HAL HJT-36 Yashas

The HAL HJT-36 Yashas () is a subsonic intermediate jet trainer aircraft designed and developed by Aircraft Research and Design Centre (ARDC) and built by Hindustan Aeronautics Limited (HAL) for the Indian Air Force and the Indian Navy. The HJT-36 will replace the HAL HJT-16 Kiran as the Stage-2 trainer for the two forces.

The jet, originally named Sitara, was designed as a conventional jet trainer with low swept wings, tandem cockpit and small air intakes for the engine on either side of its fuselage. It entered limited series production by 2010 but according to the Indian Air Force officials it remained "unfit" for service due to technological issues related to spin test (as of March 2017), an issue which was only solved in tests in January 2022.

In April 2019, Sitara flew for the first time in three years with a modified air frame to correct its spin characteristics.

During the opening ceremony of Aero India 2025, the HJT-36 was renamed as Yashas after undergoing significant design modifications. It is now capable of Stage II pilot training, counter insurgency and counter surface force operations, armament training, aerobatics and other roles.

2000s

thumb|HAL HJT-36 PT-1 (S3466) Sitara at [[Yelahanka Air Force Station ]]

The first and second prototypes of the HJT-36, labeled PT-1 and PT-2, serialed S3474 and S3466, flew on 7 March 2003 and in March 2004, respectively.
In April 2005, the project cost was revised to and timeline for Initial Operational Clearance (IOC) and the Final Operational Clearance (FOC) was expected in 2006-07 and 2007-08, respectively.
On 8 February 2007, IJT prototype PT-1 overshot the runway at Yelehanka AFS during the inauguration of Aero India after its tyres burst during take-off.
In November 2008, Air HQ initiated a proposal to for supply of 73 SP IJT aircraft from HAL.
Following the crashes and delays, in March 2009, the IOC and FOC dates were shifted to 2009-10 and 2010-11, respectively. Following ground taxiing trials, flight tests with the new engine started on 9 May 2009. However, the Russian-origin was relatively newly developed compared to the Larzac, which had 0.85 million hours of flight. This led to "teething problems" in the engines which eventually lowered the availability of the IJT prototypes and limited series production variants for test flights.

2010s

thumb|Prototype IJT (PT-2, S3474) in its hangar at [[Hindustan Aeronautics Limited|alt=|right]]In March 2010, the Air Force placed an order for 73 HJT-36 trainers for serial production at a cost of , again before the completion of IOC certification and deliveries of LSP aircraft. Clearance for the contract was approved by the CCS in February. As per MoD, the LSP aircraft order would be completed by 2011-12 and the timeline for delivery of 73 SP aircraft was between 2013 and 2017. As per delivery timeline, 6 aircraft would have to be delivered in 2013, followed by 24 aircraft in 2014 An advance payment of was done. and initial operational capability was expected by July 2011.
On 28 April 2011, the first prototype (S3466) crashed in near Hosur during routine test flight in Krishnagiri district, Tamil Nadu. Both the pilots, Group Captain Anant Mathur of HAL and co-pilot Wing Commander Patra of Aircraft and Systems Testing Establishment (ASTE), ejected safely. The aircraft was lost in the accident.
On 27 July 2012, first Engine Ground Run was performed on third prototype.
In December 2013, HAL declared that Sitara was 'weeks' from certification.
On 19 February 2014, the Indian MoD submitted a statement that the development of IJT was in the advanced stages of certification, with more than 800 test flights completed so far. The activities were progressing well with completion of sea level trials, night flying trials, high altitude trials as well as weapon and drop tank trials. The activities left for obtaining Final Operational Clearance (FOC) are the refinement of stall characteristics, and spin testing which will be commenced as soon as stall characteristics were refined. All efforts were being made to achieve FOC by December 2014. Production of aircraft was to commence immediately thereafter. However the stall cannot be tested until HAL redesigns the entire aircraft to correct its "inherent asymmetry".
As of July 2014, 6 of the LSP aircraft were produced but still not delivered due to non completion of Design and Development (D&D) activities. Afterwards the design was put to mathematical and wind tunnel tests. The modified aircraft was expected to complete the spin tests by September 2015, and the production of 85 aircraft for the Indian Air Force to begin.
In 2016, the programme and the testing came to a halt after the aircraft “departed from controlled flight” while testing spin characteristics. Post modifications, a new Anti-Spin Parachute system (ASPS) was developed to ensure safety of the aircraft and test crew during spin flight testing. Major design changes were executed in the empennage with the vertical fins pushed back by a metre and the rudder extended beyond the vertical stabiliser until the rear fuselage, increasing the control surface area by 30%. Other control surfaces that were added as compared to the original design included nose strakes, ventral fins and a leading edge strakes at the wing root.
In February 2025, at the Aero India 2025, HAL renamed the HJT-36 Sitara as the HJT-36 'Yashas'. The renaming was due to its design modification to correct "departure characteristics and spin resistance". The aircraft was recently integrated with "state-of-the-art avionics and an ultra-modern cockpit". This upgrades videos the overall weight of the aircraft and replaced the obsolete foreign line-replaceable units with Indian LRUs.
On 12 February 2025, it was also reported that the Indian Air Force has not placed any order for the updated aircraft but would lease 4 to 5 'Yashas' from HAL. Further orders will be placed if the user was satisfied with its training and operational capabilities.

Design

thumb|HJT-36 at Yelahanka Air Force Base in 2005

Airframe

HJT-36 uses light alloys and composites, with a conventional low wing design with 18° leading-edge sweepback and a 9.8m wingspan. It features a hydraulically retractable tricycle-type landing gear. The single-wheeled main units retract inward and the twin nose wheel unit retracts forward. About a quarter of the aircraft's line-replaceable units are common between it and the HAL Tejas trainer variant.

Cockpit

In the cockpit, the HJT-36 has a conventional tandem two-seat configuration with the trainee pilot forward and the instructor in the raised seat to the rear. The single-piece canopy gives both pilots good, all-round vision. The prototype aircraft used Zvezda K-26LT lightweight zero-zero ejection seats. However, these may be replaced with Martin-Baker Mk.16 IN16S seats, due to a price escalation of the former. The pilots have both conventional and manual flight controls.

The trainer has a full glass cockpit with a layout similar to current generation combat aircraft. It uses an integrated digital avionics system from GE Aviation Systems. Head-up display and repeater is produced by Elbit Systems.

In April 2005, the Larzac engine was to be replaced by NPO Saturn AL-55I (16.9 kN) to meet training requirements. The AL-55I engine would be a Joint Venture of HAL and NPO Saturn and the deal for the development of the same was signed with Rosoboronexport in August. A funding of by the Indian Ministry of Defence was released for the higher thrust engine development. The new engines also had an improved thrust of 17.27 kN and also featured a reduction of over 50 kg weight.

== Operators ==

;

: 12 LSP and 73 series production aircraft on order.

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General characteristics

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References

External links

HAL Intermediate Jet Trainer HJT-36 by Wg.Cdr Kukke Suresh VrC(Retd.) @ Bharat-rakshak.com
Bharat-Rakshak Monitor: Sitara - Intermediate Jet Trainer - HJT-36 by H. Niranjan Rao
Photos of the two prototypes @ Bharat-rakshak.com

2000s

2010s

Design

Airframe

Cockpit

See also

References

External links