Outgoing Air Chief Marshal Birender Singh Dhanoa probably in his last interview to the Indian media as Chief of Indian Air Force had high praise for American engine which powers LCA-Tejas fighter jet making it first instance where General Electric developed F404 turbofan engines got rare praise from the Air chief himself. Dhanoa while speaking at India today conclave praised F404-GE-IN20 engines which power production LCA-Tejas Mk1 fighter jets and will also be powering its upgraded Mk1A variant which IAF will order from HAL soon.

Dhanoa said that F404-GE-IN20 engines have excellent fuel efficiency which he has rarely seen among contemporary fighter jets he has flown. Dhanoa who is a Mig-21 Veteran compared MiG-21bis’s R-25 engine with F404-GE-IN20 and said that fuel efficiency you had from F404 at 8000 feet altitude you only get that around 30000 feet altitude when flying a MiG-21.

All fighter jets theoretically when flying at higher altitudes have lower fuel consumption due to lower throttle frictions due to the wider throttle opening as the air is less dense at higher altitudes and this also leads to lower fuel consumption but at low altitudes the fuel consumption is very high and the true airspeed relatively low, due to the high air density . theoretically, fighter jet flying at 8000 feet altitude will burn about double the amount of fuel then jet which is flying at 30000 feet altitude and above.

MiG-21bis’s R-25 engine which were designed in the early ’50s is not really a great benchmark to compare it to a modern engine which was designed in early 80s but F-404 has received numerous technical upgrades to keep them in pace with similar engines and the comparison more has to do with two-point defense Interceptor which was designed to replace the former in the airforce fleet.

Mig-21 and LCA-Tejas fighter jets both designed as a point defense Interceptor aircraft are small and nimble in characters due to which they have smaller internal fuel carrying capability. Mig-21 Pilots in Combat Air Patrol (CAP) missions usually took off at high speeds and gain altitudes quickly to intercept incoming threats and also that he can have enough fuel to carry out Intercept and return to the base well under 1 hour of combat range of the aircraft.

F404-GE-IN20 engines have performed better than expected in numerous times and even surprised designers of the LCA-Tejas who had factored in lower ferry and combat range. People who have flown LCA-Tejas Mk1 fighter jets coming from Mig-21 and Mirage-2000 flying background in past have called it better than M53-5 P2 turbofan engine which powers Mirage-2000 in terms of operational performance and fuel efficacy.

In numerous sorties in far fledged areas of India, while the aircraft was in trials, LCA-Tejas Mk1 was not only able to demonstrate better ferry range then what engineers had expected but also demonstrated that it can safely operate under different weather conditions. LCA due to better Thrust to Weight Ratio ( 1.07 vs Migs 0.7) has a better climb rate, less drag and requires less take off-speed and landing distance. LCA has a balanced performance in all speed regimes due to which it has better fuel efficiency then Mig-21 flying at lower altitudes. GE engineers and HAL/ADA engineers have worked in tandem to get optimum performance from the engine at various speed regimes and altitudes and LCA-Tejas jet has surprised them with better performance than expected.

The history behind the selection of LCA-Tejas Engine

In the early ’90s when India was scouting for fighter jet engines to power its LCA-Tejas fighter jets, then Russia had offered India’s its Klimov RD-33 turbofan engine which powered IAF’s Mig-29 fleet but poor operational availability record and spares issues insured that using not so reliable RD-33 engine on single-engine fighter configuration like LCA-Tejas was pretty dim from the start .

French reportedly had offered India it’s M53-5 P2 turbofan engine which powers its Mirage-2000 aircraft and was leading the race it time french existed LCA-Tejas Program when it was still in advance stages in the early ’90s. Later French was not so forward in offering their engines without their collaboration on the program which made India look towards Great Britain and Turbo-Union RB199 turbofan jet engine used exclusively on Panavia Tornado was considered for a while but it was not designed for single-engine configuration and could have required heavy modifications to make it a safer engine for single-engine fighter jet-like LCA-Tejas.

General Electric F404 engines were initially designed for Lockheed F-117 Nighthawk and McDonnell Douglas F/A-18 Hornet both in twin-engine configuration but by 90’s it was also to power Northrop F-20 Tiger-shark which was cancelled but did power early prototypes and later GE later also signed up to provide engines for the SAAB’s Gripen fighter jet program and had carried out necessary safety checks to ensure that it can be used on single-engine fighter jets like Gripen and were actively also scouting for more buyers for the same engine.

Warming of the relationships with Washington and New Delhi ensured that Indian Air Force for the first time had given the go-ahead to procure and fly American jet engines for the first time in fighter jets developed by India.

General Electric had supplied India, 8 baseline F404 engines in the mid-’90s but Pokhran-II Nuclear tests in 1998 by India ensured that American military sanctions followed soon and supply of spares and services were suspended by GE on orders from US Government . 8 engines supplied by GE to India remained operational and Indian engineers regularly carried out periodic inspections and service of the engines and also carried out engine runs in-ground test-beds to keep them ready in anticipation of the first flight of the LCA-Tejas which happened in 2001.

By the time American military sanctions were lifted off India. GE engineers on a visit to India found 4-5 engines still in airworthy conditions and stringent service intervals and proper following of the service manuals by Indian engineers ensured that over 50% of them remain active while one was out of service due to core damage and other two had been cannibalized for spares.

General Electric later supplied India with LCA-Tejas specific enhanced F404-GE-IN20 engines to India which had better thrust levels and had additional safety measures for single-engine operations, especially for extreme Indian weather conditions. F404-GE-IN20 engines will not only power 40 Tejas Mk1 fighter jets but will also power 83 Tejas Mk1A. HAL’s SPORT LIFT Trainer variant will also be powered by the same engines and upgraded F-414 engines will be used on upcoming MWF-Mk2, Navy-Mk2 fighter jets and also on early prototypes of 5th generation AMCA fighter jets.

Safety Record

F404-GE-IN20 engines have ensured that in 18 years of LCA-Tejas flight development trial program not a single aircraft has been lost due to in-flight engine failure.

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