HAL HJT-36 Yashas

Hindustan Aeronautics Limited
Industry	Aerospace and defense
Founded	December 23, 1940; 85 years ago in Bangalore, India
Headquarters	Bangalore, India
Products	Aircraft, including HAL HJT-36 Yashas trainer aircraft
Website	hal-india.co.in

HAL HJT-36 Yashas

The HAL HJT-36 Yashas (meaning Glory) is a subsonic intermediate jet trainer aircraft developed by the Aircraft Research and Design Centre (ARDC) and produced by Hindustan Aeronautics Limited (HAL) for use by the Indian Air Force and Indian Navy. It is designed to succeed the HAL HJT-16 Kiran as the Stage-2 trainer for these services.

Initially designated as Sitara, this jet incorporates low swept wings, a tandem seating arrangement, and compact side air intakes. Limited production commenced around 2010; nevertheless, the Indian Air Force classified it as "unfit" for operational deployment due to unresolved spin test complications until January 2022. After a three-year hiatus, it resumed flight in April 2019 with an updated airframe that resolved these issues.

At Aero India 2025, following substantial redesigns, the aircraft was renamed Yashas. It is now capable of supporting Stage II pilot training alongside roles such as counter-insurgency, surface force operations, weapons training, aerobatics, and other functions.

Development

In 1997, HAL began conceptualizing an intermediate jet trainer to replace the HJT-16 Kiran (introduced in 1968). Two years later, after assessment by the Indian Air Force, the Government of India awarded HAL a contract to develop, test, and certify two IJT prototypes at a cost of , with a completion deadline set for July 2004.

To adhere to stringent timelines, HAL incorporated advanced methods including Numerical Master Geometry (NMG) for aerodynamic testing in wind tunnels, structural assessments, and tooling processes.

2000s

The initial prototypes PT-1 and PT-2 (serial numbers S3474 and S3466) conducted their maiden flights on 7 March 2003 and March 2004 respectively.
By April 2005, project expenses escalated to ; Initial Operational Clearance (IOC) and Final Operational Clearance (FOC) were anticipated during 2006-07 and 2007-08.
An engine upgrade from the SNECMA Turbomeca Larzac to the NPO Saturn AL-55I (providing 16.9 kN thrust) was planned in 2005 to fulfill increased thrust requirements.
In February 2006, the Ministry of Defence proposed acquiring 12 IJT Limited Series Production (LSP) units from HAL; approval and contract followed in March 2006 valued at . Delivery schedules were postponed from 2008-10 to 2011-12. A Comptroller and Auditor General report highlighted that LSP orders proceeded prior to IOC certification from CEMILAC, which deviated from established procedures. A subsequent order for 73 Serial Production aircraft was intended after LSP completion and design refinements.
On 8 February 2007, PT-1 experienced a tyre burst leading to an overrun at Yelahanka Air Force Station during Aero India.
In November 2008, Air Headquarters recommended procuring 73 Serial Production IJT units from HAL.
On 4 February 2009, PT-2 crashed due to landing gear malfunction during a test flight shortly before Aero India.
These events caused IOC and FOC timelines to be deferred to 2009-10 and 2010-11 respectively.
The first AL-55I engine arrived from Russia on 28 December 2008—two years behind schedule—and was installed on PT-1. Flight testing with this engine commenced on 9 May 2009.
The relatively new Russian AL-55I engine faced initial reliability challenges compared to the well-established Larzac engine (which had accumulated 0.85 million flight hours), resulting in reduced prototype availability and limiting test flights for production models.

2010s

In March 2010, the Indian Air Force placed an order for 73 HJT-36 trainers to enter serial production, valued at , even before achieving Initial Operational Clearance (IOC) and completing Limited Series Production (LSP) deliveries. The contract received approval from the Cabinet Committee on Security (CCS) in February. The LSP aircraft were scheduled for completion by 2011-12, with plans to deliver 73 serial production units between 2013 and 2017, starting with six in 2013 and 24 in 2014. An advance payment of was issued.
The first flight test of a limited series production aircraft took place in January 2010, with Initial Operational Capability anticipated by July 2011.
On 28 April 2011, prototype S3466 crashed near Hosur during a test sortie; both crew members ejected safely, but the aircraft was destroyed.
The third prototype completed its inaugural Engine Ground Run on 27 July 2012.
By December 2013, Hindustan Aeronautics Limited (HAL) announced that the Sitara was only weeks away from certification.
On 19 February 2014, the Ministry of Defence stated that IJT development had progressed significantly, with over 800 test flights conducted covering sea level, night operations, high altitude, weapons integration, and drop tank trials. Final Operational Clearance (FOC) was targeted for December 2014 but awaited resolution of stall behavior and spin testing concerns. Production was planned to commence immediately after FOC; however, stall testing revealed the need for a substantial redesign to address "inherent asymmetry."
As of July 2014, six LSP aircraft were manufactured but remained undelivered due to incomplete Design and Development processes.
BAE Systems provided consultancy on design revisions, focusing especially on the tail section; these modifications underwent computational analysis and wind tunnel validation. Spin tests were anticipated by September 2015 to facilitate production of 85 trainers for the Indian Air Force.
Testing ceased in 2016 following loss of controlled flight during spin trials. Several design interventions—including nose strakes, ventral fins, wing fences, and vortex generators—were unsuccessful in mitigating wing drop issues encountered during stalls.
By March 2017, Jane's reported that unresolved stall and spin deficiencies rendered the HJT-36 unsuitable as an intermediate jet trainer for the Indian Air Force.
Collaborating with consultant Birhle, extensive airframe alterations enhanced spin recovery capabilities; the revised IJT LSP4 (S3854) conducted its maiden flight on 17 April 2019. A newly developed Anti-Spin Parachute System (ASPS) was introduced to improve test safety. Design updates included moving vertical fins aft by one meter and extending the rudder beyond the vertical stabilizer, increasing control surface area by approximately 30%. Additional control features such as nose strakes, ventral fins, and leading-edge wing root strakes were incorporated. France’s ONERA performed wind tunnel assessments to validate these modifications.

2020s

By July 2020, the enhanced ASPS was installed on the aircraft, with successful deployment trials completed by September.
In February 2021, the HJT-36 made its takeoff at Aero India equipped with upgraded AL-55I engines offering improved performance.
On 6 January 2022, the IJT demonstrated six-turn spins in both left and right directions; following internally funded design enhancements, further testing and repeated demonstrations were scheduled ahead of anticipated certification within approximately two years.
During Aero India 2025, HAL rebranded the HJT-36 Sitara as HJT-36 'Yashas' after implementing design improvements targeting departure behavior and spin resistance. The aircraft received advanced avionics upgrades, a state-of-the-art cockpit layout, weight reduction measures, and replacement of outdated foreign line-replaceable units (LRUs) with domestically produced alternatives.
As of 12 February 2025, no formal orders had been placed by the Indian Air Force for the updated 'Yashas'; however, plans included leasing four to five units from HAL initially, with potential for additional procurement contingent upon operational evaluation outcomes.

Airframe

The HJT-36 adopts a traditional low-wing configuration featuring an 18° sweepback angle on the leading edge and a wingspan measuring 9.8 meters. Its structure is composed of lightweight alloys combined with composite materials. The aircraft is equipped with hydraulically operated retractable tricycle landing gear: the main gear, each with a single wheel, retracts inward, while the twin-wheeled nose gear folds forward. About one-quarter of its line-replaceable components are common with those used in the HAL Tejas trainer variant.

Cockpit

Configured in a standard tandem seating arrangement, the HJT-36 positions the trainee pilot in front and the instructor in an elevated rear seat. A single-piece canopy offers expansive visibility in all directions. The prototype was fitted with Zvezda K-26LT zero-zero ejection seats, noted for their light weight; however, these may be substituted by Martin-Baker Mk.16 IN16S seats as a cost-saving measure. Both manual and conventional flight control systems are incorporated.

The cockpit features a fully digital glass layout resembling that of modern combat aircraft, integrating avionics developed by GE Aviation Systems. Elbit Systems supplies the head-up display (HUD) along with its repeater unit. Enhanced situational awareness is achieved through the raised rear cockpit position and a downward-sloping nose profile, complemented by multifunction displays and the HUD.

Armaments

This trainer aircraft is equipped with five external hardpoints—one located on the fuselage centerline beneath the aircraft and two under each wing—capable of supporting armaments such as rockets, gun pods, and bombs. The maximum permissible external payload is 1,000 kilograms.

Propulsion

The HJT-36 is powered by an NPO Saturn AL-55I turbofan engine equipped with Full Authority Digital Engine Control (FADEC), delivering thrust of 17.3 kN, optimized to provide favorable thrust-to-weight ratios. Initial prototypes were powered by the SNECMA Turbomeca Larzac 04-H-20 engine generating 14.12 kN thrust; however, Indian Air Force specifications required increased thrust levels.

In 2005, HAL partnered with NPO Saturn to jointly develop the AL-55I engine, backed by INR 159 crore funding from India’s Ministry of Defence. Early versions of the AL-55I had a total technical life (TTL) of only 300 hours, falling short of the required 3,600 hours. By 2013, improvements extended this to 600 hours, though the Indian Air Force desired a TTL of 1,200 hours to align with operational demands.

By July 2021, United Engine Corporation delivered two upgraded AL-55I engines featuring a life cycle extended to 1,200 hours and enhanced thrust output of 17.27 kN, while achieving a weight reduction exceeding 50 kilograms. Prior shipments included sixteen engines supplied for prototypes and limited series production. These engines are prepared for licensed manufacturing within India.

As of February 2025, UEC has provided HAL with eighteen AL-55I engines to support certification processes and initiate domestic licensed production.

Operators

: Orders include 12 LSP units and 73 production-series aircraft, with plans to procure between 200 and 250 units.

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