Depuis qq temps je cherchais, des signes de vie côté "Fan Composites" chez RR !
Normal, il va bien falloir qu'ils y passent un jour ... RB282, 285, Open Rotors, T XWB, peut être !
De vastes programmes !
En attendant, RR reste sur ses titane wide chords, conservateurs, mais de plus en plus difficiles à modeler en super swept !
Bon, les solutions viendront de joint-ventures développés avec GKN, et qq crédits de recherche British !
C'est juste en train de démarrer, donc, pas trop en avance non plus, mais ça viendra, côté GKN, il y a du répondant !
---------Un article intéressant à lire jusqu'au bout sur RR et surtout GKN !Extrait de Aero-Mag -----------
Dr Neil Calder
* Date Published:
According to Dr Neil Calder, Rolls-Royce is right to be very wary of introducing composites into fan blades and one could forgive them for taking a conservative approach to designing them in.
A look at industrial history will tell us of the RB211-22B high bypass turbofan engine, the development of which in 1970 very nearly bankrupted both Rolls-Royce and Lockheed, its launch customer for the engine on the L1011 TriStar. Instead, it drove Rolls-Royce down the road of developing the technology for titanium wide chord fan blades - a major feature of its Trent series of engines and which has subsequently put the company in such a good position with the F-35 lift fan.
The high stiffness carbon fibre material used in this early attempt at wide chord blades was Hyfil, developed within the Royal Aeronautical Establishment at Farnborough in the late 1960s and which turned out to have a fatal susceptibility to high speed chickens. The Achilles heel of high strength composites was, and still is, this damage tolerance and its variability accumulated through a sequence of complex manufacturing process steps.
The choice of partner in its newest joint venture into composite fan blade production was very critical to Rolls-Royce and this is where the GKN Aerospace approach to technology, as well as its pool of capability in composites engineering were deciding factors. Engines currently account for about a third of GKN’s aerospace business, but the company intends to increase this to around 50:50 with aerostructures.
In tracking GKN’s technology growth, it’s clear that benefits have accrued from the acquisition of the Airbus Filton manufacturing operation in 2008, but also its strong focus on internal capability development as a route to differentiation and becoming the partner of choice for primes on new and evolving programmes. It was no accident therefore that it was with GKN that Rolls-Royce formed a joint venture to develop composite fan blade technology two years ago.
Funding was announced in February this year for the Environmental Lightweight Fan (ELF) project, with £14.8 million of investment split 50:50 by the Rolls-Royce/GKN joint venture and the South East England Development Agency. Technical details of the developments here have been kept under wraps, but it’s clear that the investment in technology is rooted in a sound commercial basis. GKN figures give an eventual predicted annual revenue stream of some £100 million in this area.
The GE90 and GEnX composite fan blades achieve their required performance by the lamination of hundreds of layers of pre-impregnated fibres laid down individually by hand. The intention of Rolls-Royce and GKN appears to leapfrog this manually-intensive production method by developing much more automated processes capable of higher production rates and greater manufacturing consistency, and GKN’s capability in automated fibre placement is part of this portfolio of technologies. The task is in the stage of prototype production development, so it will be a couple of years before we see the outcome of this in blade development and a move to a more mature production capability.
There is a production rate dependency that runs through both the engineering and financial numbers. GKN is looking at fan blades for a range of aero engine products and some processes are going to be more suitable for some cases than others. The final mix of process steps has yet to be decided but they are already extrapolating this capability into open rotors, the un-ducted fans for which the proof of concept work was done with flying testbeds in the 1990s and which is still on the horizon for future high efficiency single aisle products.
The last words must go to GKN Aerospace CEO, Marcus Bryson: “There is a heck of a lot going on in technology.” This is just as well, as he also predicts “the next generation single aisle programme will create the mother of all fights for workshare.”
Bonne lecture !