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Aviation History
1988
1988 - 3597.PDF
*,**%• ^i Bulges above the fuselage of the Antonov An-225 Mriya are faired-in hardpoints for piggyback payloads, possibly including the Soviet space shuttle Buran Antonov's 'Dream' is world's largest by Alan Postlethwaite The Soviet Union expects to fly the world's largest aircraft later this month, following the roll out of the Antonov An-225 Mriya (Dream) late last month. At 600 tonnes, the An-225 is some 50 per cent heavier than Antonov's An-124 Ruslan, the heaviest aircraft yet flown, and dwarfs the USA's 379-tonne Lockheed C-5 Galaxy. The Soviets claim that the aircraft can carry a 250-tonne payload 4,500km at 750km/hr (551,0001b 2,500 n.m. at 415kt). According to the Soviet Union, the An-225 is designed to carry heavy or bulky indus trial plant. Payloads .too large to go inside will be carried piggyback on shoulder- mounted hardpoints. These include elements of the Energia heavylift launch vehicle and possibly the Soviet space shuttle Buran. Dimensions have not been released, except that the fuse lage has been stretched 8m over that of the An-124, suggesting that the An-225 has a 44m-long cargo hold with a 6-4m by 4-4m cross-section. Development has taken more than three years, the Soviets say. The aircraft is clearly based on the An-124, but with extensive changes. In addition to the 8m stretch, the single fin has been replaced by a pair of vertical surfaces at the tips of an increased-span tailplane (with marked dihedral), clearing the way for large or long payloads to be carried above the fuselage. The most significant change is to the wing, which carries six underslung engines in place of Ruslan's four. Antonov appears to have attached the An-124 wing/engine assemblies to a new centre section (with little or no dihedral) carrying the two new engines. The Mriya's engines are the same 230kN (53,8001b)-thrust Lotarev D-18T turbofans used on the An-124, says Alexandre Pavlov, deputy general director of Aviaexporf, the Soviet export agency. Production of the An-225 alongside that of the An-124 is planned, says Pavlov, but he does not reveal how many will be built. By early this year just 20 An-124s had been completed, all for Aeroflot, since the type first flew in 1982. Mriya's sheer size has surprised Western experts, who believe the aircraft must pose severe structural design prob lems in overcoming aero- elasticity effects associated with the increased wingspan. The claimed payload of 225 tonnes (Aviaexport) to 250 tonnes (Isvestia) improves on the already high ratio of payload weight to empty weight of the An-124, suggesting that Antonov has used lightweight, high-strength composites to make the enlarged wing stiff enough. The An-225 is likely to make extensive use of systems from the An-124, including the latter's quadruplex fly-by-wire flight control system. An increase in the number of main landing gear wheels from Ruslan's 20 is likely, to avoid runway damage at Mriya's 50 per cent higher gross weight. Whether the An-225 will be able to use the same 3,000m-long runways as the smaller An-124 is not clear. Certainly the increased wing- span (significantly up on Ruslan's 73-3m) will make ground manoeuvring more diffi cult, particularly when a piggyback payload is carried. Previous statements have suggested that Mriya can carry piggyback payloads of up to 40 tonnes. The existence of the new Antonov transport was first hinted at earlier this year, when the Soviet Union referred to "a specially modified aircraft" which would be used to trans port components of the Energia heavylift booster weighing up to 40 tonnes and measuring up to 8m in diameter. Soviet shuttle detailed by Tim Furniss in Baikonur The Soviet space Shuttle Buran is almost identical in size to its US counterpart, according to statements by its designer, Academician V. Glushko. Buran is 36-4m long and 16 • 5m high, with a wingspan of 24m. The US Space Shuttle is 37m long and 17 • 3m high, with a 23-8m wingspan. Buran's payload bay is 4 • 7m in diameter and 18m long, identical to that of the US Shuttle. The Soviet shuttle has a launch weight, with payload, of 105 tonnes, marginally lighter than its US counterpart. Buran's maximum payload is slightly higher than that of the US Shuttle, however, at 30 tonnes. Designed to carry 29 • 5 tonnes, the US Shuttle payload is currently restricted to less than 26 tonnes. The difference is accounted for by Buran's lack of main engines, which are instead mounted on Energia's core stage. Without payload, Buran weighs 75 tonnes at lift-off and 62 tonnes on landing, the 13-tonne difference being accounted for by consumables including orbital-manoeuvring propellants and attitude-control gases. Buran can safely land carrying a payload of 20 tonnes. Thermal protection accounts for 7 tonnes of Buran's gross weight and comprises some 39,000 tiles made from extra- fine quartz fibre, flexible organic fibres, and carbonfibre, the latter used to protect the nose and leading edges frorri re entry temperatures of 1,6066C Buran is the first, and so far only, Soviet shuttle to be built, although a second may be being prepared for flight in the shuttle assembly building at Baikonur cosmodrome. This 37m-tall, 72,000m2 building is six times the size of Nasa's Shuttle Orbiter processing facility. The nearby 60m-high 57,600m2 Energia-Buran integration building is almost twice as large as Nasa's vertical assembly building. Several shuttles will be built, the Soviets say, but only two to four shuttle missions a year will be flown. Each shuttle is designed to last 100 missions. Unmanned shuttle misssions will have a maximum endur ance of 30 days, the Soviets reveal, but will not exceed seven days until Buran is declared operational. For manned missions, which could begin in 1990 with the third flight, the Soviet shuttle will be equipped with a remote manipulator arm. FLIGHT INTERNATIONAL, 17 December 1988 11
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