what is the differnce between a jet engine and a rocket engine?

Question

how it works

Answer 1

There are many incidental differences due to their actual uses: for instance, many rocket engines simply heave mass out one end and only need a nozzle while many jet engines act upon air and have the pieces to facilitate that, including a turbine. None of these are the defining characteristic though. Just the paraphenalia that naturally follows given their crucial difference and the consequent uses.

That crucial difference is this: a jet engine need carry only its fuel as it obtains oxygen from its surroundings while a rocket engine must carry both its fuel and its oxygen since it will not get any significant oxygen from its surroundings.

(This is VERY much like the difference between an explosive, like gunpowder, and a high explosive, like TNT. And consequently, their uses differ and so do their implementations.)

Answer 2

As a gas turbine mechanic/operator, I'm having a hard time with the answers already provided. Although each one lightly touches on how each engine work pointing out similarities, none come out and clearly state that "rocket engines are no more like gas turbine engines as they are like lawn mower engines."

Except in the fact that they share a few Laws and Principles of Motion.
http://64.78.42.182/sweethaven/Aviation/AvEngines01/lessonMain.asp?iNum=0103

Traditionally, rocket engines have no moving internal parts. Meaning - no blades, pistons, rotors. Combustion happens by mixing stored fuel and oxygen in a combustion chamber. Expanded gas (exhaust) is then directed through a nozzle to increase velocity to the atmosphere. A simple bottle rocket is a great example.

A Gas turbine (jet) engine takes in air through an intake, compresses the air through a series of blades each smaller than the one before and is then directed into the combustion chamber. Here the fuel is atomized with the compressed air and directed over the High Pressure turbine where kinetic energy is converted into mechanical energy to keep the compressor and accessories turning. In some cases there may be a Low Pressure turbine in-line after the HP turbine to further extract energy to turn a generator or reduction gear.

Gas Turbines used in the aircraft application either use a turbo propellor or a turbo fan. Fighter aircraft are fitted with a rear exhaust nozzle however, the engine (or primary gas producer) is the same.

In conclusion: Not only are jet engines and rocket engines functionally different, so are their applications.

Hope this helps,

Answer 3

The purpose of both the jet engine and the rocket engine is to combust a mixture of fuel and oxidizer. This combustion process generates a high-pressure exhaust that creates thrust to push a vehicle forward. The fundamental difference between the two types of engines, however, is where the oxidizer comes from.

A jet engine obtains its oxidizer from the external atmosphere, as illustrated in the diagram below. Air enters the engine through an inlet and is then slowed down and compressed by a series of compressor blades. The compressed air is then mixed with fuel, typically a petroleum-based liquid similar to kerosene, and burned. The high-pressure gas is exhausted through a nozzle to generate thrust.

A rocket engine differs from a jet engine primarily in one key way. Whereas the jet pulls in oxidizer from the atmosphere, a rocket carries its own supply of oxygen aboard the vehicle. An example shown below is the liquid rocket engine. This class of rocket carries a liquid fuel and a liquid oxidizer in two separate tanks. The two liquids are pumped into a combustion chamber at some rate, called the mass flow rate, where they are mixed and burned. Just as in the jet engine described earlier, this combustion process generates a high-pressure gas that is exhausted through a nozzle to generate thrust.

More at URL complete with diagrams!!

Answer 4

A Jet engine, I presume, you refer to, is the propulsion mechanism for fighter jets etc.

A Jet engine is a souped up turbine engine, which uses the jet fuel to rotate a turbine, which then sucks in air and exhausts it out to produce thrust.

A rocket propelled engine is one that works on the absolute principle of ejecting exhaust and producing forward thrust. Rocket engines must provide their own intake, and thus produce their own exhaust gas, for in space there is no "intake air"

Answer 5

moving parts
a jet engine takes in air compresses it mixes in the fuel and through rotating fans at the exhaust turns the inlet fans to draw more air
rockets use force from burning materals till the matter is burned up

Answer 6

The most crucial application difference
is accelleration. Rockets can be streamlined
to give very high g forces. Whereas
jets need all sorts of air control systems
to keep them running.

Answer 7

A jet is an internal combustion engine. It compresses air, adds fuel heats it up and splits it out at high velocity causes a force.

A rocket burns stuff to create its own gasses and splits them out at high velocity, It doesn't need air so it works in space.

Answer 8

Main difference: Rockets have to carry their own oxygen, Jets get their oxygen from the atmosphere.

.