Digital active control system for load alleviation for the Lockheed L-1011

Abstract

In the spring of 1980, a long range derivative of the L-1011 TriStar entered commercial airline service with an extended wing span and a digital Active Control System (ACS). The extended wing span improves fuel efficiency by 3 to 3½ % due to a higher wing aspect ratio and lower induced drag. The digital ACS provides load alleviation functions by symmetric motions of the outboard ailerons which relieve the loads induced by the increased wing span. This load relief minimises the amount of structural modifications required to the basic L-1011 wing to accommodate the increased wing span.