Effect of Enlarging the Aircraft Vertical Tail on State Variables of Stability Response during Dynamic Coupling

Abstract

 In this paper the variables of high performance aircraft including the modification of vertical tail during the roll inertia cross coupling phenomenon is presented. To demonstrate the effects of the enlarging the area of vertical tail on stability of aircraft, the longitudinal-lateral equations of aircraft motion at steady roll rate are solved. The results indicate that damping of the modified system is increased and the longitudinal-lateral state variables response of the aircraft is improved. The increase in the area of the vertical fin is a necessary feature in the development of the aircraft to improve stability during roll and decrease the possibility of cross coupling occurrence. Also the results indicated that the critical value of roll rate in case 1,at Mach no.=0.6, takes the range of  ,while the values of critical roll rates in case 2,3 and 4 are  ,  ,  ,Respectively.  The numerical results shows 19% , 15.5% , and 15%  gain in rolling margin for cases 2, 3, and 4 respectively, when compared with original (case 1) .