ESDU TM 49:1984

This Memorandum gives a tentative method for predicting the
contribution to the rolling moment derivative due to sideslip
resulting from the interference effect of a fin on a tailplane, at
subsonic speeds. The method given is applicable to aircraft
geometries where the tail assembly consists of a single vertical
fin located on the top of the aircraft rear-body in the plane of
symmetry, with the tailplane mounted either on the fin itself or on
the rear body.

The contribution arises because the fin induces an
antisymmetrical spanwise loading distribution across the tailplane
which generates a rolling moment about the tailplane centre-line
chord. The total contribution of the tail assembly of an aircraft
to the rolling moment derivative due to sideslip is obtained by
adding this contribution due to interference effect to the
contributions provided by the fin (using ESDU 82010 or Aero
C.01.01.01), and the tailplane planform and dihedral (obtained from
ESDU 80033 and Aero A.06.01.03 respectively).

The contribution due to the interference effect of a fin on a
tailplane is often small enough, when compared to the fin
contribution, for it to be ignored when estimating the rolling
moment derivative due to sideslip for an aircraft, but it is of
more importance structurally when considering bending moments at
the tailplane root.