Bell Helicopter’s MAPL (modular affordable product line) tail-fan demonstrator took to the air at the OEM’s new XworX research center in Arlington, Texas, in July. A Bell 407 fitted with the 40-inch-diameter fenestron-like device lifted into a hover, performed several low-speed maneuvers, including pedal turns, and landed.
After the flight, pilot Jim McCollough said he found the aircraft easy to fly. “The workload in hover is very low.” Observers described the tail fan as practically inaudible: “You can occasionally hear a purring sound,” said one. The fan and duct replaces the conventional, 65-inch-diameter tail rotor and incorporates technology developed during bench testing earlier this year.
This demonstrator article was designed to allow testing in multiple duct configurations, to provide information on performance and acoustics in both hover and forward flight. The MAPL flight-test program will continue at the XworX facility and, to obtain high-altitude performance data, at Leadville, Colo.
Bell CEO Mike Redenbaugh was eager to point out that the rotor was an extension of anti-torque development at Bell that started in the 1970s, and capitalizes on trials made with a ducted tail rotor 10 years ago. “We are developing a tail rotor that will be quieter, more effective and more reliable with lower operating costs.”
Another MAPL project, this time an advanced rotor demonstrator, is scheduled to fly later this year.
The first aircraft in the MAPL family is expected to be available in 2008, although some of the new technologies are already being incorporated in Bell’s 427i. (See related story on page 109.)