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A crisis in airports – either access or availability – would push ahead the attraction of a concept long held but as-yet untested- the concept of the so-called tiltrotor aircraft.

Dave Higdon   |   1st February 2002
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Dave Higdon Dave Higdon

Dave Higdon writes about aviation from his base in Wichita Kansas. During three decades in...
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Speed- Altitude- Comfort and Vertical Takeoff!

Civil tiltrotor advances on the strength of Agusta- Bell and their beliefs in a concept.

A crisis in airports – either access or availability – would push ahead the attraction of a concept long held but as-yet untested- the concept of the so-called tiltrotor aircraft.

Interestingly- progress has been slow- even stilted- despite the obvious advantages of an aircraft that launches and lands in helicopter style while flying twice helicopter speeds in between.

Military planners love the hybrid aircraft for its inherent- helicopter-like ability to launch and land from spaces only slightly larger than required for rotor clearance – and in a battle zone- the only zoning arguments to be settled are those inherently at stake: You can use what you control in any way you need.

Alas- the world of civil transportation holds other threats and pitfalls rendering speed as the only guaranteed advantage of a tiltrotor over a helicopter. Giving speed its due- the tilt rotor holds an attraction by many an operator flying helicopters across large distances between locations for which access is assured.

Doubling cruise speeds would bring some major improvements in mission time and the number of missions possible in a day. But benefits in flexibility and utility depend largely on access to off-airport operations areas similar to those in which helicopters enjoy only limited numbers.

To realize the sort of advantageous utility the tiltrotor aircraft is truly capable of rendering- the operator needs maximum access – or- at the least- access for those places the ship may regularly travel. Still- where a company controls enough property around factories and office locations to use its own pads- even where an airport is part of the O&D equation- there’s no denying the potential of tiltrotor aircraft.

All of those benefits- from speed to access and operational flexibility- may finally start to shine in their own right in the next year as partners Agusta and Bell Helicopters near the end of 20-plus years of dreams for a civil tiltrotor aircraft.

The partnership of Bell Helicopters and Agusta grew out of decades of collaboration- starting in 1952 when Agusta – already a company with a 45-year history in aviation – became a licensed manufacturer of Bell products for Europe.

The two companies entered into a collaboration for the Bell/Agusta BA609 in 1998 after both parties recognized that the expense and risk of going alone put at risk the future of projects like the BA609 Tiltrotor aircraft and the AB139.

Due to make its first flight in the second quarter of this year- the BA609 has overcome many of the hurdles of time- costs and uncertainty. In addition- the AB139 has advanced the state-of-the-art in conventional helicopters by offering the best in power- lift and avionics in a platform with both civil and military potential.

Bell/Agusta Aerospace line launched with two strong contenders

The Bell/Agusta BA609 is a six-nine passenger transport aircraft- which combines the speed and range of a turboprop airplane with the vertical takeoff and landing capability of a helicopter.

Designed from the outset for low maintenance and maximum operational flexibility- the Bell/Agusta BA609 will offer operators highly cost-effective- point-to-point transportation at cruise speeds up to 275 knots and at ranges up to 750 nautical miles.

The configuration options for the BA609 aircraft include VIP/executive transportation- of course- as well as natural resource exploration- medical transportation- search-and-rescue- law enforcement- maritime surveillance and training- among other uses.

Although long considered a risky- expensive technological leap- the decision to produce the Bell/Agusta BA609 came after the explicit recognition of the potential for this dual-use technology to truly revolutionize the world’s air passenger transportation system. That recognition came from no less a studious body than the United States Congress and its Commercial Tiltrotor (CTR) Development Advisory Committee.

The committee’s report- prepared by the US Congress and released in December 1995- concluded that the tiltrotor is technically feasible.

The report also acknowledged the limitations of existing airport-to-airport-oriented air travel by noting that a public/private partnership should be created to address institutional- infrastructure- and coordination of tiltrotor issues and recommended that federal government take the lead to facilitate public/private decisions.

Other findings of the report deal with the potential positive societal benefits of tiltrotor- including the reduction of airport congestion- airspace improvements- a better balance of trade and the new jobs such developments would create.

Like the conventional helicopter itself- the ability to operate away from conventional runways is in large part the essential element the technology must be able to exploit for the speed advantage to be meaningful. The Bell/Agusta BA609 could help launch a dramatic shift in commercial passenger flight operations if sufficient off-airport operation sites allowed transportation between city centers- reducing the need for airports and runways while providing cost-competitive air transport.

With such access- tiltrotor craft like the BA609 will provide twice the speed and range and significant enhancements in passenger comfort as conventional rotorcraft- with speeds similar to conventional turboprop aircraft and lower overall block times.

Power for the BA609 comes from a pair of Pratt & Whitney Canada PT6C-67A turboshaft engines rated for 1-940 horsepower. With a service ceiling of 25-000 ft msl- the BA609 is also capable of hovering out of ground effect at altitudes up to 5-000 ft msl.

Prior to first flight at Bell’s Arlington- Texas- facility- the company plans to conduct an extensive series of tests using a unique elevated platform so the test crew may run the engines and cycle their position through the full range of positions- from fully vertical for launch and landing- to fully horizontal for cruise.

All the attention going to the unconventional tiltrotor concept could lead some to believe that Bell/Agusta sees only the BA609 in its future. However- despite Bell/Agusta’s enthusiasm for the BA609 and the future of the tiltrotor concept- the venture is not neglecting the future of conventional helicopters. You need only look to the development of the new AB139 medium-twin engine ship to know that Bell/Agusta sees a bright future for the helicopter for years to come.

Powered by two Pratt & Whitney Canada FADEC-controlled PT6C-67C engines- the AB139 can carry up to 15 passengers or 5-500 pounds (2-500kg) of useful load at cruise speeds up to 157 knots- while offering one of the most-spacious cabins in its class. And with two engines making a maximum of 1-725 horsepower each- the AB139 has power to spare and redundancy to tackle the toughest environments.

The AB139 combines the benefits of proven technology and the latest new-generation system integration and compliance with the demanding JAR/FAR 29 standards. Additionally- the AB139 offers the latest avionics from Honeywell’s flat-panel Primus Epic line- plus safety features in tune with the latest regulations- to offer one of the best vertical-lift values in a medium-twin class.

Less than a year after the February 3- 2001 first flight of an AB139- Bell/Agusta flew the third pre-production AB139 on October 22 at Agusta’s Vergiate plant in Italy. The certification program foresees a Tie Down Helicopter (TDH) and three pre-production aircraft. The TDH had started tests in December 2000.

At Agusta’s Cascina Costa plant in Italy- where first flight occurred- the second pre-production AB139 made its maiden liftoff on June 4- and according to the company- the flight test program is not only well underway- it’s also on time and on budget.

The flight program has provided excellent results- confirming or exceeding the estimated performances. These include a maximum continuous speed in excess of 157 knots- a maximum ceiling of 20-000 ft msl and hovering out of ground effect at 12-000 ft.

Both the maximum take-off weight of 6-000 kg- and a maximum rate of climb exceeding 2-200 feet-per-minute have been verified- and the venture expects certification of the AB139 – including IFR approval – under JAR/FAR part 29 regulations later this year.

First deliveries will follow- with more than 40 orders already on the books from customers in Australia- Europe- Africa- the Pacific Rim and the Americas.

Outlook solid: Agusta and Bell see strong future

While joint ventures may not be unusual these days- it’s an uncommonly confident partnership that collaborates on some projects while competing in the same arena with individual products. Only time will tell whether the new state of affairs for general aviation may work to the advantage of a challenging concept like the civil tiltrotor- thus adding strength and stability to the partnership.

Customers remain supportive of the BA609- despite a very public airing of problems suffered by the military variant of the program- the V22 Osprey.

Coveted by the Marines and other forces for the same traits that make it an attractive civil concept- the V22 suffered a rash of problems in the past two years that included two deadly accidents and a grounding of the Marines’ test program amid allegations of impropriety within the ranks of officers managing the program. Thanks to differences in the two designs- however- none of the military version’s problems seem to have tarnished the civil program.

If Bell/Agusta have their way- the coming years will see a new breed of business transport in the skies- machines that don’t add to the strains of airport and airways congestion.

And as companies begin to realize the improved security aspects available by avoiding airports to a greater degree than possible with fixed-wing aircraft- it’s possible that the BA609 and its successor models may enjoy a degree of success comparable to the design’s potential.

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Read more about: Bell Helicopter | TiltRotor | Agusta Westland | BA609 Tiltrotor aircraft

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