| Popis: |
In the pursuit of efficiency there is continued and developing interest in the subject of winglets and novel designs such as Blended Wing Body and Oblique Flying Wing. Winglets may exist in many modes, ranging from endplates, through folded wing tips to complex upper and lower surface partial chord devices. We have developed a design process that is directly applicable to the design of wings and winglet combinations. A set of target conditions is established. These may be, for example, minimum liftinduced drag, minimum wave drag, a known structural loading or pitching moment control. The design process is iterative and, in general, is driven towards the idealised spanwise load distribution for minimum drag. A degree of pitch control has also been demonstrated on selected configurations. The method may be used to design from “scratch” or in the corrective sense to optimise a current design for new requirements at the design point. The method has been applied to the design of several configurations of current interest, conventional A340 type wing, Blended Wing Body and Oblique Flying Wing. Winglets have been simulated by folding the outer wing through various angles. The technique has proved to be easy to use. It is enlightening as it gives, at every stage, a feel for what is happening in terms of camber development, pressure distributions and Centre of Pressure location. Favourable characteristics of the configuration can be enhanced whereas those that are not beneficial can be minimised or avoided as the design progresses. |
