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Aviation History
1985
1985 - 0030.PDF
eliptical section because it says that for ten seats or less this provides good volumetric efficiency. In other words, it combines good "walkabout" headroom with adequate space for passengers' elbows as well as for shoulders and heads while sitting. Cabin noise has yet to be quantified because no fully furnished aircraft are flying, but the flights between Israel and the United States demon strated that even the test airframes are adequately served by "hot" microphones and loudspeakers when cruising at between Mach 0 • 7 and 0-82. Systems At the heart of Astra's systems are the two Garrett TFE 731-3B-100G turbofans, each producing 3,6501b of thrust and equipped with hydraulically actuated Grum man thrust reversers. Higher- thrust versions of the TFE 731 were considered by Israel Aircraft Industries, but it was decided that the added weight and bulk would negate the extra thrust. This was already adequate, and more powerful engines would only increase fuel consumption. This will already account for the majority of direct operating costs, estimated at between US$500 and US$600 per flight hour. The engines provide power to drive one of Astra's two fully independent hydraulic systems, which operate at 3,0001b/in2. This primary system is operated by two constant-pressure pumps, each driven by one engine. It provides hydraulic power for the multi-disc brakes, the anti-skid system, the landing gear, nosewheel steering, ailerons, speed brakes, and lift dumpers. The backup system is powered by an electrically driven pump and supplies power to the emergency/parking brake and thrust reversers, as well as providing a duplicate supply to the ailerons. (Compressed nitro gen provides a backup source of power for emergency extension of the under carriage). Two independent fuel systems are installed in the Astra, each normally supplying fuel to one engine from a fuselage collector tank, but with provision for crossover. Fuel is carried both in the wings and in the fuselage behind the aft pressure bulkhead. A single-point pres sure refuelling system is installed, as well as gravity filler ports. The electrical system is 28V d.c, derived from two engine-driven 300A starter-generators operating in parallel to supply power to the d.c. distribution buses. Each generator is capable of supplying the major electrical loads by itself. Two l,0O0VA single-phase 115V, 400Hz inverters are installed to provide fixed- frequency a.c. power, including a 26V supply to the aircraft instruments. Two 24V nickel-cadmium batteries provide power to start the engines, and also permit operation of essential flight instruments and emergency equipment in the event of total generator failure. Dimensions Span Wing area Leading edge sweep 34* inboard/25' Height Length Cabin height (internal) Cabin length: (forward pressure bulkhead to aft pressure bulkhead) Cabin width 52 ft 8in 316-6ft2 outboard 18ft 2in 55ft 7in 67in 22ft 6in 57in Weights and capacities With extra Standard fuel tank Maximum ramp 23,6501b Maximum take-off 23,5001 Maximum landing 20,7001b Maximum zero-fuel 16,000l Basic operating 12,670lb Maximum payload 3,3301b Fuel with max payload 7,6501b Maximum fuel 8,6001 Payload with max fuel 2,3801b 12,7701b 3,2301b 7,6501b 9,2701b 1,6101b 28 A single electric actuator drives the flaps, and another the slats. Flaps and slats can be controlled by a six-position cockpit lever in addition to the automatic slat extension system which operates in response to angle of attack and airspeed. Flaps and slats are monitored elec tronically. Two freon fire extinguisher bottles in the rear fuselage are capable of firing dual shots into either engine in response to cockpit commands, follow ing signals from continuous detection elements routed through each nacelle. Engines are isolated from the pylons by firewalls, and the cowlings are lined inside with stainless steel foil. Pneumatic boots are employed for ice protection on the leading edges of the wing and tailplane. Certification Stall characteristics and performance are being defined and refined dur ing the next few months, in parallel with systems and certification flying which is now beginning. Some relevant data on electrical, hydraulic, engine, avionics, and fuel systems have been accumu lated during the company test phase, which has also opened up the flutter envelope. Some 350 parameters can be tele metered to the ground in engineering units for real time analysis. The manufacturer foresees^1 no major problems during the certifica tion process, having already "cleaned up" the wheel brakes, nosewheel steering, and minor premature flow separation over some sections of the wing leading edges. The Astra has cost US$100 million to develop, and half as much again to tool up for production. There is understandable reticence on the part of IAI to predict a break-even point. The programme appears to be going well, however, and is said to be on schedule, although the unusually strict security which surrounds the project has sometimes been misinterpreted as an indication of prob lems. The secrecy probably arises because IAI is a fully integrated operation, with the same security-conscious engineers work ing in parallel on the Kfir and Lavi fighters as well as on Astra. The advan tage of this arrangement, however, is the transfer of technology which this promotes. It has led to a small business jet capable of taking off with five passengers from a 5,000ft, ISA, sea level runway anywhere in the United States; climbing straight to a level cruise at 41,000ft; and flying to almost anywhere else in the United States at Mach 0-82. • FLIGHT International, 5 January 1985]
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