Figure 13. Tail control effectiveness for tent posture for tail angles of –30 (large down triangle), –15 (down triangle), 0 (square), +15 (up triangle), and +30 (large up triangle).

With, A & C, and without, B & D, leg or tail feathers. At low angle of attack, tail up produces a nose up moment relative to zero tail angle, while tail down produces a nose down moment relative to zero tail angle, C. Trimming with the tail is able to alter stability. Some reversal occurs at high angle of attack. Without leg feathers, the tail is ineffective at producing lift or pitching moment, B & D.