Process and system for determining the longitudinal position of the center of gravity of an aircraft provided with an adjustable horizontal stabilizer

A system for controlling the longitudinal position X.sub.G of the center of gravity G of an aircraft in flight, said aircraft being provided with an adjustable horizontal stabilizer which is deflectable and to which is articulated an elevator, and being provided with fuel tanks, said aircraft having a determined focus F with a longitudinal position X.sub.F, speed of engine, and Mach number, said system comprising:

• means for transferring fuel from one tank of the aircraft to another;
• and
• a device for determining the longitudinal position of the center of gravity of the aircraft, said device including:
• angular position sensing means associated with said adjustable horizontal stabilizer for measuring the deflection thereof and delivering said deflection information;
• first means for delivering information representative of the speed of the engine of the aircraft;
• second means for delivering information representative of the Mach number;
• third means for delivering information representative of the coefficient of lift of the aircraft;
• first memory means in which is stored a first function of the speed of the engine of the aircraft and the Mach number, said first function being representative of the value of the deflection of said adjustable horizontal stabilizer, in the case where the center of gravity G lies at the focus F of said aircraft, said first memory means receiving the information delivered by said first and second information deliverying means and delivering at the output of the first memory means the corresponding values of said first function;
• second memory means in which is stored a second function of the coefficient of lift of said aircraft and said Mach number, said second function being representative of a deviation of deflection of said horizontal stabilizer for a deviation of 1 percent from the position of the center of gravity, that is the deviation of deflection for which X.sub.g X.sub.F =1 percent, said second memory means receiving the information delivered by said second and third information delivering means and delivering at the output of the memory means the corresponding values of said second function;
• and
• computing means based on the position X.sub.F of the focus F of the aircraft in addition to the information delivered by the first and second memory means as well as that delivered by said angular position sensing means, and, at a point of flight for which the aircraft is in equilibrium with its elevator in aerodynamic extension of said adjustable horizontal stabilizer, said computing means generating a center of gravity signal representing the longitudinal position X.sub.G of the aircraft center of gravity, said signal being delivered to said transfer means in order to control the longitudinal position of the center of gravity of the aircraft, acting on the distribution of fuel among said fuel tanks.