In 1957, the first artificial satellite was successfully launched. This
means that the launch vehicle guidance and control (LVGC) technologies
have been developed in more than one half of a century ago. In fact,
relevant information about LVGC technologies can be found in related
books and papers. However, although technologies can be learned, systems
must be developed indigenously, especially the large-scale aerospace
systems. There are many LVGC documents in the public domain, but the
performance must be tailored to match the characteristics of the launch
vehicle (LV) design. Early application of complicated guidance law is
limited by the capacity and speed of onboard computer. Modern electronic
technology has eliminated most of the difficulties. In this paper, the
capability of the linear-tangent guidance law (LTGL) in the pitch plane with
normal perturbation force is investigated. A nominal trajectory is computed
using an assumed LV model for launching a 1,000 kg satellite to a 600 km
altitude circular orbit. Then the perturbed trajectory is computed under the
perturbation of a normal force in the pitch plane. And then the LTGL is
imposed to guide the LV back to the nominal trajectory. Simulation results
show that the error in altitude is within 8 km while the error in speed is
within 40 m/s.