Tongdao Think Tank 2024-02-07 11:29 Shanxi
According to the Sandbox on February 5, the quality of a fighter depends on the engine that powers it. The United States is able to effectively deploy a sufficient number of such advanced engines to equip a fleet of high-end fighter jets. Russia announced in December last year that its domestically produced fifth-generation engine, known in most international circles as the Saturn AL-51, will also reach mass production in 2024. The addition of these new engines will bring a significant improvement in the combat performance and stealth of the Russian Su-57 - a problem that is more difficult for Russian fifth-generation jets to solve than other jets of its class.
Breakthrough engine for the F-22
Despite the general focus on stealth and a lesser degree of data fusion in today's fighter jets, the U.S. turbofan engine advantage is equally valuable, and it stands out to the rest through a combination of high power output and well-designed radar and infrared detection mitigation.
Development of Pratt & Whitney's F119 turbofan engine began in 1983, which later became the engine for the world's first fifth-generation fighter, and both GE and Pratt & Whitney were awarded prototyping contracts.
GE has been a clear leader in aircraft engine deployment, having successfully retrofitted the F404 turbofan engine, originally developed for the F-18 Hornet, to perform stealth missions on the F-117 Nighthawk. The company has also developed the B-2Spirit's F118 turbofan engine, a non-afterburner derivative of the F110 engine with greater stealth and has been in service with a variety of fighter jets over the years, including the F-16, F-15E and the new F-110 engine.
GE's incredible forward-leaning YF120 engine design delivers higher performance, thanks in large part to its groundbreaking variable-cycle design that uses a bypass tube to allow the engine to work like a low-bypass turbofan engine in most flight conditions, but transitioning to near-full turbojet functionality at high altitudes would be more efficient.
But this high-tech approach is just as weight-loss and complex as Pratt & Whitney's more solid but still groundbreaking proposals.
Pratt & Whitney's YF119 may be a little more pragmatic, but it doesn't lack technological advancements. The YF119 draws on previous developments in the U.S. Army's Advanced Turbo Engine Inflator (ATEG) program to provide optimal efficiency for turbofan blade forming, and draws on the Joint Technology Demonstration Engine (JTDE) program to reduce the power output required for the same number of stages. As a result, Pratt & Whitney's revolutionary new engine design can reduce the number of compressor stages from 10 to just 6 for engines such as the F100, resulting in a 22 percent increase in thrust output for engine designs and a 40 percent reduction in the number of parts.
Their YF119 is designed with a multivariate, linear secondary regulator control system that enables extremely precise engine control in all flight conditions, maximizing efficiency and performance in almost all situations, and is equipped with an active management toolset and new reliability tracking systems, such as the Oil Chip Monitoring Sensor, which provides an estimated estimate of engine wear to further simplify and reduce maintenance and repair requirements.
Its three-zone afterburner places the fuel injectors in thick, curved blades designed to block the turbine's view; The blades are coated with early ceramic-based radar absorbing materials to further reduce radar detection. Engine nozzles provide 20° thrust vectoring for incredible aerobatic performance, better control at high altitudes, and more efficient flight at higher angles of attack, using wedge flaps to reduce radar echoes, while also helping to actively mix engine exhaust with ambient air to reduce thermal (or infrared) detectability.
When the YF-22 and its YF119 engines matured into the F-22 and F119, they represented the most advanced airframe combination of any fighter engine in history, with unprecedented thrust vector maneuverability, twice the thrust of Pratt & Whitney's claimed current-state turbofan engines in supersonic flight.
These new F119 engines have a greater power output under afterburner than the J58 that powers the SR-71 Blackbird, so they can output more thrust at standard military power (about 26,000 pounds each) than the F-15C engine at afterburner start. In fact, the F-22 has enough power not only to maintain supersonic speed under military force, but also to accelerate to more than Mach 1 without the use of afterburner at all. It can even maintain up to 1Mach 8 speed.
In short, the F119, exactly like the F-22, provides the United States with a decisive air superiority.
Russian Al-51
Russia's premier ** fighter - Sukhoi Su-57, went through a difficult development and production cycle, but the fact is that with a fighter like the F-22 to some extent distorts the perception of a major leap in Russian aviation technology.
Allegedly, although on the radar screen the design of the Su-57 is estimated to be thousands of times larger than the F-22, on the radar it is estimated that it is 16-30 times smaller than its predecessor, and the Su-27 - despite being far behind its foreign counterparts, still marks a significant design improvement. Still, stealth is only one of the many areas where the Su-57 program is in trouble - while production can easily become the main drawback of this aircraft (less than 57 Su-20 have been in service so far), Russia's long-standing problems with fifth-generation engines could have serious consequences for the aircraft.
The few Su-57s currently in service with Russia have an updated version of the thrust vectoring AL-41F1 engine, which also powers the country's *** Su-35S. This turbofan engine has been flying since the 80s of the 20th century, although it included an updated engine control system before it was installed on the felon.
While these engines are outdated, they produce considerable power under the afterburner, with each turbofan engine in the Su-57's fuselage capable of outputting about 32,000 pounds of thrust, almost as much as the F119 that powers the F-22, but the Russian engine had only 19,900 pounds of thrust before the military had military power, while the F119 had a whopping 26,000 pounds of thrust.
Thus, Russia claims that the Su-57 can conduct a supercruise, but its performance by American standards practically does not live up to this designation. The US Air Force considers "super cruise" to mean 1Fly at Mach 5 or higher, as many American *** fighters can actually temporarily maintain a lower supersonic speed without afterburner. However, Russia considers any supersonic flight without afterburner to be a "supercruise", so although the Su-57 may only reach 1 in dry flightAround Mach 3.
To make matters worse, however, these engines are not designed for ** applications, so Russian ** fighters are more easily detected by radar and infrared systems due to the omission of radar echo mitigation nozzles or the active mixing of exhaust gases with the surrounding environment. In short, the Su-57 may be a capable fighter, but it is not a ** fighter, and its engine is an important component of this problem.
This is where Al-51 finally comes into play. Although the Su-57 began flying in 2010, the engines that power it did not begin to be officially developed until 2015, and it is planned to begin installing it in the fuselage later this year. It is widely claimed in Russia that these new engines are comparable to or even more advanced than the American fifth-generation engines.
The Russian report emphasizes that these new AL-51 engines will be very powerful. Its non-afterburner thrust is about 24,300 pounds, which is slightly lower than that of the Raptor, but the afterburn power is a whopping 37,500 pounds. Since the beginning of the program, the Russians have claimed that significant improvements in serviceability and fuel efficiency have also been made, which seems to coincide with the stage of development of their efforts, but interestingly, there is little official discussion about any ** improved design of the new engine.
Some analysts say that these Al-51s seem to help the Su-57 further ahead of the ***
Another turbofan revolution: the adaptive cycle engine
Back in 2016, the U.S. Air Force Life Cycle Management Center Advancement Bureau quietly awarded new development contracts to GE and Pratt & Whitney to deploy next-generation turbofan engines, which are designed to power the next generation of ** fighter jets.
Historically, each turbofan design has represented a variety of compromises, including the need to balance high-end power output with remote efficiency. As a result, turbofan engines designed for cargo planes, spy planes, and more tend to prioritize fuel economy over power generation, while fighter engine prioritizes high-end performance over range. However, adaptive cycle engines, such as those being developed in the AETP program, are designed to abandon this compromise.
"The Air Force's goal is to develop next-generation fighter engine architectures and technologies to enable a generational leap in combat propulsion capabilities," said David Tweedy, general manager of GeedisonWorks Advanced Combat Engines. ”
The program, known as the Adaptive Engine Transition Program (AETP), will increase the thrust ratio by a modest 10 percent for the F135, along with a 25 percent increase in range and a significant increase in thermal management.
To achieve this, these new engines are designed to operate in different functional "modes". When pilots need the engine to perform at its best in combat, they can press the throttle harder, and the engine's management system will switch to re-ignition high-thrust mode for maximum power as prompted. Instead, while on patrol, the engine will remain in an efficient, low-burn mode to extend the mileage or loitering time provided per gallon of fuel.
In May 2021, GE's XA100 adaptive cycle engine roared out and immediately surpassed the Air Force's targets. Tweedy said they saw a more than 10 percent increase in thrust for almost the entire flight envelope, and a 20 percent increase in thrust in some areas. But thrust isn't the only area where the XA100 excels. By operating in different propulsion modes, the engine also offers a huge economic boost.
When you translate that into meaning for the platform, you'll see a 30% increase in range, or a 50% increase in loitering time, depending on how you want to take advantage of fuel burn improvements. With an increase in thrust, acceleration and combat capabilities increase significantly. ”
At one point, the Pentagon even evaluated adding these advanced new engines to the F-35 as part of its Block 4 upgrade. In the end, the US Department of Defense chose the cheaper route of simply upgrading the existing F135.
The updated engines, which will feature advanced composite and ceramic-based materials to reduce weight and further enhance their thermal management capabilities, are expected to be put into service in time to power the next generation of air supremacy fighters, Snedon said.
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