Another trainer making its Western air show debut is HAL's diminutive HJT-36 Sitara, designed to meet the Indian Air Force's intermediate jet trainer requirement. The aircraft is intended to replace the IAF's ageing Kirans in the basic training role, while the Kiran II and Iskra advanced trainers will be replaced by the BAE Hawk 132 advanced jet trainer.
For the first time in HAL's long history, the aircraft was designed using Computer Aided Design (CAD) techniques and 3D modelling. As soon as the numerical master geometry (NMG) was finalised it was made available to the aerodynamics, structural design and analysis, systems and tool engineering groups, allowing fabrication of the wind tunnel model, design of major frames, and layout of systems to be carried out in parallel.
The HJT-36 is a pretty little aeroplane, whose configuration is reminiscent of the larger MiG AT, but with some features of the Alpha Jet. The aircraft has steeply stepped tandem cockpits, covered by a huge bubble canopy, and combines a low-mounted, angular wing with modest sweep on the leading edge and taper on the trailing edge. The tailplane is set well back on the fin root. A large, perforated airbrake is mounted on the lower fuselage, roughly level with the trailing edge.
The intakes are mounted high on the centre fuselage, like those of the Aero L-39, and the single Snecma Larzac 04-20 engine is slung below the boom-like rear fuselage structure. The engine is already well proven on the Dassault-Dornier Alpha Jet, and is an engine option on the MiG-AT, though both of these larger trainers use two engines.
The aircraft has an advanced glass cockpit, with a Smiths head-up-display (HUD) augmenting 3ATI (Air Transport Instruments) active matrix liquid crystal displays, and has a GPS-based navigation system. The aircraft is fitted with Zvezda K36LT zero-zero ejection seats, and the canopy incorporates a miniature detonating cord, though the seats do have a 'through the canopy' capability.
The aircraft has conventional flying controls with manually operated ailerons and rudder and an electrically actuated tail plane and has electrical rudder and aileron trimmers.
Though intended for the basic training role, the HJT has a limited ground attack capability, and can carry up to 1,000 kg of stores on five underwing and centreline hardpoints, with the centreline hardpoint able to carry a gun pod. Performance is similar to that of the Kiran, with a maximum speed of 750kmh (Mach 0.75), and airframe limits of -2.5G to +7.5G.
The aircraft made its maiden flight on March 7, 2003, in the hands of Squadron Leader Baldev Singh, HAL's chief test pilot, just 20 months after programme launch. An initial batch of 12 limited series production aircraft has already been ordered, and HAL hopes to produce an eventual total of 200-250 HJTs, stepping up to a production rate of 20 per year.
Source: Flight Daily News
