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Aviation History
1996
1996 - 3067.PDF
CORPORATE AVIATION reliability which have endeared the marque to its operators. "Hawkers were successful because the design decisions were right. We use the same sense of values, the same strat egy of balance [in designing the Horizon]," says Norris. Typical of that balance is the Horizon's range capability: 6,100km (3,300nm) at the Mach 0.8 normal cruise speed, and only 370km less at Mach 0.82. "You don't have to back off speed to get range," says Norris, noting that a US-based operator will be able to fly coast-to-coast, either way, or reach Europe "comfortably". Despite being substantially larger than the Hawker 1000, and flying further, faster, the Horizon has significantly improved airfield performance, according to Model 4000 project manager Sam Bruner. Balanced field length is 1,600m (5,250ft), and range from a 1,200m runway is still around 3,500km. The 715m landing distance enables the aircraft to be flown into London City Airport, notes Malcolm Bowd, Hawker project engineer and one of the key people Raytheon brought over from the UK. With a 16,300kg maximum take-off weight, the Horizon is almost 2,300kgheavier dian the Hawker 1000, the fuselage 3.56m longer, and the wingspan 3.25m greater. The fuselage is all- composite, produced using the automated fibre-placement technology developed by Raytheon for the Premier I. Compared with a conventional fuselage, this provides 200mm more cabin width and dramatically reduces pro duction costs. The fuselage will be produced in three sections: nose, centre barrel and tailcone, in cluding dorsal fairing and engine pylons. The 2 5mm-thick carbonfibre/honeycomb shell encloses a cabin 2 m wide and 1.83m high (com pared with 1.75m for the Hawker 1000, which has a dropped aisle). The wing passes entirely under the fuselage. The wing is described as "third-generation supercritical", offering a good blend of high speed and low-speed performance. Compared with the Hawker 800/1000 wing, sweep is increased to give a Mach 0.84 maximum cruise capability. There are no leading-edge, high-lift devices, and the flaps have the fixed vanes typical of earlier Hawkers. This "simple, cost- effective", design enables the Hawker's flaps to be single-slotted for take-off and double-slotted for landing, says Bowd. INTERNATIONAL PARTNERS Fuji Heavy Industries of Japan will design and produce the wing as a risk-sharing partner. Existing Hawker wing-builder British Aero space put in a bid for the work, as did Northrop Grumman, but, says Norris, Fuji's proposal was the best technically and the lowest priced. The wing will be metal, with trade studies continu ing into composite control-surfaces. All fuel (6,3 50kg) is housed in the wing, and the supercritical aerofoils have been carefully designed to minimise aft loading and allow the use of manual ailerons. The wing was designed using computational fluid-dynamics (CFD), as was the aft fuselage, which is area-ruled to minimise drag caused by the engine nacelles. CFD was also used to re-profile the original Hawker 1000 nose to reduce drag at the high er cruise speed. The tail is conventional aluminium, with studies under way into a composite rudder and horizontal stabiliser. Compared with that of the Hawker 1000, the stabiliser is larger and more swept, and, like the wing, is de-iced using engine bleed-air, replacing the fluid system used on earlier Hawkers. The "over fin" which gives the tail its "Hawker" look will house the antenna for the optional satellite-communica tions system. ENGINE CHOICE Raytheon evaluated three engines — the Allison AEJ007,AlliedSignal/General Electric CFE738andPratt& Whitney CanadaPW308 — focusing on reliability, time between over hauls (TBO), fuel efficiency and thrust growth for later versions of the aircraft. The winning PW308Aprovides29.3kN(6,5751b)oftake-off thrust, flat-rated to ISA+22°C, and 15% growth within the nacelle's external lines. As a risk-sharing partner, P&WC is respon sible for the complete powerplant, including the Nordam-supplied nacelle and thrust reverser. The Canadian company has guaranteed a 6,000h TBO at entry into service, to be demon strated by a "lead-the-fleet" engine at P&WC. The digitally controlled PW308A is scaled up from the PW305B powering the Hawker 1000, with an 840mm-diameter, wide-chord fan and an increased-flow compressor. Ther modynamic thrust-to-weight ratio is increased by 8% over that of the PW305B, with specific fuel-consumption improved by 7%. Honeywell is the risk-sharing avionics integrator, supplying its latest Primus Epic system and integrating equipment supplied by AlliedSignal and other vendors before delivery to Raytheon. "We'll simply plug a panel in," says Norris. The Primus Epic avionics suite includes five large-format (200x250mm) liquid-crystal displays — two primary-flight and two multi-function dis plays and an engine-indication and crew- alerting system. Compared with the Honeywell SPZ-8000 avionics in the Hawker 1000, the Horizon system is at least 45kg lighter, has 2 3 fewer line-replaceable units and has at least twice the reliability. Avionics are located in the "benign environment" of a rack in the cabin, Raytheon says. Growth plans include display formats such as maps, charts and ground-based weather. Flight controls are manual, with a powered rudder and electrically signalled spoilers and flaps. The electrical system uses variable- frequency generators on the engines and flight- rated auxiliary power-unit (mounted in the tail- cone). The redundancy required for extended- range twinjet operations was a consideration in systems design, says Bruner. CABIN LAYOUT A typical cabin layout would include eight seats and an aft toilet widi in-flight access to the 3.1 m3 baggage bay through a secondary pressure- bulkhead. Compared with the Hawker 1000, the forward entry door has been enlarged and the baggage-bay external access improved. Digitally controlled pressurisation provides provides a 6,000ft cabin altitude at the 45,000ft ceiling. Direct climb to 41,000ft is the design objective, Raytheon says. The Hawker Horizon "...will go fast, go a long way and carry a lot of stuff', says Bruner. "This aircraft will fly halfway across the USA with a full 3,5001b payload." This "excellent" balance of speed, range and payload was one of the Hawker characteristics that Raytheon sought to recreate in the Horizon. "We have taken the best of British design and combined it with the US way of making aircraft, and come up with something truly unique," Norris believes. • FLIGHT © Reed Business Publishing 1996 The Hawker Horizon is an all-new design FLIGHT INTERNATIONAL 20 - 26 November 1996 55
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