FUTURE LARGE AIRCRAFT DESIGN - THE DELTA WITH SUCTION

Since the 1970s, large passenger aircraft design has evolved by modest , but commercially significant, incremental change following the under wing pod concept pioneered by the Boeing 707. In the 21st century, the market is likely to require greater passenger capacity to deal with a ir-side congestion and higher performance and operational efficiency t o justify investment and conserve finite fossil fuel resources. Public opinion will require far greater emphasis on control of noise and eng ine exhaust pollution. There is likely to be much increased emphasis o n pollution in the upper-atmosphere and its environmental impact. In s uch a situation, it is questionable whether the evolutionary design ro ute can produce the necessary advances and this must stimulate the sea rch for radical design alternatives. A revolutionary approach, involvi ng the delta planform combined with wing laminar Bow control and its i mpact on overall design, is given a preliminary study in this paper. T his has been carried out by assuming that major improvements in drag c an be obtained by extensive laminarisation. Using non-dimensional meth ods, the resulting broad interactive impacts on airframe and engine de sign and performance are derived. The effect of assuming varying quant ities of low-energy air sucked from the foot of the boundary layer is studied and suction-system performance examined. In addition to the la rge potential improvements in range, a strong relationship between low er drag, lower cruising altitude and lower cruise engine size is ident ified. In the study, several factors emerge which may combine to drive large aircraft design towards low aspect ratio and the integrated del ta wing planform. This paper is intended asa stimulus and a basis for further study and research.