In an important milestone, the Intermediate Jet Trainer (IJT), designed and developed by the Hindustan Aeronautics Limited (HAL) for stage-II training of Indian Air Force (IAF) pilots, has successfully demonstrated the capability to carry out six turn spins, displaying an important requirement for the platform. The aircraft will require another two years of testing after which it will be ready for induction, said R. Madhavan, Chief Managing Director, HAL.
“The IJT needs another two years of testing. There were some major modifications done in the aircraft. So all the earlier tests have to be repeated and demonstrated in the new configuration,” Mr. Madhavan said. “If the requirement [from the IAF] comes within that time, we can roll out immediately,” he stated.
With this, the HAL would have the entire range of trainer aircraft — HTT-40 Basic Trainer Aircraft (BTA), the IJT, Hawk Advanced Jet Trainer (AJT) and the Lead-in Fighter Trainer (LIFT) being conceptualised based on the Light Combat Aircraft (LCA) Tejas twin seat trainer aircraft, Mr. Madhavan noted.
Halted in 2016
The IJT, meant to replace the ageing Kirans of the IAF fleet, had earlier completed demonstration of capabilities in terms of altitude and speed envelope, load factor, satisfactory stall characteristics and limited armament capability as required by the IAF. However, the programme came to a halt in 2016 and flight testing resumed in April 2019.
The IJT programme came to a halt in 2016 after the aircraft “departed from controlled flight” and trials were resumed in April 2019 after major modifications to the aircraft with the HAL using its internal resources.
Subsequent to the temporary halting of flight tests in 2016, major modifications were undertaken such as shifting the vertical tail aft on the airframe and increasing the rudder area, and flight testing resumed in April 2019, a HAL statement said. “These modifications entailed the use of a new Anti-Spin Parachute system [ASPS] which is mandated for the safety of the aircraft and test crew during spin flight testing.”
The new ASPS was integrated into the aircraft in July 2020 and the successful streaming of the parachutes were demonstrated in September 2020.
The capability to enter and recover from spin is a necessity for a trainer aircraft to familiarise the trainee pilot to recognise departure from controlled flight and the actions required to recover from such situations. “Achieving satisfactory characteristics during spin and an assured recovery from spin form a part of very crucial flight tests due to its unpredictability,” the statement said.
Spin flight testing
Stating that spin flight testing is inherently a high risk manoeuvre and therefore progresses incrementally turn by turn, the HAL said due to the complex interplay of aerodynamic and inertia forces, the motion of the aircraft in spin was unpredictable and flight testing was the only way to assess the acceptability or otherwise of its characteristics.
On the HTT-40 BTA, the Defence Ministry has already approved the procurement of 106 HTT-40 and the IAF had issued the Request For Proposal (RFP) at Aero India 2021.
