Within the framework of the fifth generation fighter program, the aviation industry and the cooperation department must address a complex array of tasks and develop all the necessary equipment. One of the most complex tasks of this scheme is to develop engines with desired performance. A series of countries are developing future power plant solutions, and several models have been pushed into mass production. The following describes the development of the field.

U.S.A
American enterprises began to develop the engines of the fifth generation fighter aircraft, which was completed first, and then entered the mass production and use stage. As a result, the United States won the possibility of announcing a new record and a big lead ahead of its foreign rivals. Just a few days ago, American industry announced a new leap forward.


Figure 1: mass production of F-22A fighters in combat forces

Platt & Whitney Company developed in the framework of the ATF program, now equipped with F-22 fighter F119, is the first new generation of engines in the United states. It has been announced a few days ago that the engine, which has been in use, has a total flight time of 500 thousand hours. "This achievement highlights the capabilities of the existing technology," said Amanda Glod, head of F119's engine program. All of the F-22 fighters that have been produced have been flying for 200 thousand hours since 2005.

Research and development efforts to equip F119 engines for the fifth generation of fighters in the ATF program began as early as 80s. Design contract signed in 1991. A year later, the first F119 test engine was on the test rig. In 1997, the finished product was tested on a test aircraft. The test machines are Lockheed Company's YF-22 and Boeing's YF-23. The latter is not in full compliance with the military's requirements and has been eliminated in the competition. Finally, the F-22 equipped with F119-PW-100 engines was put into mass production.

The mass production F-22 fighter is equipped with 2 F119-PW-100 engines. It is a turbofan engine with afterburner and deflection nozzle (which can control thrust vectoring with single plane). The engine adopts double axle layout, and the rotor of high voltage and low voltage reverse rotation. Low pressure compressor has three grades, high pressure compressor has six levels. The nozzle is flat and has a deflection plate, which can adjust the thrust vector direction.

The total length of the F119-PW-100 engine is close to 5.2 meters, the maximum diameter is less than 1.2 meters, and the weight is 1.8 tons. The turbine inlet temperature is 1647 degrees. Thrust force is 15876 kg (16785 kg). According to the official news, the 2 F119-PW-100 engine can ensure the fighter thrust weight ratio of not less than 0.88. In the normal take-off weight under the thrust weight ratio was 1.15. The speed of the flight can be accelerated to 2410 kilometers. With no afterburner, the flight speed can reach 1960 kilometers per hour. The radius of operation is 760 kilometers, and the distance is 2960 kilometers.


Figure 2: F119 test engines with controllable nozzles

According to available data, Pu & Hui company has so far produced more than 500 units of various types of F-119 engines. First it was equipped with several F-22 test machines, and later installed in mass production aircraft. F-22 produced a total of 195, of which 187 were delivered to the air force. According to the latest information, the F-22 fighter has been flying for 200 thousand hours since it was officially put into use. At the same time, including test flight, the engine has a total operating time of 500 thousand hours. Thus, as the first mass production engine of the fifth generation fighter, the record created by F119 will not be broken in the near future.

As a complement to the expensive F-22 heavy fighter, Lockheed Martin developed the F-35 fighter. General & Hui company has developed the F135 turbojet engine for the aircraft. The engine was developed in 90s and completed in the mid 2000s. The F135 engine was developed on the basis of F119, so it was originally called F119-JSF (JSF is the name of the fighter R & D program).
F119-JSF \/ F135's first mass production prototype was made in 2007. Subsequent trimming continued, resulting in significant delays in project progress. But general & Wyeth supplied 100th F135 by 2013. At this point, the main problems were successfully eliminated and three engine modifications for three F-35 modifications were put into mass production.

As further development of existing products, F135 retains its basic characteristics. With dual loop scheme, the compressor series are the same. A single-stage high-pressure turbine is retained, so a new two stage turbine is used in the low voltage circuit. With the help of various supplementary devices or techniques, three types of engines have been developed: F135-PW-100, F135-PW-400 and F135-PW-600.


Figure 3: F-35 fighters in flight

The PW-100 engine is the basic product of this series, which is installed on the air force F-35A aircraft. The engine is 5.6 meters long, not more than 1.17 meters in diameter and weighs 1.7 tons. The maximum thrust is 13000 kg and the thrust is 19500 kg when the thrust is applied. On the basis of it, a F135-PW-400 engine equipped with F-35C based fighter is developed. The only significant difference between the engines is the use of enhanced corrosion resistant coatings. All performance indicators remain unchanged.

F-35B aircraft using 135-PW-600 engine, can short takeoff, vertical landing. Compared with the basic type, this type of engine has important difference. The utility model has a deflection nozzle which can change the thrust direction vertically and downwards. In addition, an additional drive shaft and a rotating lift fan are drawn forward from the engine. With this modification, the engine length increased to 9.37 meters, of which 1.35 meters were the largest part of the lift fan. The maximum thrust is 12250 kg and the thrust is 18600 kg when the thrust is applied.

The first frames of the F-35 series were made in 2006 and lifted off. In the past, the three types of aircraft have entered the production stage, has been produced and delivered to more than 230 users. All of these aircraft are single aircraft. The maximum flight speed is believed to be 1930 kilometers per hour. The aircraft can fly at 1470 kilometers per hour without force augmentation. The radius of operation is 1400 kilometers, and the range is not less than 2200 kilometers.


Figure 4: a F135-PW-600 engine with a lift fan

Therefore, the United States has begun to work in other countries, and has successfully developed and produced two turbojet engines for the fifth generation of fighter aircraft. These products are produced in large quantities and are already serving the armed forces.

China
China has made great achievements in the field of fifth generation fighter and engine research and development. At present, China's industrial circles are developing two aircraft models at the same time, and developing necessary equipment for them. But in the field of engine manufacturing, it's another case. China has limited capacity in the field of modern aero engine research and development, so it has to actively use foreign products.

In January 2011, the J-20 fifth generation fighter flew successfully. At present, several test machines with different configurations and on-board equipment have been fabricated and tested. For example, the J-20 test machine has two versions of power plants, namely domestic and imported engines.
There have been news of China's purchase of a highly rated Russian AL-31F engine. This type of engine will always be used by aircraft to start mass production, and domestic engines with the same performance will come out. There is also news that Chinese aircraft may be using the latest modifications of the WS-10 engine. It was developed on the basis of AL-31 engine.


Figure 5: the J-20 flight

According to the latest information, mass J-20 aircraft will be equipped with the WS-15 turbojet engine currently under development. The WS-15 project started as early as 90s, and the test-bed test began in the middle of 2000s. By the end of the 2000s, some achievements had been made. Earlier, foreign professional publications had speculated that the WS-15 project was trying to copy the American F119 engine. There are rumours that China intends to copy the latest modifications of the Russian AL-31 series engine.

According to available data, WS-15 products are turbofan engines with afterburner. It has been reported that it uses three stage low pressure compressor and six stage high pressure compressor. The total length of the engine is greater than 5 meters, and the turbine inlet temperature is about 1600 degrees Celsius. The thrust is planned to reach 19000 to 20000 kilograms.

According to the assessment, equipped with two WS-15 engine, J-20 fighter thrust weight ratio will be not less than 1.05. The maximum flight speed of 2100 km. It is not clear whether speeding up to supersonic speed without force. What is the performance of a production aircraft equipped with a trimmed engine is unknown for the time being.

The fifth generation of light fighter J-31 has continued its test flight since 2012. According to available information, at least for a certain period of time, the special configuration of the machine has been tested. The machine is equipped with two RD-93 turbojet engines. In 2000s, China straightened out the production of the Chinese version of the RD-93 engine, WS-13. For the foreseeable future, plan to equip the J-31 aircraft with an improved WS-13E engine.


Figure 6: the J-31 light fighter at the airshow

According to previously released news, the WS-13E engine will be a dual axis turbofan engine, which is further developed by the RD-93. WS-13 basic type of mass production products have eight high pressure and low pressure compressor. The length is less than 4.2 meters, the diameter is about 1 meters, and weighs 1.14 tons. The maximum thrust of the existing product is more than 8800 kg when the force is applied. The plan increases thrust to 9000-9100 kg when the new WS-13 is powered up.

Due to understandable reasons, the accuracy of WS-13E and WS-15's future projects has not been announced. China's defence industry traditionally maintains its own primary secrets and is not eager to announce the most interesting information about new projects.

Russia
Russian industry continues to tackle its fifth generation fighter, the T-50. A future engine with higher performance and new capabilities is also being developed within the framework of a large-scale program. But the complexity of the work has led to the fact that test aircraft have to be equipped with an acceptable model of existing engines. T-50's prototype is temporarily equipped with the AL-41F1 turbojet engine. Plan the next step to complete a new engine that is temporarily called "product 30" or "type 30", and put it into mass production.

In the T-50 program, "product 30" is considered the second stage engine. "Product 30" is only a temporary code of work, and the next step may be to use the new code at the beginning of the AL. Earlier reports had already drawn up design data and had begun assembling test engines. By the end of this year, "product 30" will be installed on the experimental aircraft for the first flight. New tests are planned for the next few years and national trials in 2020.


Figure 7:T-50 one of the test machines

A few days ago, the Russian newspaper "newspaper" reveals new details from lyulika anonymous sources on the "30 products" the progress of the project: the company is the three class ground work, in order to complete the task in a predetermined period before, to ensure strict implementation of the schedule. At the same time, there are some problems with the collaboration unit: the engine control unit, the supplier, has not completed its task. Upon completion of the current work, the test engine is scheduled to be installed on the flight test room for flight test. The first test flight is planned for November 6th. However, the test schedule is likely to be adjusted if the collaboration unit fails to complete its tasks as planned.

"The newspaper reported that" the sources also confirmed that the AL-41F1 engine and the future of these existing products have significant difference: using new type of turbine and full digital control system, it will achieve greater thrust, lower fuel consumption targets. All of this will enable the aircraft equipped with "product 30" to fly supersonic without the use of force, which will have a positive effect on the use of the aircraft as a whole.

According to various data, the maximum thrust will reach 11000 kg when the engine does not operate in the future, and it will reach 18000 kg when it is powered up. Thus, the T-50 aircraft will not be less than 1 weight ratio (depending on the maximum takeoff weight), flight speed is estimated to be 2500-2600 kilometers, non afterburning maximum flight speed of 2000 kilometers per hour. The type 30 engine will be equipped with a deflection nozzle that can control thrust vectoring. This will allow the aircraft to be more maneuverable in all flight conditions.


Figure 8:T-50 the AL-41-F1 engine used on the prototype

Epilogue
Although radio electronic systems are growing rapidly and increasing in importance, the engine will remain one of the most important and complex parts of the future aircraft. The special requirements for the fifth generation fighter also put forward the corresponding requirements for engine manufacturing. Designers need to perform particularly complex tasks, otherwise they can not meet all the requirements of the user, and can not develop aircraft with the desired performance.

At present, a number of countries are tackling their own fifth generation fighter at the same time, but far from being fully planned. Not only that, at present, only one country's fifth generation fighter aircraft has been put into mass production. Other countries are still in the experimental phase or the experimental design stage. But it is clear that the United States will be broken in the next few years, because a number of foreign models may soon be put into mass production.

The situation of engines used in future fighters looks similar, but there is a clear difference. For example, the United States already has two models of mass production engines, one of which has three modifications. Russia has only one model in preparation for testing. The progress of China's project is almost unknown. At the same time, it is clear that the future of the engine and its supporting equipment research and development continue, and gradually achieved rapid results. The ultimate goal of all projects is to start mass production of new engines for mass production aircraft. Two new generation engines have completed the task, and others need to continue their efforts.

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