Stability characteristics and airworthiness requirements of blended wing body aircraft with podded engines

Blended-Wing-Body (BWB) aircraft have a relatively short fuselage and no horizontal tail, and they usually adopt podded engines and a V tail instead of a vertical tail. Generally, BWB aircraft have decreased longitudinal and directional static stability and damping. In this paper, the three-axis static and dynamic stability characteristics of an example BWB aircraft with podded engines are studied. According to the differences in flight characteristics of BWB aircraft and conventional aircraft, the different airworthiness requirements for BWB aircraft are analyzed: first, based on current airworthiness regulations and transport aircraft flying quality specification, the relaxation requirement of longitudinal static stability for BWB aircraft is studied; second, the influences of podded engines on longitudinal trim, attitude and trajectory responses and maximum directional control power requirement of BWB aircraft are analyzed; third, the changes in the proportional relationships between the takeoff characteristic speeds of the example BWB aircraft are analyzed. In view of these variations in directional control power requirement and relationships between takeoff characteristic speeds, new recommendations for airworthiness evaluation are proposed for BWB aircraft. The conclusions of this paper are helpful references for configuration design, flight control law design and airworthiness evaluation of BWB aircraft.