Determination of Vortex Paths by Series Expansion Technique with Application to Cruciform Wings

A series method of determining two-dimensional vortex paths is considered and applied to the computation of vortex positions behind a slender equal-span cruciform wing at any angle of bank as a function of the distance behind the trailing edge. Calculated paths are shown for four bank angles. For a bank angle of 45 deg comparison is made with the results of a closed expression given in NACA TN 2605. For other bank angles water-tank experiments provide qualitative comparison. Satisfactory agreement is found for a sufficient distance downstream to include most practical missile-tail positions. The interference forces on an equal-span interdigitated cruciform tail behind a slender equal-span cruciform wing are calculated for four angles of bank from the vortex positions found by use of the series.