Saturday, October 1, 2005
Seeking Tomorrow's Heavy Lifter
It will take 20 years to develop the technology needed for a new, efficient heavy-lift helicopter. The U.S. Army-led Joint Heavy Lift initiative is the latest effort to get that done.
By 2008, the U.S. Army plans to field the first light, highly mobile combat brigade equipped with Future Combat Systems technology. Development of these interim brigade combat teams is the first major step in the Army's Transformation program; 32 are to be created by 2014 and equipped with the Future Combat Systems' series of armed and armored vehicles. Those vehicles are to have a maximum weight of 19 tons.
To support these brigades, the Army is leading pursuit of a new, heavy-lift rotorcraft that could be used by all U.S. military services and carry more than 20 tons hundreds of miles at speeds possibly in excess of 300 mph.
To launch this Joint Heavy Lift program, the Army's Aviation Applied Technology Directorate issued a call last April for manufacturers to submit technical and cost proposals to allow the program to assess possible concepts and designs. The directorate said it would award up to five contracts worth roughly $3 million in mid-September.
The intent was to award at least one contract covering each of three speed bands, assuming meritorious proposals were received for each. The speed ranges are: 160-200 kt., 200-250 kt. and 250-300+ kt.
True to their word, Joint Heavy Lift officials on Sept. 15 said they had selected five proposals for further development and study. Sikorsky Aircraft won contracts to pursue two proposals in the program's Concept Design and Analysis phase. Boeing also won two contracts--one by itself and one with Bell Helicopter. A company called Frontier Aircraft got the fifth contract.
Once the contracts are signed, the winners are to submit concept designs for an advanced vertical takeoff and landing system that "enables future joint concepts of operations," including such things as conducting mounted and dismounted vertical envelopment; executing operational maneuver and sustainment operations at extended ranges simultaneously into unprepared, complex terrain locations under extreme environmental conditions, 24/7; and overcoming enemy anti-access strategies from land and sea bases as part of joint expeditionary operations.
The focus of the next phase will be on identifying viable concepts and substantiating their achievable performance.
This phase will run 18 months. A technical team of Army, Navy, Marine Corps, Air Force, Pentagon and NASA representatives will evaluate the proposals and manage the efforts.
In posting the awards, the Army clarified the specifications against which the proposals will be judged.
The baseline specification is to maneuver a Future Combat Systems Stryker/LAV Vehicle over a 250 nm. radius, under 4000-ft. density altitude and 95F conditions, from/to land or sea bases and operating areas. Eight specific excursions to these conditions will also be investigated, the Army said. These include cargo loads of 16-26 tons, mission radii of 210-500 nm, and density altitudes up to 6,000 ft. The proposals also must show full compatibility with a future ship.
The Army has a stated need for an aircraft to provide logistical support of the Future Combat Systems. While Army Transformation calls for light combat brigades to be in action within a decade, the Joint Heavy Lift aircraft would not enter service until at least 2022, according to Col. Tim Crosby, the Army's project manager for cargo helicopters. Development costs are estimated at $11-$15 billion.
Those eliminated from the competition included Piasecki Aircraft Co., whose proposal was based on a compound-helicopter derivative of the Sikorsky UH-60 Black Hawk, and a team led by the Georgia Institute of Technology that included Groen Brothers Aviation. That team proposed a heavy-lift gyrodyne with tip-jet-powered rotors for vertical lift and standard, wing-mounted turboprop engines for forward flight.
Sikorsky's awards cover a proposal for a 165-kt. aircraft and a 245-kt. one, both based on the X2 technology program it launched last June.
The slower aircraft, the coaxial-rotor X2 Technology Crane, is intended primarily to carry external cargo loads, though it will have a cabin.
The 245-kt. aircraft would be the X2 Technology High Speed Lifter, an advancing blade concept aircraft incorporating two mid-ship propulsors.
Sikorsky had said it expects to fly next year a small, 5,000-lb. X2 technology demonstrator built by its Schweizer Aircraft subsidiary.
One Boeing award covers what is called the Advanced Tandem Rotor Helicopter, another 165-kt. aircraft. Boeing is studying several design possibilities, ranging from a larger, more powerful Chinook-type helicopter to a completely different tandem rotor concept that could look like its Heavy Lift Helicopter concept of the mid-1970s. That helicopter, designed and built but never assembled, was much like the Sikorsky S-64/CH-54 Skycrane.
If Boeing stays with its basic CH-47 Chinook design, the engines would have to be upgraded to the 6,000-shp range, with a newer, more powerful gearbox. The basic fuselage would also have to be enlarged to allow internal loads.
The other award covers a Quad Tilt Rotor proposal for a 275-kt. aircraft. The Bell/Boeing proposal is for a quad-tilt rotor with a fuselage larger than the Lockheed Martin C-130 that would be designed to carry any Future Combat Systems vehicle more than 1,000 mi. at more than 300 mph. and to carry more than 90 passengers.
Bell and Boeing have started wind-tunnel testing of the Quad Tilt Rotor using a 7X10-ft,, low-speed wind tunnel at Texas A&M University. The design is being pursued under engineering contracts from the U.S. Defense Advanced Research Projects Agency.
Bell plans to present details of the Quad Tilt Rotor Joint Heavy Lift entrant at the Assn. of the U.S. Army meeting in Washington Oct. 3-5.
Frontier Aircraft's award covered a proposal for a 310-kt. "optimum-speed tilt rotor. Optimum-speed rotor is a hingless, rigid rotor concept with rotor blades operating at the optimum rotational speed to produce very low disk loading and rotor tip speeds. The blades are light but stiff, with cross sections that vary from root to tip. The stiffness also varies from root to tip. Frontier founder Abe Karem developed the A160 Hummingbird Warrior UAV using optimum-speed rotor technology. Last year, he sold the A160 and the company that built it, Frontier Systems, to Boeing. Frontier Aircraft is based in Lake Forest, Calif.