CENTER-OF-GRAVITY VARIATION INFLUENCE ON FLIGHT RANGE OF TRANSPORT CATEGORY AIRPLANE

Abstract

The method of transport category airplane flight range estimation taking into account its center-of-gravity position variation in the process of fuel utilization at cruising flight mode is presented. The method structure includes the following models:

– Interinfluence of main parameters on each other in the process of fuel utilization;

– CG position influence on required thrust values in level flight;

– Estimation of CG position influence on lift-to-drag ratio in cruise mode;

– Quantitative estimation of center-of-gravity position variation influence on airplane flight range.

Simulation of the main parameters is based on authoring researches, which established interinfluence among geometrical and aerodynamic parameters of wing, parameters of horizontal tail and center-of-gravity position variation caused by fuel utilization in cruise flight. Such model allows estimating of airplane center-of-gravity influence their values and their relative position.

Aerodynamic parameters variation caused by center-of-gravity shift resulted in necessity to take this influence into account, for required engine thrust variation; that is shown in the publication in the form of dependences P(M, m, x_CG) allowing to take into account the required thrust variation and their influence to range variation.

On the base of interinfluence model and taking into account required thrust variation (when center-of-gravity position shifts), lift-to-drag variation has been obtained and analyzed in the form of dependences K, KM(M, m, x_CG) for middle airplane of transport category.

Expression for estimation of airplane flight range under variable values of its mass and center-of-gravity position is obtained on the base of these models; that allows flight range increasing by means of center-of-gravity position dedicated shift.

On the example of mid-range transport airplane, it is shown, that at Mach number M = 0.7 and center-of-gravity shift back from x_CG = 0.20 to x_CG = 0.35, the increase of lift-to-drag ratio makes ΔK = 0.43.

On the base of presented models, it is shown, that airplane center-of-gravity position influences lift-to-drag ratio, fuel efficiency and as a result on flight range at cruising flight mode.

Application of aft center-of-gravity position allows decreasing of engine required thrust (decreasing fuel consumption), and increasing of lift-to-drag ratio and airplane flight range.