Stability and Control Characteristics Analysis and Flight Quality Assessment of One Stealth Blended Wing Body Aircraft

The development of aviation technology focuses on the continuous emergence of the new layout of the form of aircraft. Each new layout creates leap in aircraft performance, even great changes in flight quality. Compared to a conventional long range civil transport support aircraft, the stability and control characteristics of one stealth blended wing body aircraft designed with V-shaped tail and strake are significantly different in the aspects of longitudinal stability, transverse heading stability, aileron control effect, rudder control effect. In this paper firstly the general layout design features and aerodynamics properties of one stealth blended wing body aircraft designed with V-shaped tail and strake are introduced and analyzed. In order to guarantee the safety of real flight test and the following optimized flight control system design, taking the scaled flight demonstrator LingQue-B of one stealth blended wing body aircraft designed with V-shaped tail and strake as research object, longitudinal stability and transverse heading stability and control characteristics are analyzed based on the small perturbation theory of aircraft flight dynamics. According to China national military flight quality standards of manned fixed-wing aircraft, the flight quality assessment of scaled flight demonstrator LingQue-B for one stealth blended wing body aircraft designed with V-shaped tail and strake is conducted and analyzed. The flight quality assessment consists of flight mode analysis of longitudinal short period mode and Phugoid mode as well as transverse heading flight mode, which include transverse heading mode and Dutch rolling mode and spiral mode. It can be concluded from the stability and control characteristics analysis results that the longitudinal static stability varies with the angle of attack variations greatly, and the transverse heading static stability is comparable to that of one civil transport aircraft designed with a conventional layout. Through flight quality assessment, the analysis results illustrate that at the left border of flight envelope the longitudinal short period mode becomes unstable, which is consistent with the rapid pitch oscillation phenomena that occurred during virtual flight test of the scaled flight demonstrator LingQue-B in wind tunnel. And at the right border of flight envelope the Dutch rolling mode appears and presents level 2 flight quality. Against the longitudinal short period mode unstable problems during virtual flight test, longitudinal stability augmentation control design as stability improvement measure based on flight quality assessment and analysis is proposed and validated by software simulation. The innovation of this paper lies in the research method combination of virtual flight experiments in wind tunnel and aircraft flight dynamics modelling to analyze stability and control characteristics and assess flight quality of one stealth blended wing body aircraft before the real flight test. Therefore, it not only avoids the risks and unknown factors caused by the real flight test, which is developed for stability and control characteristics analysis and flight quality assessment as well as optimized control system design validation, but also saves a lot of considerable economic costs.