Current Statistical Trends for H – and V-Tail Coefficients

During Phase 1 (conceptual design) of an aircraft design project, the initial empen­nage is sized using statistical data. Section 3.20 provides preliminary statistics of the empennage tail-volume coefficients. Figure 12.11 provides additional statis­tics for current aircraft (twenty-one civil and nine military aircraft types), plotted
separately for the H-tail and the V-tail. Statistics for aircraft using FBW are included in the figure. It is advised that readers create separate plots to generate their own air­craft statistics for the particular aircraft class in which they are interested to obtain an appropriate average value.

For civil aircraft designs, the typical H-tail area is about a quarter of the wing reference area. The V-tail area varies from 12% of the wing reference area, SW, for large, long aircraft to 20% for smaller, short aircraft. There may be minor changes in empennage sizing when more detailed analyses are carried out in Phase 2 of the design.

Military aircraft require more control authority for greater maneuverability and they have shorter tail arms that require larger tail areas. The H-tail area is typically about 30 to 40% of the wing reference area. The V-tail area varies from 20 to 25% of the wing reference area. Supersonic aircraft have a movable tail for control. If a V-tail is too large, then it is divided in two halves.

Modern aircraft with FBW technology can operate with more relaxed stabil­ity margins, especially for military aircraft designs; therefore, they require smaller empennage areas compared to older conventional designs (see Figure 12.18).

In this book, trim surfaces are earmarked and not sized. Designers must ensure that there is adequate trim authority (i. e., the trim should not run out) in any condition. This is typically accomplished in Phase 2 after the configuration is finalized.