Engesa Osório EE-T1 120mm - Brazil goes to the tank championship in Saudi Arabia Pt. 2/2

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Engesa Osório EE-T1 120mm

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*Note for those who like osorio,the official name of the osorio has always been EE-T1, and the name EE-T2 was never formally made official, being sometimes used within the company among some of the staff.

Back to Saudi Arabia 1987: The Definitive Stage

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On July 7, 1987, the French AMX-40, the British Challenger Mk.1, the M-1 Abrams and the EE-T1 Osório were formally presented to Prince Sultan.

In early 1986, the 120mm cannon tower arrived and was mounted on the new chassis, integrating modifications suggested by tests conducted by the Brazilian Army, coupled with lessons learned from the previous Arabian desert visit. This marked the birth of the definitive Osório, set to compete for the export contract to Saudi Arabia. To boost its chances, it was renamed “Al Fhad,” honoring the Saudi monarch.

Now armed with the 120mm cannon, the Osório underwent further testing in Brazil in early 1987, simulating Middle Eastern environmental conditions. The 120mm cannon prototype headed to Saudi Arabia in July 1987, joining definitive tests alongside its competitors. The Engesa team was confident this time, having ample time to prepare the vehicle.

The rigorous tests took place in a desert area located in the southern part of the Arabian country, known as the “Empty Quadrant,” spanning two intense months. On July 7th, the French AMX-40, the British Challenger, the U.S. M-1 Abrams, and Brazil’s EE-T1 Osório were formally presented to Prince Sultan. The four contenders commenced trials the following day.


Osório in mobility test in Sharourah Saudi Arabia.

Running until September 10th, the tests, conducted with Saudi crews chosen by lottery, involved:

  • Covering 2,350 km, including 1,750 km in the desert.
  • Acceleration, braking, and 180-degree pivoting.
  • Fuel consumption on roads and in the desert.
  • Vehicle idling for six hours with the engine on.
  • Traveling 6 km in reverse.
  • Towing a 35-ton tank for 10 km.
  • Removing and installing tracks.
  • Crossing three-meter-wide trenches.
  • Starting the vehicle on 65% slopes.
  • Maneuvering on a 30% lateral slope.
  • Firing while stationary at stationary and moving targets (max distance of 4,000 m).
  • Firing while in motion at moving targets (max distance of 1,500 m).
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Notably, some test results were highlighted by Odilon Lobo de Andrade, Engesa’s Technical Director, in a July 2002 Hobby News article:

“In the firing and autonomy tests, the Osório outperformed the U.S. rival by far. The Osório was the only one to hit a stationary target at 4,000 m. Tests also involved mobile targets at distances of 1,500, 2,000, and 2,500 m, totaling 12 shots—6 by the country of origin’s crew and 6 by a Saudi Army crew. Of the 12 targets, the Osório hit 8, the M-1 Abrams 5, and the AMX-40 and Challenger only 1. In the autonomy test, the Osório covered a straight-line distance of 400 km, leaving its rivals behind.”

The final announcement came in February 1988. Among the contenders, the French and British vehicles were discarded. The Osório and the Abrams were included in a “short list” as “potentially purchasable.” Technically, the Osório exceeded expectations and even surpassed the Abrams in some scenarios. Although there was no official declaration of a winner from the Saudis, Engesa’s team remained optimistic about potentially selling their vehicle to Saudi Arabia. There were even preparations for a sales contract, envisioning an assembly line in the Middle East.

Meanwhile, Abu Dhabi’s “Wild Race” 1988

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The Saudi competition echoed across the region, leading the United Arab Emirates (UAE) to invite Engesa in 1988 to showcase the Brazilian MBT in Abu Dhabi alongside the Italian OF40 MK3 and the AMX-40. The UAE already had some Italian-origin armored vehicles, the OF-40 model, and sought to supplement them with more modern options. Expectations were high for a competition akin to what had occurred in Saudi Arabia. However, what unfolded became something unusual, earning the reputation of a “wild race in the desert.” Crazy or not, the Osório “ran” impressively.
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During that event, an amusing incident occurred, also recounted in the Hobby News article: the Italian vehicle suffered an engine fire and got stuck in a sand dune, seemingly destined to be abandoned in the desert. The Brazilian team, having participated in demonstrations worldwide, from the icy terrains of Canada to the vastness of China, decided to lend a helping hand to the disheartened Italians. They towed the stuck Italian vehicle with a cable and brought it back to the Arab base.
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Nevertheless, the UAE refrained from commenting on the three vehicles, postponing a new series of tests for a more opportune moment. However, in 1993, they chose the French-made Leclerc. The number of units surpassed the Saudi order (as detailed below), with 436 cars, including variants, being ordered. At the time, it was said that this order, Leclerc’s sole export, practically covered the vehicle’s development costs—a golden opportunity that Engesa had hoped for.

Engine and Transmission:

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Both versions of the Osório tank were powered by the turbo diesel engine MWM 834, also referred to in some sources as MWM TBD 234. This 12-cylinder power unit with direct fuel injection was manufactured by the German company Motoren-Werke Mannheim AG. The cylinder block had a 60-degree spread angle, producing a maximum power of 765 kW (1040 hp) with a displacement of 21.63 dm³. The specific fuel consumption of the Diesel engine was 200 g/kWh. The fuel tanks of the P1 and P2 had a capacity of 1380 dm³, providing a range of over 550 km without refueling.

Ventilators were mounted beside the engine under the roof of the housing. Special attention was given to ensuring the proper functioning of the cooling system, particularly in regions with high temperatures. Experts from Hélice Howden assisted in adapting the cooling system for use in Brazilian tanks. The cooling system had a capacity of 120 liters of coolant.

Despite considerations of the German MTU engine, the MWM engine was ultimately chosen due to arguments emphasizing its durability and reliability, convincing Brazilian decision-makers of its sufficiency for the expected tank mass.

Both engines were equipped with the hydro-mechanical transmission system LSG 3000 developed by the German company ZF, although British transmission systems were also considered. Both systems were used as a dual power transport system. The LSG 3000 propulsion system included a torque converter clutch, main shaft, three rows of planetary gears, and a lateral converter P25000.
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Transmission System:

  • The system allowed four forward gears and two reverse gears.
  • The tanks could execute turns with a radius of B/2, meaning “pivot in place.”
  • Tank P2 could accelerate to a speed of 30 km/h in 8 seconds, while P1 could reach 32 km/h in 5 seconds.
  • On paved roads, the tanks could travel at speeds exceeding 70 km/h.

Engine Replacement:

  • Designers foresaw the possibility of a rapid engine replacement, with well-trained technicians capable of completing the process in approximately 20 minutes.

Braking System:

  • The initial braking phase utilized a hydrodynamic brake. When the driver pressed the brake pedal, a special angle in the brake chambers allowed fluid to fill, generating braking torque based on rotor speed differences.

Suspension:

  • Both tanks featured hydro-pneumatic suspensions, similar to those used in Challenger tanks.
  • Each wheel bearing had a 200 kg actuator cylinder acting as elastic damping elements.
  • Suspension deformation was 400 mm, with 330 mm representing dynamic deflection.
  • The suspension operated effectively in temperatures ranging from -40 to +50 degrees Celsius.
  • The quick return of wheels to their initial positions reduced track ripple, enhancing chassis efficiency.
  • The suspension was chosen for its minimal impact on crew, weapons, and equipment vibration.
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Track Chassis:

  • The track chassis of both tanks consisted of twelve wheels, two tensioners, two drivers, and six upper track support rollers.
  • Tensioners had the same structure as support wheels, connected to the tracks with steel bands.
  • Each track had 92 cells connected by screws and hooks, capable of enduring over 8000 km.

Fire control system

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Fire Control System of the P2 Tank

For the second 120mm tank (P2), the fire control system utilized the Centaur AFCS (Marconi, UK). This version included a VS58010 Vicas system integrated into the periscope sight. To facilitate shooting during nighttime or low visibility conditions, the USFA UA9090 thermal imaging allowed seven times magnification, developed by the Dutch company Philips. Additionally, there was the option to install another thermal imaging system of French production. A desktop for operating thermal imaging equipment was located at the gunner’s position. The thermal image was also stabilized and displayed on monitors positioned for the gunner and commander.

The commander had an independent panoramic view marked with the VS58019 symbol. This enabled them to aim and fire the cannon at any time of day independently of the gunner. The VS580’s field of view of 16 degrees equated to a 3x enlargement, while the 5-degree field of view was 10x. According to the VS580 information, the gunner had only a 10x enlargement. In the case of a tank like the P2, it indicated key features in the laser locator based on the YAG rod. The laser wavelength was the same as that used in the P1 rangefinder. Distance measurement could be made in the range of 400-10,000 m with an accuracy of 7m. The laser rangefinder could also be equipped with the commander’s sight, and the stabilization of visual fields from both positions could be activated independently of the cannon stabilization. Information about the relative position of the cannon and mirror was obtained by comparing the mirror and cannon angle positions.

Regarding the Centauro system settings for firing, it listed a 16-bit processor converter. Both models featured a backup protection mechanism designed in case of a fire control system failure, located at position L35 (sometimes referred to as L30), providing 10x magnification.
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Each Osório tank could also fire indirectly if desired, but the fired ammunition would have lower accuracy compared to self-propelled cannons. With this type of firing, the correct angle for a particular distance was determined by increasing the bubble level. In both tank versions, there was an azimuth index displaying the turret angle concerning the hull rotation axis and a device for determining the inclination angle.

Additionally, it was possible to mount an infrared observation device on the P2 hatch roof.

Armament:

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The Second Version of Osório Tank - P2

The P2 version of the Osório combat vehicle was equipped with the GIAT Vecteur smoothbore Gl EFAB 120mm cannon, a French-origin smoothbore. During the peak gas pressure, it reached 630 MPa. Upon recoil, it extended to 485 millimeters. Unlike the L7 on the P1 prototype, the P2 Gl was not equipped with a smoke extractor. Powder gases were removed from the tube using compressed air, with the cylinder positioned beside the cannon. According to experts, this French gas removal method proved more effective than utilizing a smoke extractor. The Gl cannon’s thermal sleeve was made from a magnesium alloy. A breech with a vertical sliding wedge was installed, allowing for six shots within a minute. Using a kinetic energy penetrator, the absolute firing distance was 2 km. During firing with an anti-tank projectile, the recoil force reached 275 kN, while for a HEAT projectile, it was 365 kN.

No synchronization device was installed on the P2 armored cannon. Therefore, in this prototype, synchronization between the barrel axis and the sight had to be performed using a telescope and a specially marked disk placed at the correct distance from the tank. As with the previous barrel, in the Gl version, priming was used to initiate ignition. The cannon’s elevation angle in the P2 was identical to the PI.
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The following types of ammunition could be used in the cannons: APFSDS (OFL) Gl—stabilized arrow ammunition, with a separate shoe, weighing 6.3 kg and an initial velocity of 1650 m/s. It could penetrate armor (RHA) more than 500 mm thick at a 60-degree angle; HEAT (Gl POL)—multipurpose ammunition weighing 13.7 kg and an initial velocity of 1100 m/s.

Similar to the 105mm version, 12 cartridges were stored in the rear of the turret, while in the P2, 28 were stored in the front of the hull.
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In Brazil, cannon ammunition was not provided, necessitating acquisition from the United Kingdom and France. In both tanks, a fan was positioned at the loader’s position to vent gases that entered the combat compartment after opening the breech.

Initially, considering the P1 used a cannon from the United Kingdom, the same was considered for the P2, specifically the L11 120mm caliber used in the Chieftain and Challenger tanks, but this purchase was quickly abandoned. Due to substantial recoil, it could only be installed in tanks weighing over 50 tons. Another argument against it was that, despite being the primary armament for basic British combat vehicles, it was no longer part of the latest project. Thus, serious consideration was given to purchasing a 120mm Rh-120 cannon. However, Rheinmetall management issued a statement that the West German government did not permit its sale to Brazil. Eventually, the cannon for the P2 version was purchased from France. According to information from ENGESA, authorities requested studies so that the P2 could be armed with the 125mm D-81 TM cannon.

The weapons in both vehicles were stabilized in two planes, enabling precise firing while in motion. Active stabilization provided gyroscope signals indicating changes in turret and cannon positions used in the tanks. With the disks moving vertically and rotating the cannons and turrets, the cannon remained in the correct position. Each vehicle used a firing guidance system; both were equipped with a GCE 628 targeting system developed by the British company Marconi. According to some sources, the system was linked to the firing control system. Guided discs allowed precise weapon aiming and maintained the position, enabling quick changes. The maximum turret rotation speed was more than 33 degrees per second. There were functional areas with units mounted on the right side of the gunner’s position. Triggers for firing the cannon and machine gun were in positions convenient for the gunner and commander. In case of malfunctions, both vehicles could use a guidance system to employ manual mechanisms. On the right side of the driver’s position, a switch was available. Before driving the armored vehicle, with the driver’s head exposed in the hatch, this switch deactivated the stabilization system and the drives that moved the turret and cannon.

More images and versions that can be put in the game:

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EE-T1 P2 120mm 1986 Brazil (note the side exhaust and the cooling system with or without a fin on the top of the engine)

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EE-T1 P2 120mm “Al Fhad” 1987 Saudi Arabia (note the rear exhaust and finned cooling system on top of the engine)

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Osorio-7
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United Arab Emirates

EE-T1 P2 120mm 1988 United Arab Emirates (note the rear exhaust and the cooling system without the fin on top of the engine)

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EE-T1 P2 120mm Current Days (note the rear exhaust and the cooling system without the fin on top of the engine)

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Cutaway

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General Characteristics:

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General Characteristics Osório P2 (120mm Cannon) Osório P1 (105mm Cannon)
Crew Four soldiers Four soldiers
Weight 43.7 tons 41 tons
Dimensions:
- Hull Length 7.13 m 7.13 m
- Length with Cannon 10.10 m 9.36 m
- Width 3.26 m 3.26 m
- Tower Height 2.37 m 2.37 m
- Ground Clearance 0.46 m 0.46 m
- Track Spacing 2.63 m 2.63 m
- Total Track Length 4.49 m 4.49 m
Armament:
- Primary 120mm caliber cannon 105mm caliber
- Additional 7.62mm caliber machine gun 7.62mm caliber machine gun
- Firing Capacity 40 projectiles (12 in turret,28 in hul (40 projectiles, 12 in turret,28 in hul
- Firing Capacity with 7.62mm Machine Gun 5000 projectiles 5000 projectiles
- Firing Capacity with WKM Machine Gun 600 cartridges 600 cartridges
Propulsion Unit:
- Engine 12-cylinder MWM TBD 234 turbo 12-cylinder MWM TBD 234 turbo
diesel diesel
- Liquid Cooling Power 765 kW or 1040 hp 765 kW or 1040 hp
- Unit Power Factor 19 kW/t 19 kW/t
Speed:
- On Paved Roads Over 70 km/h Over 70 km/h
- Maximum Reverse Speed 45 km/h 45 km/h
- Acceleration 30 km/h in 8 seconds 32 km/h in over six seconds
Fuel Tank Capacity 1380 dm³ 1354 dm³
Transmission Hydro-mechanical ZF LSG 3000 Hydro-mechanical ZF LSG 3000
- Number of Gearbox Gears 4 forward, 2 reverse 4 forward, 2 reverse
Suspension Hydro-pneumatic Hydro-pneumatic

Performance Metrics:

  • Autonomy: 550 km, with some sources suggesting 500 km.
  • Ground Pressure: 0.085 MPa.
  • Obstacle Surpassing Capability:
    • Trench Width: 3 m.
    • Vertical Wall Height: 1.3 m (although some sources indicate 1.15 m).
    • Ford Depth: 1.2 m, and after armored preparation - 2 m.
    • Slope: 65%, compared to 60% per other sources.
    • Side Slope: 40%, contrasting with 30% in other accounts.

Source:

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Jane’s A&A 1987-88 and Jane’s A&A 1993-94

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Engesa EE-T1 Osório - Forças Terrestres - Exércitos, Indústria de Defesa e Segurança, Geopolítica e Geoestratégia
ecsbdefesa.com.br – UMA REALIDADE BRASILEIRA: CARROS DE COMBATE TAMOYO E OSÓRIO
ecsbdefesa.com.br – TANQUE BRASILEIRO OSORIO
ecsbdefesa.com.br – BRAZYLIJSKIE CZOTGI OSORIO
Armorama :: EET-1 OSÓRIO: O sonho brasileiro by Paulo Roberto de Castro
Engesa EE-T1 Osório - Forças Terrestres - Exércitos, Indústria de Defesa e Segurança, Geopolítica e Geoestratégia

Videos

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https://www.youtube.com/watch?v=em7FP3pooG4
https://www.youtube.com/watch?v=FSEwiEEwIT4
https://www.youtube.com/watch?v=1jg83UVnFIk
https://www.youtube.com/watch?v=QHOMcwx5pmY
https://www.youtube.com/watch?v=J5FL1PV_J8E&t=180s
https://www.youtube.com/watch?app=desktop&v=_8v-IgHo2KY

15 Likes

Definitely deserves a place in War Thunder, +1

What about this then ? I don’t know much about Osorio but it seems T2 was also used at some point, at least by Engesa. Here is the rest of the album which was shared in old forum.

7 Likes

So, according to Engesa, it never called it EE-T2, the Brazilian army itself was the one who did it. This was documented in Expedito Carlos’ book.
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4 Likes

It’s great that you saw this detail

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Ohh I see, that makes sense. I got another question, this one is kind of hypothetical situation but isn’t army to decide the designation if it was accepted to service ?

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This is a long subject, because the army never wanted the osorio ee-t1 p2 120mm, this was a project for sale abroad and by law the Brazilian army had to stay, possibly whoever did this painting was following orders from someone they didn’t know .But in the manufacturer’s official papers it is EE-T1 P2 120mm. For example, this miniature model of the osorium is completely wrong, it is a mistake and starts to be repeated for many years.

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1 Like

This would be such a fun tank to play. I look forward to the LatAm tech tree! +1

2 Likes

If 105 is beautiful, 120 is perfect

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BIG BOI
Hype for 2024

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Big +1

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+1
Also, it was equipped with a Laser Warning Receiver

(Basically talking about how the armour wasn’t good compared to the Chally/Abrams so they relied on mobility, also detailing the Laser Warning Receiver)

2 Likes

Yes, the engineers chose not to include composite armor in the prototype, but the plan if it went ahead was reasonable

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2 Likes

it will definitely be similar to the of40, light fast and made of paper, maximum BR of 9.3

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Unless the developers want to add composite armor lol

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It was the OF40 MK3 not a C1 Ariete

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it was fixed, thanks for remembering

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Good
+1

2 Likes

more details

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2 Likes

nice details

2 Likes

If gaijin uses any Brazilian vehicle, the community will go crazy

6 Likes