The saying, “Change is the only thing constant,” has been exemplified by the field of technology for many years and truly throughout history.
Technology has continued to develop over the years, and with the increasingly complex means of transport of humans and goods from one point to another and even to another planet, jets and rockets are now commonplace.
However, a look at the jet engine versus rocket engine can tell us much about these two wonderful inventions. This article will tell you everything you need to know about their major differences.
Jet Engine
The jet engine also a reaction engine that is designed based on Newton’s third law of motion. The jet engine has a fan, turbine, compressor, mixer, combustor, and propelling nozzle.
If you’re asking, “How does a jet engine work?” The fan takes air in, compresses it, mixes it with fuel, and ignites it in the combustor. The ignited fuel expands and gets blasted out the nozzle to give the jet forward thrust.
The engine’s combustion requires atmospheric oxygen to initiate and sustain the combustion process it needs to run. This is why a regular jet cannot fly outside of the atmosphere into space. There are no oxygen atoms there.
The jet engine is also known as a gas turbine. It burns aviation kerosene which is less viscous than regular gasoline and has a lower freezing point than its counterparts.
Rocket Engine
The rocket engine is another example of a reaction engine designed based on Newton’s third law of motion. The rocket engine gets its thrust for take-off by ejecting mass rearward.
The rocket engine consists of a rocket nozzle, propellant, tank pumps, and power head. The engine is designed to run with liquid hydrogen and liquid oxygen as an oxidizer, or oxidizer mixed with exploding within the combustion chamber.
The combustion produces hot exhaust gas that comes out of the nozzle, where it accelerates to flow exiting, and thrill. This approach does not consume atmospheric oxygen intake like we see with automobiles and jets.
The liquid hydrogen starts burning with the liquid oxygen it carries with it within the rocket. Being that the liquid hydrogen is the fuel with the lowest molecular weight, rocket fuel was able to be used in a rocket application in order to minimize weight.
Differences Between Jet Engine Vs. Rocket Engine
Even though the jet engine and rocket engine are made to operate under Newton’s third law, both engines combustion processes involve two different descriptions of components, which each help to enable thrust.
There are a couple of differences between the two engines. Below are a few important differences between rocket vs. jet engines.
Oxygen intake
The combustion process in a jet engine is physically made to run simultaneously with the mix of jet fuel and outside oxygen. In this process, the oxygen is sucked in through the fans, mixed with the fuel, ignited in the combustion process, which creates thrust.
Conversely, a rocket engine does not have outside oxygen for its combustion process. A rocket engine has burning liquid oxygen it carries along with the rocket.
Fuel type
Jet engines and rocket engines are made to use different fuel types. Jet engines are made to work with aviation kerosene, however, a rocket engine is designed to work on liquid hydrogen. The fuel powering a rocket is more powerful and efficient than jet fuel.
Liquid hydrogen is capable of burning without atmospheric oxygen. It is ignited with liquid oxygen carried along with the rocket. Whereas, aviation kerosene depends on atmospheric air oxygen to complete a jet’s combustion process.
Engine Speed
The speed record from a jet that flies the fastest is the SR-71 Blackbird. The aircraft flies at around 3,418 km/h (2,124 mph).
A rocket engine records a speed rate on the order of 2,500 – 4,500 m/s. That is about 9,000 – 16,200 km/h which is equal to about 5,600 to 10,100 mph. A rocket engine produces a faster speed rating than a jet engine, without question.
Fuel Consumption
An rocket jet engine uses about 11, 000 pounds of rocket fuel per second, or an order of magnitude of two million times that of regular fuel consumption by a car.
A normal jet engine is said to consume about 0.683 liter (liters) of aviation kerosene, per second, or 40.98 liter (liters) per minute, or 2,458.8 liters (liters) per hour.
Engine Price
The price range for each type of jet varies, but most are around $10 – $40 million per engine. Each rocket engine is about $40 – $145 million per engine (depending on the type of rocket).
FAQs.
Q: Are rocket engines more powerful than jet engines?
Yes! Rocket engines are much more advanced than jet engines, in the context of jet engine vs. rocket engine efficiency. Rocket engines utilize their own oxygen, as they can operate in the lack of oxygen in space.
Jet engines utilize oxygen in the air to burn fuel; therefore they operate like car engines. Jet engines cannot ‘breathe’ in space, however, because there is not enough oxygen around to support combustion. This is the most significant advantage rocket engines have over them.
Q: Are rocket and jet engines the same?
No! A rocket engine and jet engine are very different engines because jet engines are fundamentally dependent on atmospheric oxygen and rocket engines have oxygen built inside them. Additionally, rockets are designed to create thrust by expelling gas.
Jets don’t create thrust without its wings to push against. Because jet engines rely on outside oxygen, they can only operate in our atmosphere with oxygen, while rocket engines, using their built dent oxygen, can operate in the atmosphere and out in space.
Q: What is the difference between jet and rocket propulsion?
The main difference between jet and rocket propulsion is the oxidant. Jet propulsion utilizes an outside oxidant (oxygen); while rocket propulsion uses a built in oxidizer with its fuel and takes it with it from the Earth to outer space.
Jets are designed to thrust forward using the combusted fuel and the means of the oxygen; while rockets are designed to thrust forward by developing thrust through rearward expulsion of mass at high velocity.
Q: Which one is faster, jet or rocket?
A Rocket is obviously faster than a jet because of the extremely high speed of the mass it ejects. A rocket flies at about 2,500 – 4,500 m/s which is about 9,000 – 16,200 km/h or 5,600 – 10,100 mph. The fastest jet ever (Lockheed SR-71 Blackbird) flies at around 3,418 km/h (2,124 mph).
The speed of rockets is also much higher than jets, because rockets fly very fast due to the distance they have to travel between Earth and outer space; hence their speed, is measured uniquely in meters per second (m/s), or kilometers per second (km/s).
Please note rockets have greater force than jets as well if you’re comparing rockets vs. jet engines based on thrust.
Q: Why don’t jet engines work in space?
Jet engines aren’t effective in space because they require atmospheric oxygen to function properly, which is not present in space.
They are designed to operate with solid or liquid fuel, which has abundant oxygen in its make-up, while atmosphere is not abundant in space.
Jets are not built with their own oxygen like rockets which could be used fine in space. Also, rockets fly at much faster speeds than jets do and travel into space at much faster speeds, so jets can’t get into space as quickly as rockets.
Q: Why don’t airplanes use rocket engines?
Rocket engines are relatively heavy rockets compared to airplane engines. They are about 3,150 kilograms (7,000 pounds), which would make the rocket engine a significant burden on an airplane.
In addition the rocket carries its own fuel and oxidizer too when sending it into space. So, in order to install a rocket engine on an airplane you will need to compromise on passenger capacity, fuel amount or cargo carrying capabilities.
Since most airplanes are used to move people and stuff around better to use a lighter engine.
Q: What are the 2 main types of rocket engines?
If your asking, What are the two main types of rocket engines? There are solid rocket and liquid rocket engines.
The solid rocket uses a solid propellant that has a mixture of fuel and oxidizer. The propellant is contained in a solid cylinder adapted to have a hole that is the combustion chamber.
Alternatively, the liquid rocket’s propellant, fuel, and oxidizer, are kept separate in liquid forms. The fluids are pumped into the combustion chamber of the nozzle to serve as the burning process.
Liquid rockets are a superior comparatively to solid rockets because they allow the propellant, thrust, and entire system to be flexible.
Q: Do rockets have jet engines?
Absolutely not! Rockets cannot work on jet engines because the air turbine engines are constrained to operate in environments that allow atmospheric oxygen to offer support to the combustion process. Rockets do not work in space because oxygen is not present for combustion.
Rocket engines are for space and overcome all of the limitations of airplanes. They are uniquely manufactured as reaction engines that can create thrust through high velocity rearward mass ejection.
Q: How are rockets the same as jet engines?
Rocket engines are the same as jet engines because they are closely related to the same principles that belong to Newton’s third law of motion.
They both create thrust due to a and unique internal pressure difference by creating exhaust gas that gets ejected equally in the opposite direction.
Both jet engines and rocket engines go through the same air-fuel mixture process that will cause combustion in each vehicle.
Jet engines are continuously supplied with oxygen from the atmosphere around them while rockets have self-contained oxygen systems and can fly directly into space.
Q: What is the difference between a jet and a missile?
A jet is a type of aircraft developed to fly using an internal combustion process and wings for thrust. Pilots to operate and guide jets. Jet aircraft are designed specifically to convey people or cargo from location to location.
Missiles are guided self-propelled rockets designed as weapons of war. While jets are designed to transport humans with pilots navigating the journey, missiles do not actively transport humans, and do not have a pilot. The payload is normally built-in.
Q: Do jet engines need oxygen?
Yes! Jet engines need to take on oxygen to complete the combustion cycle, just as a normal vehicle does on the road. This is a big reason why it cannot fly above the atmosphere into the vacuum of space where oxygen is readily available.
Oxygen is critical to how a jet operates. The jet engine needs oxygen as it combines with the fuel-air mixture which ignites the combustion process sustaining the engine as long as the engine is delivered oxygen normally.
In a typical manner a jet alone cannot sustain without oxygen, it does not matter how high you fly, it can’t be higher than the atmosphere!
Q: How do rockets burn in space without oxygen?
Rockets are designed to have their own oxidizer most often liquid oxygen in a delivery manner to burn rocket fuel as well as support combustion.
This is a major advantage rockets possess over airplane. The rockets ability to have take oxygen conveniently in the payload allows them to fly in space.
Because rockets carried enough oxidizer and fuel, the added weight makes rockets very heavy. As such, the crew size is typically much smaller than average jet aircraft with crew sizes where 5 to 7 is average size.
Final Words
Clearly, rockets and jets are two of the most advanced forms of transportation. The technology behind how they work is just amazing. In hindsight, we’ve discussed some of the differences between jet engines vs. rocket engines to help draw a line of separation.
The primary difference mentioned above between the two engines lies in the type of oxygen consumed and how that oxygen is consumed. A jet engine consumes atmospheric oxygen, while, a rocket engine consumes liquid oxygen that is carried within.
There are some other differences as noted above. So the next time you or someone is asking, “What is the difference between a jet engine and a rocket engine?” pass this article on to them.