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Aluminium-Lithium Alloys - Application on Helicopters
G. Donzelli, G. Crespi, C. Zanotti, A.F. Smith
Because rotorcraft are usually more weight-critical than their fixed wing counterparts, the lower density of aluminium-lithium alloys is particularly attractive for helicopter structural applications and will therefore be used extensively on the Anglo-Italian EH101 helicopter. In order to minimise costs, the necessary qualification and certificate procedures have been shared by the two collaborative partners in this project, with AGUSTA having taken responsibility for evaluating sheet material whilst WESTLAND have dealt with extrusions and forgings. Corresponding plate will not be used due to unacceptably low fly : buy ratios. The approach toward aluminium-lithium sheet has been to develop both "damage tolerant" and "medium strength" categories from a single starting temper by alternative artificial ageing treatments, with target property levels being those of the "conventional" aluminium alloys being replaced. Vith regard to forgings, the critical dependence of properties upon processing parameters and microstructure has been recognised and has entailed extensive testing of each forging configuration to be used. All sheet, extrusions and die forgings for construction of the main cabin frame are made from the 8090 "ingot metallurgy" aluminium-lithium alloy. In addition, a small number of components and specifically those comprising the undercarriage assembly, will be made from the "powder metallurgy" aluminium-lithium Al-905XL alloy. Vhilst investigations and property characterisation is continuing, the extensive studies carried out so far have generated sufficient data and confidence to enable construction of the EH101 to proceed using these new alloys. This paper details some of the work carried so far and the generated data has facilitated preparation of joint AGUSTA-WESTLAND material specifications, necessitated due to the current lack of National and International documents. There is no doubt that the EH101 will emerge as the first aluminium-lithium helicopter.
17th European Rotorcraft Forum 1991, Berlin
21,0 x 29,7 cm, 15 Seiten
DGLR-Bericht, 1991, 1991-08, 17th European Rotorcraft Forum Proceedings; 1991; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn
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Stichworte zum Inhalt:
helicopters, eh 101 helicopter, aircraft construction materials, aluminum-lithium alloys
Dieses Dokument ist Teil einer übergeordneten Publikation:
17th European Rotorcraft Forum Proceedings