A universal time of flight equation for space mechanics

A universal time of flight equation for any orbit is developed as a function of the initial and final radius, the change in true anomaly and the initial flight path angle. Lambert's theorem, a new corollary to this theorem, a trigonometric variable substitution and a continuing fraction expression are used in this development. The resulting equation is not explicitly dependent upon eccentricity and is determinate for -2n < (change in true anomaly) < 2n. A method to make the continuing fraction converge rapidly is evaluated using a top down algorithm. Finally, the accuracy of the universal time of flight equation is examined for a representative set of orbits including near parabolic and near rectilinear orbits.