John E. Green

Aircraft Research Association

Climate change, fuel burn targets and the options and limitations facing the designer



The evidence from climate science increasingly points to reducing CO2 emission as the main priority for reducing the impact of aviation on climate.  Ambitious targets for reducing fuel burn have been declared by industry and government agencies and a number of road maps have been published to show how CO2 emissions might be brought down by 2050.  The purpose of this presentation is to test these targets against ‘the laws of physics’. ACARE has said of its targets for 2020, ‘The objectives are not achievable without important breakthroughs, both in technology and in concepts of operation - evolutions of current concepts will not be sufficient’. Although the emphasis in these words comes from ACARE, there is little at present to convince us that the air transport community – manufacturers, airlines and air travellers – have accepted them.  The presentation will review the options open to the aircraft and engine designer, the air traffic managers and the airlines as customers of the manufacturing industry.  Recent developments suggest that the need for radical measures, as envisaged by ACARE, has not yet been taken to heart and that, increasingly, the civil aviation community is looking to biofuels to come riding over the horizon, like the US Cavalry, to rescue us.


An aerodynamicist trained at Cambridge and the RAE, his primary field of research was turbulent boundary layers. His research at RAE was cut short by appointment as Head of the Subsonic/Supersonic Wind Tunnels Division, then Propulsion Division, then Noise Division, before becoming Head of Aerodynamics Department. Subsequent appointments were: Director Project Time and Cost Analysis, MOD(PE); Deputy Head of British Defence Staff, Washington; Deputy Director (Aircraft), RAE; Chief Executive of the Aircraft Research Association. He retired in 1995 and since then has worked part-time as ARA consultant Chief Scientist.  He is a Past President of the Royal Aeronautical Society and the International Council of the Aeronautical Sciences.  Since the launch of Air Travel – Greener by Design in March 2000 he has been Chairman of its Science and Technology Sub Group.