MAXIMUM ENERGY LEGS: GLIDE SPEEDS IN AN INHOMOGENOUS AIRMASS

Abstract

Glides around a turnpooint, on course or to a finish, are an important feature of sailplane racing and the traditional approach of adopting a singlespeed to fly, or MacCready setting, for legs with different winds can be significantly sub-optimal. The best glide angle over the ground is achieved at lower speeds with a tail wind and at higher speeds with a head wind. Thus, a pilot who flies at the speed for the best glide angle over the ground for each leg can start the final glide at a lower altitude than a pilot flying the same speed for each leg. Similarly, a pilot flying at the appropriate speed for the wind on each leg will arrive at the goal sooner than the pilot flying at a constant speed. The methodology for determining the altitude required to achieve a goal and the optimal speeds to fly for multiple legs with differing wind speeds, as well as representative results, are presented.