There are two types of conventional rockets. The first and oldest type is the solid fuel rocket. Solid fuel rockets have fuel that is in a solid state. The engine consists of the fuels around a hollow core. This hollow core acts as the combustion chamber and nozzle for the rocket. Solid fuel rockets are usually small and use a from of gunpowder, which is a mixture of potassium nitrate (KNO₃), Carbon (in the past usually in the form of charcoal, but has been substituted for more pure form of carbon.) and solid sulfur. When these burn the KNO₃ produces oxygen causing the carbon and sulfur to burn. The energy released from this reaction creates a lot of heat very quickly, causing the gasses produced from the reaction to expand rapidly. This rapid movement of the gas particles causes a forward impulse force in the form of thrust.

The second type of conventional rocket is the liquid fuel rocket. Liquid Fuel Rockets are a lot more efficient than a solid fuel rocket, mainly because they can be built lighter because you don�t need the hollow core of the solid fuel rockets. Liquid rockets usually have two separate tanks for holding the reactants. One usually contains the combustible fuel (i.e. kerosene) and the other usually contains the oxidizer. (Usually liquid oxygen.) The fuel can be anything that is a liquid that will burn, and give off a gas and lots of heat energy. Some of these substances include Gasoline, kerosene, nitrogen, and even hydrogen.

In a liquid fuel rocket engine the fuel and oxidizer are pumped into the combustion chamber, and are then ignited either by an igniter (a alcohol burner in Goddard�s rocket) or just by the heat energy produced by the reaction before it. Either way once the activation energy is reached the combustion begins giving off tremendous heat energy, causing the resulting gases to expand being forced out the nozzle of the chamber again causing thrust. Because all of the products of the reactions are gases in a liquid fuel rocket that can sometimes be as harmless as water, liquid fuel rockets are considered to be cleaner than solid fuel rockets.

All Conventional rockets all work on the same basic principle; they all use heat from a chemical reaction to produce heat that causes the gases that are produced from the reaction to expand causing pressure to build up in the combustion chamber, causing the gases to reach a high escape velocity generating a thrust.

We can figure out approximately much pressure is built up in the combustion by: 1) Using Hess� Law or the values given to us for how much heat energy is produced in the reaction. 2) then using our calorimetric equation (q = m ∙ C ∙ Δ T) and solve for Δ T and then by using the Combined gas law

and solve for the P₂ we can find the pressure inside the combustion chamber. The using physics equations you should be able to find the thrust.

An ion drive is a much more complicated system to explain and understand, but once you know how it works it is much easier build and maintain. An ion drive uses a �cathode� or and electron gun, that shoots a stream of electrons, (much the same as in your television set) which is shot towards an anode, a positively charged ring and a magnetic field (either produce by a magnet or an electromagnet). This beam of electrons is used to ionize the propellant, by giving the atoms of the propellant electrons to make them stable. The ions are drawn into the extraction grid, (Looks like two or three section of a screen door that has a lot of high voltage current running through it.) the gird draws in the ions and shoots them out into space with an extremely high velocity generating a forward thrust. The ions are then shot again by neutralizer in order to keep the spacecraft from gaining a charge.