Graham Warwick/WICHITA
RAYTHEON AIRCRAFT'S new Premier I light business-jet is not a Beech, nor a Hawker. It is the first all-new aircraft to carry the Raytheon name and, for the year-old company, it represents both the launch of a new light jet family and the first step in a revamp of its entire product line.
The Raytheon Model 390 Premier I is a six-passenger aircraft with a composite fuselage, swept wing, Williams-Rolls FJ44-2A turbofans and Rockwell-Collins Pro Line 21 flat-panel avionics. Its first flight is planned for the third quarter of 1997 and the first deliveries for the fourth quarter of 1998.
At $3.9 million, the Premier I is priced between Cessna's CitationJet and Citation Bravo, but offers a larger cabin, higher performance and lower cost of operation than either aircraft, says Raytheon. "The Premier I is a light jet with a mid-jet cabin, high speed and a price well below that of any other light jet," says President Roy Norris.
Raytheon's first all-new business jet was conceived in secret at the company's Andover, Kansas, plant, where designers were given a challenge: "We did not want another 'me-too' aircraft," Norris says. "There had to be an undeniable, dramatic, improvement over the CitationJet" - which he describes as a "microjet". The result, he believes, "...is the most significant new-aircraft entry into the market in the last 25 years.
"The Premier I offers a mid-jet cabin at a microjet price. It will reduce the microjet to a toy," Norris argues. "The Premier I is a real, practical, business aircraft" which will appeal equally to entrepreneurs and corporate flight-departments, he believes.
According to Norris, the Premier I "...is the first light jet to take advantage of new developments in aerodynamics and construction". The aircraft has a high aspect ratio swept wing, whereas Citation light jets have straight wings. "Straight wings are inefficient," he argues. "You go to a jet to improve speed and efficiency. Why take half of it away with a straight wing?"
The second major innovation is the cabin, Norris says. "With previous aircraft, you had to compromise on cabin size when moving from a turboprop to a light jet. The jet needed a small [fuselage] cross-section to achieve its speed. The Premier I uses advanced aerodynamics, combined with a composite fuselage giving a substantially increased internal size while maintaining an external cross-section similar to that of other aircraft," he adds.
WIDER INSIDE
Carbonfibre/honeycomb-sandwich construction eliminates all internal fuselage frames and increases the available cabin volume by 13% over conventional construction, says Model 390 chief engineer David Bernstorf. Fuselage skins are 20mm thick, reducing the inside diameter by just 40mm, compared to 150mm for a conventional fuselage.
Fuselage outside diameter is 1.8m. The cabin interior is 1.7m wide and 1.6m high, with a flat floor, dropped aisle and a full-width private lavatory aft. "The cabin cross-section is embarrassingly close to that of the Hawker 800," Norris admits. "A customer can step up from a [Beech] King Air 90 or 200 and not feel that the cabin is compromised," he says.
Raytheon talked to more than 100 customers and worked with an advisory group of more than 20, representing operators of the King Air 90 and 200, CitationJet, Citation V, Learjet 31, and Hawker 800, in defining the aircraft. Premier I marketing manager Ken Mikolajchak says that surveys showed that a six-passenger interior was "highly desirable" for comfort. The aircraft carries six passengers in individual seats, the centre seats swiveling through 180¡ to berth with the forward seats, he says.
Fuselages will be produced using automated fibre, or tow, placement (see box). Compared with hand lay-up, used to produce Beech Starship fuselages, tow placement is "extremely cost-efficient", says Norris. Numerical control (NC) machines will be used to produce the fuselage. "This reduces the cost of growing the aircraft. We can change the length, the diameter, the number of windows, even the loft lines, by changing the NC tape," he says, acknowledging that Raytheon plans a Premier II and III.
Bernstorf says that the composite fuselage offers several advantages, including lower cost and weight, a quieter cabin, resistance to fatigue and corrosion, reduced manufacturing variability, and a smoother finish. Over 100 fuselages, the production cost will average $300,000, compared to $416,000 for a conventional aluminum unit, Raytheon estimates.
SWEPT FOR SPEED
With a 20¡ leading-edge sweep, high aspect ratio, and a supercritical aerofoil section "with some degree of laminar flow", the wing is designed to give the Premier I a 460kt (850km/h) cruise speed. Flaps extend out to 75% chord, to achieve a 3,000ft (900m) take-off field-length. As a result, the ailerons are small, and roll-control augmentation is provided by the outer of three spoiler panels on each side. Flight controls are manual.
Passing the wing under the fuselage avoids penetrating the pressure vessel and provides for a flat cabin floor. There are composite fairings forward of and under the wing, but the aft fairing is part of the rear fuselage, which deepens behind the pressure bulkhead to provide more volume in the aft baggage-compartment.
The all-metal wing has two main spars and a rear auxiliary spar to carry the main landing gear. One-piece ribs will be produced using high-speed machining, and skins will be riveted automatically. Fuel is housed in wing tanks running from the centreline out towards the tips. Instrument flight-rules range with four passengers is 2,800km (1,500nm).
While trade studies continue into a composite tail, the present metal empennage "...looks most sensible", says Norris. Wing leading-edge anti-icing is by engine bleed-air, but the horizontal stabiliser features electro-impulse de-icing. This is easier to install than bleed-air anti-icing, more reliable than pneumatic boots and consumes less power than electro-thermal de-icing, Bernstorf says.
Power comes from a pair of 10kN (2,300lb)-thrust Williams Rolls-Royce FJ44-2As, uprated versions of the turbofans powering the CitationJet. This engine features a 500mm-diameter integrally bladed fan, with 16 wide-chord blades; a three-stage axial low-pressure (LP) compressor; single-stage centrifugal high-pressure (HP) compressor; single-stage HP turbine; two-stage LP turbine; full-length bypass duct; and fluted exhaust mixer.
A single-channel electronic control-unit is provided, with back-up hydro-mechanical control. Thrust reversers are not fitted, but a ground-idle position provides the same benefits, Bernstorf says, and avoids the need for the pop-out exhaust paddles used on the CitationJet to "spoil" thrust when taxiing. Single-point refueling is an option.
Rockwell-Collins is launching its Pro Line 21 integrated avionics on the Premier I, the first business jet to feature large liquid-crystal displays (LCDs). Standard equipment includes two 200 x 250mm LCDs side-by-side on the pilot's panel. Attitude, altitude, airspeed and horizontal situation are presented on the primary-flight display (PFD); engine instruments and navigation information on the multi-function display. Engine instruments can also be presented at the top of the PFD.
A smaller LCD electronic horizontal-situation display is featured on the standard co-pilot's panel, along with conventional attitude, altitude and airspeed instruments. Options include a PFD for the co-pilot and, later, a fourth large LCD for an engine-instrument and crew-alerting system.
Raytheon's intention was for navigation to be accomplished entirely using satellites, but the company will now include conventional radio-navigation sensors, Bernstorf says. A single global-positioning/flight-management system with dual control/display units will be standard.
PLANNING AHEAD
Premier I concept development and risk reduction began in 1994, and led to a decision to proceed in March. Advanced design is now under way, and the design team has been relocated to Plant 3 at Wichita, Kansas, where the aircraft will be assembled. Product development is scheduled to begin at the end of 1995, and production will start in late 1996. Three aircraft will be used in a flight test programme beginning in the third quarter of 1997, and leading to US Part 23 certification in the fourth quarter of 1998.
Design of the Premier I is being accomplished entirely using the CATIA computer-aided design system. Integrated product teams (IPTs) have been established for the wing, fuselage, empennage and nacelles. "Performance, weight, cost and process requirements are flowed down to the IPTs," says new-programmes manager Lyn Roberts. A programme integration team provides support across the IPTs in areas such as processes and interfaces.
"There is major investment throughout the company on re-engineering, and the process piece is critical to success," Roberts says. According to Norris, the processes developed for design and manufacture of the Premier I will be used in all future Raytheon aircraft. "With such a jump in performance and value for money, clearly this is the beginning of a new family," he says.
Source: Flight International
