Jet aircraft

Jet planes move using special engines.

These engines push hot air out the back. This push helps the plane fly fast.

Most jets have wings that stay still. They fly much faster than propeller planes. They also fly very high in the sky.

Some jets fly for people to travel. These are called commercial jets. They can carry many people far away.

Other jets are used by the military. Some are used for defense. They can go even faster than travel jets.

Jet engines are a great way to fly. It is amazing how they work!

A jet is an aircraft that moves using jet engines.

These engines work by letting out hot gas. This push helps the plane fly very fast. Most jets have wings that do not move. They fly much faster than planes with propellers. They also fly very high in the sky. Most jets fly around 10,000 to 15,000 meters high.

Two men worked on these engines. Frank Whittle worked in England. Hans von Ohain worked in Germany. In August 1939, the first jet aircraft flew. It was called the Heinkel He 178.

Later, many jets were made for people to travel. These are called commercial jets. The de Havilland Comet was one. The Boeing 707 also became very popular. Some jets use a turbofan. A turbofan is a type of engine that uses less fuel.

This helps planes fly long distances. Some jets are even faster than others. The SR-71 Blackbird was a very fast military jet. It could fly at Mach 3.35. That is over three times the speed of sound!

A jet aircraft is a plane that moves using one or more jet engines. These planes usually have wings that stay in one place. Most jets are built to fly at very high speeds. They often fly at speeds called transonic, which is just below the speed of sound. Many jets cruise at Mach 0.8, which is about 981 km/h. They also fly very high up in the sky. They often stay between 10,000 and 15,000 meters high.

Flying this high helps the engines work in the most efficient way.

Jet engines work by pushing out hot gas to create movement.

There are different kinds of engines used for different jobs. A turbojet has a very high exhaust speed. These are great for flying at supersonic speeds, which is faster than sound. A turbofan is another type of engine. High bypass turbofans are very good at saving fuel. Most large passenger airliners use these efficient engines today. The engine must push gas out to replace energy lost to air drag and gravity. This is called propulsive efficiency.

Inventors worked hard to make these engines a reality.

Frank Whittle was an English inventor and an officer. He began developing a jet engine in 1928. In Germany, Hans von Ohain worked on similar ideas in the early 1930s. They worked on these ideas at the same time but separately. In August of 1939, the world saw the first jet aircraft fly. This plane was called the Heinkel He 178. It flew in Rostock, Germany, using von Ohain's design. It was a very big moment for science.

Many different jets were built for many different reasons.

The Messerschmitt Me 262 was the first jet fighter to be used in combat. It entered service in April 1944. The British made the Gloster Meteor, which was the first production jet. In the United States, the Lockheed P-80 Shooting Star was a famous jet fighter. Some jets were even built to carry nuclear weapons, like the North American B-45 Tornado. The fastest military jet ever was the SR-71 Blackbird. It could reach a speed of Mach 3.35.

Today, we see jets used for travel and even for special science tasks.

The de Havilland Comet was the first commercial jet service. It flew from London to Johannesburg in 1952. Later, the Boeing 707 became a very popular plane for people to fly on. Some special planes, like the Concorde, could fly faster than sound. The Concorde flew for 27 years starting in 1976. You might also see helicopters that use small jets to help them move. Even some people use jet-powered wingsuits to fly for short times!

A jet aircraft is a vehicle propelled by one or more jet engines. Most jets are fixed-wing aircraft, meaning their wings do not move during flight. These machines are designed to fly at very high speeds. They often operate at transonic speeds, which is just below the speed of sound. Many jets cruise at Mach 0.8, roughly 981 km/h (610 mph). They typically fly at altitudes between 10,000 and 15,000 meters. This high altitude allows jet engines to operate with maximum efficiency.

To fly efficiently at high speeds, engineers use the Whitcomb area rule. This rule states that the total cross-sectional area of an aircraft should follow a specific shape called a Sears-Haack body. By following this rule, designers can minimize shockwaves. Shockwaves are a problem because they waste energy during flight. The engine itself works by expelling hot gas to create thrust. This process is measured by propulsive efficiency. This is the percentage of energy from the fuel that actually moves the plane. It is never 100% because some energy is always lost to air drag and gravity.

There are several distinct types of jet engines used for different purposes. A turbojet has a very high exhaust speed. This makes it ideal for supersonic flight, which is faster than sound. However, turbojets are not very efficient for slower, subsonic flight. A turbofan is a different design that uses a large fan. High bypass turbofans are very efficient and are used by most modern airliners. Low bypass turbofans are often used for transonic or low supersonic speeds. Other propulsion types include ramjets, pulsejets, and even rocket engines.

The history of jet flight began with independent work by two inventors. Frank Whittle, an English officer, began developing jet engines in 1928. Hans von Ohain worked on similar concepts in Germany during the early 1930s. In August 1939, the Heinkel He 178 became the first jet aircraft to fly. This flight took place in Rostock, Germany, using von Ohain's design. Early engines faced a problem called "creep," which is metal fatigue from high heat. This caused early engines to burn out quickly. Eventually, the axial-flow engine design became the industry standard by the 1950s.

Military jet development moved very quickly during the mid-1940s. The Messerschmitt Me 262 was the first operational jet fighter. It entered service in April 1944 and had 300 aircraft go into combat. The Gloster Meteor was the first production jet from the United Kingdom. In the United States, the Lockheed P-80 Shooting Star was introduced by the end of 1945. During the Korean War, a jet-to-jet dogfight occurred in 1950. A US pilot shot down two North Korean MiG-15s in this historic encounter. The fastest military jet ever recorded was the SR-71 Blackbird. It could reach speeds as high as Mach 3.35.

Commercial aviation was transformed by the arrival of jet travel. The de Havilland Comet began the first commercial jet service in 1952. It flew from London to Johannesburg and offered a smoother ride than propeller planes. However, the Comet suffered from metal fatigue due to design defects. This allowed the Boeing 707 to enter the market in 1958 and become very successful. The 707 used underslung engines, which were safer if a fuel leak occurred. Later, supersonic transports like the Concorde entered service. The Concorde flew at Mach 2 for 27 years, from 1976 to 2003.

Jet technology connects to many different areas of science and engineering. It relates to thermodynamics through engine heat and energy conversion. It also connects to aerodynamics through the study of air resistance and shockwaves. Even specialized vehicles like helicopters use jet technology. Some compound helicopters use auxiliary turbojets to add extra thrust. There are even jet-powered wingsuits that allow humans to fly for short periods. In the most extreme cases, the X-43 scramjet can reach speeds of Mach 9 to 10. This shows how jet propulsion continues to push the limits of speed and flight.