By Staff Correspondent
The Intermediate Jet Trainer (IJT), designed and developed by HAL for the Stage–II training of IAF pilots, has successfully carried out six turn spins to the LH and RH sides. The aircraft was piloted by Gp. Capt HV Thakur (Retd) and Gp. Capt A Menon (Retd).
Given the right resources and backing, HAL can design products that can meet any requirement of the Indian Armed Forces, says Mr R Madhavan, CMD. Mr Arup Chatterjee, Director (Engineering and R&D), added that by demonstrating its capability to have six turn spins on both sides, the IJT has achieved a significant milestone.
He attributed the success to the synergy between designers, flight operations and certifying agencies (RCMA and DGAQA). He further hoped that with the completion of spin certification of HTT-40 and the progress achieved in IJT, HAL will soon have state-of-the-art trainers for stage I and II training of IAF pilots.
The IJT, which was conceived by HAL as a replacement to the ageing Kirans of the IAF fleet, had completed a demonstration of its capabilities in terms of altitude and speed envelope, load factor, satisfactory stall characteristics and limited armament capability as required by IAF, much earlier. The only pending task was spin testing. During spin testing in 2016, the aircraft departed from a controlled flight, bringing the programme to a temporary halt. However, HAL decided to use its internal resources to complete the critical Spin testing further.
The capability to enter and recover from spin is necessary 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 spin flight testing is inherently a high-risk manoeuvre and, therefore, progresses incrementally. Due to the complex interplay of aerodynamic and inertia forces, the aircraft’s motion in spin is unpredictable, and flight testing is the only way to assess the acceptability or otherwise of its characteristics.
The spin flights are carried out in good weather conditions with a team of designers, flight test engineers and safety pilots monitoring the various parameters during the flight and therefore time-consuming. Several flight tests are required to be carried out before 6-turn spin flights are undertaken as well as several flights are further required before full spin certification is achieved.
After the temporary halting of flight tests in 2016, HAL undertook major modifications like shifting the vertical tail aft on the airframe and increasing the rudder area, and flight testing resumed in April 2019. These modifications entailed using 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 plane in July 2020, and the successful streaming of the parachutes was demonstrated in September 2020. Despite the delays due to the COVID-19 pandemic, HAL could commence the stall and spin testing of the IJT in its new modified configuration in November 2020.
Wg. Cdr M Patel (Retd) was the test director, and Gp. Capt. KK Venugopal (Retd) was the safety pilot in command at telemetry.