The Fanblade

Rolls-Royce engineer Alan Newby told the Royal Aeronautical Society’s annual conference last week that the company thought that the ACARE targets for emissions were achievable, and outlined a range of EU-backed projects in which it was involved under ACARE, such as CleanSky. The 2008 Addendum to the ACARE Strategic Research Agenda (SRA2) places more emphasis on environmental performance of aircraft, and the development of alternative fuels. The targets set when the SRA1 was first launched in 2001 were 80% NOx reduction, and 50% reductions for noise and CO2, by 2020. Rolls is taking a pick-and-mix approach to readying technologies, so it can pull together those that the market wants when it wants them, said Newby. This includes the development of a so-called ‘Game Changer’ design, with a 50:1 bypass ratio, the ‘open rotor’ propfan. Rolls believes that is has solved noise issues which were originally seen as a barrier to a realistic application, by careful design and placement of blades. Various other speakers at the conference gave a fascinating insight into how technologies are being considered – from ACARE’s ‘Out of the Box’ program, which brainstormed ideas such as launcher rails and floating runways to see if they might just work one day, to a description of the highly successful Omega programme from Professor Ian Poll of Cranfield University, who has also been instrumental in the Greener by Design initiative. Both Omega and GbD aim to communicate facts about aviation and the environment, to inform policy-makers (among others) so they can make sound decisions. Poll pointed out that aircraft currently fly higher than that requried to achieve minimum environmental impact, but that this is because wings are over-sized to meet airfield performance (the constraint being airfields sized predominantly in wartime). Smaller wings and longer runways could allow an optimum 25,000ft cruising altitude, with the added benefit that contrails would not be formed. The effect of contrails is hard to quantify but the net effect is negative, so the fewer there are the better. Poll stressed the need for rigorous academic treatment and extolled the virtues of not allowing commercial interest to hijack the debate. Proceedings will be available soon from the Royal Aeronautical Society conference office.