International Corporation) and ATI (Advanced Technologies Inc.), the Vigilante is based on the Ultrasport Model 496 experimental helicopter kit (manufactured by ATIís American Sportscopter division), a 2-seater with a Hirth 95hp engine and a useful load of 260kg. Originally created for the Ballistic Missile Defense Organization (BMDO) and Jet Propulsion Laboratory (JPL) to provide a stable, unmanned platform for an optical camera to monitor anti-ballistic missile tests, the airframe known as Vigilante 496 has since been modified for Navy requirements.
After abandoning the land-based Navy trials of the Vigilante 496 in 1998 due to flight control system problems, ATI and SAIC took the aircraft back to the design stage in an effort to overcome these problems and compete for the recent VTUAV contract. The new Vigilante 500 model includes an improved flight control system, a new airframe with a smaller streamlined shell for reduced drag, improved efficiency and reduced radar cross section. A heavy fuel engine required for Navy use was also planned, and the aircraft redesignated the Vigilante 600. The Vigilante was projected to have an endurance of 16 hours, a radius of operation at 925km, and a top speed of 250km/h. SAIC chose not to submit a proposal for the VTUAV competition, citing what they considered to be a "punitive" contract fee arrangement. However, the "Vigilante" will be used as the flight demonstration vehicle for a recently awarded NASA Revolutionary Concepts (REVCON) program investigating the feasibility of "swashplateless" helicopter flight.