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FlightGlobal.com [ Search the site ] [ Search ] * Home * Premium * Archive * Video * Images * Forum * Blogs * Jobs * Shop * RSS * Email Newsletters You are in: HomeAviation History19861986 - 3547.PDF Previous page Next page IFrame IFrame Automatic tape-laying machinery ensure that close manufacturing toler ances are met. Periodic teardown and test of production items should create enough confidence to minimise the NDT require ment in the future. At present the majority of Westland composite production comes from manu facture of blades at 40 per month for the latest Sea King, and for retrofit. The blades can be made to match the weight and weight distribution of the previous blades, but have four times the guaranteed life. The expected life is unlimited, but the new limit matches that set for the airframe. Looking ahead, a composite pre- production blade for the Lynx Mk 7 has been built, and the Lynx 3 (probably to be in production during 1989) is projected to have a 160kt airspeed, again using composite blades. The W.30-300 has already shown in tests that vibration is much lower with composite blades, even without the head spring absorber of the -100 (which weighs 1201b). This should be a 150kt machine. The EH.101 will use a blade profile that is very little different from a scalded up Lynx blade (61ft diameter instead of 42ft). The inboard aerofoil section is modified, with more reflex camber to balance the pitching moment of the outer section (a greater fuselage upwash over the nose interacts with the rotor disc airflow). Its operating speed will also be a nominal 150kt. Westland has also put in an unsolicited proposal to Sikorsky for Black Hawk development. An example was fitted with Berp blades in late October, and it is hoped to demonstrate this early next year. The company hopes to meet the US Army requirement for an auto-manufactured blade that is much cheaper than its metal equivalent. After the speed record, work goes on with G-LYNX as part of the original Blade moulds have to be manufactured to extremely fine tolerances. Pre-preg composite material is stored at -18DEGC to maximise shelf life, and is used in strict date order, under computerised stock control, to ensure consistent quality contract from the UK Ministry of Defence. Instrumentation readings from the run-ups and the record were checked, "stock" was taken of damage in stress- critical areas, and life-expectancy adjust ments made to this particular aircraft. One blade is fitted with transducers at the leading and trailing edges and tips. It is being used to amass data in a pressure- plot survey both for the company and the RAE. No specific problem is being pursued, but a greater understanding is sought of how the rotor is achieving its benefits, particularly in fact-finding on local stall points. In the longer term, the use of fibreoptics for strain sensing in composite components is receiving considerable attention. An important area of helicopter refine ment that is proving difficult is the reduction of rotorhead and hub drag. For example, the aerodynamic drag of the EH.101 head is reckoned to consume 50 h.p. in the hover, and rotorheads in general may contribute between one quarter to one third of the high-speed drag of a helicopter. Mast drag alone is signifi cant, as the drag of a rotating cylinder is an order or two greater than that of an airfoil of equivalent surface. The problem is that fairings conflict with design requirements and easy maintenance. The refinement of rotor blades and tips goes on. The RAE director of future studies is looking at what might be termed "Berp IV" work (Berp I was composite manufacture, II was tip design, and III was building the tip). The direction of this research could be aeroelastic tailoring, to minimise further the interaction between blades and fuselage. The RAE is also active in the ageing of composites-co-ordinating continuing work on the relationship between artificial and natural ageing. Sea King composite blades have been ageing naturally in the Australian desert for three years, so far. Both in the outback and in the computer, composites are truly being tried in the furnace, for their vital role in helicopter rotor construction. D FLIGHT INTERNATIONAL, 27 December 1986 27 [IMG] Sign up to * Flight Digital Magazine * Flight Print Magazine * Airline Business Magazine * E-newsletters * RSS * Events Click to find out more * Disclaimer * Terms & Conditions * Privacy Policy (c) Reed Business Information 2008 * Subscriptions * Flight Newsletter * About Us * Media Centre * Contact us * Site Map * RBI media jobs UK