
293Trajectories
of complex variables and solved it. The particular solution was the (relatively) constant
yaw of repose, and the complimentary solution was the transient epicyclic motion. In the
modied point mass approach, we extract the particular solution and ignore the transient
motion, instead concentrating on the yaw of repose, the drift, and the effect of the yaw
drag. We assume that the epicyclic pitching and yawing motion are negligible everywhere
along the trajectory, i.e., in many instances, reasonable, since it should damp early in the
trajectory and thus contributes little to the drift. We proceed by dening another unit vec-
tor ...