22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-P1.3

WINGGRID AT TRANSONIC SPEEDS: IMPACT ON PERFORMANCE, CHALLENGES TO SOLVE

H. D. La Roche
La Roche Consulting Dynaero & OneraLa Roche Consulting, Switzerland

Keywords: subsonic, transsonic transport, wing design

Based on the reported successful fullscale testing of the Winggrid device in 1997 and tests 99 idaflieg design showing a span efficieny of 2 cf. [1], [3], [4], assessments have been made exploring application of the device on different aircraft including tentative study at higher subsonic speeds. Motivation for these latter attempted studies is the fact, that further development of business and transport aircraft may benefit from winggrid technology due to its potential to improve aerodynamic performance, its potential to reduce span and its support of the classic Cayley type morphology already well established (in contrary to the Blended Wing Body Concept), cf [3]. It may be also interesting in terms of air traffic considerations due to its low energy wake. The studies made will cover aerodynamic operation of the WINGGRID and design for high subsonic speeds: If wave drag can be kept small (operation below Mach-divergence) increase of L/D for commercial type transports of 10% to 30% can be realized, equivalent at present fuel prices to 4% to 12% direct operating costs. Assessed is design and structure of a wing with winggrid including transonic behaviour. Trade-offs analysed are highly dependent on how the properties of a wing with winggrid is exploited, such as e.g.: -increased wingtip stall resistance -bigger wing volume for same total lift -smaller span with same L/D -increased payload per span -increased range -consequences of rectangular lift distribution over span

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