What is an afterburner in a jet engine? What does it do?

 An afterburner is a component present on some jet engines, mostly those used on military supersonic aircraft. Simply put, an afterburner works by injecting jet fuel into the exhaust air and igniting it. The ignition of the jet fuel increases pressure within the exhaust of the engine, thus increasing thrust. When you see flames coming out the back of a jet engine like on military aircraft, this is because they have engaged their afterburner.

The F-15 has two engines which under normal power produce 14,590 pounds of thrust. The F-15 can not reach its maximum speed of Mach 2.5 using normal thrust. When the afterburners are in use the F-15's engines each produce 23,770 pounds of thrust. The afterburners can be used as long as there is fuel. The objective of an afterburner is to increase the thrust by about a factor of 1.5 to 2.0 for short periods.

Jet engine thrust is governed by the general principle of mass flow rate. Thrust depends on two things: the velocity of the exhaust gas and the mass of that gas. The afterburner increases thrust primarily by accelerating the exhaust gas to a higher velocity. While the mass of the fuel added to the exhaust does contribute to an increase in thrust, this effect is small compared to the increase in exhaust velocity. The purpose is to provide an increase in thrust, usually for supersonic flight, takeoff, and combat situations.

Afterburning significantly increases thrust without the weight of an additional engine, but at the cost of very high fuel consumption and decreased fuel efficiency, limiting its practical use to short bursts. An afterburner uses the unburned portion of the air passing through the engine it is attached to, to add an enormous amount of extra thrust. Most afterburners will burn substantially more fuel than the jet engines they serve, with fuel consumption tripling compared to normal operation.

How do jet engines start?

 Starting a jet engine is nothing like starting a car, and just starting one is considered the most stressful part of its entire life. The heat produced during engine start at the inlet to the turbines shoots up to the highest Turbine Inlet Temperature at any point of engine operation, which is why the process is so carefully controlled.

The main challenge with starting a turbine engine is ensuring there is sufficient airflow before introducing fuel. If the compressor blades are not pushing enough air through the engine, introducing fuel and beginning combustion will cause the engine to overheat and damage it. This is called a hot start.

The start function involves turning the shaft that the compressor is mounted on up to a rotational speed of approximately 41 to 62 percent of maximum RPM. On most large commercial jets, this is achieved using the Auxiliary Power Unit, a separate small turbine engine located in the aircraft's tail that produces bleed air from its high-pressure compressor. This air is used to spin the turbine blades of the main engine. If the APU is not working on the ground, a start cart can be brought to the aircraft; it is literally an APU in a wheeled cart, and start carts are at every major airport.

Once the shaft reaches the correct RPM, the Fuel Control Unit begins to introduce fuel into the combustion chamber where high energy igniters light it off. The starter remains engaged and continues to assist the rotating shaft until the engine reaches ground idle, usually around 70 percent N1, where it becomes self-sustaining. On smaller engines this process can last approximately 15 to 25 seconds, but on large high bypass fans it can take 40 to 45 seconds or more.

Once one engine is running, its bleed air can be used to start the remaining engines through a process called cross-bleed, avoiding the need for the APU entirely.

How many Bollywood actors have a private jet?

 Shah Rukh Khan:

The king of Bollywood, Shah Rukh Khan, is on the top of the celebs having their jets. Known for his luxurious life, Shah Rukh Khan is one of the wealthiest Bollywood celebrities. He travels in his private jet along with his wife, Gauri khan. Shah Rukh Khan has given Bollywood some of the best movies like Kuch Kuch Hota Hain, Kabhi Khushi Kabhi Gham, Kal ho naa ho, and much more. It is his vast net worth of 600 Million dollars that has bagged him a lavish lifestyle and a stylish private jet.

Salman Khan:

Bollywood’s bhaijaan, Salmaan Khan, is also known for his luxurious life. Continuing his legacy of a lavish lifestyle, Salman khan also has a stylish private jet. Salman Khan’s busy schedule and huge fan following is another reason for his private jet. He is one of the successful as well as the richest actors of Bollywood. Salman Khan is credited for the massive success of movies like Kick, Hum Aapke Hain Kaun, wanted, Bajrangi Bhaijaan, Bodyguard, and much more. His latest movie Radhe: your most wanted Bhai, is much awaited by his fans.

Ajay Devgn:

Ajay Devgn is another popular actor in the list of Bollywood celebs having a private jet. Ajay Devgn has been a part of many successful Bollywood movies like Drishyam, Raid, Singham, Golmaal, etc., and he also has a huge fanbase. The considerable fanbase and busy schedule prompt him to travel through a private jet. The actor has a net worth of 30 Million USD that makes him capable of owning a private jet. The actor with his beautiful wife Kajol prefers traveling through their jet. His wife, Kajol, also has a net worth of 16 Million USD.

Hritik Roshan

The Krish of Bollywood and the superhero of youngsters, Hritik Roshan, is also one among those celebs who have their private jet. Hritik Roshan is one of the most dashing actors of the Bollywood industry, and his private jet is also very stylish.

Shilpa Shetty:

Not only actors but our favorite Bollywood heroines also have their private jets, and Shilpa Shetty comes on the top of the list of those actresses. Shilpa Shetty, who had started her career from Baazigar, has achieved significant milestones in her life. She lives an extravagant life. She, along with her husband Raj Kundra, remains one of the most famous couples in terms of living a flourished life. The couple visits to different places in their private jet.

Amitabh Bachchan:

One of the seniormost Bollywood celebrities who has featured in successful movies like Pink, Sholay, Baghban, Kabhi Khushi Kabhi Gham, etc., Amitabh Bachchan, has a net worth of around $400 Million (Rs. 2800 Crore). Amitabh Bachchan is also one of those Bollywood celebrities who have their jet. Mr. Big B says that a private jet is very useful for him for traveling at his convenience. He utilizes the time spent in his private jet for staying updated with news and keeping himself active on social media.

Madhuri Dixit:

One of the most beautiful actresses in the Bollywood industry, Madhuri Dixit, also owns her private jets. Madhuri Dixit is always known for her graceful moves, fine acting, and on-the-point expressions. The considerable income from movies and from shows like Dance Deewane, where she is a judge, has helped the actress to maintain her private jet. Won’t you like to know the net worth of this gorgeous actress? It is approx. $35 million, which makes up to Rs. 264 Crore in Rupees.

Priyanka Chopra:

Priyanka Chopra, the Desi Girl of Bollywood, is also on the list of those celebs who have their private jets. A private jet is very useful for this busy star. Priyanka, who has a lot of work internationally as well as nationally, has to travel a lot. Her real-time work commitment makes her travel to various continents on a regular basis. A private jet is also convenient for her because she can complete her sleep while traveling.

Sunny Leone:

Baby doll of Bollywood, Sunny Leone, has also managed to earn a lot of name and fame in the Bollywood industry. This popular item girl also possesses her private jet.

Diljit Dosanjh:

This Bollywood star from Punjab also possesses his jet. Diljit Dosanjh, who has featured in many Punjabi movies like Sardaarji, Shadaa, Jatt and Juliet, 1984, etc., has made a debut in Bollywood through Udtaa Punjab. He has also played an important role in movies like Good News, Arjun Patiala, Soorma, etc. Besides, he has also sung some of the most popular songs, not only in Punjabi Cinema but also in Bollywood.

Anil Kapoor:

One of the fittest and most versatile actors of Bollywood, Anil Kapoor, has his jet. He even uses this plane to travel across borders. He is often found partying in his private jet. He says that he loves to travel with his family in his private jet. A net worth of USD 12 million is undoubtedly an indicator of Anil Kapoor’s huge success and popularity even today.

Akshay Kumar:

Akshay Kumar, known for his daring nature and humorous style, also has his jet. His habit of being punctual on sets is both a reason and a consequence of a private jet. Akshay Kumar says that he likes to travel through his private jet as it is less time-consuming. Akshay Kumar has a net worth of approx. $350 million that he has earned from his blockbuster movies like Housefull, Good News, Mission Mangal, etc.

Why has it been so hard for China to build aircraft jet engines?

 Empirical evidence proved it is more difficult to design and build aircraft engines than it is to build atomic bombs or send satellites to space. The jet engine is HARD.

It took many decades for US, British and French engine makers to perfect the technologies that they use today. China couldn't just acquire the plans and start making them. Creating turbine parts that can survive extreme heat has been a major engineering challenge. Meeting it has required fundamentally rethinking the material structure of the turbine blades, making metals do things that they do not normally do in nature. Turbine blades may be operating in temperatures far exceeding their melting point, and thus must be cooled to typically 85% of melting temperature to maintain integrity. Blades must be cast with intricate internal passages and surface hole patterns needed to channel and direct cooling air within and over their exterior surfaces.

The turbine blades in a modern jet are a single metal crystal. Even if you have a jet and can take it apart that tells you nothing about how to cast the turbine blades, and you can have a turbine blade that looks fine but self destructs after 200 hours. As an example, the load on a single turbine blade that's only 3 inches long can be as much as 35 TONS due to the centrifugal force on a turbine spinning at 20,000 rpm at temperatures over 1,100F. Only single crystal nickle-steel can sustain that kind of load for 2,000 hours without fail.

One of the biggest reasons why China is so lagging behind in jet engine is the Culture Revolution, which thousands of scientist/engineers were purged, thus created a talent gap which China took a generation to pick up. By the time China got its sanity back, it's already in the 1970s. Chinese engines have to compete with mature jets already in the market place, and US and UK engines didn't. This let them make profit while they were making junky engines. China doesn't have that luxury.

China has been making jet engines for decades, starting with WP-5 in 1956, which is a licensed copy of Soviet VK-1, which itself a knock-off from Rolls Royce Nene. China and UK signed a license deal in 1974 for the Rolls Royce Spey engine, but since UK committed to transfer technology, but not manufacturing know-how, by the time China overcame all the technical difficulties associated with manufacturing the jet engine, it was already mid-2003. China probably will surpass France by end of the 2020s, as China has multiple engine developments in the pipeline.

Can small private jets fly internationally?

 Yes, they are treated the same way as most general aviation aircraft, and yep, they do it all the time. International flight can be as short as from Buffalo, NY, across the lake to Toronto, Ontario, Canada, or from Arizona to Mexico, and a Cessna Citation X can fly from Detroit, Michigan to Toronto, Canada, or from Phoenix AZ to Mexico City. It does not even need to be a jet. Even you can fly internationally in a Cessna 172.

The smallest business jets are the Very Lights (VLJs) like the Hondajet and Phenom 100, and those aircraft have a max range of 1,500 miles (ish). I’m assuming by international you mean long trips across oceans, and the small jets won’t have life rafts or some cockpit equipment required to fly across the ocean, which is fine because their cabin about the size of a train compartment. Also there’s limited luggage room, potentially filled largely with survival equipment required for 100nm over water flights. From the US to Europe, we’d preferably go Bangor, Maine to Goose Bay to Keflavik, and from there it depends on final destination. In general, trips like this make sense only for ferrying or special purposes.

A private jet can fly around the world with careful planning, but due to the range of most small jets, multiple stops for refueling must be made and the route would have to be carefully planned not only for fuel and range but also to ensure that one is flying within the airspace of friendly countries. It totally depends on the capability of the airplane and the length of the route you are asking about, and whether they are permitted will depend again on the abilities of the airplane, the crew qualifications and on‑board equipment, and will they be permitted to land at the International airport.

In Canada, any general aviation aircraft with fewer than 15 persons aboard and no cargo or commercial goods is cleared through customs and immigration in the same manner. General aviation aircraft are cleared at their fixed base operator, and some airports have a dedicated customs ramp to clear private aircraft. Between 2 and 48 hours prior to arrival, the pilot in command will call the Telephone Reporting Centre with aircraft make, model and registration, last airport of departure, airport of arrival, estimated arrival time, passenger and crew manifest, and declarations. If the aircraft is released, everyone is free to disembark, and if the aircraft is referred for inspection, two or more officers will be dispatched to attend the plane.