Staying above it all: George Jetson would recognize Moller's M200G Volantor; multifuel vehicle's target applications include public safety, recreation

Diesel Progress North American Edition, Dec, 2007 by Mike Brezonick

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For as long as there have been airplanes and automobiles, there has been a dream to combine the two in something that would let the driver escape the surly bonds of earth and motor freely through the air. And usually, when envisioned by futurists and science fiction authors, it looked like a flying saucer.

That vision is becoming reality, thanks to Moller International of Davis, Calif. Earlier this year, the company announced that it would take orders for its M200G Volantor, a directed-thrust vertical take-off and landing (VTOL) vehicle. And while it's really not intended to be a flying car in the classical sense--more on its target applications later--it does resemble the classic image of a flying saucer and is instantly recognizable to anyone who ever saw an episode of "The Jetsons."

Company founder Dr. Paul Moller called the M200G "the ultimate off-road vehicle," able to travel over any surface.

"It's not a hovercraft, although its operation is just as easy," he said. "You can speed over rocks, swampland, fences or log-infested waterways with ease because you're not limited by the surface. The electronics keep the craft stabilized at no more than 10 ft. altitude, which places the craft within ground effect, where extra lift is obtained from operating near the ground. This lets you glide over terrain at 50 mph that would stop most other vehicles."

That operating height is considered desirable because as it operates no higher off the ground than its "wingspan," it is considered a ground-effect machine and thus is not regulated by FAA controlled airspace rules. That means the user does not require a pilot's license.

The M200G vehicle is powered by eight Rotapower engines, each rated approximately 90 hp at 6500 rpm. The engines are supplied by Freedom Motors, a Moller subsidiary also based in Davis, and are rotary engines based on the original Wankel engine design that was further developed by Outboard Marine Corp., from whom Freedom purchased the core technology.

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Capable of operating on gasoline or ethanol, the company said the engines have demonstrated the ability to meet ultra-low emissions vehicle (ULEV) standards without aftertreatment. In addition, Freedom Motors indicated that the technology developed to reduce emissions and fuel consumption also allows the use of any type of fuel with modest changes in the fuel injection system for operation with diesel fuel.

The engines directly drive eight enclosed ducted fans with composite fan blades that lift the vehicle to its operating height, as well as provide for forward movement. Each of the engine-fan assemblies is computer controlled, with engine speed determining how much thrust is produced by each.

Each fan is controlled by an independent flight control computer. This computer control strategy ensures stability, the company said, as any uncommanded change in the altitude of the aircraft is detected and corrected within about one-tenth of a second.

The eight ducted fans are positioned in a circular pattern around the 10 ft. diameter vehicle and embedded into the saucer-like fuselage. Four of the ducted fans incorporate moveable vanes on the underside that deflect the thrust to control the direction of travel--vertical, horizontal, banking, turns, etc. No traditional aviation systems--ailerons, flaps, elevators--are required since the speed of each engine determines the local, instantaneous thrust level while the vanes provide the local, less time-sensitive thrust direction.

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For redundancy, the Volantor uses a voting computer system to manage stability and control. The system manages sensors that measure angular rate, angular acceleration and altitude, and determine the precise position and motion of the Volantor in relation to the directions of the operator as communicated through a fly-by-wire control system.

The only pilot input is through two hand-operated controls that direct the redundant computer-controlled system to carry out the desired maneuvers.

The left-hand control twists to select desired operating altitude and moves fore and aft to select the rate of climb and descent. The right-hand control twists to select direction and moves side to side to provide traverse movement during hover and early transition. This same control moves fore and aft to determine speed and braking.

"Most VTOL aircraft are extremely intolerant to failures of their propulsion systems," noted Bruce Calkins, general manager of Moller International. "The M200 and M400 series Volantors have been designed to withstand a failure of an engine during VTOL operations by using multiple engines to provide thrust.

"If an engine were to fall while the aircraft is in hover, our redundant propulsion system can accommodate the failure by providing additional thrust from the other engines. We also have redundant control system components using multiple computer-assisted flight controllers. During flight tests we have induced engine failures and had no significant loss of control or stability."