Dolphin-style gliding

Abstract

A quasisteady dolphin flight technique is presented for the analysis of minimum-time planar flight through an arbitrary deterministic vertical wind distribution. A piecewise constant wind distribution is assumed. The MacCready construction for optimal thermal-to-thermal soaring is applied over each segment of constant wind intensity using a shifted velocity polar. By neglecting the sailplane dynamics, a composite 'virtual poIar' is constructed from these piecewisei'MacCready optimal flight conditions. The usual MacCready theory then can be applied directly to this virtual polar to predict average minimum-time travel speeds, glide angles, and other performance quantities. After a discussion of the virtual polar, several performance comparisons are given for various wind distributions, wing loadings and sailplane types.