Weight prediction of flight control subsystem

Sammanfattning

A common dilemma in aircraft design is the importance of knowing weight characteristics at early design stages, since sizing of many important components is dependent on these. Yet precise weight data cannot be determined until the aircraft and its subsystems have been designed in detail. Therefore the field of weight prediction was developed to provide satisfactory predictions of final weights in the early design phases. This project concerns the development of an early weight prediction method for the Flight Control Subsystem. Previous methods in literature consist of rather simple empirical equations that only considered one or a few input parameters. A more robust prediction method should be possible if more design parameters are taken into account. The method implemented is constructed using a “bottom up” approach where the masses of major components in the flight controlsystem are estimated and summed to form a mass estimate for the whole system. The method can account for systems using hydraulic, electrohydrostatic and electromechanical actuators, or any mix of the three. It allows for any combination of nine types of control surfaces of the primary and secondary control system, and also provides estimates for required control forces and moments, FCS power requirement, moments of inertia on the airframe and other useful information on the system. The method is validated on three fighter aircraft, the Saab Gripen, the Boeing F/A-18A and the McDonnell Douglas F-15C. From this limited validation the method produced more accurate results than previous ones.