Sitara - Intermediate Jet Trainer - HJT-36
H. Niranjan Rao
photos courtesy of Sanjay Simha
The seed to design and
develop an Intermediate Jet Trainer was
planted in July of 1999. This bold move bore fruit
on 07 March 2003 when the IJT prototype flew for
the very first time. The official flight followed on
21 March 2003 in the presence of many
dignitaries. On both these occasions Squadron Leader Baldev Singh was able to execute planned manoeuvres
for a duration of about twenty minutes on the
aircraft. The rapid success of the IJT brings
into focus numerous aspects within the Indian
aeronautical industry. In this article we will
briefly examine some of them. The IJT was conceived
to replace the Kiran . The Kiran was designed in
the 1960s and it is the current entry-level jet
trainer. It is also used by the national aerobatic
team, the Surya Kirans (Sunrays). The general level
of satisfaction in the Indian Air Force with
its performance is very high. However over the years
the IAF had seen a sea of change in their
operational aircraft. With the induction of several
high-tech platforms like the MiG-29, Mirage
2000, and now the Su-30MKI, a need arose to revise
the training of pilots.
The Kiran was able to
meet the immediate expectations but emphasis was
placed on acquiring an Advanced Jet Trainer (AJT).
The AJT acquisition has run into rough weather over
the issue of cost. At this point an indigenous
alternative must have seemed attractive. However
indigenous development of an AJT was a complicated
matter. In the early 1980s, the Government of India
had launched the Light Combat Aircraft (LCA)
programme to indigenously design and produce a
combat aircraft capable of meeting India's defence
needs. The LCA programme though enormously slow in
actually producing the aircraft, was very quietly
contributing to the confidence and the technical
competence of the aeronautical community in India
. Thus in 1999 a proposal from Hindustan
Aeronautical Limited (HAL) and a nudge from the
heads of the technical advisory community was enough
to drive the idea of designing and developing an
Intermediate Jet Trainer (IJT) within a very
reasonable price and little time.
Research & Design Center (ARDC) was tasked with
design and development of the IJT. Partnering with
the ARDC was the Aeronautical Development Agency
(ADA), the agency responsible for the design and
development of the Light Combat Aircraft (LCA). A
number of Public Sector Units (PSUs) and associated
government agencies also participated in the IJT
project. Two foreign companies that made major
contributions to the project were Snecma Moteurs/Turbomeca
and Smiths Aerospace. As with all major defence
projects, the Government of India (GoI) provided the
financial support for the IJT.
experience gleaned from the LCA project was arguably
the most important of the enablers for the IJT.
Teams that worked on the IJT had been exposed to the
LCA while working in various capacities on that
project. Beyond that, at this point in time, it is
rather difficult to pin point the contributions made
by the LCA project, time will expose those important
details . The role of Government of India (GoI)
is also describable as that of an enabler. The GoI
has shown interest in defense related fields in the
recent past, however, this is one effort that stands
out. It is interesting to note that the GoI has
visibly seized upon the ability, confidently 'pick a
winner' in the aerospace market. Although difficult
to quantify, this will definitely bode well for the
Government in the future.
The ARDC relied
on software to reduce the design & development
cycle. The software from Unigraphics provided two
major functionalities: 3-D CAD/CAM and data
management. The 3D CAD/CAM was used to design
subcomponents, components, and large assemblies and
even complete mock-ups of the aircraft. The data
management software allowed the data associated with
these designs to be shared among various teams.
Coupled with Virtual Product Development (VDP)
modeling and support for product development process
threads, various teams were able to create, test,
document and manufacture components digitally.
Collaborative building and the ability to test
different versions of the same component in real
time optimized time utilization .
and Turbomeca delivered two of the Larzac 04H20
engine that powers the current and probably the next
IJT. The 1440 dN jet engine was first fully flight
qualified on an Alpha Jet flying test-bed .
Smiths Aerospace was selected to provide an open
architecture mission control computer, head-up
display units, HUD repeater, a rear entry panel, and
altitude and heading reference system and air data
computers. It may be noted that Smiths also works
with HAL on supplying instruments for the IAF's
Jaguars and the proposed BAE Hawks . Thales of
France supplied the 3ATI and 4ATI displays, along
with angle-of-attack, temperature sensors and
discussion, we rarely make an argument for basing
aircrafts acquisition on Human Engineering (HE)
factors. Basically HE, with respect to an aircraft,
relates to aircrew-aircraft compatibility. The
clearance over the head of a pilot, the ability to
see over the nose or over either sides, seat shape
and size, clearance during ejection, reach to
various instruments: mostly associated with
dimensions within the cockpit. The Hindustan Jet
Trainer (HJT) 36 is the first Indian trainer built
with Indian anthropometrical data of a male pilot in
mind. The entire layout of the cockpit, including
the main instrumentation panel, is based on HE.
Again, software was used to design and animate human
movements. With emphasis on HE during the design
phase and with total control over it due to the
acquiring of data related specifically to Indian
pilots, training future pilots should become that
much more efficient .
a grant of Rs. 180 crore in 1999, the plan is to
build a few more aircrafts for demonstration and
certification processes. To the credit of the
management team, these funds will suffice till the
aircraft reaches serial production. Considering all
factors, the development costs are a fraction of
what most similar aircrafts have cost . As
compared to the Kiran, plans call for an increased
lifespan (10,000 hours), more armament carrying
capabilities (1000 kg) and a higher maximum speed
(700 kph). A second prototype is expected in August
of 2003, which will be fitted with advanced avionics
. As a vote of confidence, the Chief of Air
Staff has placed an order for 16 HJT-36s, meant for
the national aerobatic team, the Surya Kirans. A
second vote came from the Scientific Advisor to the
Defence Minister Dr. V.K. Atre, who said, "We are
few more steps to the AJT and a larger LCA, the
mid-combat aircraft" .
As we look into
the future we expect improvements in the present
HJT-36 prototypes. Few details have been released by
HAL on what the final HJT-36 will contain. One would
expect it to be a mature product with standard
features such as fly-by-wire flight controls, wide
angle HUD, HOTAS controls, MIL STD data-bus,
helmet-mounted target designation and integration
with equipment and weaponry from disparate sources.
Snecma has already proposed an enhanced jet engine
for the production IJT and hopefully that is just
the beginning. There is also talk of a production
run of 200 aircraft .
A favourite with the
crowd is the possibility of morphing the IJT into an
AJT. Two design ideas leap out with this in the
background. The first is to add another engine. A
tandem engine configuration have been seen in
recently designed AJTs, the HAL designed AJT would
look fairly similar to those. The second suggestion
revolves around replacing the present Larzac engine
with a more potent engine, perhaps a de-rated Adour.
The Adour is currently in use in the indigenously
manufactured Jaguar aircraft. No matter which design
is preferred by HAL and its design team, the
pressure to design and develop an Indian AJT will be
allows India to build any of the following:
1] A basic trainer, suitable for basic jet training.
2] A trainer for basic combat use of unguided
weapons, air-to-air missiles and sea targets.
3] A combat trainer with under-wing hardpoints
capable of launching guided missiles and using
guidance equipment pods.
4] A single-seater tactical fighter, with guns,
all-weather radar for use of AAMs and ASMs.
5] A Coast Guard SAR aircraft, with a nose-mounted
6] A sporty private jet for enthusiasts.
Intermediate Jet Trainer
project has proved that international cooperation is
the way of the future. This sort of venture is bound
to attract several investors from all over. The
author extends his congratulations to all the
parties and wishes HAL and the development team the
very best for the future.
Overall Wingspan: 10.00 metres.
Overall Length: 11.00 metres.
Overall Height: 4.40 metres.
Normal Training Weight: 3500 kg
Max Take Off Weight: 4500 Kg
Max Mach Number: 0.75 Mach
Max Dive Speed: 750 km/h
Service Ceiling: 9000 metres.
Maximum Load Factor: +7g / -2.5g
1. Indigenous IJT takes to skies on maiden flight.
2. Light Combat
3. Indian jet
trainer takes flight.
4. First flight
of India's Larzac-powered HJT36 trainer, Snecma
Moteurs - Press Release March 7, 2003.
Aerospace, HAL sign HJT-36 avionics contract.
6. Thales News,
Solutions' 3D CAD/CAM and PDM software chosen for $1
million contract with HAL,
10. Indian Jet
Trainer Makes Debut Flight.
11. India Few
Steps Closer to Making AJT: Aatre.