Use of maximum lift and angle of attack, a review of experience within BAe Military Aircraft

Abstract

AbstractPrior to the adoption of modern flybywire high authority flight control systems, the usable lift or angle of attack was usually dictated by the wing stall and subsequent loss of control of the aircraft.With the advent of the high authority FCS, with high levels of integrity, the designer of modern combat aircraft faces the possibility of providing good levels of aircraft control up to and well beyond the AoA at which maximum lift or loss of control would have occurred in the past. Further, the use of such control systems has allowed maximum advantage to be taken of control configured vehicle technology to enhance the performance of the aircraft within the conventional angle of attack range.This paper provides a review of the experience which has been gathered within BAe Military Aircraft, Warton, in the use and benefits of these technologies with regard to the high AoA capability and impact on maximum usable lift. Examples are drawn from the Tornado, Jaguar FBW and EAP aircraft programmes, all of which have employed flybywire control, to some degree or other, combined with varying degrees of CCV technology, leading to their adoption on the Eurofighter 2000 programme.In doing this, some of the engineering compromises which the modern aircraft designer faces in achieving the customer required levels of aircraft performance will be addressed, together with the outcome which has satisfied these purposes in the particular example considered. In particular, the power of the modern FCS places an increased reliance on the knowledge of the aerodynamics of the aircraft, around which the FCS must be designed. This raises particular challenges in the increased AoA ranges which associate with the maximum lift of these high performance configurations.The paper concludes with an indication of the developments in technology which are evolving and which will lead to further advances and increased capability combat aircraft in future years.