- IAR SOIM - LITTLE HAWK
- Written 2000
- The Romanian aircraft manufacturer Avioane Craiova
SA was established in 1972 to develop and build aircraft for the
Romanian Air Force. Its position near the town of Craiova is in the
south west of the country. Their first aircraft, the IAR-93 YUROM,
was a joint venture with the Yugoslavians. This was initially a
single-seat close air support, ground attack and reconnaissance
aircraft. It first flew on the 31 October 1974. The experience gained
from this aircraft, and its development over the years, enabled
Avioane Craiova to produce the first Romanian designed, Romanian
built aircraft: the IAR-99. IAR stands for Industry Aeronautical
Romania. The first IAR-99 was developed for the advanced trainer and
ground attack roles and is now known as the 'Standard'. It first flew
on the 21 December 1985. The aircraft was ideally suited to the
Romanian Air Force requirements at the time. However, with the MiG 21
'LANCER' upgrade it quickly became obvious that a new '99' (military
trainer) was required. Similarly, with the Company's new-found
freedom other markets were now open to them. It was with this in mind
that the IAR SOIM (Little Hawk) was conceived. The initial aim was to
develop a new trainer to meet their home Air Force's Operational
Requirements but it quickly became obvious that the aircraft would be
suitable for the old Eastern and Western customers alike. It was
further decided to make the aircraft suitable for the whole training
environment (from basic to advanced training) as well as the Close
Air Support (CAS) role.
- As part of an AFM visit to the factory I performed
a three-flight evaluation of the prototype SOIM aircraft. All the
flying activities were performed at the Romanian MoD Flight Test
Centre, which was based at Avioana Craiova. The flights included
general handling, low level flying (70-100m above the ground),
systems functioning and formation flying. However, Avioane Craiova
wanted to emphasize that this was the development SOIM and that small
changes to the aircraft were already planned from the initial flight
testing results.
- IAR SOIM PROGRAMME
- The decision to produce a new trainer was made in
late 1996. The aerodynamics of the IAR-99 Standard were considered
suitable enough for a Lead-In-Trainer (LIT)/CAS aircraft and as such
is was clear that the new aircraft needed the majority of the
development work spent on its cockpit to bring it up to the modern
standards. A two-stage programme was developed to allow the first
Certification process to produce the LIT version, followed by a
second stage to certify the CAS aircraft. It was decided that the
aircraft should be able to carry both Western and Eastern
air-to-ground and air-to-air weapons, as well as other 'smart' pods
for the various attack options and electronic counter measures (ECM).
- The avionics upgrading process began in 1990 with
two aircraft (Sn 708 and 709) being equipped with Honeywell avionics.
The first flights of these aircraft were performed on the 9 August
1990 and the 22 August 1990 respectively. A further aircraft (712)
was fitted with Collins equipment and made its first flight on 6
November 1991. However, it was not until the IAR 109 SWIFT that the
avionics integration started to progress rapidly. This aircraft was
meant as an 'all-through' trainer (basic and advanced) with modern
avionics and weapon delivery systems. The SWIFT was a joint venture
with Israeli Aircraft Industries (IAI) and included Bendix-King
avionics as well as Israeli systems. The SWIFT (7003) made its debut
flight on the 2 December 1993. It was with the knowledge from all of
these development aircraft that the IAR SOIM (718) was produced
leading to its first flight on the 22 May 1997. To date only one SOIM
has been produced, with the next three aircraft due to come off the
production line early next year.
- SOIM DESIGN
- The aircraft was designed to meet modern European
standards (MIL-8785B), with the main aim of being simple and easy to
maintain at an affordable cost. Its basic construction was of
aluminium alloy with fibreglass wing tips, tail fin tip cover and
some doors and covers. The aircraft was fitted with a Rolls-Royce
Viper Mk 632-41M engine built under Licence by Turbomecanica based in
Bucharest. This engine was chosen because it has been proven to be
very reliable, easy to re-light and has an engine life of at least
4000 hours. It was also relatively cheap, which was important during
the selection in order to keep the overall aircraft costs down. The
engine produces 4,000 pounds of thrust at sea level (17.8 KN). The
wing was designed as a straight taper, fitted with two internal
structurally integrated fuel tanks per side. There were a further two
fuel tanks fitted in the fuselage, giving a total capacity of 1,370
litres (2,425 pounds/1,102 kilograms) internally and with two
external tanks 1,820 litres (3,225 pounds/1,466 kilograms). On the
prototype aircraft refuelling was by gravity (similar to a car
refuelling nozzle) rather than a pressure system as is normal on
equivalent Western trainers. I was told that this was deliberate
because many of the developing markets might prefer this capability.
However, pressure refuelling (as fitted on the IAR-93) will be
offered as an option. The hydraulic system powered the undercarriage,
airbrakes, flaps, main wheel brakes and ailerons; the ailerons also
had a mechanical backup. An anti-skid system was fitted to the wheel
brakes. The prototype SOIM was fitted with a Martin Baker Mk-10L
ejection seat but it is planned to offer the Romanian equivalent
ejection seat, made by Aerofina, as a customer option. At present the
seat ejects through the canopy but the testing of miniature
detonating chord (to shatter the canopy first) has been completed and
will be a further option.
- Avionics
- The cockpit was very modern and had been put
together well with some novel features. A Modular Multi Role Computer
(MMRC), designed and produced by Elbit Systems of Israel, controlled
the whole avionics suit. This computer acted as the heart of the
system running through a MIL-STD-1553B Data Bus. The front cockpit
was fitted with a Flight Vision Systems' Head Up Display (HUD), a
Multi Function Colour Display (MFCD) on the left head down and a
Multi Function (monochrome) Display (MFD) to the right head down
(both Elbit). There was no HUD in the rear cockpit but the HUD
symbology was reproduced on a dedicated MFD, the ASHM (Aft Station
HUD Monitor), mounted in the upper centre position of the front
panel. If needed the symbology could be swapped on to the right
Head Down Display (HDD). Beneath the HUD was an Up Front Control
(UFC) panel used to interface with the avionics system, including
changing the radio frequencies, transponder codes, navigation
functions and so on. The navigation system was called a 'hybrid'
system because it combined a relatively cheap Litton inertial
platform with a GPS to gain accuracy. Other than the cost, the
advantage of such a system is the 'alignment' time, which was just 30
seconds. The cockpit could be 'monitored' by a high-resolution colour
camera system, which could film the HUD and one of the HDDs. (A
useful pilot debriefing tool at the end of a sortie.) Mission
planning could be performed back at the squadron with the mission
details being loaded by a data transfer system in the rear cockpit.
- Weapon Systems
- The SOIM had five external stations for carrying
ordnance and/or fuel tanks: two on either wing and one under the
fuselage. The fuselage station could be fitted with a semi-conformal
gun-pod, fitted with a fast firing (3,000 rounds per minute)
twin-barrel, 23 millimetre cannon or a 'smart' pod (LASER/FLIR, ECM,
Photo-reconnaissance). The four pylons under the wings were capable
of carrying a large variety of both former Eastern and Western
weapons (up to 660 pounds/300 kilograms per pylon), including bombs,
rockets, air-to-air missiles and smart bombs and pods. However, at
the time of the assessment only the testing of Eastern ordnance had
been completed, with the Western weapon testing due to be completed
by the end of 2000. The aircraft was fitted with an Elbit stores
management system, which was controlled by the MMRC. Avioane Craiova
made the pylon release units. The payload configuration could be
displayed pictorially on the MFCD. The cockpit employed the
Hands-On-Throttle-And-Stick (HOTAS) concept allowing most of the
'fighting' functions to be performed by switches on these two
controls. But to aid weapon management the aircraft was fitted with a
Display And Sighting Helmet (DASH), designed by Elbit. In essence the
technology displayed weapon sighting and navigation information on to
the visor of the helmet. A helmet tracker mounted on the canopy
followed the head movement in order to display the correct
information correlated with the outside world. This potentially was a
very impressive system that was going through its development and
certifying stages.
- On the self-defence side the aircraft was fitted
with an Elbit chaff and flares system (auto or manual dispensing) as
well as an all-round radar warning receiver produced by Elisra,
Israel. However, perhaps the most surprising use of the computing
power on the aircraft was a Virtual Radar (VR). This was a computer
generated radar display (via the MMRC) designed to give the trainee
pilot some experience in radar techniques and switching. The VR had
two modes: the first, was that up to four SOIMs could be 'joined up'
via data link to produce a pseudo radar picture by the computer
interpreting the other aircrafts' GPS co-ordinates and then
displaying their relative positions on the radar screen. Giving the
impression that they were being identified by radar. The trainee
pilot could then manipulate standard radar controls in the cockpit to
become familiar with the techniques. The second VR mode was even
simpler in that the MMRC internally generated targets on the radar
screen for the trainee to encounter. Although, only five such
scenarios are planned it would give the pilot a degree of radar
familiarity. Unfortunately, as there is only one SOIM at present the
multiple aircraft mode of the VR could not be tested.
- Emergency Training
- Following the theme of 'if you have computing
power you might as well use it' the aircraft was fitted with a Fault
Simulation Panel (FSP). This enabled the rear cockpit
pilot/instructor to 'inject' emergencies/faults into the front
cockpit. For example, engine fire, generator failure, oxygen problems
and so on (10 faults in all). In theory this was a good idea but
procedurally its use would have to be carefully considered. For
instance you would not want the student to close the engine down,
while reacting to a simulated fire emergency! However, all of the
engine switches could be easily guarded from the rear cockpit to
prevent this from happening but it would need careful thought. The
other aspect of the system that may need to be reconsidered is that
at present if a fault is simulated there is no way that the
front-seat pilot can confirm the fault validity without the aid of
the rear occupant. This may be a problem if non-aircrew passengers
are carried in the back seat. Some form of duplicate switch in the
front cockpit to 'arm' the system seems sensible and might aid
general system integrity.
- FLIGHT PREPARATION
- The preparation for the flight was relatively easy
with a good set of documentation in English. The flying helmet was of
American design and the strapping-in procedure was standard, as it
was a Martin Baker seat. I then spent an hour or so sitting in the
front cockpit of the aircraft in the hangar with electrical power
connected. The Chief Test Pilot, Cristian Muscalagiu, gave me a good
briefing on the aircraft, including the starting procedure. Because
the aircraft was fully powered it meant that I could 'play' with the
systems before the first flight, which is the best pre-flight
training you can have. By the end of the session, I felt at home with
the systems. It also served to highlight just what a simple aircraft
this was - ideal for a 'first-jet' trainer.
- At the aircraft I followed Cristian on his
walk-round with very little to mention other than the odd accumulator
pressure to check in the wheel well. Once in the aircraft it was very
comfortable and quite roomy. As I had performed all of the checks the
previous day in the hangar the pre-start time was minimal. In fact
other than switching the avionics and radios on to ask for start, and
then off again, there were only five switches (and ensuring the main
fuel cock was open) that needed to be selected before the start
button was pressed. Then at 10 per cent rpm, and with an oil pressure
indication, the HP fuel lever was moved forward to on. At this point
light up occurred, with the start taking about 25 seconds to
complete. The engine was not fitted with any form of digital fuel
computer (FADEC) to control the engine, but even opening the HP fuel
lever as quickly as possible I could not cause a hot start. Again,
relatively cheap and simple. Once the start had finished it was then
a case of putting all the switches forward and setting up the
avionics. Firstly, the aircraft's position co-ordinates were checked
(either on the HUD or one of the HDDs) before switching the
navigation system to align. It was an absolute joy when the system
really did take 30 seconds to be ready to go. The other avionics
switching was relatively simple through the menu driven displays. On
the first trip it took 7 minutes and 28 seconds after engine start to
be ready to taxy, but by the third trip it was down to just over 4 minutes!
- Taxying the aircraft was relatively simple using
the differential braking system; ie, pushing the brake pedal on the
side that you wanted to turn to get the nosewheel to castor in the
desired direction. However, it was noticeable that the undercarriage
oleos (suspension) were very spongy. This was not too much of a
problem at the start of the sortie or even during the take-off.
However, it was a major cause for concern on the landings, where the
aircraft had a tendency to roll from side to side quite harshly
during the landing roll-out, particularly under heavy braking -
something I would not expect a student to have to cope with! I later
found out that this was because the oleo struts incorporated only one
damping cylinder instead of two, but the design work had already be
done to fit the dual cylinder version. These would be standard on the
production aircraft.
- FLYING QUALITIES
- Pre-take-off checks were minimal and basically
required a 'left-to-right' check of the switches and that take-off
flap had been selected. Even the emergency briefing was easy because
the ejector seat had a zero height, zero speed capability. Once lined
up the technique was to apply full power against the brakes to check
the engine parameters (101.5 per cent rpm, 700 degrees jet pipe
temperature for my flights), before releasing the brakes. The
acceleration was reasonable with the nosewheel being raised at 165
kph (89 knots), resulting in the aircraft lifting off the ground at
210 kph (114 knots) after 20.5 seconds. The undercarriage was
selected up when clear of the ground; however, it was recommended not
to raise the flaps until the speed and height had reached 250 kph
(135 knots) and 100 m (333 ft) respectively. This was because there
was a slight tendency to sink as the flaps came in. Once airborne the
aircraft was stable with reasonably light aileron control forces.
However, the pitch control forces were high and needed active
trimming to keep them light and manageable. The stick-top trimmer
(for pitch and aileron force reduction) was very powerful and quick
acting, which helped the situation. The Company did inform me that
they were planning to review and hopefully reduce the pitch
manuvring forces.
- General Performance
- The first check of performance was to time a level
acceleration from 250 kph (135 knots) to 735 kph (400 knots). This
was a particularly interesting test because the aircraft had a
relatively small amount of engine thrust matched with a light
take-off weight (approximately 9,700 pounds/4,410 kg for my flight).
The acceleration took 1 minute 28 seconds, which was reasonable for a
jet trainer. By comparison the Aerovodochody L159 took approximately
1 minute for the same test but it does pack a large engine producing
over 55 per cent more thrust. The next test on my performance list
was a timed climb from 1,600 m (5,250 ft) to 3,100 m (10,170 ft), at
350 kph (190 knots). This took 1 minute and 17 seconds, or to put it
another way the aircraft was climbing at 3700 feet per minute at a
mean altitude of 7700 feet; again, not sparkling but satisfactory for
this class of aircraft, albeit in the clean configuration. As far as
the aircraft's rate of roll was concerned this was approaching
fighter standards at 102 degrees per second at 350 kph (190 knots)
and 140 degrees per second at 550 kph (300 knots).
- As discussed earlier the forces required to pitch
the aircraft were high, needing approximately 35-40 pounds of force
to pull 4 'g' (without trimming). Another area that was interesting
on the aircraft was the directional stability, which was quite weak.
This caused the prototype to 'snake' directionally (left to right
twisting movement, around the 'y' axis) whenever the aircraft was
disturbed, either using the aircraft's controls or by turbulence. As
a trainer aircraft this would not be too detrimental because the
techniques are the important learning points not necessarily
accuracy. However, when it comes to weaponry a stable platform is
vitally important. The Company informed me that ventral strakes (to
be fitted under the rear fuselage) had already been designed and
would be fitted as standard on production aircraft to eradicate the problem.
- The gear and flap up stalling qualities of the
aircraft were benign with a gentle nose drop at approximately 180 kph
(97 knots); with gear and full flap down the stall occurred at 145
kph (79 knots) with a marked pitch nodding motion. I then tried a few
aerobatics (at a height of 2,500 metres, 8,200 feet) to see how much
height was required for each manuvre and to experience the
general flying qualities of the aircraft. The loop was performed at
500 kph (271 knots) and, at 4 g, took 1,050 m (3,450 ft) to complete.
The 'Split S', which is a combat manuvre involving rolling
inverted at 250 kph (135 knots) and then completing the second half
of a loop by pulling through to regain level flight, took 900 m
(2,950 ft) to complete, again at 4 g. Unfortunately, due to air
traffic height restrictions, only the aircraft's incipient spinning
(recovering after one turn) characteristics could be assessed. Using
either the technique of releasing the controls or the normal spin
recovery technique (full opposite rudder followed by forward stick)
the aircraft recovered quickly without cause for concern.
- Emergency Landings
- Simulated emergency landings were practised from
various positions, heights and speeds. They resulted in good
judgement exercises for the pilot but were not representative of a
modern fighter aircraft. This was due to the low drag of the aircraft
even when the gear and flaps were selected down. The general
technique in the vicinity of an airfield was to select the airbrakes
out (to simulate a damaged, shutdown engine) and then to put the gear
down to increase the drag. The flaps had to be selected quite early
on in the procedure to get the drag up to an acceptable level. This
prevented the usual technique (like in the BAe Hawk) of staying high
and selecting the flap down when you were absolutely certain of
making the runway. Cristian informed me that they were considering
changing the landing flap setting, which would increase maximum flap
from 40 degrees down to 60 degrees down. This would allow the desired
increase in drag when required and would mean, in a real emergency,
that the pilot could conserve height for longer knowing that he could
get down easily when a runway landing was assured. This
modification should make the aircraft's gliding qualities more
representative of a modern fighter.
- TACTICAL ASSESSMENT
- As with any fighter pilot the most interesting
stuff is when you start operating the aircraft in its intended
environment. For the advanced trainer and CAS role this means low
level flight, formation and weaponeering. Unfortunately, no ordnance
was available to be either carried on the aircraft or dropped, which
restricted the assessment to the handling of a clean aircraft in the
tactical environment and the symbology aspects of weapons release.
- Low Level Flight
- Navigationally the aircraft was well suited to
flying at low altitudes because of good steering information, backed
up with GPS accuracy. The guidance was displayed in the HUD as well
as on the HDDs. The HDDs also gave good situational awareness by
displaying a 'gods-eye' view of the route as well as marking
restricted zones and other airspace information - not as good as a
moving map but a lower cost alternative. The steering waypoints
(places to fly to) could be either inputted manually into the
navigation system or be prepared back in the Squadron and then loaded
into the aircraft using the Data Transfer capability. Guidance around
the route could be set to allow manual sequencing of the waypoints or
this function could be set to automatic; in automatic mode the
computer changed to the next steering point as each waypoint was over-flown.
- The ride quality was typical of an aircraft with
low wing loading (small mass supported by a large wing area),
reacting to the turbulence and giving a bumpy ride. However, even
over some quite big hills the ride was not uncomfortable at the
suggested low-level speed of 450-500 kph (250-300 knots). This
low-level speed was quite low for an advanced trainer or CAS
aircraft, although the Company did inform me that low-level could be
flown at speeds as high as 650 kph (350 knots). This is closer
to a fighter low-level speed of around 775 kph (420 knots). It was
easy to maintain accurate height above the ground using the radio
altimeter readout in the HUD. Lookout was generally good with only
the forward canopy frame restricting the view. On this prototype
aircraft the slightly reduced directional stability meant that the
aircraft's nose tended to oscillate left and right by up to +/- one
degree. This had little effect on the overall training value of the
low-level flying.
- Weapons Capability
- The aircraft comes equipped with the majority of
the modern weapon delivery modes. For dropping bombs the three main
modes were CCIP, CCRP and Dive Toss. For CCIP (continuously computed
impact point) the aircraft's computer is continuously looking at the
aircraft's height, speed, weapon trajectory characteristics and other
pertinent parameters to try to work out where a bomb would fall if
released immediately. The symbology displayed on the HUD illustrated
this position to the pilot by displaying a bomb 'fall' line and a
circle with a point in the middle to define the impact point. This
type of delivery is the simplest to use and requires the pilot to
'fly' the bomb fall line through the target and drop the bomb as the
circle passes over it. However, CCIP bombing does need the pilot to
be able to see the target. If the target is obscured but the location
is known the GPS co-ordinates can be entered into the system. Now the
pilot simply flies the bomb fall line through the predicted target
position (marked by a box in the HUD) and 'commits' to dropping the
bomb by pressing the pickle button. The computer then looks at all
the same parameters used in CCIP mode but it does not release the
weapon until it considers the target will be hit. This is called CCRP
mode (computer calculated release point). A combination of the two is
known as Dive Toss. Here the pilot has a square in the HUD that he
can position over the target and press a button to designate the
target under the square. Once the designation button had been pressed
the square was ground stabilized over the spot. Small corrections can
be made using a controller on the throttle. Once the pilot is happy
that the target is accurately designated he commits in the same way
as CCRP. Now he is able to continue the dive towards the target
waiting for the bomb release or he can perform a pull-up manoeuvre to
make the bomb come off earlier (by literally tossing the bomb at the
target). This allows a quicker turn away from the target area, which
may be heavily defended. All of these modes were well produced and
for training exposure were excellent.
- The air-to-ground gun mode was similar to the CCIP
bombs mode in that a continuously computed impact point for the
bullets was displayed in the HUD. All that was required was to
accurately track the target with the sight and open fire. The
aircraft was not fitted with a laser ranging capability, although it
was a customer option. For air-to-air gunnery the same principle was
used but a 'Snap Hotline' was added, that ran through the targeting
circle to indicate the fall line of the bullets. This line varied its
shape considerably as the SOIM was manoeuvred, indicating the dynamic
nature of air-to-air gunnery. Trying to follow a second aircraft,
which was trying to manoeuvre away, was very demanding and generally
resulted in 'snap' shots rather than continuous tracking.
- For air-to-air missile combat the main sighting
capability would come from the helmet display system (DASH). This
form of targeting is ideal, as it simply requires the pilot to look
in the direction of the target and place the designating box over it.
When the correct lock has been achieved the missile can be released.
Unfortunately, the system was not ready for outside assessment but it
is hoped that it will be included next time. Radar missile handling
could only be simulated using the computer generated Virtual Radar
mode. This was reasonable training exposure but had no combat significance.
- Overall, the weapon training value of the aircraft
was good but it was not possible to determine the accuracy level of
the equipment without releasing some actual weapons. In the CAS role
the small directional disturbances would effect absolute accuracy and
make hitting the target more difficult. The addition of the new
ventral stakes should eradicate the problem and will be the subject
of the next article!
- Formation
- During the formation assessment the aircraft was
relatively easy to fly (with active pitch trimming!) and the engine
response was good. Up-and-away manuvring by a second aircraft
was easy to follow and would be a good introduction to formation
flying for the ab initio pilot. During the formation take-off and
recovery to land the aircraft trajectory variations, with the
selection of the services (gear, flap, etc), were all manageable and
the engine response was quick enough to cope.
- OVERALL
- Avioane Craiova SA emphasized that the aircraft
flown during the assessment was a prototype and that it was still
under development. As such, they had some modifications already
planned to address the majority of the concerns raised during flight
test. It is reasonable to say that at present the aircraft is not as
sophisticated as the latest British Hawk aircraft or even the
Czechoslovakian L159; however, it is closing the gap and, according
to Avioane Craiova, they are not after taking customers away from
these aircraft (at least not yet!). They believe that they have an
aircraft that is good value for money and therefore might appeal more
to the developing markets, where some nations cannot afford the top
level of sophistication. From what I have seen they may be right. As
an entry level Lead In Trainer the IAR SOIM is fitted with a
sufficiently complex suit of avionics and weapon delivery systems to
make it effective. As far as the CAS role is concerned the flying
qualities will need some improvement (as planned) and some weapon
system and accuracy testing will be needed to ensure that the 'green'
writing in the HUD is producing the required results when real
weapons are dropped. At the end of the day you get what you pay for
but in this very competitive market you can get a lot more for your
buck than you used to - this aircraft proves that.
- LEADING PARTICULARS
- Length 36.11 feet (11 metres)
- Height 12.79 feet (3.87 metres)
- Wing Span 32.31 feet (9.85 metres)
- Empty Weight 7,055 pounds (3,207 kilograms)
- Take-off Weight Clean 9,680 pounds (4,400 kilograms)
- Maximum Take-off Weight 12,258 pounds (5,572 kilograms)
- Maximum Load Factor +7 to -3.6 g
- Maximum Speed 510 knots (940 kph)
- Maximum Level Speed 467 knots (860 kph)
- Maximum Climb Rate At Sea Level 6,900 feet
per minute (35 m/s)
- Take-off Distance (Trainer) 1,500 feet (457 metres)
- Take-off Distance (CAS) 3,150 feet (960 metres)
- Landing Distance (Trainer) 1,805 feet (550 metres)
- Landing Distance (CAS) 1,970 feet (600 metres)
- Endurance (Without Tanks) 2 hours, 40 minutes
- Max Range (With Tanks) 595 nm (1,100 km)
- Typical Cruise Speed Mach 0.6 @ 33,000 feet
- Sustained Turn Rate 20 deg/ sec @ Mach 0.42,
3,000 feet
- Service Ceiling 42,322 feet (12,903 metres)
- Pylon Carrying Capability 550 pounds (250
kilograms) per pylon
- BACK
TO TOP