ASPECTS OF DESIGN, ENGINEERING AND OPERATIONAL ECONOMY OF LOW DRAG AIRCRAFT

This chapter discusses the fundamental aspects of design, engineering, and operational economy of a low-drag aircraft. The lower drag and the correspondingly increased effective lift-to-drag ratio would help to reduce the direct operating costs of laminar flow airliners and freighters operating at high-subsonic or even low-supersonic cruising Mach numbers, that is, with shock-free flow over the wings, over stage distances equal to or greater than 3000 nm. Laminar flow military transports or freighters of very long range could be designed capable of operating without refueling over stages up to 8000 nm or more, carrying payloads of the order of 12–15 percent of the takeoff weight. It is characteristic for low-drag aircraft that their wing loadings will be lower than those of corresponding conventional aircraft. Larger wing size results for a given all-up-weight, as a very small profile drag, which is not very sensitive to wing area, has to be matched by an equally low-induced drag. Thus, the resulting low-drag aircraft designed to carry a given payload over a given stage distance has not only a lower takeoff weight but also a lower wing loading than the corresponding aeroplane of conventional design. The low-drag aircraft will, therefore, have shorter takeoff and landing distances, because of lower wing loading and, on account of its smaller takeoff weight, will be capable of using more primitive airstrips. Alternatively, when constructing new airbases, less concrete will have to be poured into the ground.