With limited presence of foreign exhibitors, Indian companies dominated the show
Prasun K. Sengupta
Compared to its predecessors, the 14th Aero India expo was a heavily truncated event with the traditional static outdoor exhibits displaying only a few products developed by the ministry of defence-owned Hindustan Aeronautics Ltd (HAL) and Bharat Electronics Ltd (BEL). The foreign exhibitors had only a symbolic presence. This was due to the expo’s dates being announced only last October after the conclusion of the earlier-postponed Defexpo-2022 at Gandhinagar, Gujarat that same month, which had lavishly laid-out outdoor exhibits by the defence R&D organisation, BrahMos Aerospace, Larsen & Toubro, etc. And since HAL was nominated by the MoD to be the nodal agency for organising Aero India 2023, it used this opportunity to maximise public exposure of its military-technical/ military-industrial activities.
Tejas Mk.1 Variants
The Indian Air Force (IAF), which presently operates two squadrons of the Tejas Mk.1 light multi-role combat aircraft (L-MRCA)—32 single-seaters and eight tandem-seaters–in February 2021 placed orders for 83 Tejas Mk1A L-MRCAs (73 single-seaters and 10 tandem-seaters) worth Rs 45,696 crore, with deliveries to commence next August at a rate of 16 per annum and concluding in 2029. Each single-seater will have an acquisition cost of Rs.309 crore (USD 42 million), while the tandem-seater will cost Rs.280 crore (USD 38 million).
About 85 private-sector vendors are involved in the production of Tejas Mk.1A with tier-1 enterprises including Bengaluru-based Dynamatic Technologies Ltd (front fuselage), Hyderabad-based VEM Technologies (centre fuselage), Adani Defence & Aerospace-owned and Bengaluru-based Alpha Tocol (rear fuselage), Coimbatore-based Larsen & Toubro or L & T (wings), while the tail-fin and rudder will be supplied by the National Aerospace Laboratory and Tata Advanced Materials Ltd.
As of date, 463 vendors are partnering for the project, including five tier-1 enterprises. Of the current vendors, 230 are in Karnataka and 131 of them are MSMEs. The indigenous content in the aircraft is presently about 52 per cent and the HAL is looking at ways to increase it in the raw materials to 65 per cent. Out of the Tejas Mk.1A’s 351 line-replaceable units (LRU), 191 have been indigenised through private-sector enterprises and defence public-sector undertakings such as the HAL and BEL, while out of the balance 156 LRUs, 91 are at various stages of indigenisation. Of these, more than 40 are the result of the MoD’s Technology Development Fund allocated by the MoD for MSMEs.
In August 2021, the HAL inked a Rs 5,375 crore (USD 716 million) contract with GE Aviation for the supply of 99 F404-GE-IN20 turbofans, each rated at 84kN thrust with reheat, along with support services to power the Tejas Mk.1As, while on December 16, 2021, the HAL signed a Rs 2,400 crore contract with the BEL for the development and supply of 20 types of LRUs. Imported items on the aircraft include the Quartz-built nosecone and a fixed in-flight refuelling (IFR) probe from UK-based Cobham, the active electronically scanning X-band EL/M-2052 multi-mode radar (AESA-MMR) from the ELTA Systems subsidiary of Israel Aerospace Industries (whose radar beam can move up to 60 degrees in any direction from the perpendicular: up, down, left or right), the EL/L-8222 Mid-band/high-band jamming pod, and the Targo helmet-mounted sight from Elbit Systems.
The first Tejas Mk.1A made its maiden flight early last May and is now undergoing 24 months of flight-testing. Like the Tejas Mk.1, the Mk.1A variant will be certified for a total technical service-life (TTSL) of 3,000 flight-hours or 30 years, with the time-between-overhauls being 1,500 flight-hours. With the NAL’s assistance, efforts are now under way to increase the L-MRCA’s TTSL to 5,000 flight-hours. The 13.5-tonne Tejas Mk.1A will have a maximum take-off weight (MTOW) of 13,500 kg, inclusive of a payload capacity of 3.5 tonnes and internal fuel capacity of 2,486 kg, giving an unrefuelled endurance of 57 minutes.
Tejas-AF Mk.2 MWF
The Tejas-AF Mk.2 has since 2014 been transformed into a medium-weight MRCA to replace the IAF’s Mirage-2000Ns and MiG-29SMT M-MRCAs. The IAF has committed to 10 Tejas-AF Mk.2 squadrons, which will come in two phases, six squadrons to begin with followed by four squadrons. The IAF had issued its preliminary air staff qualitative requirements in July 2019. By February last year, the M-MRCA’s design configuration was frozen, systems architecture was finalised, critical design review was completed and its detailed design drawings for more than 15,000 parts were ready for manufacturing of the five projected low-rate series production (LSP) aircraft, inclusive of three single-seaters, one tandem-seater and one for structural fatigue tests.
To be powered by a single 98kN-thrust F414-GE-INS6 turbofan (four of which have already been received), the Tejas-AF Mk.2 will have an airframe that is 1,350mm longer and 300 mm wider, a maximum take-off weight of 17.5 tonnes, payload capacity of 6.5 tonnes, internal fuel-carrying capacity of 3,300 kg, and an unrefuelled flight endurance of 120 minutes. The aerodynamic layout includes twin canards in a close-coupled configuration positioned slightly ahead and above the wing-plane for allowing low-wing loading to be maintained by generating additional lift, reducing transonic and supersonic wave-drag, improving longitudinal control and providing better aerodynamic stability.
Last September, the MoD sanctioned Rs.9,000 crore as R&D funds for the project. The first Tejas-AF Mk.2 LSP will be rolled out by December with its maiden flight being slated for December next year. Thereafter, flight-tests will commence and are expected to be completed by 2027. The M-MRCA will have a total of 11 hardpoints for carrying a variety of imported and indigenous weapons. Indigenised new-generation on-board mission suites will include a dual-colour (infra-red/ultra-violet) infra-red search-and-track sensor; cockpit with panoramic active-matrix liquid-crystal display, smart HUD and sidestick controls (similar to those on the Dassault Rafale M-MRCA); six missile approach warning sensors; unified multi-band internal electronic warfare suite; multi-functional air-data probes mounted aft of the radar bulkhead; a BEL-built digital flight-control computer Mk.2; L & T-built on-board oxygen generation system (not present on Tejas Mk.1/Mk.1A variants); HAL-developed GTSU-135 jet-fuel starter with inflight re-ignition capability; high-speed deterministic Ethernet interface; retractable IFR probe; and the X-band ‘Uttam’ AESA-MMR, developed by the MoD-owned defence R&D Organisation’s LRDE laboratory.
For advancing the R&D process and improving aircraft serviceability and turnaround times, ADA, with the IAF’s assistance, has done software-driven rationalisation of structural design criteria like reserve factors and safety factors for aircraft weight reduction, optimisation of LRU maintainability and accessibility through usage of immersive virtual reality software tools, usage of model-based design and 3-D design tools, adopting design-for-manufacturability and assembly (DFMA) and improved tooling for standardisation of parts, and conducting of digital mock-ups and tolerance stacking-up analysis in the design processes for achieving improved and quicker clearances for structural parts, pipelines and wiring looms/harnesses. Overall, the airframe design is modular to enable the undertaking of mid-life upgrades within an air base itself, without the need for depot-level maintenance, repair and overhaul infrastructure. The HAL plans to create three production lines, which will work together to produce 24 Tejas-AF Mk.2s annually.
The solid-state ‘Uttam’ AESA-MMR developed since 2012 by the DRDO’s Electronics & Radar Development Establishment (LRDE) will be series-produced by the HAL’s Hyderabad-based facility, with Hyderabad-based Astra Microwave building its front-end antenna array that contains multiple transmit-receive modules made of gallium arsenide. Since 2019, the prototype radars have flown on board Tejas Mk.1 LSP-2 and LSP-3 aircraft, accumulating 136 flight-hours on them. In addition, the LRDE had leased a Raytheon Hawker-800XP airborne testbed (called Virupaksa) from Zephyr Aerospace Pvt Ltd for conducting another 100 hours of flight-tests. The challenges for any AESA-MMR developmental effort are three-fold: a) Development of the hardware. b) Development of software algorithms. c) Integration of the AESA-MMR with the rest of the fire-control system of the MRCA.
Hardware development is fairly easy and is done at the laboratory-level. Software algorithm development too is easy since most of it was already done for the EMB-145I Netra AEW & CS platform’s S-band AESA antenna and thus involved a simple migration of the required 18 modes of operation (air-to-air, air-to-surface and air-to-sea) from S-band to the Uttam’s X-band. The last one was the most challenging since a fully functional AESA-MMR has to be synchronised with the rest of the on-board avionics suites and it must be ensured that the fully integrated fire-control system can withstand the high G-loads of the MRCA while at the same time avoiding electromagnetic interference effects, for instance the AESA-MMR interfering with one’s own radar warning receivers (RWR).
AMCA Variants
The detailed design of the twin-engine, fifth-generation advanced medium combat aircraft (AMCA) and its critical design review have been completed—a fifth generation stealth fighter—and it is at the stage of critical design review. The AMCA is being developed in two versions—the Mk.1 that will be powered by fourth-generation F414-GE-INS6 turbofans and the Mk.2 that will be powered by a fifth-generation 110kN turbofan, which is projected to be co-developed with an international partner like SAFRAN, GE Aero Engines or Rolls-Royce. R&D work by the ADA on the AMCA has been under way since 2010 and formal sanction for the programme was obtained in December 2018. The AMCA is expected to be allotted a budget of Rs 16,000 crore. However, project approval by the Cabinet Committee on Security (CCS) is still awaited. The HAL commenced production of the Mk.1’s first of five prototypes in July 2022.
As per present plans, the Mk.1 variant will be rolled out in 2026 and its first flight will occur in 2027. The IAF expects the Mk.1 variant to complete its development by 2032, following which it intends to order two squadrons of the Mk.1 variant before moving on to the more advanced Mk.2 variant for equipping five squadrons. In all, the IAF is expected 125 AMCAs in both variants. Specifications of the AMCA include a length of 17.6 metres, wingspan of 11.13 metres, height of 4.5 metres, wing area of 55 square metres, empty weight of 12 tonnes, internal fuel capacity of 6.5 tonnes, internal weapons payload of 1.5 tonnes, maximum external weapons payload of 5 tonnes, maximum takeoff weight in stealth mode of 20 tonnes, and 25 tonnes in non-stealth mode. A great majority of the different mission avionics being developed for the Tejas-AF Mk.2 M-MRCA will also find their way on board the AMCA Mk.1. The MoD will create a special-purpose vehicle for the series-production of AMCA.
Naval TEDBF & HLFT-42 LIFT
The ADA claims that the projected twin-engine deck-based fighter (TEDBF) will not be a fourth-generation aircraft carrier-based M-MRCA, but will emerge as a generation-five minus aircraft. Its basic design has been completed and the ADA is now conducting the preliminary design. It will have an all-up weight of 26 tonnes and like the AMCA Mk.1, will be powered by twin F414-GE-INS6 turbofans. Its landing gear will enable the TEDBF to operate from both STOBAR and CATOBAR flight-decks.
The maiden flight of the first prototype is projected at 2026. The TEDBF, required for replacing the Indian Navy’s (IN) existing MiG-29K M-MRCAs, will have a length of 16.3 metres, wingspan of 11.2 metres, height of 5.1 metres, internal fuel capacity of 5.5 tonnes, and a maximum take-off weight of 26 tonnes. The wing-folding mechanism has now been finalised. In addition, the TEDBF will be an optionally manned platform and will also be able to undertake MUM-T maritime strike sorties along with unmanned airborne surveillance vehicles. There is already an automated take-off mode of operation in the existing two LCA (Navy) Mk.1 prototypes. The IN has indicated that it would like to procure close to 100 TEDBFs. Mission avionics developed for both the Tejas-AF Mk.2 and AMCA Mk.1 will also find their way on board the TEDBF.
The HAL used Aero India 2023 to unveil its conceptual Hindustan Lead in Fighter Trainer (HLFT-42), which will come equipped with a fly-by-wire flight system, IRST sensor, AESA-MMR, IFR probe and a weapons payload similar to those found on operational MRCAs. Expected to be powered by an indigenous 81kN thrust Kaveri turbofan, the HLFT-42 will have a length of 16 metres, wingspan of 9 metres, height of 4.6 metres, maximum take-off weight of 16.5 tonnes, internal fuel capacity of 3.5 tonnes, and an external weapons-carrying load of 4.5 tonnes distributed among 11 hardpoints.
Powerplant Developments
The DRDO’s Bengaluru-based Gas Turbine Research Establishment (GTRE) revealed at the expo that it has concluded 75 hours of high-altitude chamber tests of the indigenously built 46kN thrust Kaveri derivative turbofan at the Central Institute of Aviation Motors (CIAM) in Russia, simulating an altitude of 13,000 metres (42,651 feet). R&D work on this turbofan began in 2019 and is being carried out in two phases. The ongoing Phase 1 is the technology demonstration stage and involves modifying and testing three existing Kaveri turbofans to meet design requirements.
For Phase 2, the GTRE has received funding to pass on to Godrej Aerospace to manufacture five new Kaveri derivative prototype turbofans. Two of the modified turbofans are presently undergoing technology demonstration tests. By last month, the two technology demonstration turbofans had completed more than 140 hours of testing in total, including about 70 hours of ground testing at the GTRE test cell facility in Bengaluru. This turbofan is being developed to power the stealthy RPSA unmanned aerial vehicle that is being developed by the Bengaluru-based Aeronautical Development Establishment.
The HAL revealed at the expo that it is developing the PTAE-W, an upgraded variant of its 4kN thrust PTAE-7 turbojet by using 3-D printed components and also increasing the fuel carrying capacity to increase flight endurance, and its cruise speed to Mach 0.7 when powering the HAL-developed Cats Warrior loyal unmanned wingman, plus an air-launched tactical subsonic cruise missile that will arm the Tejas-AF Mk.2 M-MRCA. However, the HAL’s Aero Engine Research and Design Centre (AERDC) ran into problems when developing the 25kN thrust HTFE-25 turbofan, following which a major re-design effort had to be undertaken. The HTFE-25 turbofan thus continues to languish in its prototype evaluation phase.
In sharp contrast, the Hindustan Turbo Shaft engine (HTSE-1200) of 1,600shp shaft power rating, has made impressive progress and is loaded with some of the concurrent technologies like high-pressure compressor, effusion-cooled combustor, single-crystal (SX) turbine blades, 3-D printed parts, laser shock peening, FADEC, atomisers, and a high-speed gearbox. On the material and processes front, the HAL has developed SX blades with the DRDO’s DMRL laboratory for the HTSE-1200. The coating by EBPVD method is also being established with RCI Hyderabad and is being utilised on SX blades. The process has been proven on sample blades.
Similarly, the laser shock peening process is being utilised through the UK-based Coventry University, while atomisers are being co-developed with the Indian Institute of Science (IISc). A special ceramic composition had to be formulated for making strong ceramic moulds which can withstand metallostatic pressure of liquid CMSX-4 alloy at 1,500 degrees Celsius and above during casting operations. The challenge of maintaining the required temperature gradient has also been overcome by optimising the casting parameters. A multi-step vacuum solutionising heat treatment schedule for the complex CMSX-4 superalloy to achieve the required microstructure and mechanical properties has also been established. Further, a stringent non-destructive evaluation methodology for the blades along with the technique for determining their crystallographic orientations has been developed.
At the expo, Safran Helicopter Engines and the HAL signed a workshare agreement for the joint development of a variant of the Aneto-1K engine intended for the futuristic 13-tonne IMRH (Indian Multi-Role Helicopter) and its naval version, the DBMRH (Deck Based Multi-Role Helicopter). This agreement follows the memorandum of understanding signed on 8 July 2022 and stipulates the sharing of activities within the joint venture where both parties have agreed on an equivalent repartition. In particular, HAL will take part in the design, development and production of some of the core engine components, which is a breakthrough achievement in terms of expertise and know-how in the country. HAL estimates that the IAF requires 200 units of the IMRH, with the army and navy requiring 100 and 14 respectively, collectively valued at Rs.1,41,300 crore USD 20 billion).
HAL could not give any figures for the Indian Coast Guard’s requirements. Current plans call for the HAL building three flying prototypes, one ground-test vehicle and a single structural fatigue-testing specimen. The IMRH will have an overall length of 25.16 metres, width of 4.74 metres, and an overall height of 6.22 metres. It will have an articulated five-bladed main rotor system, articulated four-bladed tail rotor system, twin engines with FADEC, a new-generation glass cockpit, an indigenous four-axis automatic flight-control system, and crashworthy main and nose landing gear. Its performance parameters include a service ceiling of 6.5km, internal fuel capacity of 2 tonnes, cabin capacity for carrying 36 troops, maximum cruise speed of 260kph, maximum payload capacity of four tonnes, range of 800km and an endurance of three hours.