Tiltrotor test program moving ahead quietly in Italy and U.S.
The second prototype of the Bell/Agusta BA609 tiltrotor is now flying in airplane mode, after starting its flight test regimen in helicopter mode on November 9 last year. It operates from Cameri, an Italian Air Force airfield near Milan.
The program has been gathering flight time relatively slowly. At last count, the 609 had logged only eight hours in the air. AgustaWestland said it had completed another seven hours in ground tests. Nacelle angles were tried throughout their entire range, from 95 to 0 degrees. Prototype No. 2 had reached 230 knots and an altitude of 9,000 feet.
In Arlington, Texas, at Bell’s flight-test facilities, prototype No. 1 has accumulated 137 flight hours and 127 ground hours. Maximum airspeed attained so far is 310 knots, 35 knots above the target maximum cruise speed of 275 knots. In altitude tests, the BA609 has reached its 25,000-foot service ceiling. Maximum acceleration has been 2 gs. Helicopter-mode climbs achieved 2,600 fpm and descents to more than 1,800 fpm. Airplane-mode climbs reached 3,500 fpm and descents 5,000 fpm. So far, prototype No. 1 has been tested to a weight of 17,000 pounds, slightly above the target 16,800-pound mtow.
The third prototype, said to be on the production line in Vergiate, should fly sometime next year. The fourth prototype is on the assembly line in Texas.
Tests of the two flying prototypes are progressing in parallel, involving a series of flights, inspections and analyses. Engineers on both sides of the Atlantic share their experience so that a sortie in Cameri benefits from both aircraft test programs, an AgustaWestland spokesperson explained. Although the airframe is regularly checked, such inspections are not as extensive as they were on the first prototype. The latter first flew in March 2003 and underwent a complete disassembly after 14 hours.
AgustaWestland is in charge of the government/military version of the BA609. As was true early in the program, there is no difference with Bell’s civil version. Variations will later come in kits–a hoist, for example. AgustaWestland insists it already has an undisclosed government customer, and the U.S. Marines have expressed interest in acquiring the aircraft for training purposes. The BA609 is much smaller than the Bell Boeing V-22 Osprey and could therefore become a suitable, more cost effective lead-in.
Organizing flight tests for such a hybrid design forced AgustaWestland to change the way it usually tests rotorcraft. Cameri airfield was chosen rather than the firm’s flight test center in Vergiate because of airspace constraints–Vergiate is very close to Milan Malpensa airport. Most often, this poses no problem, as helicopters in flight testing need little airspace, but because the BA609 flies twice as fast as a typical helicopter, the chase aircraft is a fixed-wing airplane, which needs much more airspace to maneuver. Testing at Vergiate could have interfered with the airport’s airspace.
AgustaWestland could have moved the flight tests to other company facilities in Brindisi, but that location is much farther away and therefore impractical because most development engineers are based near Milan. So AgustaWestland made an agreement with the Italian air force to use nearby Cameri Air Base. As the test pilots expand the flight envelope, “we can move back to Vergiate,” a company spokesperson said.
Last year, Bell and AgustaWestland further postponed the expected year of certification, from 2009 to 2010. AgustaWestland said the first two years of production are allocated, representing “more than 60 aircraft.” Bell has a 60-percent stake in the BA609 program, AgustaWestland having the remaining 40 percent.
The BA609 can seat six to nine passengers. Its target useful load is 5,500 pounds. Powered by a pair of 1,938-shp Pratt & Whitney Canada PT6-67As, its design range is 750 nm.