An analysis is described of side-force and yawing-moment-in-sideslip of conventional transport aircraft based on available wind tunnel and full-size aircraft data. After a chapter on general design requirements the analysis is divided in a part which describes the tail-off characteristics and a part which describes the contribution of the tail surfaces to side-force and yawing-moment-due-to-sideslip. Particular attention is paid to the drfferent contributions to the sidewash as expenenced by the tail surfaces. Also rudder characteristics are discussed.