What is a disadvantage of a progressive burn motor?

A progressive burn motor typically starts with a low initial thrust that gradually increases as the combustion process continues. This characteristic can create potential stability issues during the early flight phase of a rocket launch. The low initial thrust may not provide sufficient stabilization for the rocket, especially if it is designed to be a high-performance craft. If the rocket does not have enough force acting on it at lift-off, it may struggle to maintain a straight path, leading to erratic flight behavior or even failure during its ascent.

In contrast to this, other aspects such as inconsistent thrust levels, the complexity of ignition systems, and risks of overheating are valid considerations but are not as directly related to the fundamental nature of progressive burn motors. Inconsistent thrust levels can be a concern in other types of motors but progressive burn motors are specifically designed to provide a steady increase in thrust. While the ignition complexity may vary, it doesn’t specifically tie to the nature of progressive burn. Additionally, overheating can affect any type of motor but is not a defining disadvantage of progressive burn designs. Thus, the low initial thrust resulting in potential stability issues is a key characteristic that places this particular option in the context of progressive burn motors.