The idea of a rocket is very simple. Gasoline and liquid oxygen are pumped to a combustion chamber. A reaction is created and it enlarges therefore shoots the rocket up. To get propulsion the reaction is forced through a nozzle to get higher velocity. To keep a one pound objects in the air rockets burn two types of fuel, liquid fuel and solid fuel. The solid fuel is gunpowder but it explodes instead of propelling the rocket up and the liquid fuel is gasoline.
Solid fuel rockets have been the first to be recorded in history. The first rockets(solid fuel) were invented by the Chinese. The biggest problem was once it was lit it could not be stopped. So solid fuel rockets are only used for missiles, flares, and booster rockets.
A rocket engine is not a conventional engine. A conventional engine moves pistons up and down and turns a cars wheels.
