Once ignited, the rocket chambers are self-supporting and detonators are not needed and combustion is usually done by the total consumption of fuels. In fact, chambers often ignite spontaneously when restarted for a few seconds after they are stopped. If not designed for re-ignition, many rockets cannot be restarted after cooling without at least minor maintenance, such as replacing the pyrotechnic detonator or even refueling.  Advisory Circular 101-2(0) After playing a lot of the Kerbal space program and watching Space X launches, I became interested in space and rockets. I did some research on how to make a homemade sugar rocket, but I couldn`t really find any information about the rules and regulations in Victoria, Australia, to make and launch them. Does anyone know if you need a permit or what rules apply to the introduction of a permit? I live on a rural farm in Victoria, so I have plenty of space to start one Although there are regulations for the use of model rocket engines in ACT, there are currently NO rocket engines allowed and therefore all model rocket engines are illegal in ACT. Rocket engines generate thrust by ejecting an exhaust fluid that has been accelerated to high speed by a propellant nozzle. Liquid is usually a gas produced by high-pressure combustion (150 to 4,350 pounds per square inch (10 to 300 bar)) of solid or liquid fuels consisting of fuel and oxidation components in a combustion chamber. As the gases expand through the nozzle, they are accelerated to a very high (supersonic) speed, and the reaction to it pushes the engine in the opposite direction. Combustion is most often used for practical rockets because the laws of thermodynamics (especially Carnot`s theorem) dictate that high temperatures and pressures are desirable for the best thermal efficiency. Nuclear thermal rockets are capable of achieving higher yields, but currently have environmental problems that prevent their systematic use in the Earth`s atmosphere and cislunar space. Thermal rockets use an inert fuel heated by electricity (electrothermal propulsion) or a nuclear reactor (nuclear thermal rocket). Gaseous propellants usually do not cause sudden takeoffs, in rockets the total area of the injector is smaller than the neck, so the pressure of the chamber before ignition tends towards the environment, and high pressures cannot form, even if the entire chamber is filled with flammable gas during ignition.
The shape of the jet varies for a fixed-surface nozzle, since the rate of expansion varies with altitude: at high altitude, all rockets are severely underexpanded, and a fairly small percentage of exhaust gas expands forward. In chemical rockets, the combustion chamber is usually cylindrical and flame carriers used to hold some of the combustion in a slower part of the combustion chamber are not required. [ref. necessary] The dimensions of the cylinder are such that the propellant can burn completely; Different rocket fuels require different combustion chamber sizes. There are usually two agencies that control missile activity in Australia. Both have rules that must be followed when using model rockets in Australia. A rocket engine uses stored rocket propellants as a reaction mass to form a high-speed propulsion jet from liquid gas, usually at high temperatures. Rocket engines are jet engines that generate thrust by ejecting mass backwards, according to Newton`s third law. Most rocket engines use the combustion of reactive chemicals to provide the necessary energy, but there are also non-burning forms such as cold gas engines and thermal nuclear rockets. Vehicles powered by rocket engines are commonly referred to as rockets. Rockets, unlike most internal combustion engines, carry their own oxidizing agent, so rocket engines can be used in a vacuum to power spacecraft and ballistic missiles.
Rocket engine nozzles are surprisingly efficient heat engines for generating a high-speed jet, due to the high combustion temperature and high compression ratio. Rocket nozzles give an excellent approximation of adiabatic dilation, which is a reversible process, and therefore offer yields very close to those of the Carnot cycle.