Israel Aircraft Industries (IAI) Lavi
By Ruud Deurenberg
During the fifties and sixties the Tsvah Haganah Le Israel - Heyl Ha'Avir (Israel Defence Force/Air Force (IDF/AF)) relied on France for its combat aircraft. When, after the Six Day War (5 to 10 June 1967), France did not delivered the 50 Dassault Mirage 5Js Israel had ordered and paid for, Israel decided to develop its own combat aircraft. The first such attempt resulted in the Israel Aircraft Industries (IAI) Kfir (Lion Cub), a multi-role fighter developed from the Mirage 5, of which a total of 212 were produced. To replace the Kfir, Israel developed the Lavi (Young Lion).
Israel has been embroiled in more wars in recent times than any other nation, with the result that Israeli pilots are very combat experienced, and most likely to know exactly what they want in a fighter, within the constrains of affordability. When, in 1979, the Lavi program was announced, a great deal of interest was aroused for these reasons.
The Lavi program was launched in February 1980 as a multi-role combat aircraft. The Lavi was intended primarily for the close air support (CAS) and battlefield air interdiction (BAI) mission with a secondary air-defense mission. The two-seat version could be used as a conversion trainer. As originally conceived, the Lavi was to have been a light attack aircraft to replace the elderly McDonnell Douglas A-4 Skyhawk, the McDonnell Douglas F-4 Phantom II and the IAI Kfir, remaining in service with the IDF/AF. A single-seater, powered by a General Electric F404 turbofan, it was soon perceived that this solution gave no margin for future growth, and an alternative engine was chosen, the much more powerful Pratt & Whitney PW1120. With the extra power came demands for greater capability, until the Lavi began to rival the F-16, which was already in service with the IDF/AF.
The full-scale development (FSD) phase of the Lavi began in October 1982. Originally, the maximum take-off weight was projected as 17,000 kg, but studies showed that with only a few design changes, and thus a slight increase in weight, the Lavi could carry more armament. The prize was tried to kept at the same level. With a prospective IDF/AF requirement for up to 300 aircraft (including 60 combat-capable two-seaters), the full-scale development (FSD) phase was to involve five prototypes (B-01 to B-05) of which two, B-01 and B-02, were two-seaters and three, B-03, B-04, and B-05, were single-seaters.
A full-scale mock-up of the Lavi was revealed at the beginning of 1985.
The first Lavi (B-01) flew on 31 December 1986, piloted by IAI chief test pilot Menachem Schmul. The handling was described as excellent, with a high degree of stability in crosswind landings, and the flight test program proceeded space. The second Lavi (B-02) flew on 30 March 1987. Both Lavi B-01 and Lavi B-02 were tandem two-seaters, with the rear cockpit occupied by test equipment.
Then, on 30 August 1987, the Lavi program was canceled, after Lavi B-01 and Lavi B-02 had made more than 80 flights. The two prototypes had flown at speeds from 204 km/h up to Mach 1.45 at 23o angle of attack. Much systems, including the digital flight control, were tested within this envelope.
The third Lavi (B-03) and subsequent Lavi prototypes (B-04 and B-05) would be fitted with the definitive wing with increased elevon chord and the last three prototypes would also have the complete mission-adaptive avionics system. Lavi B-04 and Lavi B-05 were just about to receive the definitive wing when the program was canceled.
The first production aircraft were intended to be delivered in 1990 and initial operationally capability (IOC) was planned for 1992. At the height of the production, a total of twelve aircraft would be produced in one month. The Lavi would have been the most important aircraft of the IDF/AF in the nineties.
Comparisons with the Lockheed Martin F-16 Fighting Falcon are inevitable, as the US fighter made a handy yardstick. The Lavi was rather smaller and lighter, with a less powerful powerplant, and the thrust-to-weight ratio was slightly lower across the board. The configuration adopted was that of a tail-less canard delta, although the wing was unusual in having shallow sweep on the trailing edge, giving a fleche planform. The straight leading edge was swept at 54 degrees, with maneuver flaps on the ourboard sections. The tips were cropped and fitted with missile rails to carry the Rafael Python 3 air-to-air missile. Two piece flaperons occupied most of the trailing edge, which was blended into the fuselage with long fillets. The wing area was 38.50 square meters, 38 per cent greater than the wing area of the F-16, giving an almost exactly proportionally lower wing loading, while the aspect ratio at 2.10, was barely two-thirds that of the F-16. Pitch control was provided by single piece, all-moving canard surfaces, located slightly astern of and below the pilot where they would cause minimal obstruction in vision. Grumman was responsible for the design and development of the wing and the fin, and would produced at least the first 20 wings and fins.
Predictably, relaxed static stability and quadruplex fly-by-wire (FBW), with no mechanical backup was used, linked to nine different control surfaces to give a true control configured vehicle (CCV). In comparison with the F-16, the Lavi is very unstable, with an instability of 10 to 12 per cent. The surfaces were programmed to give minimum drag in all flight regimes, while providing optimum handling and agility. It was stated that the Lavi had an inherent direct lift control capability, although this was never demonstrated.
The powerplant intake was a plain chin type scoop, similar to that of the F-16, which was known to be satisfactory at high alpha and sideslip angles. The landing gear was lightweight, the nose wheel was located aft of the intake and retracting rearwards, and the main gear was fuselage mounted, giving a rather narrow track. The sharply swept vertical tail, effective at high alpha due to interaction with the vortices shed by the canards, was mounted on a spine on top of the rear fuselage, and supplemented by the two steeply canted ventral srakes, mounted on the ends of the wing root fillets. Extensive use of composites allowed aerolastic tailoring to the wings, so that the often conflicting demands of shape and rigidity could be resolved to minimize drag in all flight regimes. Composites were also used in the vertical tail, canards, and various doors and panels. A total of twenty-two per cent of the structural weight compromise composite materials. IAI claimed a significant reduction in radar cross section (RCS).
Standard practice with high performance jet aircraft is to provide a second seat for conversion training by shoehorning it in, normally at the expense of fuel or avionics, or both. IAI adopted a different approach, designing the two-seater first, and then adopting it into a single-seater, which left plenty of room for avionics growth. In fact, the first 30 production aircraft would all have been two-seaters to aid service entry. Many of these aircraft were later to have been fitted out for the suppression of enemy air-defense (SEAD) mission.
The powerplant of the Lavi was the Pratt & Whitney PW1120 turbofan, rated at 6,137 kg dry and 9,337 kg with reheat and was a derivate of the F100 turbofan. The development of the PW1120, according to IDF/AF specifications, started in June 1980. It retained the F100 core module, gearbox, fuel pump, forward ducts, as well as the F100 digital electronic control, with only minor modifications. Unique PW1120 components included a wide chord low pressure (LP) compressor, single-stage uncooled low pressure (LP) turbine, simplified single stream augmentor, and a lightweight convergent/divergent nozzle. Full scale testing was initiated in June 1982, and flight clearance of the PW1120 was tested in August 1984. The PW1120 had 70 per cent similarity with the F100, so the IDF/AF would not need a special facility for spare parts. It would be built under licence by Bet-Shemesh Engines Limited in Israel.
IAI installed one PW1120 in the starboard nacelle of an F-4E-32-MC of the IDF/AF (Number 334/66-0327) to explore the airframe/powerplant combination for an upgrade program of the F-4E, known as Kurnass 2000 (Heavy Hammer) or Super Phantom and to act as an engine testbed for the Lavi. The powerplant was more powerful, and more fuel efficient than the General Electric J79-GE-17 turbojet normally installed in the F-4E. The structural changes included modifying the air inlet ducts, new powerplant attachment points, new or modified powerplant baydoors, new airframe mounted gearbox with integrated drive generators and automatic throttle system. It also included a modified bleed management and air-conditioning ducting system, modified fuel and hydraulic systems, and a powerplant control/airframe interface. It was first flown on 30 July 1986. Two PW1120 powerplants were installed in the same F-4E and it was flown for the first time on 24 April 1987. This proved very successful, allowing the Kurnass 2000 to exceed Mach 1 without the afterburners, and endowing a combat thrust-to-weight ratio of 1.04 (17 per cent better than the F-4E). This improved sustained turn rate by 15 per cent, climb rate by 36 per cent, medium-level acceleration by 27 per cent and low-level speed with 18 bombs from 1,046 km/h to 1,120 km/h. It was demonstrated at the Paris Air Show in 1987 carrying the show number 229 and civil registration 4X-JPA. However, McDonnell Douglas refused to approve the modification, because it offered a flight performance equal to that of the F/A-18C/D, and endangered any future sales of the F/A-18C/D.
The internal fuel capacity was 3,330 liters (2,722 kg), some 16 per cent less than the F-16, although this was claimed to be offset by the low drag of the Lavi airframe and the low specific fuel consumption (sfc) of the powerplant. Single point high pressure refueling was adopted for quick turnaround, and provision made for air refueling with a female type receptacle compatible with flying boom-equipped tankers. To aid the flight test program, the Lavi prototypes were also equipped with bolt-on refueling probes. The external fuel capacity was 4,164 kg in two 2,548 liter drop tanks on the inboard pair wing stations.
Specification of the Pratt & Whitney PW1120
The Lavi had an AiResearch environmental control system for air-conditioning
pressurization, and powerplant bleed air control. A pneudralics bootstrap
type hydraulic system with a pressure of 207 bars with Adex pumps was also
installed. The electronic system was powered by a Sundstrand 60 kVA
integrated drive generator, for single-channel AC power at 400 Hz, with a
SAFT main and Marathon standby battery. Sundstrand also provided the
actuation system, with geared rotary actuators, for the leading-edge flaps.
The Lavi had an AiResearch emergency power unit (EPU) and a Garrett secondary
The avionics of the Lavi were modular - they could be upgraded by loading
new software into the Elbit ACE-4 mission computer. The purpose was that the
airframe would not require many modifications during its life. The avionics
suite was stated to be almost entirely of Israeli design. The flexibility and
the situational awareness were emphasized to reduce the pilot workload at high
g and in a dense threat environment. The air data computer was provided by
A wrap around windshield and bubble canopy gave excellent all-round vision. But where a steeply raked seat and sidestick controller similar to the F-16 might have been excepted, IAI selected a conventional upright seat and central control column. The reasoning was as follows. The raked seat raised the pilot's knees, causing a reduction in panel space which could ill be spared while neck and shoulder strains were common in the F-16 when a pilot craned around in his steeply raked seat to search the sky astern while pulling high g. The sidestick controller was faulted on three counts:
The cockpit layout was state of the art, with HOTAS (hands-on-throttle and stick), and a Hughes Aircraft wide-angle diffractive optics head-up-display (HUD) surmounting a single El-Op up-front control panel, through which most of the systems were operated. Furthermore, the cockpit had LCD technology powerplant indicators. Elbit Computers Ltd was selected as prime contractor for the integrated display system, which included the HUD, the three head-down displays (HDD) (two of them were color presentations and the third black and white), display computers, and communications controller, which included an Elta ARC-740 fully computerized onboard UHF radio system. Data-sharing between the HDDs would ensure display redundancy. The navigation system included the Tuman TINS 1700 advanced inertial navigation system. Control-column, throttle and display keyboard were all encoded in the display computers, which would themselves had a back-up function to the main aircraft computer, the Elbit ACE-4.
Elbit ACE-4 Mission Computer
The Elbit ACE-4 mission computer was selected for the IAI Lavi. It was compatible with both the MIL-STD-1750A and MIl-STD-1553B standards and could be used for display, digital radar, stores management and (future) avionics integration. It had a memory of 128 K.
Elta EL/M-2035 Multi-Mode Pulse Doppler RadarThe Elta EL/M-2035 multi-mode pulse-Doppler radar was a development of the Elta EL/M-2021B multi-mode Doppler radar of the IAI Kfir-C2. The radar was very advanced and had a coherent transmitter and a stable multi-channel receiver for reliable look-down performance over a broad band of frequencies and for high resolution mapping. An Elta programmable signal processor, backed by a distributed, embedded computer network, would provide optimum allocation of computing power and great flexibility for growth and the updating of algorithms and systems growth.
The radar could provide speed and position of targets in the air and on the ground, and could provide the pilot with a map of the terrain the Lavi was overflying. It could track several targets at 46 km distance in at least five air-to-air modes (automatic target acquisition, boresight, look down, look up and track while scan (TWS)). The radar had at least two air-to-ground modes (beam-sharpened ground mapping/terrain avoidance ans sea search). After the cancellation of the Lavi program the radar was offered for multi-role fighter retrofits, including the Denel Cheetah E.
Elta/Elistra Electronic Warning System
The electronic warning system of the Lavi was designed by Elta and Elistra
and was based on an active and passive integrated electronic support
measures/electronic countermeasures (ESM/ECM) computer-system, and was capable
of rapid threat identification and automatic deception and jamming of enemy
radar stations. It was carried internally. This system could also be used in
the future environment of more sophisticated enemy radar systems. The Lavi
could eventually carried podded power-managed noise and deception jammers.
Lear Siegler/MBT Fully Digital Flight Control System
The Lear Siegler/MBT fully digital flight control system for the Lavi had
quadruplex redundancy with stability augmentation, and had no mechanical
backup. It compromised two boxes, with two digital channels built into each
box. The twin-box configuration hinged on the survivability issue, which was
given great emphasis. If one was damaged, the other would provided sufficient
control authority to regain base. Each digital channel had associated with it
an analogue channel that could have take over its function in the event of a
failure. The design total failure rate was not greater than 1 in 107
hours. The program was launched in October 1982, and production deliveries
would began in 1988.
Elbit SMS-86 Stores Management System
Elbit was selected during early 1985 to develop the SMS-86 stores management
system for the Lavi. The system, which was fully computer-controlled,
compromised two units. The stores management processor included one
MIL-STD-1750 computer and two MIL-STD-1553B data-bus interfaces. The armament
interface unit included a stores interface compatible with the MIL-STD-1750.
The SMS-86 was capable of managing both conventional and smart weapons.
The weapons carriage of the Lavi was mainly semi-conformal, thus reducing
drag, with two hardpoints beneath each wing (the inboard pair was wet for the
carriage of two 2,548 liter auxilliary fuel tanks), plus the wingtip rail and
seven underfuselage hardpoints (three tandem pairs plus one on the centreline).
The main air-to-air weapon was to be the Rafael Python 3, an Israeli-designed
short range infra-red (IR) homing dogfight air-to-air missile, while a DEFA
Type 552 (Improved) cannon was housed in the starboard wing root. The
air-to-ground weapons used by the Lavi included the Hughes AGM-65B Maverick,
the IAI Gabriel IIIAS, rockets, and the Mk 81, Mk 82, Mk 83, Mk 84, and M117
DEFA Type 552 (Improved)
The DEFA 552 (Improved) is a single-barrel, five-chamber, revolver type automatic aircraft cannon with a high rate of fire (1,100 to 1,500 rounds per minute (rpm)). It is gas actuated, electrically controlled and fires electrically initiated 30 mm ammunition. The ammunition is belt fed from the left in the Lavi.
The 30 mm DEFA 552 cannon arrived in Israel on the Dassault Mystere IVA fighters and it turned out to be a very effective cannon. Israel Military Industries (IMI) was able to get the licence rights to manufacture the cannon and it became very popular with the IDF/AF - it was used in the Dassault Mirage IIICJ, the IAI Kfir and the McDonnell Douglas A-4 Skyhawk.
In its present form, the modifications and improvements results from its extensive use in combat by the IDF/AF.
The optional ammunitions for the DEFA Type 552 (Improved) can include:
Rafael Python 3
When the Shafrir 2 entered service with the IDF/AF in 1978, the engineers of
Rafael started the development of the Python 3, driven by the desire for a
larger warhead to increase lethality. A revised airframe with large,
highly-swept wings was combined with a new pattern of infra-red (IR) seeker
with a plus or minus 30 degree gimbal angle. The Python 3 has a weight of 120
kg and can be operated in boresight, imaged or radar-slaved mode, and allows
all-aspect attacks. The maximum speed is Mach 3.5, and the Python 3 can pull
40 g. The high-explosive (HE) warhead weights 11 kg and is detonated by an
active laser fuze. By the time of the war in Lebanon in 1982, the Python 3
was in service with the IDF/AF, and played a major role in the successful air
battles against the Syrian air force over the Bekaa valley. It was credited
with about 50 air-to-air victories. The Python 3 has been exported to China
and South-Africa, and may be licence-built in China as the PL-8.
Hughes AGM-65B Maverick
The AGM-65 was developed during the war in Vietnam as a replacement for the
AGM-12 Bullpup. The AGM-65B weights 212 kg and has the advance of 'scene
magnification', which enables it to be locked-on to the same target as an
AGM-65A from twice the range. The maximum launch range depends on the size
of the target. The maximum aerodynamic range is about 23 km, but a more
realistic range is 15 km. The high-explosive shaped-charge warhead has a
weight of 57 kg. The AGM-65B is white, with a clear seeker dome and has
'SCENE MAG' stenciled on its side.
IAI Gabriel IIIAS
The Gabriel IIIAS is a radar-guided anti-ship missile and entered service
with the IDF/AF in about 1985. The Gabriel IIIAS weights 560 kg, has a range
of 33 km and has a 150 kg semi-armor piercing (SAP) warhead. It is powered by
a solid-propellant rocket motor and is inertially guided at a radar
altimeter-controlled altitude of 20 m, with the option of a midcourse update
from the Lavi. In the terminal phase, the Gabriel IIIAS descends to strike
the target at the waterline.
The Lavi could carry the Mk 80 series of bombs (113 kg Mk 81, 227 kg Mk 82,
454 kg Mk 83, and 907 kg Mk 84) with an explosive content of circa 50 per
cent. The Mk 80 series are based on studies done by Douglas Aircraft in 1946.
The production began during the Korean War (1950 to 1953), but the first
saw first service in the Vietnam War (1965 to 1973). During the Vietnam War,
the Mk 81 bomb was found to be ineffective, and the use was discontinued. A
number of different fins can be fitted to the Mk 80 series. The low drag fins
include the low drag, general purpose (LDGP) fin and the high drag fins
include the air inflatable retard (AIR) fin and the Snakeye (SE) fin. The
Korean War-vintage 340 kg M117 bomb has an explosive content of circa 65 per
cent and was widely used during operation Desert Storm by the Boeing B-52G
The total cost for the development and production of the Lavi was 6,400 million US dollar in 1983 and approximately 40 per cent was paid by the US government. The fly-away price for the Lavi would be between 15 and 17 million US dollar. The development costs of 1,370 million US dollar were relatively low, because much use was made of existing technology.
Even before the first Lavi (B-01) flew, the storm clouds were gathering. In 1983, the US government refused to give the export licences for a number of essential parts (for example the wings), because the parts provided high technology products. A total of 80 US firms would provide technology through licences. In 1984 the licences were awarded. Furthermore, the US government was not prepared to give money and technology to an aircraft that could be a major concurrent for the F-16C/D and the F/A-18C/D on the future export market.
In the spring of 1985, Israel was in an economic depression and the Lavi program was almost canceled.
Then, a dispute arose as to the final unit cost, the Israeli figure being far less than the US calculations showed. The US Congress withdrew financial support for the Lavi program.
The Israeli government could not finance the project without US support and canceled the Lavi program on 30 August 1987. The vote was 12 to 11 to cancel the Lavi program. After the cancellation the US government offered the A-10A, AH-64A, AV-8B, F-15I, F-16C/D and UH-60A as replacements for the Lavi, all Israeli wishes that were previously rejected. In May 1988, Israel ordered 30 F-16C Block 40 and 30 F-16D Block 40 under Peace Marble III.
The Lavi program was a truly national program, and everyone in Israel followed the progression. The cancellation of the program was a true sad event.
After the Cancellation
Although the flight performance envelope was not completely explored, it seems probably that the Lavi would have been at least the equal of the F-16C/D in most departments, and possible even superior in some. It had been calculated that the Lavi could reef into a turn a full half second quicker than the F-16, simply because a conventional tailed fighter suffers a slight delay while the tailplane takes up a download, whereas with a canard fighter reaction is instantaneous. By the same token, pointability of canard fighters is quicker and more precise. Where the Lavi might really have scored heavily was in supersonic maneuverability, basically due to the lower wave drag of a canard delta.
It was originally planned to use Lavi B-03 as a ground test vehicle, but it was completed as a two-seater, by using parts of either the Lavi B-01 or the Lavi B-02, and had approximately 15 per cent larger elevons. The Lavi TD (Technology Demonstrator) carried a belly-mounted instrumentation and a telemetry pod. The Lavi TD was rolled out after the cancellation of the program. It was intended as a demonstrator for IAI's advanced fighter/cockpit technologies, which the company is applying by retrofit to a number of earlier combat aircraft, and as an equipment testbed. The Lavi TD (B-03) flew for the first time on 25 September 1989, piloted by IAI chief test pilot Menachem Schmall from Ben Gurion International Airport. An immediate application involved the improved digital flight control system integrated with the advanced maneuver and attack system. It was still flying in 1994.
Lavi B-02 is on display at the IDF/AF Museum in Hatzerim. It does not have the powerplant installed, because it was removed for use in the Lavi TD (B-03). The PW1120 turbofan is not manufactured anymore, so IAI need it as long as it works.
Lavi B-01, Lavi B-04 and Lavi B-05 were sold to the metal industry and were melted to aluminum blocks in 1996. The metal industry was not allowed to disassemble the aircraft or sell some of the parts. The event was well covered by the Israeli media.
At the beginning of the nineties there were rumors that Israel had delivered a Lavi to South Africa.
The Chinese Chengdu J-10 (F-10) seems to draw heavily on the Lavi program. However, a close examination of the model of the J-10 shows nothing more than an old technology fighter with the shape of a modern one. A prototype was in the final stage of construction at the end of 1997 and Israeli and Russian companies were competing to provide the radar and the associate air-to-air missiles and air-to-ground weapons.
An editor of Flight International flew the Lavi during 1989, and published his experiences of the flight in 1991 during operation Desert Storm. He wrote:
Serials of the Israel Aircraft Industries (IAI) Lavi
Specification of the Israel Aircraft Industries (IAI) Lavi
Source: Aircraft of the World.