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European and FAA certification of the BA609, the first civilian tiltrotor, is expected in 2008. |
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The footprint of the BA609 is comparable to that of the S-76C+ (Sikorsky). |
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The BA609 reaches a top speed of 275 knots and cruises at 25,000 ft — between the operating envelopes of helicopters and fixedwing turboprops. |
Two years ago, Bell/Agusta Aerospace Co., Ft. Worth, made aviation history with the inaugural test flight of the world's first civilian tiltrotor, the BA609. The exotic aircraft combines the VTOL capability of a helicopter and the cruising speed and range of a turboprop fixed-wing aircraft. And though the revolutionary aircraft costs much more than similarsized turboprops and business jets, it doesn't need any concrete for takeoff and landing.
The civilian version of the Osprey V-22 tiltrotor aircraft recently flew for the first time since 2003. The scheduled pause in flight testing was for developmental engineering, Bell says. The military Osprey program was temporarily derailed in December 2000 after two crashes killed 23 Marines.
During the recent 78-min flight, the crew tested hover mode forward, sideways, and backwards, and navigated the pattern at 86 knots with 75° forward tilt on the outboard nacelles. The aircraft is now being tested in airplane mode, where it can reach a top speed of over 275 knots (about twice the speed of typical helicopters of comparable capacity). The BA609 can cruise at up to 25,000 ft and has a range of 750 nautical miles. There is seating for nine passengers plus two pilots. Dual certification (European and FAA) is planned for 2008 with deliveries following soon after. Bell has 60 orders for the aircraft.
The powerplant consists of two Pratt & Whitney PT6C-67A turboshafts. Overall length is 44 ft (13.31 m), overall height, 15 ft (4.50 m), and rotor diameter, 60 ft (18.29 m). It sports an advanced glass cockpit with digital flight controls, and the fuselage is graphite composite skin over an aluminum frame. The cabin will be pressurized to 5.5 psi at 25,000 ft.
Bell/Agusta offers this scenario for the craft:
An executive takes off from the helipad of his country house outside London, flies in comfort to a meeting in Frankfurt in just 60 min, then flies on to Zurich, Milan, and home again for an early dinner. And all of this with a minimum of ground transportation.
TILTROTOR VERSUS HELICOPTER
Why would anyone risk such relatively new technology when helicopters are tried and true? Well, range for one thing. A tiltrotor has three to four times the range of a helicopter. Also, top speed is greater by a factor of two or three, and the ceiling is 1.5 to 2 times higher.
And two engines are better than one. The aircraft can fly to safety and land using only one engine. Its hovering ability combined with the speed of a turboprop allows it to move quickly and land in a small area.
The BA609 is currently being planned in civilian configurations only. The closest to a military configuration would be the SAR (search and rescue) configuration for Coast Guard-type aircraft.