Engesa Cascavel EE-9 M4 ET-25

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Engesa Cascavel EE-9 M4 ET-25

Introduction:

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During the Iran-Iraq War, Iraq sought strategic advantages and turned to the Brazilian defense industry, specifically Engesa, to develop a wheeled armored anti-aircraft vehicle. In response, Engesa designed a turret with a 25mm automatic cannon to be mounted on EE-9 Cascavel vehicles, resulting in the EE-9 with the ET-25 turret. This initiative marked a significant chapter in Brazil’s defense exports and its response to evolving wartime needs. For further details, I recommend reading the article written by Darren Hazes on the website:EE-9 M4 ET-25 - Tank Encyclopedia

Redesigned ET-25:

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  • The redesigned ET-25 featured a smaller and more compact turret to accommodate the 25 mm gun. The turret size was reduced, as it no longer needed to store 90 mm ammunition like the ET-90. The front of the turret was also significantly reduced due to the smaller caliber.

  • A round commander’s cupola was introduced to provide the commander with better all-around visibility. A spotlight was added to the left front of the turret.

  • The redesigned turret was only 50 kg lighter than the ET-90 turret, weighing 2,200 kg compared to the ET-90’s 2,250 kg. This may be attributed to the introduction of electric turret drives, which were essential for dealing with more agile and faster helicopters.

  • While an ex-Engesa employee recalled that the ET-25 turret was manually operated, it seems that the turret came from the factory with electric turret drives. The employee’s recollection might refer to the ET-25 prototype, which appeared to be a repurposed ET-90 II turret.

  • The timeline becomes somewhat unclear from this point onward, primarily due to a single image of the EE-9 with the new ET-25 turret being tested in Iraq with an Iraqi paint scheme. This hull could be the same as the ET-25 prototype, but the ex-Engesa employee remembered that the turret was tested on one of the Iraqi hulls.

  • The sequence of events appears to be as follows: An Iraqi delegation visited Engesa’s factory in September 1986, led by the Minister of Military Affairs, General Abdul Jabbar Shanshal. Engesa’s founder, José Luiz Whitaker Ribeiro, showcased the EE-9 ET-25 to the Iraqi general during this visit. The vehicle was presented in a brown and dark green camouflage, with the EE-T1 P2 Osorio tank displayed behind it.
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  • In February 1987, the vehicle was presented to a Kuwaiti delegation at Engesa’s facilities. The reason for Kuwait’s interest in the vehicle is unknown. The turret was disassembled from the hull but retained the brown and dark green camouflage. Subsequently, the turret seemed to have been sent to Iraq for final testing, where it was mounted on an Iraqi EE-9 M4 hull. However, it failed to generate sufficient interest and was eventually returned to Brazil.
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EE-9 ET-25 in Detail:

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  • The EE-9 ET-25, intended for Iraq and mounted on an EE-9 M4 hull, weighed approximately 12.5 tons (13.8 U.S. tons) when combat-loaded.
  • It measured an estimated 5.3 meters (17.4 feet) in length, including the gun, as the muzzle brake appeared to extend slightly beyond the hull, and 5.25 meters (17.2 feet) without the gun.
  • It had a width of 2.59 meters (8.5 feet) and a height of about 2.57 meters (8.4 feet) to the top of the turret, or about 3.2 meters (10.5 feet) if the .50 caliber machine gun mount (ET-50) was included.
  • The EE-9 ET-25 had a crew of three individuals, consisting of the commander/loader (left turret), gunner (right turret), and driver in the front hull.
Specifications (EE-9 ET-25)
Weight (Combat-Loaded) Approximately 12.5 tons (13.8 U.S. tons)
Length (Including Gun) Approximately 5.3 meters (17.4 feet)
Length (Excluding Gun) Approximately 5.25 meters (17.2 feet)
Width 2.59 meters (8.5 feet)
Height (Top of Turret) Approximately 2.57 meters (8.4 feet)
Height (With .50 Cal Mount) Approximately 3.2 meters (10.5 feet)
Crew Three (Commander/Loader, Gunner, Driver)

Hull:

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  • The hull of the EE-9 M4 was constructed from welded bimetallic steel plates.
  • The hull featured two covers mounted above the Boomerang suspension, effectively functioning as fenders and much smaller spaced armor. These fenders could also have depressions in the middle to hold additional jerrycans.
  • The upper front plate of the hull had 16 mm (0.63 inches) of bimetallic armor at a 60-degree angle. The sides and rear had 8.5 mm (0.33 inches) thickness at various angles, and the upper and lower hull had 6.5 mm (0.26 inches) thickness.
  • The front of the EE-9 was intended to protect against .50 caliber machine gun fire at an unknown range, while the entire vehicle was protected against 7.62 mm AP rounds at 100 m (109 yards) and standard 7.62 mm rounds at 50 m (54 yards).
  • The average effectiveness of the bimetallic plates was about 1.8 times the thickness of an equivalent homogeneous plate against 7.62 mm or 1.5 times the thickness against .50 caliber machine gun rounds. This meant that against .50 caliber fire, a 16 mm bimetallic plate could be used instead of a 25 mm homogeneous steel plate. These protection advantages over homogeneous plates effectively meant that the Cascavel saved a lot of weight without compromising protection.
  • The outer layer would break and blunt the incoming projectile, while the inner layer would relatively move with the bullet, slowing it down and stopping it without breaking.
  • The EE-9 M4 had two headlights and integrated blackout lights on both sides of the lower front plate.
  • A rearview mirror could be mounted on both sides of the upper front plate.
  • Below the driver’s vision block was a foldable windshield, which the driver could use when driving with an open hatch.
  • The driver had access to 3 periscope sights mounted in a kind of vision block in front of him. These periscopes and other periscopes or sights would not have been active or passive night vision equipment unless the Cascavel was ordered with such devices. The standard periscopes were manufactured by D.F. Vasconcellos.
  • A ventilation inlet was installed on both upper side plates of the hull. These ventilation inlets are recognizable by their baffle shape.
  • A siren was installed behind the ventilation inlet on the right side of the vehicle.
  • The fuel tank cap of the Cascavel was located on the left side, in the middle of the upper side hull plate, with the fuel tank installed on the hull floor.
  • The EE-9 had a large ventilation grille at the rear of the vehicle, resembling the M8, and had a rear light on both sides of the ventilation grille.
  • The engine could be accessed through two large hatches on the top rear of the hull.
  • The engine exhaust was located on the upper right rear plate, as was unique to the EE-9 M4s.
  • An interior sketch of an EE-9 M4 is available, and it shows the driver’s seating arrangement and various controls.
  • The M4 used an adjustable ZF 8062 hydraulic steering wheel and had two pedals: the accelerator on the right side of the steering wheel and the brake to the right of the accelerator.
  • The gear selector was located to the right of the driver, and the handbrake was located on the left.
  • A control panel was located in front of the driver on the left for various functions, including the headlights, siren, windshield, various meters, and interior lighting.
  • To the right was the pressure selector for the Central Tire Inflation System (CTIS).

Mobility:

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main technical details about the mobility of the EE-9 M4:

  • Engine: The EE-9 M4 was equipped with a Detroit Diesel 6V53N V6 engine producing 212 hp at 2,800 rpm and 598 Nm at 1,800 rpm. The engine had a total cylinder capacity of 5,212 liters, with a cylinder bore of 98 mm and a stroke of 114 mm.

  • Performance: The M4 Cascavel had a top speed of 95-100 km/h (59 mph) and an operational range of 750 km (466 miles). It had a turning radius of 8.12 meters (8.88 yards) and could ford a depth of 1 meter (3.3 feet).

  • Off-Road Capabilities: The Cascavel could handle a slope of 65 degrees, climb a vertical obstacle of 0.60 meters (2 feet), cross a trench of 1.65 meters (5.4 feet), and had a ground clearance of approximately 0.5 meters (1.6 feet).

  • Suspension: It utilized a 6x6 drive, with the rear wheels being part of the Boomerang suspension. The Boomerang suspension, combined with the Engesa 2 transfer case, allowed the Cascavel to traverse challenging terrains and provide maximum traction in most situations.

  • Transfer Case: The Engesa 2 transfer case enabled the Cascavel to switch between low and high speeds. Shifting into low speed sacrificed power for increased torque, enhancing its climbing ability.
    image

  • Wheel Configuration: The vehicle had flat-rolling tires with a size of 12 x 20 and a diameter of 0.5 meters (1.6 feet). The distance between the front and rear axles was 3.05 meters (10 feet), and the distance between the two rear wheels was 1.4 meters (4.6 feet).

  • Transmission: The EE-9 M4 used an automatic transmission, specifically the Detroit Allison MT-643, with four forward gears and one reverse gear. This transmission could handle up to 250 hp and was the only transmission used in the EE-9 series capable of accommodating the Detroit 6V53 engine.

  • Boomerang Suspension: The Boomerang suspension was a unique invention by Engesa in 1969, designed to allow trucks to transport oil to refineries in challenging terrains with poor infrastructure. It was a single-axle, two-wheel drive suspension system, providing maximum traction by ensuring that the wheels remained in contact with the ground.

  • Suspension Details: The Boomerang suspension used leaf springs for damping. The two front wheels provided steering, and the wheels of the Boomerang suspension rotated at the same speed. The front wheels were damped by large coil springs. The vehicle used hydraulic disc brakes and was also hydraulically steered.

  • Central Tire Inflation System (CTIS): M4s came standard with a Central Tire Inflation System (CTIS). This system allowed for adjusting tire pressure at various speeds to optimize traction and fuel efficiency. It was operated by the driver through a switch, with air pressure supplied by a Bendix Tu-flo 500 air compressor.

Turret:

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main technical details about the EE-9 ET-25 turret:

  • The EE-9 ET-25 used a fully welded bi-metal steel construction for protection against small arms fire.

  • The specific armor layout of the ET-25 turret is unknown, but it likely resembled the armor layout of the ET-90 II turret. This would mean 16 mm of bi-metal armor on the front and 8 mm on the sides, rear, and top, similar to the hull’s armor layout.

Features of the ET-25 turret included:

  • A wedge-shaped front with the 25 mm KBA automatic cannon mounted in the middle.

  • A 7.62mm coaxial machine gun located on the left side of the turret, with a separate mounting system that seemed linked to the elevation of the main armament.

  • Two lifting hooks attached to the front plates on either side of the turret.

  • An auxiliary searchlight mounted on the front left side of the turret.

  • A spent cartridge ejection system located in a depression on the front right side of the turret. This ejection system was further protected by two steel covers.

  • The turret had three electrically operated 81 mm smoke dischargers on each side of the rear side plates.

Crew positions:

  • The commander’s position was on the left side of the turret, with access to a raised cupola. The cupola could also accommodate the ET-50 .50 caliber machine gun for the commander and had a rear-opening hatch. The commander had access to an unknown 3x magnification day periscope, which could be replaced by a 2.7x magnification night vision periscope. Additionally, the commander had access to four 1x magnification periscopes located circularly around the hatch.

  • The gunner was located on the right side and had access to a day/night sight as the primary gun sight. The specific sight type is not specified, but given that Engesa and Iraq widely used the SS-122 sight on the Cascavels and considering the listed magnification levels, it is highly likely that the ET-25 used an SS-122 sight. The SS-122 sight was an image intensifier that provided 10x magnification for the daytime view and 9x for the passive night vision channel. Mirror sights were linked to the main armament to allow automatic elevation of the sight mirrors in line with the gun elevation.

  • The sighting system on the ET-25 featured an integrated laser rangefinder and had brackets for air coupling. However, the description of the turret does not mention access to a system that provides a mobile sight reticle for the sights. This meant target engagement had to be done through manual operation of the turret units, and the required lead for engaging fast-moving helicopters had to be estimated by the gunner. Consequently, while the EE-9 ET-25 was meant to serve as the last line of defense for a convoy, it did not have all the potential tools at its disposal to reliably engage fast-moving helicopters.

Turret movement:

  • The turret used an electrically powered elevation and traverse system operated by the gunner’s controls. This allowed the ET-25 turret to have a turret rotation speed of 36°/s and an elevation speed of 21°/s.
  • The turret offered a gun depression of -10° and an elevation of +55°.
  • The turret had a turret diameter of 1.6 meters, the same as other EE-9 turrets, and had a penetration depth of 0.63 meters inside the hull.

Cannon:

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Oerlikon 25mm Cannon (KBA) of the EE-9 ET-25:

  • Total length: 2,888 mm
  • Barrel length (including muzzle brake): 2,173 mm
  • Total weight: 112 kg
  • Dual-belt feed system
  • Firing modes: single shot, programmable rapid single shot (up to 200 rounds per minute), fully automatic firing (up to 600 rounds per minute)
  • Widely used on infantry fighting vehicles, reconnaissance vehicles, armored vehicles, and anti-aircraft systems
  • The EE-9 ET-25 differed from other vehicles using the cannon as it did not feature multiple cannons or a dedicated fire control system for tracking aerial targets
  • 325 ready-to-use rounds, including 190 highly explosive incendiary rounds and 135 APDS (Armor-Piercing Discarding Sabot) rounds designed for armor penetration
  • APDS rounds could penetrate up to 25mm of steel at a distance of 2,000 meters, with a 30-degree slope
  • Effective firing range of 3,020 meters and a maximum firing range of 5,850 meters
  • Flight time for APDS ammunition to reach a target at 2,000 meters: 1.7 seconds
  • Time to explosion for incendiary ammunition: 3.3 seconds
  • Equipped with 200 ready-to-use rounds for the 7.62mm caliber coaxial machine gun model F-1
  • Option to mount a .50 caliber machine gun, with implications for replacing 7.62mm ammunition boxes with .50 caliber ammunition boxes
  • The quantity of 25mm reserve ammunition is not specified.

Specifications:

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EE-9 M4 ET-25 Specifications Data
Dimensions (Length-Width-Height) 5.3 (with gun) x 2.59 x 2.57 m
Total Weight 12.5 metric tons (13.8 US tons)
Crew 3 (Driver, Commander, Gunner)
Propulsion Detroit Diesel 6V53 Engine, 212 hp (or OM352A 172 hp Engine)
Speed (Road) 95-100 km/h (59 mph)
Operational Range 750 km (466 miles)
Armament 25 mm KBA Autocannon, 7.62 mm N model F-1 (coaxial), Optional .50 Caliber Machine Gun (top of the turret)
Armor (Hull) Front 16 mm (0.63 inches), Side 8 mm (0.32 inches), Rear 8 mm (0.32 inches), Top 6.5 mm (0.26 inches), Floor 6.5 mm (0.26 inches)
Armor (Estimated ET-25 Turret) Front 16 mm (0.63 inches), Side 8 mm (0.32 inches), Rear 8 mm (0.32 inches), Top 8 mm (0.32 inches)
Produced 1

Source:

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EE-9 M4 ET-25 - Tank Encyclopedia

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Opa VEIO DA HAVAN
Man, I find it great that you are posting a lot of Brazilian made vehicles in the forum. You are doing an amazing job at the suggestions and helping to show people that Brazil was a powerhouse of tank designing back then. If you need help with something you can DM me, I’d be glad to.

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