Having a basic understanding of solid rocket motors, the next questions to ask ourselves are:
- What shape should our propellant be?
- What size nozzle throat should we use?
To answer these, we must first learn about how our propellant actually burns.
Our propellant is made up of different particles bound together which then burn up and leave the motor as gas. As shown in the image below, the most simple motor we can have is a hollow cylinder with an opening at one end. In this setup, the propellant burns and is expelled through the top.
Although the propellant is made up of different particles, we can think of it as one solid material having the same burn rate everywhere on its exposed surface at a given pressure. As shown below, the propellant burns up overtime,