Checking out the Intermediate Jet Trainer (IJT) at HAL, Bangalore

(Photos: courtesy Ajai Shukla)

An IJT prototype in its hangar at HAL Bangalore; Ajai Shukla with some of the designers in the IJT project.

Sitting in the hangar at HAL Bangalore in its red and white livery, the IJT (also known as the Hindustan Jet Trainer, HJT-36) makes a handsome picture. A first glance brings to mind the Czech L-159 Advanced Jet Trainer, but flight hangar chief, Vishwanath Rao, asserts vigorously that the IJT has been designed ground-up at HAL using advanced CAD/CAM techniques.

Trainee Indian Air Force (IAF) and Indian Navy (IN) pilots will train on the IJT after completing basic training on the obsolescent, piston-engine HPT-32 basic trainer, in which the instructor and the trainee sit side-by-side. The IJT will replace the Kiran trainer, bridging the gap between the HPT-32 and the newly inducted Hawk Advanced Jet Trainer (AJT) jets. For that reason, the flight characteristics of the IJT have been tailored to lie midway between the HPT-32 piston-engine basic trainer and the Hawk AJT.

Climbing into the aircraft, the first thing that strikes one is the view from the rear seat, which is far superior to AJTs like the Hawk. The raised rear cockpit gives the IJT its “L-159-type look”, but then other differences in the fuselage become quickly apparent. The real selling point, though, is the cockpit instrumentation, which takes the IJT into the front ranks of Stage-2 trainers.

Sitting in the cockpit, the complexity of the display is far closer to an AJT than to a basic trainer. HAL engineers insist, though, that flying the IJT will be simpler than the Kiran. The cockpit design philosophy is to allow the pilot to fly by “feel”, even while providing a more “instrumented” cockpit environment, to prepare for flying the AJT.

I’ve sat in a Kiran cockpit; I can confirm that the IJT is from a different planet. It is a wonderfully crafted, fully glass cockpit, but the Multi-Function Displays (MFDs) are very different from more complex aircraft. Here, the screen provides a digitised image of conventional flight instrumentation; the altitude indicator, airspeed indicator, turn-and-bank indicator, etc, are displayed on the MFD. This gives the trainee a feel of the glass cockpit environment, even before graduating from traditional instrumentation.

All three cockpit MFDs are identically constructed and wired, allowing the instructor to project any information he likes into the trainee’s cockpit. It allows the instructor to simulate flight emergencies, by keying in instrument malfunctions from his rear cockpit. In case of a real MFD failure, the instrumentation can be switched to either of the other two MFDs. This allows redundancy in terms of flight safety, while easing inventory management.

Based on growing confidence during testing, all the instrumentation is now being moved onto just two MFDs, including angle of attack information.

The IJT, on which work began in 1999, has seen the fastest design cycle in any Indian-built aircraft, and it compares favourably with international design cycle times. About 150 design and manufacture stations were used, relying heavily on Computer Aided Design (CAD) 3-Dimensional modelling. Metal cutting began in 2001, and the first flight took place in 2003. HAL engineers claim that it took just 20 months from metal cutting to flight.

HAL also takes pride in the way it squeezed the design cycle time by dovetailing the stages of design, tooling and manufacture. The IJT project engineers say that design drawings were released almost as they were completed, allowing the jigs to be designed and manufactured almost concurrently. As the contours of the IJT were defined, the jig designs were done and the manufacture of the prototypes, therefore, could get underway without any delay.

The design team admits to a series of design problems that had to be overcome. At first, the controls of the IJT were heavy; the design team had to entirely rework the shape of the nose. As the aircraft weight went up, the need for more engine power arose. But the initial specifications of the IJT had deliberately kept the weight low, giving the designers some margin for the inevitable rise in weight during design. As one engineer told me, “When you design an aircraft, it will always end up heavier than what you planned, so the lower the weight you target initially, the lower the final weight will be.”

The engine issue is still being sorted out. The first three IJTs currently use the Snecma Larzac engine, which is also used in the Alpha Jet. HAL bought those three engines from Snecma for the development phase; NPO Saturn was still developing the Russian AL-55I engine in Russia, which will power the production version IJTs. The AL-55I has 20% more thrust than the Larzac. In 2005, HAL and Rosoboronexport signed a $350 million contract to build 250 AL-55I engines under license in HAL, with an option for 1000 more.

The IAF has already ordered the Limited Series Production (LSP) of 12 IJTs. HAL says that the first of them will roll out in 2008-2009. The production rate will go up to 12 per year by 2010. By mid-2010, HAL expects the IJT to be fully certified; at that stage series production will start. In 2011, the IJT is likely to begin its induction into service as a full-fledged trainer for cadets.

HAL estimates that the sale price of the IJT will be around $10 million per aircraft. That will make it the most competitively priced intermediate trainer in the world.