During World War II, there was a significant amount of research put into developing rocket-powered aircraft and missiles on both sides. The principles of rocket propulsion developed in this time period have served as the basis for the advancements seen in the field. These principles have taken man to the moon and are used on modern day military aircraft. Rocket propulsion systems, much like other types, rely on Newton’s third law of motion in order to generate thrust to create lift for both aircraft, rocket boosters, and missiles.

Rocket Propulsion

All rockets are based on Isaac Newton’s Third Law of Motion: “Every action has an equal and opposite reaction.” That is to say that if an object is pushing matter behind it, the object will move forward. In rockets, the matter that is being pushed is either a gas or liquid that is quickly burned and passed through the engine.

In a rocket propulsion system or engine, fuel is mixed with a source of oxygen referred to as an oxidizer. The mixture is then exploded in the combustion chamber, which produces extremely hot exhaust. This exhaust is then sent through an exhaust nozzle to make thrust and accelerate the flow of the engine. Unlike propeller and gas turbine engines that use atmospheric air, rocket engines rely on exhaust gases to produce their lift, which is what allows them to be used in space where there is no atmospheric air to pull into the propulsion system.

Liquid vs. Solid Fuel Rocket Engines

Liquid fuel rockets have an oxidizer and the fuel is stored in liquid form in separate locations. They are then sent to the combustion chamber where they are ignited or burned. However, solid-fuel rockets store their propellant mix in a single location in solid form. Solid-fuel rocket propulsion system fuel does not normally ignite until heat is applied to the substance. Liquid fuel rocket propulsion systems are more complex as they have additional tanks, pumps, and controls and can stop the propulsion of the engine by shutting off the propellant supply. Liquid fuel rocket propulsion systems are not normally loaded with fuel until just before use. Solid-fuel rocket propulsion systems on the other hand, cannot be shut off unless the fuel is removed or the casing storing the fuel is destroyed. However, it can sit for a significant period of time with the fuel loaded in the rocket.

Future Rocket Propulsion Systems

Electromagnetic propulsion systems are one of the current areas of research. The goal is to create an electrically powered spacecraft propulsion system. These engines accelerate ions by using electrostatic forces, and use a number of methods such as electromagnetic or electrostatic forces to directly accelerate the mass. Electric power is used to ionize the atoms and then to make a voltage gradient that is used to accelerate them to high exhaust velocities. These systems have not been able to produce sufficient force on their own to work in all cases, but they have been combined with nuclear electric systems to generate the appropriate amount of power to generate the appropriate amount of thrust. Other rocket propulsion systems that have been tested or are under research include electrothermal thrusters (that use electromagnetic fields to make a plasma to heat propellant which is then converted into kinetic energy), pulsed plasma thrusters, and pulsed inductive thrusters. Some of the rocket propulsion systems that remain science fiction but are not excluded from potential research include: a bias drive, disjunctive drive, differential sail, and a hyperspace drive based upon the Heim theory.

Rocket Design

The basic design of all rockets is pretty straightforward. A rocket is a cylindrical shell made of metal that ends in a cone at the front and consists of fins at the back. Both the cone and the fins help the rocket glide through the air without being tossed around. The cylindrical shape of the rocket allows it to be sleek while still having enough room to include any essential equipment such as a control circuit, parachute, or fuel compartment.How Do Rockets Work

A rocket engine is very different from the engine found in an automobile. Rocket engines include a fuel compartment which usually holds gasoline, an oxidizer that contains liquid oxygen, two fuel pumps, a combustion chamber, and a nozzle. As gasoline leaves the fuel compartment, it is mixed with liquid oxygen from the oxidizer which causes it to burn rapidly. The oxidized gasoline is then pumped into the combustion chamber where it is ignited by a spark and then forced out of the nozzle (exhaust pipe).

A parachute is generally essential to every rocket design. As all rockets are made to be blasted high into the sky, a parachute is the only thing that protects the rocket from crashing back into the ground when the fuel is completely burnt. Parachutes also tend to make it easier to find rockets that have already been launched as the open parachute is usually relatively large and colorful.

Since parachutes are important to the survival and longevity of all rockets, it is also important to protect the parachute. Parachutes are usually quite flammable and are vulnerable to the emissions of the rocket fuel as it is burned and pushed out of the rocket. To prevent the parachute from being destroyed, it is almost always wrapped in a recovery wadding made of tissue paper soaked in boric acid or some other flame retardant.

Another vulnerability that the parachute suffers from has to do with elasticity. The parachute of the rocket is quickly and forcefully pushed out of the rocket and then catches itself on the air, all the while tugging on the cords that connect it to the rocket. To prevent these cords from breaking in mid-flight, they are attached to a shock cord (bungee cord) that stretches as the parachute interacts with the air.