Spin Flight Testing of India’s Intermediate Jet Trainer Begins After 4 Years

Hindustan Aeronautics Limited (HAL) has commenced spin flight testing of India’s indigenous Intermediate Jet Trainer (IJT).

Developed by HAL the aircraft will replace the ageing Kiran fleet of the Indian Air Force (IAF).

The flight testing of IJT (HJT-36 Sitara), designed and developed by HAL for the stage-II training of IAF pilots was put on hold after the aircraft had encountered problem in the spin test flights in the year 2016.

The company redesigned the aircraft by moving the vertical tail aft and extending the rudder surface with advice from U.S. aviation technology and Bihrle Applied Research Inc. testing firm. It resulted in significant airframe changes, first visible when the redesigned jet flew in April 2019. HAL said the changes were incorporated in two aircraft with the involvement and clearance from certification agencies after every stage.

Post modification, the jets underwent significant flight tests to assess the general handling with the new configuration of fin and rudder. They have now been incorporated with necessary safety devices such as Anti-Spin Parachute Systems. During the first flight, initially, the aircraft was taken through one turn spin to the left and right, to test the spin characteristics.

The spin testing of an aircraft is the most crucial phase of its flight testing. Accordingly, the testing will gradually progress to assess the behaviour of the aircraft till six turn spins to either side meets the targeted requirement.

The IJT has already been tested to its full envelope in terms of speed, altitude and load factor (‘g’ envelope). It has also been integrated with drop tanks and bombs.

IJT ware fitted with AL-55i Jet engines produced in-house at HAL Engine Division, Koraput. IJT incorporates the simplicity necessary for ease of conversion from Basic Piston Trainer and the sophistication required for quick conversion to the complexities of an Advanced Jet Trainer.