So, you're stuck on one side of the ranch and you're wondering what's up on the other side. Go there? Pshaw. Send your drone.

Some of the coolest new technology in UAVs comes from Advanced Technologies, Incorporated. Unlike the Predator and Global Hawk, the Vigilante family of UAVs is VTOL. And unlike the Fire Scout, Northrop Grumman's VTOL UAV, if you want to go along for the ride in a Vigilante™, you can. The Vigilantes can be used to deliver supplies to marooned troops, reconnaisance, or -- who knows? -- perhaps even to pick up of casualties from a battle zone, all by itself.

Manned Or Unmanned: Pick Your Flavor

There are two variants of Vigilante. Both have a maximum gross weight of 1,100 pounds, a main rotor diameter of 23 feet, an overall length of 26 feet; their shrouded tail rotors stand eight feet tall.

The Vigilante 496 OPV (optionally-piloted vehicle) can hit a TAS of 75 knots; and has an operating ceiling of 12,000 feet. Although its 12 cubic foot interior may seem a little cramped, this little UAV can carry a payload of up to 300 pounds. That's in addition to its full fuel load of 18 gallons. A Hirth engine gives the 496 about five hours in the air.

The Vigilante 502 is a UAV only aircraft with a somewhat sharper performance edge. The 502 tops out at 117 knots TAS and can fly as high as 13,000 feet above sea level. But the 502's better performance comes at a price. Its interior capacity is only five cubic feet and its maximum payload just 150 pounds. Still, the 502 is designed for much better endurance, with a 36-gallon fuel capacity in a crashworthy fuel system. It's more streamlined and boasts a Rotax 914 turbo engine.

Linux Is Pilot In Command

In both aircraft, the avionics system uses a high-quality navigation sensor, an integrated INS/GPS solution, and an integrated air data system. With all that, ATI says the machiens have a "robust fault detection and recovery" capability.  The thinking ability of both choppers is based on a PC104-based processor suite using proven, off-the-shelf hardware. The brains behind the system: a low-cost, non-proprietary Linux operating system.

Obviously, a VTOL UAV presents some rather special challenges for any ground-bound pilot. To compensate, the Vigilantes' operating systems incorporate special controls and displays. The idea: meet the special requirements of rotary wing vehicles, especially distinguishing between hovering and forward flight modes.

The pilot has several different ways to interact with the Vigilantes. They include real-time flight director style commands, supervised autonomy of waypoint-based navigation, and fully autonomous flight (for recovery after lost link).

The Ground Control Station (right) features redundant command/status RF links in 900 MHz and 2.4 GHz. There is also a 72 MHz backup safety pilot command link and a 425 MHz flight termination link. A variety of additional real-time sensing elements are recorded by the ground station including: engine health & status instrumentation, EGT and CHT, separate rotor and engine speed, electrical power system status, a radar altimeter (0-600m), and an ultrasonic ground proximity warning system. 

Mission control is done via the GCS through redundant frequency-hopping digital datalinks having a 20 nautical mile range. The operator may select levels of control authority over the vehicle ranging from hands-off, waypoint inputs (from A to B at C speed at D altitude) to joystick controlled velocity commands (climb at x rate, turn at y rate, cruise at z rate, etc). Automatic takeoff and land, pre-programmed lost link recovery, and emergency autorotations are also executed without operator intervention. The remote pilot gets a sense of where he is by looking at digital maps, air vehicle health displays, and payload operations screens on the GCS display. A stand-alone Flight Termination System is optionally available.

FMI: www.saic.com/products/aviation/vigilante/vig.html