Which best describes the thrust curve of a progressive motor?

The thrust curve of a progressive motor is characterized by a general increase in thrust during the burn phase. This type of motor is designed to provide a gradual ramp-up in thrust, allowing for a smooth acceleration of the vehicle. The progressive buildup of thrust is beneficial in various applications, including model rocketry and certain aerospace scenarios, as it helps manage the forces experienced by the rocket or vehicle during launch and ascent.

This behavior is important because it contributes to improved stability and performance by increasing the dynamic pressure on the airframe gradually, rather than subjecting it to sudden and potentially damaging forces. The smooth increase also allows for better control and guidance during flight, particularly in the early phases of ascent when aerodynamic forces are significant.

In contrast, other types of thrust profiles, such as those with sharp decreases or constant thrust, do not reflect the defining characteristics of a progressive motor, as they would either lead to a quick loss of performance or lack the necessary power variation that a progressive motor is designed to deliver.