Flyf15 From , joined Dec 1969, posts, RR:
Reply 2, posted (11 years 4 weeks 22 hours ago) and read 2614 times:
Winglets increase efficiency by reducing induced drag. Induced drag is created as a byproduct of lift. Horizontal stabs don't have a significant amount of lift, and are therefore not needed. The "winglets" you see on some horizontal stabilizers, such as the A300-600ST and 747 Shuttle Transport are added for additional stability.