The An-124 is significantly more advanced in its technology and has a much better performance than anyone expected. The An-124 is clearly a replacement for the An-22 Antea, itself the largest aircraft in the world at the time of its appearance. The An-124 is due to enter service early next year. The An-124’s capability in this area appears significantly superior to that of the C-5 – "an older design". The An-124 appears to be able to haul 25,000 lb (11,000 kg) more than the US aircraft over the same distance, or to carry a similar payload 500 nmi (900 km) farther than the C-5. The Soviet type can carry a 25 per cent greater maximum payload and has a significantly larger cabin cross-section. Moreover, all this has been achieved within a maximum take-off weight.
One of the single most important features of the design is an advanced wing section, with the flat top and undercut trailing edge. Such a section makes it possible to design a wing of greater span for a given weight, while providing more internal volume for fuel.
Important weight reductions also result from the use of artificial stability, provided by a four-channel analogue fly-by-wire system. There is a mechanical back-up in the pitch axis, but this is restricted in authority through the use of very high stick forces. The result is that the An-124 can be effectively controlled with a relatively small, low-set, fixed-incidence tailplane, further reducing structural weight, drag and system complexity.
More weight is saved1 by using 12,125 lb (5,500 kg) of composite material. While this is not used for the primary structure or the control surfaces, it is used for much of the rest of the aircraft.
The attention to weight is also apparent in the cabin. Both weight and fuel consumption are cut by the simple but unusual expedient of accepting2 a lower pressure differential in the main hold (0,25 bar/3.6 lb/in2) than in the upper cabins. This reduces fuel burn.
In detail, the An-124 is clean and straight-forward. The wing is with full-span slats and simple slotted Fowler flaps in three spanwise sections on each side. There is a small slot built into the outer end of the two inboard flap sections on each side to smooth the flow between them. The wing is completely free from vortex generators and fences, a particularly marked contrast to previous large Soviet aircraft.
Like the C-5, the An-124 features a complex landing gear which allows operations from semi-prepared surfaces and moves the aircraft vertically for loading. The An-124 gear features twelve independent twin-wheel members: two forward-retracting nose units, and five main gears on each side. Each main gear unit swings upwards and inwards. The An-124 is designed to operate from hard but semi-prepared surfaces such as the packed-tundra runways of Siberia.
On the ground, the suspension of each main unit can be raised or lowered under central control to tilt the aircraft for loading. Loading is also facilitated3 by the quartet of 5-tonne electric cranes travelling on rails in the cabin ceiling.
Power for the An-124 is provided by four Lotarev D-18T turbofans.
The onboard data and diagnosis system. Based, on a digital computer, this is a multi-purpose device which monitors systems, detects and diagnoses failures in flight, and can be used to calculate the most efficient way to load the aircraft.
2800 знаков
Notes:
1. is saved - (зд.) сэкономлено
2. to accept - принимать, допускать
3. to facilitate – облегчать
UNIT 14
DORNIER 228
Vocabulary: power-to-weight ratio, improvement, fatigue test, to claim, to obtain, complication, push-rod, friction, to droop, centring spring, circuit, trimming, to reinforce, stall, substantial, bus, inverter, boost pump, cut-off, cross-feed switch, nozzle, steering, throttle, flat-rated, torque limit.
Exercises:
I. Read the text and answer the questions:
1. What does the text deal with?
2. What is described in detail?
3. What is considered briefly?
4. What is the key idea of the text?
