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Aviation History
2003
2003 - 0446.PDF
Cover story BAE Systems' Hawk New Dem onstrator Aircraft (HNDA) is the latest in a long line to bear the Hawk name. Based on the Hawk 127 variant sold to Australia as a lead-in fighter trainer, the HNDA is a work in progress, rather than a final product. The aircraft is being used to develop and test new concepts and components. The most significant difference between the HNDA and the Royal Australian Air Force's 127 is its Adour 951 engine. The 127 has the 5,8001b-thrust (2S.4kN) Adour 871. The 6,5001b-thrust Adour 951, with full-authority digital engine control (FADEC), is under development for the South African Air Force Hawk. The HNDA is powered by a hybrid version incorporat ing the 951's FADEC, but not its single- crystal turbine blades, and with a thrust output identical to the 871's. Over its 30-year life the Hawk has under gone several changes. While the HNDA may look like the original Royal Air Force Hawk Tl, under the skin it is almost a totally new aircraft. The wing, verti cal and horizontal tail and fuselage have been strengthened to student pilots with a flight in its demon strator aircraft. During the pre-flight inspection, Paul Hopkins, chief test pilot, combat and train ing aircraft, pointed out some of the fea tures. The extended nose can house a for ward-looking infrared sensor and laser designator, as well as other mission avion ics. The wing incorporates a slight fixed leading-edge droop to improve rum perfor mance in the Mach 0.4-0.7 speed range. While the aircraft would be clean for our flight, it is capable of carrying external stores on a centreline and four underwing pylons, as well as wingtip missile rails. Fuel tanks can be carried on the centreline and two inboard wing pylons, increasing unre- fuelled range. Beneath the vertical fin is a brake parachute and box to accommodate chaff and flares. There are provisions for a radar warning receiver. Cockpit access was via an external stand, but integral boarding steps are available. The relatively wide front cockpit made strapping into the Martin Baker MklOLH zero-zero ejection seat relatively easily. Front cockpit layout mimics that of the RAAF's Boeing F/A-18s. The forward instru ment panel is dominated by three 130 x 130mm (5 x 5in) colour liquid-crystal improve fatigue life. Engine thrust has been increased from a baseline 5,2001b, while time between over hauls has improved from l,200h to 4,000h. The cockpit changes are the most strik ing. Aside from the locations of the throttle and stick, there is little else in common between the earliest and latest Hawks. The HNDA has a head-up display (HUD) and three multifunction displays (MFDs), quite a change from the original's analogue gauges. BAE is proposing a 128 version of the Hawk for the advanced jet trainer compo nent of the Royal Air Force's Military Flight Training System (MFTS) programme, and gave Flight International the opportunity to sample what may lie in store for future MFDs. The dual- combiner HUD has a total field of view of 25Q. Below the HUD is a data-entry panel, similar to the upfront controller found in later model Lockheed Martin F-16s. Secondary flight instruments are posi tioned between the centre MFD and the data-entry panel. As is the case with the F-16 and F/A-18, the primary instrument flight display is the HUD. Side consoles contain numerous switches for systems operation. Cockpit lighting is night-vision compatible, with goggle storage space pro vided on the rear of the right console. Dual mission computers and avionics components are integrated via a 1553B databus. The 128 will incorporate an open- systems architecture to facilitate upgrades, BAE says. The rear cockpit, normally the Cockpit changes are the most striking. Aside from the locations of the throttle and stick, there is little else in common between the earliest and latest Hawks instructor's station, closely duplicates the front, with the capability to override essen tial controls. The rear seat is notably higher than the front seat, giving the instructor a direct view forward. While there is no HUD in the rear cockpit, a high-mounted centre MFD acts as a repeater. Field of view from both seats is excellent. After cockpit safety checks were com pleted, the jet fuel starter was initiated. This acts like an auxiliary power unit, providing power for systems and bleed air for engine start, making the HNDA fairly self-suffi cient. The combined inertial navigation/ global positioning system was initialised using current GPS position. Full alignment to 1.5km (0.8nm) accuracy took 3.9min. Pushing the engine start button caused the onboard oxygen generating system to drop off line as bleed air was routed for starter engagement. The throttle was imme diately placed to "idle", with the FADEC controlling the start. Light off occurred at 24% NH (high-pressure spool speed), with idle RPM of 56% NH being reached in 36s. After pre-taxi checks, air traffic control cleared us to taxi. Unlike first-generation Hawks, the HNDA has nosewheel steering. Hydraulically actuated, this allowed easy tracking of the taxiway centreline en route to runway 26. Flaps were set to half in preparation for take-off. Acceleration on take-off roll was brisk. The rotation speed of 120kt (220km/h) was reached 18s after brake release. Control forces were light and about half aft stick travel was required to attain a 10s nose-up attitude. The 6,100kg (13,4401b) aircraft (with 1,225kg of fuel) lifted off after about a 600m (2,000ft) ground roll. Gear and flap retraction caused no discernible stick-force changes as we accelerated to a climb speed of 350kt. The initial climb to 10,000ft over the Irish Sea took about 2min, for an average climb rate of 5,000ft/min (25m/s). Once level, power was set to 84% NH to simulate a medium-altitude transit to a working area. At 330kt indicated airspeed and M0.59, fuel flow was 408kg/h (9001b/h). Slowing down to 300kt and M0.55 reduced fuel flow to 354kg/h. Designed to enhance manoeuvrability, the combat flap system is armed by a push button on the throttle. When armed, the wing flaps extend to the quarter, or 12.5Q, position below 350kt. At 330kt and maxi mum power, without the combat flaps extended, the HNDA was able to sustain around Z.Sg. With the flaps armed, the sus tained # rose to about 4.5, a marked increase in manoeuvrability. Stick forces in the pitch axis were light, increasing directly as a func tion of g. With a full-up Adour 951, sus tained g capability will no doubt increase. A series of half-deflection aileron rolls at CONTINUED ON P30 www.fliqhtinternational.conn FLIGHT INTERNATIONAL 25 FEBRUARY - 3 MARCH 2003 27
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