![Diagram of a solid rocket engine.](http://static.sciencelearn.org.nz/images/images/000/000/410/full/Solid-rocket-engine20151021-1314-kvvria.jpg?1674164259)
A solid rocket engine contains fuel and oxidiser that have already been mixed together and set as a solid. The centre is normally hollow to increase the surface area available for reaction to take place.
A solid rocket engine contains fuel and oxidiser that have already been mixed together and set as a solid. The centre is normally hollow to increase the surface area available for reaction to take place.