SASDI Ghepardo

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SASDI Ghepardo
Ghepardo.png
Line-drawing of a Ghepardo.
Type Wheeled Armoured Fighting Vehicle
Place of origin  Van Luxemburg
Service history
In service 2004-present
Used by Van Luxemburg
Production history
Designer SASDI, consortium consisting of:
Automobili Monteluci
Müller Maschinenbau
Walter Technologie
Hembrug Wapeninrichtingen
Armurerie Saumur
Designed 1993-2004
Manufacturer Müller Panzerwerke
Produced 2003-present
Specifications
Weight 44,000 kg
Length 8.9 m
Width 3.1m
Height 2.6m
2.2 m (suspension in lowest position)
Crew 3 (commander, gunner, driver)

Armor Welded composite steel-ceramic hull, ERA kit available
Main
armament
Hembrug Wapeninrichtingen 120mm L55 calibre smoothbore cannon
Secondary
armament
2 * 7.62 mm Müller MG-61
Engine Automobili Monteluci DVS Flat-12 Diesel engine
AC permanent magnet electric motor
1200 hp + 400kW
Power/weight 27.27 hp/ton (ICE)
9.09 kW/ton (electric)
Transmission 17-speed automatic torque converter gearbox
Suspension HPVS Hydropneumatic
Ground clearance variable
Operational
range
800km
Fully electric: 7km
Speed Road: 140 km/h
Off road: 60 km/h
Fully electric: 40 km/h


The ‘’’Ghepardo’’’ is a wheeled armoured fighting vehicle conceived and produced by the Van Luxemburger defence vehicle consortium SASDI. It serves as a highly mobile alternative to the heavier main battle tanks of the Arméi, and was specifically designed to be able to take advantage of Van Luxemburg’s excellent infrastructure with its exceptional road speed of 140 km/h.

History

The conception of the Ghepardo began when Arméi generals realized that in case of a foreign invasion, the small Van Luxemburger defence forces would have to rapidly redeploy to the war theater, which could be the location of a amphibious or airborne landing anywhere in the country. Whilst rapid redeployment by road was normally only viable for lighter vehicles, Arméi High Command sought a more potent weapon that could deal with enemy armoured vehicles more effectively, whilst also providing fire support to mechanized infantry, like the SASDI Landsknecht could. The demand was thus for a potent wheeled main battle tank, that could outrun its tracked counterparts but was also better armed and armoured than the regular wheeled armoured fighting vehicles that were available to the Arméi.

This requirement was thus put forward to the defense vehicle consortium that had previously cooperated on the Landsknecht light tank. Consisting of Automobili Monteluci, Müller Panzerwerke, Walter Technologie, Hembrug Wapeninrichtingen and Armurerie Saumur, the consortium had cooperated to develop earlier vehicles to the full satisfaction of Arméi High Command before, and was thus granted the contract for this new project.

Even though the first prototype was tested in 1993, it took until 2004 before the first production Ghepardo was assembled at Müller Panzerwerke, having been the subject of extensive redesigns and updates to conform to new demands set by the Van Luxemburger military. Since then, many Ghepardo’s have been produced and they have become an important part of the Arméi’s armoured core.

Mobility

For the Ghepardo, Monteluci engineers were called upon by SASDI to design the propulsion and drivetrain systems. As the Ghepardo has wheels instead of tracks, less power is required to attain similar or higher speeds compared to tracked vehicles. This means that Monteluci engineers could do with designing a smaller engine, which is more fuel efficient and thus allows the Ghepardo to have a longer range.

The proposed engine for the SASDI vehicle was a 1200 horsepower 18-litre flat-12 engine, with two sets of twin turbochargers, coupled to a torque converter automatic gearbox with 12 gears forward and 5 in reverse. Through various locking differentials, the 1200 horsepower of the Monteluci engine are transferred to 8 wheels.

The choice for a Flat-12 engine was made by the Monteluci engineers because of its lower signature, making it possible to reduce the signature of the entire vehicle. The 12 horizontally opposed cylinders receive their air through two bi-turbochargers. The highly responsive biturbochargers make it possible for the driver to have power available at all times, as the nature of the design of a biturbocharger tries to eliminate any kind of lag in the power band. In order to make sure enough boost pressure is available, the engineers decided to make use of two separate biturbochargers, one for each cylinder bank. The Diesel fuel is fed through a common-rail injection unit that injects the fuel under high pressure (1850 bar) directly into the combustion chamber. Due to the use of direct injection and advanced turbocharger technologies, the 18-litre engine of the Ghepardo is able to put out 1200 horsepower.

To put this amount of horsepower through to the driven wheels, Monteluci makes use of an automatic gearbox with torque converter, a simple and proven system that can handle the massive amount of torque produced by the engine, while being very reliable. The hydraulically-operated fluid coupling of the automatic gearbox and its supporting systems have been placed in front of the engine rather than behind it, in order to facilitate the various locking differentials that are necessary to give the Ghepardo its 8-wheel drive system.

The exhaust system is mounted below the engine, which creates an extra buffer between the engine and the vehicle hull, protecting the engine in case of an explosion below the vehicle. The exhaust system is equipped with several mufflers to reduce the sound produced by the flat-12, and thus reduce its tactical presence on the battlefield.

As the Ghepardo will also be used as a reconnaissance vehicles in some strategies, Monteluci engineers were faced with the requirement to make the vehicle as silent as possible, to reduce the risk of being noticed on the battlefield during reconnaissance missions or missions otherwise requiring low vehicle observability. As the flat-12 engine could not live up to the desired noise levels set by the engineers, various options were considered, including the mounting of a smaller engine to power the vehicle at low speeds. However, the Monteluci engineers eventually concluded that the best decision was to include an electric motor to power the vehicle in a low-observability mode, but this conclusion was made only after the proposing engineer was clubbed to death for proposing a hybrid drive system in the first place.

The electric motor and all supporting systems (including the battery pack) have been mounted above the flat-12 engine, a minor compromise in vehicle signature for allowing the Ghepardo to run silently. The electric motor is an alternating current permanent magnet motor, which can provide up to 400 kW of electric power and 2,200 Nm of torque, both available at any given moment. The electricity needed to power the electric motor is provided by a total of 10 80Ah NiMH batteries, centered as much as possible inside the vehicle’s hull for weight distribution purposes.

To transfer the power to the wheels, the electric motor is coupled to a system of planetary transmission gears that effectively provide the electric motor with its own automatic transmission. To allow the vehicle to make use of either conventional power from the flat-12 engine, the electric motor, or even both (for brief stints), both the power output from the conventional engine and the electric engine are combined into a power split device, another set of planetary gears that allows the driver to switch between the various power modes, or even combine them.

The electric motor and its assorted systems can provide power for about 7 km, at a maximum speed of 40 km/h. Should the vehicle drive slower than 40 km/h, range will increase likewise. During this “stealth mode”, all electric power needed by the vehicle (for example for radio communication and battlenet systems) is provided by the battery pack that also powers the electric motor. Intensive use of onboard systems will decrease range. When running silently on the electric motor, the engine is shut down but can be started within 800 milliseconds, or less than a second, thanks to a starter/generator that starts the engine using the V-belt. This allows the engine to be started in record time, enabling the crew to move their vehicle rapidly if deemed necessary. When the vehicle is stationary, power for the onboard systems is also provided by the battery pack that powers the electric motor. If necessary, a universal charging cord can be used to attach solar panels or a small generator to the battery pack, in order to recharge the batteries without having to make use of the main engine. There is a small portable diesel generator in the engine bay which can provide additional power (similar to an APU) if necessary. In case the main engine is running, the batteries are recharged using the power generated by the main engine.

The driver also has the choice to combine the electric motor and main engine to provide more power together, for example during acceleration. This allows the Ghepardo to accelerate to 30 km/h within 5 seconds and to 60 km/h in 17 seconds, making it one of the fastest armoured fighting vehicles on the market today. It’s practical top speed is 140 km/h. In top speed runs, the Ghepardo has attained speeds as high as 165 km/h. It also has excellent maneuverability, with all 8 wheels being used for steering, making it possible for the vehicle to drive sideways within a 90 degree radius.

The wheels themselves consist of a rubber outer shell, with a kevlar inner coating to protect against light gunfire. In case of penetration, a sealant can close the gap created in the inner kevlar layer if not penetrated by more than 5 mm’s. In order to protect against heavier weaponry and further penetration by light weaponry, the wheels have been filled with nitrogen and are segmented, meaning that a hit in one section of the tyre will only slowly deflate that particular section. To provide more protection, each cell of the honeycomb created by the sectioning of the wheel has been protected with an a kevlar layer to prevent projectiles from penetrating more than one cell of the wheel. In every wheel, thousands of cells make sure that the wheel wil not be rendered useless immediately after a projectile impact.

As wheels have the disadvantage of having more ground pressure than tracks regularly used on armoured fighting vehicles, engineers built a small compressor into the Ghepardo. This will give the driver control over the air pressure in his tyres, allowing him to eliminate the ground pressure for as much as possible by deflating the tyres on soft soil and inflating them again when on solid ground, which allows for higher speeds. In case part of a tyre has been punctured, the compressor unit can continue to pump pressurized air into the section, allowing the tyre to remain somewhat inflated, allowing better movement.

For suspension, engineers continued the use of the Hydropneumatic Vehicle System (HPVS), used on a great number of other military vehicles. This system works with hydraulic cylinders, mounted behind every wheel (thus, 4 on each side). The cylinders have been connected with each other along the length of the vehicle, together with nitrogen-filled hydraulic accumulators. If a wheel hits a bump, the nitrogen is compressed by the hydraulic oil inside the hydraulic unit, if the wheel then returns to the normal driving situation, the nitrogen will expand once again to return the suspension to normal circumstances. A constant hydropneumatic suspension with onboard damping is thus available. The system, however, is progressive, which means that the system can take into account the type of terrain the Ghepardo is currently on, as well as differences in weight. As the hydropneumatic cylinders are only connected length-wise, the suspension left and right has essentially been separated, which means that all wheels will have equal ground pressure in uneven terrain, dividing the ground pressure more evenly over the entire vehicle. A downside of the lengthwise cylinder connection is that a vehicle would be likely to nose-dive during braking or lean backwards during acceleration. To combat this, the HPVS system of the Ghepardo is equipped with a computer that can measure pitch, roll, acceleration and deceleration in both lateral and longitudinal directions , as well as various other variables in relation to the actions of the driver and the condition of the surface. The computer, also connected to several gyroscopes, can thus monitor the movements of the vehicle, and anticipate and act upon changes in the suspension level by reducing or increasing the level of hydraulic fluid in specific cylinders or in all cylinders, through a central pump with a reservoir for hydraulic fluid. The driver also has the ability to make the vehicle kneel or tilt to one side, but can also choose to lower or higher the entire suspension, thus allowing the AFV to reduce its silhouette by being lower, or having more ground clearance in a higher suspension setting. The body computer also knows when the gun is discharged, and the system will move to counteract the recoil of the system to make sure the vehicle will remain stable.

The cylinders used in this system have very few moving parts, meaning they require little maintenance, and will not require replacement often. The system itself is light, reliable and relatively small, and ready for a long service life. Furthermore, should replacement be necessary, a mechanic can mount a new cylinder unit (which can be ordered complete or in parts, with complete units only requiring basic mechanical skill to mount into the hull and connect the hydraulic tubing). Also, the HPVS system is, in soldier terminology, idiot-proof by being able to withstand the extra stresses of exceeding the maximum weight of the vehicle. All cylinders are encapsulated in armoured units behind armoured skirts, protecting the system from being damaged. Should one of the cylinders be damaged, despite these protection measures, the central body computer of the suspension system can detect a leak in the system and shut off the leaking cylinders by closing valves. This prevents a leak from draining the system and allows the Ghepardo to continue, despite damage to the suspension system. Mobility is guaranteed, even in case of damage to the wheels (or even removing one or two wheels), due to the excellent stabilisation systems HPVS offers.

Furthermore, the system has several additional features, such as the crosswise stabilization of the vehicle that takes place automatically under a speed of 3 km/h. If necessary, the driver can also engage it at speeds above this limit. The stabilization system makes sure that the hull and turret of the vehicle remain as level as possible while the vehicle itself is at a side slope. This is done by locking the cylinders of the suspension in a level position on one side of the vehicle. This prevents the vehicle from tipping over, making it easier to cross steep side slopes. Also, there is a system on board that stabilizes the vehicle in corners, to reduce vehicle roll. This is done by temporarily deactivating the hydropneumatic suspension in high-speed corners, reducing the rolling movement caused by the suspension system. If necessary, the system can also be turned off by the driver or commander.

Next to these features, HPVS also offers a vehicle weight indicator, making it easy to remind the driver or commander of the weight of the vehicle. Also, a system has been installed that can keep the vehicle completely level when standing still, as long as the slope the vehicle is on is not too extreme.

Armament

In order to comply with the Arméi demands, the Ghepardo was fitted with a 120mm L55 smoothbore main gun, produced by Hembrug Wapeninrichtingen. From the outset, the Ghepardo was envisioned as being equipped with an autoloader in an attempt to save on weight and crew size. Therefore, the turret was specifically designed to accommodate such a system, and the autoloading system is capable of holding 20 rounds, with an additional 15 rounds carried in the bustle. The main gun is capable of firing a variety of ammunitions, including APFSDS-T, HEAT, but also gun-launched anti-tank missiles.

In addition, the Ghepardo comes equipped with two secondary weapons, both being Müller MG-61 7.62mm light machine guns. One of these weapons serves as the coaxial weapon of the main gun, whereas the other is at the disposal of the commander, normally used in an anti-aircraft or anti-personnel role.

Protection

One considerable challenge for the developers of the Ghepardo was finding a suitable tradeoff between protection and mobility; the vehicle should not become too heavy, or else the ground pressure of the wheels as well as its overall weight would prevent it from being as mobile as the original order had intended.

Therefore, the Ghepardo is fitted with a light composite ceramic armour, which can be boosted in terms of protection by the addition of explosive reactive armour slabs from a specifically designed kit. In addition, the Ghepardo has an air conditioning and filtering system that is powerful enough to protect the vehicle occupants against NBC strikes.