| The Brazilian EE-T1 Osório
Main Battle Tank was an advanced design with main efforts on
firepower and mobility, which resulted in high standards within
its weight category.
EE-T1 Osório Main Battle
Engesa was formed as a private firm
in 1963. Initially, it was involved in renovating World War II-vintage
tanks. Engesa built wheeled APC's, such as the EE-11 Urutu amphibious
APC, the EE-9 Cascavel armored reconnaissance vehicle, the EE-17
Sucuri tank destroyer, and the EE-3 Jararaca scout car, in addition
to a wide range of other products. The EE-11 Urutu armored troop
carrier is an amphibian that can also be used by naval forces. It
is still used by the Brazilian Army. It made a success in the international
sales market, and is in service ia at least six Armies worldwide,
in addition to the Brazilian Army. In terms of product development,
all of Engesa’s armored fighting vehicles and armored personnel
carriers shared the same characteristics: simple and flexible design
concepts, low cost, good performance and reliability, ease of use,
and simple maintenance. These characteristics were the major selling
points of Engesa’s products to its customers in the developing
Engesa's APC's were all based on
a new proprietary suspension system, called "Engesa Boomerang".
This ingenious suspension system, along with many other modifications,
expanded the life span of many otherwise obsolescent World War II-vintage
vehicles. Engesa's weapons were exported almost exclusively to the
developing world, especially to countries in the Middle East, Latin
America, and Africa. By the mid-1980s, Engesa had expanded to a
group of twelve subsidiaries and employed more than 5,000 people.
| The medium tank MB-3
Tamoyo, the first All-Brazilian tank, produced by Bernardini
Chronology of Main Battle Tank development
|1982: conceptual development of a new light MBT (the MB-3 Tamoyo)
1985: construction of first prototype with
1986: delivery of a second prototype
with 120mm gun.
1990: agreement with Saudi
Arabia to establish a local armament plant for the assembly
of Osório MBT.
Brazil emerged in the mid-1980s as
the leading arms producer and exporter among the defense industrializing
countries, and the sixth largest arms exporter in the world. Although
there were over 500 manufacturers of defense-related equipment in
Brazil, three firms have been largely responsible for Brazilian
defense exports: in aircraft, Embraer; in armored
fighting vehicles, Engesa; and in missiles, Avibras.
Engesa was well positioned to take
advantage of Brazil’s nonaligned position in the international
system and its affinity with other developing nations. The company
has exported its armored and reconnaissance vehicles to over 20
countries in the Middle East and Africa. Annual export earnings
amounted to over US$53 millon for the 1977-82 period and US$122
million for the 1983-88 period. The largest regional market was
the Middle East, to which Brazil sold roughly half of its arms from
1977 through 1988, with nearly half of all Brazilian arms transfers
from 1985 to 1989 going to Iraq. A related factor was Engesa's well-known
after-sales support in terms of guaranteed access to spare parts,
training for system operators, and maintenance (including front-line
repair during the Iran-Iraq war).
However, with the end of the Iran-Iraq
war and the decline in state support, the Brazilian arms industry
collapsed in the late 1980s, and by the mid-1990s had virtually
disappeared. In early 1990, Brazil's two major manufacturers, Engesa
and Avibras, filed for bankruptcy. Engesa has been dismembered,
with some of its companies sold to private interests, and ordnance-related
firms taken over by the state and integrated with the Indústria
de Material Bélico do Brasil (IMBEL - Brazil's Industry of
War Weapons and Equipments).
| EE-T1 Osório,
in a different cammo outfit. This picture was largely used for
promotion, and appeared in various publications.
Development and Production History.
In the early 80's, Saudi Arabia began
searching for a new main battle tank (MBT), with the objective of
replacement for their AMX-30 MBT's. At first, they wanted the Leopard
2, which had just began to be received by the Bundeswehr, as the
Saudis were impressed with the success of the Leopard 1 both in
Germany and in other European countries as well. However, the German
government refused to sell weapons to countries that were not NATO's
members. This way, a new market was opened, and Engesa decided to
go for it.
At first, Engesa searched for a partner
for the project's development, and contacted Tyssen-Henschel in
Germany, but the conversations came to nothing. Then, Porsche showed
interest in participating in the Brazilian MBT project. However,
the German government once again intervened and the German-Brazilian
cooperation project was cancelled.
That being the situation, Engesa
decided to go on with the project by itself, a decision that would
prove later to be too risky. In face of the way the Brazilian state
participated in the Brazilian armament industry at that time, some
restrictions imposed by the Brazilian Army had to be considered.
The first one stated that the new MBT should weigh no more than
36 tons, which was a technical impossibility, as it would set the
Brazilian MBT outside of the first class MBT's weight, which was
between 44.5 tons (T-72) and 62 tons (Challenger), at that time.
The second Brazilian Army's restriction was that the maximum width
of the new MBT could not be larger that 3.20 meters, a limit imposed
by the Brazilian railway structure.
Engesa's engineers accepted the second
restriction, but rejected the first, and the target weight was stipulated
as 42 tons, on grounds that most of the transportation would be
realized by roads, anyway. Another important decision was that the
development would consist of a basic chassis and two different types
of turret, allowing the possibility of two different main gun possibilities:
the 105 mm and the 120 mm. Engesa was determined that the first
prototype had to be ready in one year, so the company decided that
it would develop the project of the chassis, and the projects of the two turrets were
to be realized by Vickers Defence Systems, Great Britain.
The first turret, the "default",
was designed to accommodate the British 105mm L7 series gun, which
was NATO's main battle tank gun specification, until the 120 mm
L/44 Rheinmetall gun was adopted, but that was still
to happen in the future. The British 105 mm L7 series gun was an
excellent option, because it was used by many countries, was a tried and proven weapon, its
cost was reasonable, and there were many types of ammunition available
for its use. The fire control system for this turret, fully computerized,
consisted of a laser range finder and a LRS-5DNLC Olp Belgian periscope,
and the commander had an LRS-5DN periscope. This fire control system
and the main gun were fully stabilized.
| EE-T1 (120mm Gun
version) prototype, just after firing a round, on the firing
The second turret was developed
for being used by the Saudi Arabia's Army. This turret would receive
the French smooth-bore 120mm GIAT G1 gun, because tests proved
that the British rifled 120mm L11 gun
had stronger recoil forces, that a 42 ton MBT would not support.
The German Rheinmetall 120 mm L/44 smooth-bore gun was not tested
because of the weapons selling politics of the German government
at that time.
As a result of all that, the tank
was either armed with an L7 105mm gun with 45 rounds stowage or a
GIAT 120mm gun with 40 rounds. One 7.62 mm MG was mounted coaxial,
another one (or 12,7mm) was used as ADMG (5000 rounds / 3000 7.62mm
The 105 mm rifled gun was the well
proven British L 7 series, with a fume extractor, and a thermal
sleeve. Various kinds of ammunition were used with this gun including:
APDS, APDSFS, HEAT, HESH, and Smoke. The 120 mm was a French GIAT
smooth bore gun, firing APDSFS-T and HEAT-MP ammunition. Both the
guns with their respective ammunition were to be produced under
license in Brazil, by Engesa.
The EE-T1 firing at night.
The 120 mm GIAT gun could be fired by both the gunner and
the commander, both using a passive thermal imager. The Osório's
fire-control system, at that time, could only be compared
to the one used by Germany's Leopard 2.
The computerized fire control system,
by Marconi Command and Control Systems, used a SFIM stabilized periscope
with laser range finder for the gunner and another one for the commander.
A Philips/TRT stabilized thermal periscope was linked to both sights.
This fire control system was state-of-the-art and assured a very
high first round hit probability.
Initially, Engesa wanted to use
an MTU engine, since they were used with great success with the
Leopard 1 and 2, and also because MTU already was operating in Brazil.
But its price was way too high, and the MWM 1,000 hp diesel TBD
234 turbo charged diesel engine was selected, coupled to a ZF LSG
3000 transmission. Both companies, MWM and ZF, were already operating
in Brazil. This engine was tested for over 3,000 km in Saudi Arabia,
and proved to be most efficient and easy to maintain. The suspension
was of hydro pneumatic type (like the one used by the British Challenger)
and designed by Dunlop. The Osório MBT was provided by an
auxiliary power unit in the left hull rear. Fuel capacity was of
The EE-T1 Osório armor was
entirely developed by Engesa and was a combination of aluminum/steel
and carbon fibers and ceramics (bimetal+composite/laminate armor).
This armor was said to provide complete protection against all HEAT
threats existent at that time.
The Twilight of the EE-T1 Osório Main Battle Tank Project.
|Osório MBT twilight
- an ambitious project, an engineering
achivement, with no market.
The Osorio MBT exemplifies the way
Engesa approached development of new weapon systems.
First, following the Saudi Arabian
requirements for a light main battle tank, the company conducted
a market feasibility study of other developing countries, where
bridges and roads could not support MBTs within the 60 ton class
such as the U.S. M1A1 Abrams, the German Leopard 2, or the British
Challenger. Second, Engesa searched for the best available armor,
engines, suspension system, electronics, and gears. In keeping with
its strategy of finding suppliers who would share the development
costs, Engesa succeeded in attracting many international defense
equipment suppliers because the Osorio MBT program represented the
only new tank development project in the 1980s and 1990s. For example,
Dunlop, supplier to the British Challenger MBT, was willing to provide
the Osorio’s hydropneumatic suspension system (which keeps
the tank lower on the ground than the more conventional torsion
bar suspension). Within Brazil, Engesa could rely once more on the
transnational automotive industry, particularly West German companies,
to supply the diesel engine and the gear box.
The development of this MBT also
reflects the inherent difficulties facing a company based in the
developing world in moving up the high-technology ladder to the
production of more advanced weapon systems. First, the financial
resources required are enormous. Since Saudi Arabia gave the go-ahead
for prototype production of the Osorio in 1985, Engesa proceeded
to spend US$100 million in R&D and prototype development. This
design of the Brazilian armaments industry was sophisticated, and
demanded a high investment in technology. It was equipped with computers
and endowed with a modern weapons system. The EE-T1 Osório
Main Battle Tank was an advanced design in all aspects of tank development
(Firepower, Protection and Mobility), which resulted in high standards
within its weight category.
However, by the mid-1980s, Engesa
was unable to find a buyer for it. Despite an announcement in August
1989 by the Saudi Government that they were going to buy 318 Osorios
(renamed Al Fahd, the Lion Of The Desert), the contract (worth US$7.2
billion) was never signed. In April 1990, after laying off 3,000
workers, Engesa filed for bankruptcy protection.
Even though in 1990 Engesa had won
the evaluation process by the Saudis, the Osório project
came to an abrupt end with Operation Desert Storm against Iraq in
1991. After Desert Storm, Brazil was no match for United States
competition, given the close ties that developed between Saudi Arabia
and the United States and, last but not least, the outstanding performance of the M1A1
Abrams during the war with Iraq.
| OSÓRIO EE-T1 (120mm
GIAT gun version) SPECIFICATIONS:
| Length (Hull) (mm)
| Length (Gun Forward) (mm)
| Width (Maximum) (mm)
| Width (without Track Skirts) (mm)
| Height (Maximum) (mm)
|| 2,890 (2,680 according to the used AAMG)
| Height (Turret Roof) (mm)
| Ground Clearance (mm)
| Empty (kg)
| Combat (kg)
| Cannon - Type/Caliber
|| GIAT 120 mm smooth-bore gun.
| - Ammunition
|| 40(APDSFS-T and HEAT-MP)
| - Stabilizer
| - Traverse (º)
| - Elevation (º)
|| -10 to 20
| - Max. Slew Rate (Elevation) (º/s)
|| 11 - 15
| Machine guns - Coaxial - Type/Caliber
|| Hughes X34/7.62
| - Range (meters)
|| 1,000 N/A
| - Antiaircraft - Type/Caliber
| - Range (meters)
|| over 1,500
| - Ammunition 7.62 mm
| - Ammunition 12.7 mm
| Smoke Grenade Launchers
|| Hydro pneumatic
| Tracks - Manufacturer/Width (mm)
| - Length of Track on Ground (mm)
| Drive and Performances:
| Engine - Type
|| MWM TBD 234-V12
| - Performance (kW)/at rpm
| Transmission - Type
|| ZF LSG300 Automatic
| - Gears - Forward/Reverse
| Fuel/Fuel Capacity (liters)
| Power-to-Weight Ratio (kW/t)
|| 17.5 (17.3)
| Ground Pressure (kg/cm.2)
|| 0.85 (0.80)
| Max. Road Speed (km/h)
| Acceleration (0 to 32 km/h (20 mil/h) (in seconds)
| Range (on Road) (km)
| Gradient (%)
| Side Slope (%)
| Trench Crossing (meters)
| Vertical Obstacle (meters)
| Fording without Preparation (meters)
| - with Preparation (meters)
| Deep Fording (meters)
| Fire Suppression System
|| yes - Automatic
| NBC System
| Hull - Front Type/Max. Thickness (mm)
|| Bimetal + Composite/Laminate N/A
| - Sides Type/Max. Thickness (mm)
|| Bimetal + Track Skirts /N/A
| - Rear Type/Max. Thickness (mm)
|| Steel /N/A
| - Bottom Type/Max. Thickness (mm)
|| Steel /N/A
| Turret - Front Type/Max. Thickness (mm)
|| Bimetal + Composite/Laminate /N/A
| - Sides Type/Max. Thickness (mm)
|| Bimetal + Composite /N/A
| - Rear Type/Max. Thickness (mm)
|| Bimetal N/A
| - Top Type/Max. Thickness (mm)
|| Bimetal N/A
| Fire Command System:
| Ballistic Computer
|| yes - Digital
|| Stabilized by SFIM
| Rangefinder Type
| Driver Periscope
|| Optical or Passive Thermal Imaging
| Other Information:
|| ENGESA Engenheiros Especializados SA, Brazil
| Development (from Year)
|| 1985 (with 105 mm L 7 series gun); 1986 (with
120 mm GIAT smooth-bore gun).
- Military Analisys Network
Armas de Guerra do Brasil
(Brazil's Weapons of War): Editora Nova Cultural Ltda.,
São Paulo, Brasil, 1989 (in Portuguese).
Osório, by Reginaldo da Silva Bacchi (in Portuguese).
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1997-2006 Fabio Prado .
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