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Un-Piloted Hybrid Plane: Potential Escort for V-22?

The U.S. Marine Corps is showing interest in a new type of hybrid vertical-takeoff and landing rotorcraft, called the canard-rotor wing. The technology--which allows the rotorcraft to shift to fixed-wing flight in midair--is in development by the Defense Advanced Research Projects Agency and the Boeing Co.

The Marine Corps is "looking at the requirement" for such a system, said George Muellner, president of Boeing Phantom Works, in St. Louis. The most likely application for the canard-rotor wing, he said during a briefing to reporters, is to "support V-22 operations."

The V-22 Osprey--a hybrid aircraft that flies like a fixed-wing turboprop and takes off and lands vertically--is the Corps' choice to replace its aging troop-transport and rescue helicopters. The Marine Corps had planned on buying nearly 400 Ospreys. That number could change, however, since the V-22 program is being restructured and will be slowed down, as a result of two accidents last year that killed 23 Marines.

If the Osprey became operational one day, the canard-rotor wing could be a suitable escort aircraft, according to Muellner. "It can operate out of the same areas, but has much higher speed [up to 400 knots]. It could be a fighter escort for the V-22."

Phantom Works currently is testing a 1,400-pound unmanned version of the aircraft. The Defense Advanced Research Projects Agency (DARPA) wants to have the option of possibly developing both piloted and un-piloted versions.

"It has all the benefits of the rotary wing and the benefits of the fixed-wing aircraft," Muellner said. "It takes off as a rotary wing, once airborne, gains speed, the upper wing turns fixed, and turns into a fixed-wing aircraft."

The canard-rotor wing vehicle has been named the "Dragonfly." The first prototype will be 18 feet long, about 6 feet tail, with a 12-foot rotor diameter.

As described by Muellner, the Dragonfly combines the hover efficiency and low-speed flight characteristics of a helicopter with the subsonic cruise speed of a fixed-wing aircraft. In both rotary-wing and fixed-wing flight modes, the aircraft is powered by a conventional turbofan engine, using diverter valves that direct the thrust to the rotor blade tips, or aft to the jet nozzle. The Dragonfly has a canard, instead of a conventional tail. The rotor is not driven by a transmission box connected to an engine, but rather by gas extracted from the main jet engine, Muellner explained.

Asked whether the Dragonfly would have any future commercial applications, Muellner said the size would be a problem. "We are not sure that it can be scaled," he said. "It's very large. The rotor has to handle a large gross weight."

The first Dragonfly prototype has been shipped to Boeing's facility in Mesa, Ariz. The plan is to begin flight tests in 2002, he said.

The possibility of a Dragonfly-type aircraft becoming a V-22 escort in the future is an intriguing concept, said Gary B. Simpson, director of military business development at Bell Helicopter Textron. The company, in partnership with Boeing, is the manufacturer of the V-22 Osprey.

"If Boeing is taking [the canard-rotor wing] seriously, we need to take it seriously too," Simpson said in an interview.

Bell Helicopter currently is focused almost exclusively on the redesign of the Osprey and on restoring credibility to the program, said Simpson. He noted that the company currently is having "a tough time," as a result of the two mishaps this past year. In the near term, it is hard to predict when the V-22 will fly again, said Simpson. It could be up to a year. "We cannot put a date on it," he said. The program currently is in a "research mode."

The Bush administration requested about $1.5 billion in fiscal year 2002 for 12 aircraft, which is the minimum number needed to keep Bell from having to lay off the V-22 work force, officials said. Assuming the program gets back on track, Simpson said, the Marine Corps might be interested in a so-called AV-22 variant, as an armed escort for the V-22.

The canard-rotor wing, in a V-22 escort role, would be one among other ideas that Simpson outlined as possible options.

The AV-22 would carry the same ordnance load of an A-10 fixed-wing close-air support aircraft, he said.

"You could put those systems internal to the aircraft, to reduce the cross section," Simpson said. The AV-22 would look like a narrow V-22. But it would be much larger than the civilian tilt-rotor, the Bell/Agusta 609. The 609--made by a commercial joint venture between Bell Helicopter and Agusta, of Italy--is about one-third the size of the V-22.

A Bell/Agusta 609 potentially could serve in an armed escort role, assuming that it could be reconfigured as a gunship, said Simpson.

An armed 609 also would be considered as a possible replacement for the Marine Corps' Cobra gunship, in 2015 or 2020, said Simpson.

"We examined the possibility of a stop-full rotor system" for a transonic, low-observable tilt-rotor airplane, he said. Under this concept, the aircraft takes off as a tilt-rotor, converts like a tilt-rotor and, at 170-180 knots, it would feather and fold the rotor system, pulling it back into the nacelle, said Simpson. That would help reduce the radar cross section, he added. "We've done one wind-tunnel test on it."
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Author:Erwin, Sandra I.
Publication:National Defense
Article Type:Brief Article
Geographic Code:1USA
Date:Aug 1, 2001
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