Hindustan Aeronautics Limited Resumes Spin Tests of Intermediate Jet Trainer (IJT)

Hindustan Aeronautics Limited Resumes Spin Tests of Intermediate Jet Trainer (IJT)

The Indian Air Force (IAF) Intermediate Jet Trainer (IJT) designed and developed by HAL to replace the ageing Kiran aircraft fleet commenced spin flight testing in Bengaluru, India. The flight was piloted by HAL’s test pilots Gp. Capt H.V. Thakur (Retd) and Wg. Cdr P. Avasti (Retd). The IJT has already been tested to its full envelope in terms of speed, altitude and load factor (‘g’ envelope) and has also been integrated with drop tanks as well as bombs. For spin test, HAL redesigned the aircraft by moving the vertical tail aft and extending the rudder surface. The spin testing of an aircraft is the most crucial phase of its flight testing.

These changes for ensuring a satisfactory spin behaviour required extensive redesign of the rear fuselage and the rudder. The changes have been incorporated in two aircraft with the involvement and clearance from certification agencies at every stage. Post modification, the two aircraft underwent significant flight tests to assess the general handling with the new configuration of fin and rudder. These aircraft have now been incorporated with the necessary safety devices (Anti-Spin Parachute Systems). During the first flight, initially the aircraft was taken through one turn spin to the left and right hand sides to test the spin characteristics.

The Hindustan Aeronautics Limited (HAL) Intermediate Jet Trainer (IJT) christened as HJT-36 Sitara (Star) is indigenously designed and developed by HAL to replace ageing fleet of KIRAN (HJT-16) Jet Trainer aircraft in service with Indian Air Force for Stage II training of its pilots. IJT will be fitted with R AL-55i Jet engines produced in house at 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. As of September 2005, two prototypes have been built logging around 120 flights with series production expected to follow shortly.

Over 200 HAL IJT aircraft expected to be ordered procured between 1967 and 1989. The IAF military training program is divided into three stages: stage 1 is a primary training program based on the HAL HPT-32 propeller aircraft; stage 2 is undertaken on a basic jet trainer such as IJT or Kiran with a higher degree of complexity; stage 3 is conducted on an advanced jet trainer, comprising all phases of combat training. The IJT is also intended for light attack missions carrying up to 1,000 kg of armament. The HJT-36 is a conventional jet trainer with low swept wings, tandem cockpit and small air intakes for the engine on either side of its fuselage.

For these spin tests, HAL redesigned Intermediate Jet Trainer (IJT) by moving the vertical tail aft and extending the rudder surface to ensure satisfactory spin behavior, which required extensive redesign of the rear fuselage and the rudder.