Editing Lockheed L-1011 TriStar (section)

====Flying surfaces====
Lockheed developed some aerodynamic improvements for the TriStar 500 which included a modified wing-to-body fairing, a fillet below the central intake, extended wingtips, and "active ailerons" or active control system (ACS). The new fairing reduced drag, while the fillet reduced noise in the rear cabin. The wingtip extensions increased aspect ratio, thus reducing induced drag, but resulted in increased bending. The ACS developed to solve this, provided gust alleviation, improving ride during flight, reduced fuel burn, and increased fatigue life.

Earlier TriStar 500s were delivered with the standard wing; these were later retrofitted with ailerons and extended wingtips. Pan Am was the first customer to order the -500 with the extended wingtips and active ailerons. Aircraft serial number 1176, the first for Pan Am, was the first TriStar 500 to be fitted with them as standard.