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Aviation History
1999
1999 - 1716.PDF
Jkraine is trying to vin over Western Europe with an mproved An-70 MDREW DOYLE/MUNICH PHOTOGRAPHS/MARK WAGNER CHEDULED TO APPEAR at Paris, the Antonov An-70 is competing for the European common medium transport air craft requirement, for which it is now aown as die An-7X. The German Government tasked Daimler- i hrysler Aerospace (Dasa) with conducting a t xhnical evaluation of the An-70 to see whedier it could fulfil the European Staff Requirement (ESR) for a common tactical airlifter. Dasa found it would be possible to "Westernise" the Ukrainian aircraft to meet European Staff Requirements. In reaching its cc mclusions, however, Dasa had not been able to fight test the aircraft to confirm data supplied l;/ Antonov. Dasa concedes that the amount of data available was limited, but points out that the flight test data confirmed die results of extensive windtunnel testing. In terms of payload/range capability die propfan-powered An-70, widi its 1321 maxi mum take-off weight (MTOW) and payload of 3 St, would meet the requirements, although Antonov is still working on improvements. "They are still short of dieir design goal but, widi die existing powerplant, they achieve die ESR," says Claus Frey, die Dasa evaluation team leader. The flight certification procedures being used for the An-70 correspond to European Joint Airworthiness Requirements GAR) 25 standards. Frey says the An-70 is a "convention al design" as far as stability and control is con cerned, and redundancy assures safe operation following any failure considered to have a greater than 10'probability of occurring. While a significant part of die An-70's flight envelope has yet to be explored, the risk of any required modifications to the aircraft's config uration is considered "minor". Short take-off/landing (STOL) performance was also found to be satisfactory, widi a 1,060m (3,500ft)-long runway required at a take-off weight of 112t and at ISA+15 conditions. The aircraft comfortably meets die ESR require ment of a 1,500m field length at a take-off | IPARIS99 weight of 120t, and is capable of a non-STOL landing at its maximum take-off weight of 13 21. Dasa looked at aerodynamic data derived from over 14,000h of windtunnel tests, using 2 2 models, which showed the An-70 would have a stall speed in the landing configuration of 13 2 kt (2451cm/h), against the ESR requirement of 140kt. Maximum speed, atMach 0.73, slighdy exceeds die ESR stipulation of M0.72, while die An-70's cruising speed isM0.68. Also compliant is the type's initial cruising altitude of 31,000ft (9,450m) and maximum cruising altitude of 40,000ft. "We were quite confident that the development of the aircraft with diese goals is achievable in the way that Antonov designed it so far," says Frey. Dasa also paid close attention to the aircraft's unusual contra-rotating ZMKB Progress D-2 7 propfan engines, rated at 9,700kWr (13,000shp) for take-off. The D-2 7 does not yet meet spe cific fuel consumption targets, and Dasa found die technological risk in achieving diis to be "medium". The An-10's contra-rotratingpropfans give an efficiency gain of10% over conventional turboprops //* ~%m I I • INTERNATIONAL 9 - 15 June 1999 -
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