“Jet Engine” is the most critical component – core technology – of Jet fighters. Ipso facto, India remains a laggard in designing, developing, and transferring technology for the indigenous production of jet fighters. Consequently, the capability of the Indian Air Force is dependent on foreign sources.
An attempt is made to provide a “Perspective” covering “Top Jet Fighter Engines” capabilities and their future growth besides India’s quest for jet fighter engines. Per se, Jet Fighter Engine comparison variables include thrust-to-weight ratio; Dry thrust ratio; maximum thrust achievable on dry power; After Burner; Bypass; Fuel consumption; Mechanical reliability and maintainability to include Service Life; and IR Signature.
The USA heads the list with its F-135 (CTOL) for F-35 (N/cm2 (191.35 kN, 10.715 cm2); and F-135 (STOL) for vertical takeoff (182.4 kN, N/cm 210.715 cm2). Its GE F404 (78.7 kN, 3.959 cm2) and F-414-400:N/cm2 (97.37 kN, 4.745 cm2) are way behind. India has been supplied with upgraded GE F404 engines (85kN thrust) to power India’s Tejas Mk-1 and Tejas Mk1A. On offer for Tejas Mk-2 and the AMA is an upgraded version of the GE F-414 INS6 engine (110 kN).
By contrast, China has made significant progress in jet engine technologies, particularly by reverse engineering. China has indigenized AL-31FM2 for Chengdu J-20 (142.2 kN, 31,970 lbf); AL-31FN Series 3 for Chengdu J-10B (134.35 kN, 30,203 lbf); AL-31FN for Chengdu J-10 (124.54 kN, 27,998 lbf). Moreover, China has developed WS-10A Taihang for Chengdu J-10/Shenyang J-11 (120–140 kN, 27,000–31,000 lbfm). Most importantly, China has under development WS-15 Emei for Chengdu J-20 (156 kN, 35,000 lbf); and WS-19 Huangshan for J-35 fighters (98.1 kN, 22,100 lbf). China has also developed WS-10B for JF-17s (135 kN, 30,000 lbf by Janes in 2020] and (144 kN, 32,000 lbf, by Chinese media).
Next, JF-17 Thunder was inducted into the Pakistan Air Force in 2010. The earlier fighters were powered by the RD-33 (78 to 88 kN; 18,000 to 20,000 lbf) thrust class. Its successor the RD-93MA originally intended to be used in the JF-17 Block-III failed to cut. WS-13 Taishan, an upgrade of RD-93, with a thrust output of (86.37 kN, 19,420 lbf), a lifespan of 2,200 hours, and a thrust-to-weight ratio of 8.7 is reportedly powering the latest JF-17s. An improved version of the WS-13, with (100 kN, 22,000 lbf), is also reportedly under development. Also, inducted are the Chinese J-10CE fighters with far superior engine characteristics (Shenyang WS-10 140kN).
Next, the “Top Jet Engines” of Russia includes AL-51 for Su-57M (107.9 kN, 24,300 lbf for dry and 166.8 kNn 37,500 lbf in afterburner); AL-41F (176 kN, 40,000 lbf); AL-41F-1S 117S for Su-35 and Su-30SM2 (142.2 kN, 31,970 lbf); AL-41F1(11&) and AL-41F: N/cm2 (175 kN, 6.433 cm2) for Su-57, Su-70 (147.1 kN, 3,070 lbf); AL-31F: N/cm2 (122.58 kN, 6.433 cm2); AL-31FP (122.6 kN, 27,560 lbf) for Su-MKI India; etc.
Also featuring in the “Top Jet Engines” includes: EJ200:N/cm2 (3.848 cm2, 90 kN) for Eurofighter Typhoon by Rolls Royce; M88-2:N/cm2 (3.805 cm2, 73.9 kN) for French Rafale; and RM-12 (Gripen A/B/C/D) (3.948 cm2, 80.5 kN) Sweden.
Japan too is domestically developing the XF9 engine (107 kN/24,000 lbf or more in dry) and (147 kN /33,000 lbf or more with afterburner). Under development for the future fighter engine program is a target of a maximum thrust of 20 tons (196 kN / 44,000 lbf).
Where does India stand in the jet engine technology race to achieve over 190 kN/40,000lbf capability? Despite Hindustan Aeronautics Limited (HAL), Gas Turbine Research Establishment (GTRE), DRDO with Aeronautical Development Agency (ADA), Aeronautical Development Establishment (ADE), and many other labs, India lacks an innovation ecosystem that is competent to design, develop and build high-tech jet engine technologies.
Of course, India has developed advanced radars, BVRAAMs, digital fly-by-wire (DFBW) Flight Control System (FCS), Digital Flight Control Computer (DFCC), a quad-redundant flight critical system, OFP software, pilot-in-the-loop flight simulation facility and other systems for jet fighters
Some of the fundamentals are highlighted. Jet engines are complex machinery: advanced materials and process technology, combustion technology, and Computational Fluid Dynamics (CFD) in engine design procedures – containing at least 30,000 moving and static parts, requiring high-end metallurgy research as well as a very high degree of precision and skill in forging, casting, and machining. Now, they have improved turbine inlet temperature and compressor pressure ratio. The core functional aspect of the turbine has been transformed with a greater bypass ratio and nacelle performance which also boosts emissions. Once designed and put together, jet engines require extensive testing in wind tunnels and subsequently on flying test beds, having to clock hundreds and thousands of hours to understand the fatigue characteristics and the degradation of each part. Nations avoid the transfer of technology easily.
Next, the superalloys – higher heat-resistance materials – must withstand combustion heat beyond 1,800°C to generate 110-kN dry and 130-kN wet thrust or higher. India lacks proven silicon carbide (SiC) and ceramic matrix composite materials which are a choice for aerospace structural parts. Also, alloying elements are Ni-based superalloys like cobalt, chromium, aluminum, titanium, iron, molybdenum, niobium, tantalum, tungsten, ruthenium, and hafnium. Nickel-based superalloys – for the turbine blades and turbine disks – are often used in jet engine turbines, where they perform well at high temperatures. Most engines use titanium because it has a high strength-to-weight ratio. The low-pressure compressor blades and several high-pressure compressor blades are made of Ti-6Al-4V alloys which are also used for the fan blade. Turbofan engines are widely used in modern fighter jets. They use a combination of a bypass fan and a core engine. The bypass fan draws in and accelerates a large amount of air, creating additional thrust. This design provides better fuel efficiency and reduced noise compared to turbojets.
Yet another significant feature concerns the engine’s life that depends on design life. Modern fighter jets are designed to withstand 8,000 hours of flight time during their operational lifespan. This means that with an average of 200 hours in the air per year, they can continue to perform well for 30–40 years. Life span depends on various factors including Overhaul Cycles; Flight Time; and Engine Life. During overhaul cycles, engine parts are inspected, repaired, or replaced to restore functionality. The time between overhauls (TBO) varies by engine type and category – 6,000 hours or more. The hot section is inspected and overhauled every 2,000 hours, and the cold section is inspected and overhauled every 4,000 hours.
Although a new design and test facility at the HAL Aero Engine Research and Development Centre (AERDC) was inaugurated in Bengaluru in December 2023, it has to send its jet engines to Russia for testing under simulated conditions of high altitudes. This process is time-consuming.
Ipso facto, India is way behind other countries that are manufacturing jet fighters, particularly China and also arch-rival Pakistan. The current Indian plan includes: The upgradation of Su 30-MKI (Super Cruise capability); Tejas Mk-1, Tejas Mk-1A, Tejas Mk-2 LCAs; and AMCA Gen-5 fighter. GE F404 engines (85kN thrust) to power Tejas Mk-1 and Tejas Mk1A. The LCA Mark-2 project is expected to use a GE F-414 IN engine (110 kN). The first batch of AMCA Mk1 is to be powered by the GE F414 IN.
41x F404 engines were ordered between 2004 and 2007 for the first two squadrons of the TEJAS MK-1. A $716-million contract was signed by GE with HAL for 99xF404 engines for 83 MK-1A variants in 2021 to be delivered by 2027 – a total of 123 Jets worth 6 fighters and 1 training squadron – to replace 6 of the 8 MiG-21 fighter squadrons.
For the LCA Mk-2, the contract for 100xF414-GE-INS6 is to be signed very soon with 80% technology transfer to include critical technologies, enabling “greater transfer of US jet engine technology than ever before. The LCA Mark-2 is supposed to replace the Mirage 2000 (3 squadrons), the MiG-29s (5 squadrons) the Jaguar strike aircraft (6 squadrons), and the 2 remaining MiG-21 Bis squadrons. India needs to order at least 8-10 LCA Mark-2 squadrons (150-180 planes) by 2025 and the rest is made up by the AMCA production line if it starts in 2030.
The first batch of AMCA Mk1 is expected to be powered by the GE F414 IN. GE has submitted a proposal for the co-development of a 110 kN thrust engine with Indian agencies. Technologies developed for a 116 kN thrust derivative of GE’s F414 engine will be the baseline in this offer of cooperation. Following the recent approval of the AMCA, a stealth fighter Gen 5 aircraft, the DRDO is hopeful of finalizing a deal for the new engine for the program by 2025. As per reports, the GE F414 engine is also underpowered to meet all the requirements of IAF in the medium-weight fighter class of 15–18-ton range to enable a 5-ton combat payload and a combat range of 600 km on internal fuel. Even the AMCA/TED BF are all slated to be powered by GE F414 IN, which would limit the size and payload as well as the range of the fighter jets by design.
Even the ongoing talks with the French engine manufacturer Safran and the British engine manufacturer Rolls Royce are to co-develop a 110 kN engine with the flexibility to produce up to 130 kgs of thrust for its indigenous AMCA and 6th generation fighter programs. Safran recently offered to set up a production line in India for their Snecma M88 engine that powers the Dassault Rafale in an attempt to make the Rafale aircraft more lucrative in the tender for 114 Multi-Role Fighter aircraft (MRFA). Safran is already heavily investing in 6th-generation fighter aircraft with an afterburner thrust of 125 kN.
Recently the CCS gave its approval to over Rs.26,000 crore for the procurement of 240 AL-31FP (27,560 lbf, 122.6 kN with an assigned life of 4,000 hours and an MTBO of 1,000 to 1,500 hours) aero-engines for IAFs Su-30 MKI under the “Buy Indian Category with the HAL as the supplier. The new batch of AL-31GP engines will come equipped with Full Authority Digital Engine Control (FADEC) aimed at enhancing the operational efficiency and performance of the Su-30 fleet. Currently, the AL-31FP engines feature less than 54%indigenous content.
Therefore, the key issue that needs to be addressed is simple. Are the present plans adequate to build the IAFs jet engine capabilities to match Chinese not only the AL-31 and WS-10 series but also the under-development WS-15 Emei for Chengdu J-20 stealth fighter (156 kN, 35,000 lbf). China has also developed WS-10B for JF-17 Thunder (135 kN, 30,000 lbf by Janes in 2020] and (144 kN, 32,000 lbf by Chinese media).
If so, India needs to make at least a 130 KN (dry thrust) engine if not a 156 kN engine, either indigenously or as a licensed assembly. In retrospect, for the AMCA, a jet engine of 180 KN (wet) at one of the highest fuel efficiencies currently available in jet engines is the requirement.
The choices available are simple. It can be done either by forging a deal with the USA to use the GE F136/XA100 models which are developed to the prototype stage or by a deal with Russia to use AL-51 (107.9 kN, 24,300 lbf in dry, and 166.8 kN, 37,500 lbf in afterburner)/AL-41F (176 kN, 40,000 lbf). Both models can be pursued through diplomatic means.
Simultaneously, entrust jet engine development to Private Indian and foreign companies with 100% FDI automatically allowed in the design and production of a jet engine. India should set aside at least $ 500 million (nearly Rs.4200.00 crore) for such an engine project. Meanwhile, acquire 2x squadrons of Gen-5 jet fighters either from the USA or Russia most urgently to match China’s J-20 Gen-5 fighters.
In conclusion, the Indian jet engine program is in desperate need of a boost as the future of the AMCA program is at stake. An entirely new engine needs to be developed in collaboration with a foreign partner. Simultaneously, resort to “reverse engineering” like the Chinese to upgrade available engines.
