Watching the recent SpaceX Starship tests got me to thinking:
Could you actually make a rocket using grain as the propellant? Image from https://www.teslarati.com/spacex-starship-sn5-second-hop-plans/
Grain, especially dry grain is quite flammable, and grain explosions are a thing that can happen when the grain is finely dispersed.
The rocket would either have to be a solid-fuel or hybrid rocket. Salami rockets have been successfully made and tested.
Given the right binder and oxidiser, what are some estimates of how well a grain rocket would perform, in terms of Isp and likely max altitude?