Marines after eliminating oil leaks install a Caterpillar C7 engine on a Stryker machine
Recent conflicts that required more substantial protection for armored vehicles, as well as the emergence of more efficient but heavier onboard systems, had a direct impact on engine production. It is worth looking at how some manufacturers respond to such requests.
The modes of operation of the engines of military vehicles differ significantly from the modes of operation of their commercial counterparts. The latter, as a rule, are used more frequently, since such vehicles, such as a car or a bus, are used daily by their owners, sometimes for hours at a time, stopping many times and starting to move around in cities or moving monotonously along motorways.
Military vehicles, especially such heavy categories as Tanks, self-propelled howitzers and larger BMPs and armored personnel carriers, are used only during exercises or during deployment and therefore they need a sharp increase in speed and good off-road patency over rough terrain or sand, which requires significantly more power.
Military engines must also have the ability to work on slopes, run without preheating and run on alternative fuels. They also need special air filtration systems that have undergone rigorous tests that would allow engines to work in any desert in the world.
Another specific military requirement is to increase radiation resistance in order to protect electronics from an atomic explosion, which was a famous requirement of the Cold War, when it was assumed that military units of armored vehicles could survive the attack and continue to fight in post-nuclear space.
Mobility issues
Today, the most pressing issue is mobility, since in recent years, due to the installation of additional protection systems, equipment and sensors, the mass of heavy armored combat vehicles has significantly increased. As a result, the requirements for military engines provide for a certain specific power or horsepower per ton. According to Cummins commercial director (a renowned diesel engine manufacturer) Nigel Cheeseman, by and large, approximately 25 hp are needed. per ton.
"Machine manufacturers will choose the engine based on the requirements for torque and power, and this is not necessarily the largest engine available - the tonnage of the machine will meet the need for power and then they [manufacturers], starting from this, will be able to make the choice of the necessary engine" .
However, the more power the engine generates, the more expensive it is, and therefore machine manufacturers, along with power, never for a moment forget about economic efficiency.
Chizman said there are two ways to increase power: re-adjusting existing engines and installing a new engine.
“As a rule, manufacturers took the standard engine, but nowadays the machines have a large carrying capacity and therefore they need more power. But it is clear that the military would like to leave the same engine, since it reduces installation and maintenance costs to a minimum. All hardware and installation remain the same, but the electronics or software in the engine is changed to get more power, ”he said.
“Everything consists in different working conditions in a typical civil automotive environment and in military conditions. Military equipment is used much less frequently, that is, it allows us to move barriers or some technical limitations. If the engine does not operate at full capacity for a long time, then you can improve certain parameters in the engine. "
“What we need to do is create a new torque curve that is programmed electronically. Adjustment is essentially a torque curve. Engineers generally adjust to get more power; it is based on the working cycles of the military transport system and the analysis tools we use. In general, there is already enough potential engine refinement. "
Modernization of BMP WARRIOR
Over the past decade, the mass of the tracked BMP Warrior of the British Army has increased significantly, and in this regard, the question of upgrading this machine has become acute. The Warrior power unit has not yet been modernized, and Caterpillar is working with the British Department of Defense on this. At the moment, an eight-cylinder hp 550 engine is installed on the Warrior BMP.
Transmission is a mechanical system and. Consequently. prone to blocking, so there are plans to introduce an integrated controller and other improvements for the driver. An electronically controlled common fuel line may be installed, but this is a more difficult job. However, fuel pumps are also nearing the end of their service life, and replacing them will cost tens of thousands of pounds. In addition, there are problems with the obsolescence of the fire extinguishing system.
The cooling system also needs upgrading; A transition from an old, inefficient copper system to an aluminum one can increase efficiency by 15-20%.
Like the modernization of the American Bradley, the modernization of the BMP Warrior should be neutral, that is, there should be no changes for the machine itself or they should be minimal. In order to increase power, an improved fuel pump and turbocharger will be introduced; in this case, the power will increase by 100 hp compared to what is now. This will allow the platform to return after increasing its mass (from 25 tons to more than 30 tons) to its initial mobility characteristics.
The exhaust system will receive additional protection, such as insulation with a decrease in the number of "hot spots", which will help maintain thermal efficiency. The cooling system is also being finalized; Caterpillar manufactures experimental power units for testing as part of the WSCP (Warrior Capability Sustainment Program) program. These tests will go through the entire 2016 year before the final decision is made.
It is also scheduled to implement a program to extend the life of the British Army Challenger XBT Challenger in order to return to its original levels of mobility. Work on the WSCP program will be included in the program to extend the life of the Challenger 2, which is still to begin. As expected, it will include installation of a common fuel line, aimed at combating the obsolescence of the fuel pump and reducing fuel consumption, increasing the power of the 2-cylinder engine, improving the exhaust system, cold start, etc.
Oldies update
Cases of operation of cars quite long time, thirty, forty and more years are not rare. Here there is a need for restoration or overhaul, within the framework of which the question of what to do with the engine will certainly arise. In this case, the existing engine can either undergo a complete restoration, or a new one can be installed. On some older machines, engine replacement is not possible, since they are no longer manufactured.
Chizman said that a similar engine could be provided, “it is unlikely that it will be the same in terms of installation, but it can be as close as possible to the original, with minimal changes in installation. In this case, some additional piping system or additional brackets or connection points may be needed, but it should be installed in the machine with minimal technical changes. ”
In addition to adjusting the engine. may change the "iron" in order to obtain greater power. and this is achieved mainly by modifying the turbocharger and upgrading the piping system, pipes, exhaust nipples and other secondary parts.
“Another system that needs refinement is the filtering system,” continued Cheeseman. “Since the military Cummins models are, first of all, work on JP-8 fuel ... then we must provide a certain level of filtration.”
“We could change the engine filtration system to deal with the sulfur in the fuel and allow the engine to run on the JP-8. This is a matter of accessibility, as cars are often parked in aviation hangars or near aircraft, where there is JP-8 fuel, so it is also necessary that the machines can work on it. "
The MTU 890 series engine is mounted on a Puma German Army BMP
Big business
BMPs are a significant part of the Cummins business, in particular, this applies to ISBe 6.7l and ISL 9l engines (HP 185-450).
The company said that “the 6.7l engine is popular in the automotive and construction markets, but this is one of those main engines that we have redesigned for military use. On most BBMs with Cummins engines, there is either an ISBe 6.7l engine or an ISL 9l engine. The first one is available with power up to 360 hp. "
“Modernization of engine components allows us to meet military requirements, for example, it is adjustment of filters for military fuel. In some cases, we were able to simplify engine technology and eliminate exhaust gas recirculation.
Cummins also offers its V903 engine (525-675 hp) with a volume of 14,8 liters, which since 80-s has been installed on the Bradley infantry fighting system of the British Army. The preferred business model for the company is to offer more performance enhancements to existing engines, rather than performing an expensive replacement procedure.
The idea behind this strategy is that, in field conditions, mechanics and mechanics continue to work with the engines with which they are familiar, so in this case a smaller amount of training is required, in addition, the supply of spare parts and tools has also been debugged. For more than thirty years of the life of the machine, this will significantly save. Cummins constantly offers upgrades to its products, and the V903 engine has not bypassed this process. In order to meet the requirements of increasing power, he received additional components of the electronic adjustment, a modified fuel system and several variants of turbocharging.
Another world-famous engine manufacturer, MTU, does not consider the engine as a separate product. Its concept is to supply the engine as part of a whole propulsion complex (or power unit), which includes transmission, cooling, air filtration, exhaust system. In fact, the manufacturer of the machine, using several quick disconnects, should simply connect the power unit with the fuel, coolant, oil and electrical wiring, and then the machine can already move.
MTU has developed engines for various heavy machines by weight, and these are 55 tons and more. These include MBT, self-propelled howitzers and large BMP. Fighting vehicles weighing less than 20-40 tons fall into the middle category by weight.
Engine Upgrades V903
Although the Cummins V903 engine is installed in the American Army’s Bradley combat vehicle, its engine compartment is relatively small. This means that there is relatively little room for changing engine components or replacing it with a larger engine.
Therefore, in order. To obtain the necessary power, some upgrades were carried out in the existing volume; This affected the cooling system and other components.
Cummins has raised the power of the VTA903E engine with 600 and 660 HP up to standard power 675 hp (received the designation VTA903E-T675) using components from the second option.
This upgrade was first implemented in the program for the M109A7 self-propelled howitzer, but as far as possible it is identical to the previous version of the M109 howitzer engine. The modified VTA903E-T675 engine is also slated for installation on an upgraded version of the Bradley ECP2 BMP.
Current machines on which the V903 engine is installed:
• armored earth-moving machine M9ACE (Armored Combat Earthmover) power 295 hp;
• amphibious-tracked amphibious vehicle Amphibious Assault Vehicle (AAV7A1) hp 400;
• amphibious tracked amphibious vehicle Amphibious Assault Vehicle (AAV7A1 RAM / RS) hp 525;
• MLRS M270 power 500 hp;
• MLRS M270 power 600 hp;
• MLNO M270A1 with HP 600 power. with Centry fuel control;
• BMP Bradley M2A2 horsepower 600;
• Bradley M3A2 intelligence machine with 600 horsepower;
• BMP Bradley M2A3 horsepower 600;
• Bradley M3A3 intelligence machine with 600 horsepower;
• self-propelled 155-mm howitzer AS90 with power 660 hp; and
• 155 self-propelled howitzer Paladin Improved Management with horsepower 675.
Heavy category
The head of the sales department at MTU, Giovanni Spadaro, said that in the difficult category there are only a few companies on the market that can provide the right engines.
“The situation with the current MBT fleet is such that during the development and manufacture of each tank it was intended to use its own unique engine of local development, but these engines were never installed on other machines in large quantities,” he explained.
However, the German tank Leopard 2 was exported on a large scale with an installed power unit from MTU based on the 870 series. Although the development of local engines, in particular in the Middle East and East Asia, continues, they are rather stimulated by a political desire to be independent in military technology rather than purely economic reasons, and here Mr. Spadaro is unsure whether this will result in promotion to foreign markets.
“Heavy tracked vehicles like MBT or howitzers need more power, so they need special military-type engines, such as our MTU 870, 880 or 890 engines,” he said.
As for wheeled vehicles, they differ significantly in that they have a mass limitation associated with the wheel configuration (approximately 35 tons) and therefore the requirements for maximum output power are approximately 800 hp. For this reason, modifications of the engines of trucks are usually installed on wheeled vehicles.
The 199 Series MTU engine is a ready-made commercial military solution that meets these requirements. Spadaro noted that his company never stopped investing in promising developments. The result was the 880 series engine, which is currently installed on the export version of the French Leclerc tank, the Korean K9 Thunder howitzer and the German PzH2000 self-propelled howitzer.
Can not compare?
Talking about new developments, Spadaro stated with complete confidence that the 880 series is “the most advanced engine for heavy tanks in the world” and that there is no comparable product here.
The 880 series was further refined by integrating a common-rail fuel injection system that enables the use of various injection electronics, which improves engine efficiency, leads to less fuel consumption and allows for more flexible engine control.
However, Spadaro sees a downward trend in engine sizes for future cars. In order to comply with this, MTU developed the 890 series, which he called not just an evolution, but a “revolution” regarding the weight and size and energy-consuming characteristics of the engine. The 890 engine is installed on the Puma BMP of the German army and has almost the same power with significantly smaller sizes, for example, when compared with models of the 880 series.
“We do not just provide the engine, but provide a complete propulsion system, including a transmission, an advanced starter-generator, installed between the engine and transmission, which produces 170 kW of power to drive the cooling system fans,” says Spadaro.
“From the volume that was allocated to us for the engine compartment, we filled almost 92% with components, that is, very little air around the power plant and everything is tightly packed in this volume. He passed the qualification and at the moment some of the machines are already in operation, and some are still in production. ”
The 880 engine is available in two configurations, the 8 and 12 cylinders. The first produces the same power 1000 hp, as the ten-cylinder 890 German BMP Puma. With regard to the size of the power unit, the 890 series engine takes approximately 70% of the equivalent volume of the power unit based on the 880 series engine.
As for engine speed, 880 runs on 2700-3000 rpm, and 890 series engines develop from 3800 to 4250 rpm. The 890 series engines have a more integrated design, pipelines and oil pumps are already built into the internal circuit of the engine itself.
Among other applicants, the 890 and 880 series engines were also considered for the US Army program on the Ground Combat Vehicle ground combat vehicle (before it was closed). In addition, the company MTU is not averse to participate in the new program for a promising combat vehicle Future Fighting Vehicle.
Electric drive
Due to its characteristics such as rotational speed, power and dimensions, the 890 series engines are also suitable for electric propulsion systems.
In a mechanically driven system, the power generated by the diesel engine is mechanically transmitted to the wheels or tracks through the gearbox. In electrically driven systems, a diesel engine is connected to a generator, which transforms the energy produced by the engine into an electric one. This electrical energy is used to drive one or more electric motors that drive a car and can also be used to supply onboard consumers.
However, Spadaro said that at present the demand for electric-powered cars is limited: “In our opinion, now customers are more likely to look for options with less risk due to time and budget constraints. Traditionally, the military business has always been a driving force in new technologies. Therefore, I believe that this is just a period that we need to go through due to financial difficulties. ”
The company offers complete power units based on the 890, 880 and 199 series. MTU EuroPowerPack, based on the 880 series, is a rear-wheel drive system for the prototype of the Turkish Altay tank, which combines the MT 883 MT engine with the Renk HSWL 295 TM transmission.
For the middle category, the company is also able to provide complete propulsion systems. However, this option is also not excluded: the manufacturer of the machine receives only the engine and the cooling system from the MTU company and manufactures the rest of the components itself or receives them from another supplier.
MTU also develops other engines for special military tasks. A very recent example: for the British Ajax reconnaissance vehicle (formerly Scout SV), the 199 series engine was selected. The basis for this engine is the engine for a truck, which was modified by MTU by military standards.
Component development
Honeywell supplies AGT1500 gas turbine engines for M1 Abrams tanks of the US Army. He, after the German tank Leopard, is one of the most successful Western tanks in the export market. According to the company, the AGT1500 engine is installed on Abrams tanks from the 1979 of the year, in which a total of more than 40 millions of miles have passed. The company also added that in the framework of the recent modernization program of the TIGER (Total Integrated Engine Revitalization) power plant, the aim of which was to reduce operating costs, 13% fuel savings were achieved compared to the previous engine version.
The company is constantly working to improve the engines, increasing their efficiency and power and reducing the size and weight. A company spokesman said that this is achieved through "modern heat-resistant materials, smaller gaps, improved aerodynamics and improved auxiliary cooling circuits."
Efficiency can be achieved by improving the fuel injection system, where the correct ratio of chemicals in the combustion chamber can be rewarded. He also said that optimization of the air-fuel mixture can be achieved through improved fuel atomization methods, improved combustion chamber designs and improved cooling schemes.
The company confirmed that since military machines are operated in adverse environmental conditions, air filtration is a "significant problem."
According to a company representative: “Proper maintenance of the air filtration system is imperative in order to ensure that the engine does not suffer from the absorption of sand and dust. All engine interfacing to the “outside world”, including suction and exhaust, cooling system, fuel system, controls, power supply, starters and air filtration, should be packaged in a single unit to ensure proper engine operation and its maximum efficiency. For gas turbine engines, modern computer-based fluid dynamics instruments are used to reduce inlet and outlet losses and improve the internal and external cooling circuits. ”
In October, 2015, the company Honeywell received a contract worth 20 million dollars from the US Army under the TIGER program to continue to supply parts for the engine AGT 1500
Major improvements
MTU takes the engine as a basis, adds turbochargers to increase power, introduces lubrication in the dry crankcase and other modifications to make the engine suitable for a finished military product. The company implemented a similar scheme on the new Ajax machine, the base of which is the General Dynamics ASCOD machine, which is in service with Spain and Austria. The 6V 199 engine is also installed on the GD Piranha V wheeled vehicle, which Denmark selected in April 2015.
Caterpillar engines are installed on the Stryker US Army and tactical cars and trucks, as well as on the tactical vehicles of the Marine Corps, which in total amounts to 95% of the entire wheeled vehicle fleet of the US armed forces. Also, the engines of this company are installed on armored vehicles of the British army.
The company installs its C9.3 diesel engine on the Singapore Technologies Kinetics Terrex 2 8xNNXX (Terrex 8 has an 1 hp engine) and offers the C450 engine for the Marine Corps ACV9.3 program. It has two power levels (1.1 hp for combat orders and 600 hp in other cases), between which the driver can switch.
According to a Honeywell representative, close cooperation between the engine supplier and the platform manufacturer is very important when installing the engine on the machine.
“The solutions are to optimize the intake and exhaust systems, integrate the control system and integrate with the transmission. Each machine has its own unique features regarding engine integration. ”
The company also noted that in addition to ensuring proper integration of all components in the engine, repair shops should have all the necessary spare parts to maintain the health and readiness of any machine. In October, 2015, the company Honeywell received a contract worth 20 million dollars from the US Army under the TIGER contract to continue to supply parts for the AGT 1500 engine.
The company is optimistic about the future and believes that the military engine market keeps afloat, despite financial difficulties. “Although military budgets for current and new developments are limited, heavy armored vehicles will remain an integral part of the armed forces for decades to come. In addition to new projects, there is still a huge number of heavy armored vehicles around the world that need new upgrades and major repairs. Funding for new development programs will be limited, which, as a result, will bring to the fore the modernization of existing machines and systems. ”
Materials used:
www.shephardmedia.com
www.cummins.com
www.mtu-online.com
www.honeywell.com
www.cat.com
www.wikipedia.org