How Do Rockets Work
Rockets are our species' best way of escaping the atmosphere of Earth and reaching space. But the process behind getting these machines to work is far from simple. Here's what you need to know about getting a rocket into space.
How do rockets work
Human beings have been using controlled explosions to propel objects for many centuries. One such example, rockets, are commonly used today as fireworks, signal flares, weapons of war, and, of course, for space exploration.
Rockets are basically a special kind of engine that burns fuel to create propulsion. In most cases, rockets will convert their fuel payload into hot gases that are expelled out of their rear to propel them in a given direction.
In this sense, you might be tempted to think of rockets acting by simply pushing themselves through the air. But, since rockets can also operate perfectly well in the vacuum of space, this isn't really what is going on.
In fact, they operate using the principle of Newton's "Third Law of Motion", which, put simply, states that "for every action, there is an equal and opposite reaction". In this sense, rockets can be said to be taking advantage of momentum -- the force that a moving object has.
But there is a bit more to it than that. Other forms of combustion engines, like car or airplane engines, including jet engines, need air to work (specifically, they need the oxygen it contains). For this reason, they cannot operate in the vacuum of space.
Unlike combustion or jet engines, rockets carry their own supply of oyxgen of other oxidizer with them. Just like the fuel, these can be in either solid, liquid, or hybrid form (more on these later).
The process works both in the presence of an atmosphere and in the vacuum of space. The actual workings of the rocket usually take place in the absence of air -- in fact, unlike cars and airplanes, rockets do not have any air intakes.
For rockets, lift is less of an important consideration, as its trajectory and "flight" are more a factor of its propulsion and trajectory of flight as considerations for overcoming drag tend to take precedence. That being said, lift is important for the stabilization and control of the rocket during flight and is usually provided by the fins, nose cone, and body tube.
Other types of rockets use parallel staging. In this case, smaller first stages are strapped to the body of a central "sustainer" rocket. At launch, all of the engines are ignited. When the propellants in the strap-on rockets are extinguished, they are discarded while the sustainer engine continues burning. The Space Shuttle uses parallel staging, while rockets like NASA's Titan III's and Delta II's use both serial and parallel staging.
Once the first stage has completed its duty, rockets usually drop that section and ignite their second stage. The second stage has less work to do (because it has less mass to move) and has the advantage of having a thinner atmosphere to contend with.
For this reason, the second stage often only consists of a single engine. Most rockets will also jettison their fairings at this