Putting the Puma through its Paces

5/12/2017 | Words: Nina Felicitas Kunzi | Pictures: MTU, Carl Schulze

Puma, powerpack

Scheduled to replace its predecessor, the Marder, by 2020, the Puma Infantry Fighting Vehicle ranks as the Bundeswehr’s showcase armored vehicle project. Defense concerns Rheinmetall Landsysteme and Kraus-Maffei Wegmann have been developing and fine-tuning this cutting-edge vehicle for a decade and its performance and progress on the defense scene have attracted keen interest among observer countries. With its ultra-compact, high-performance MTU PowerPack, the vehicle delivers outstanding maneuverability and transport capabilities across the full spectrum of global climate conditions. We visited one of the locations where the Puma is assembled.
 
The Bundeswehr’s Puma first sees the light of day in the remote and largely rural Lueneburg Heath region of northern Germany. With around 3,500 inhabitants, the village of Unterluess is around an hour’s drive away from the nearest major population centers of Hamburg to the north and Hanover to the south. Here, in an area covering more than 50 square kilometers (around 7-times the size of the VW facility in Wolfsburg) is where the Puma armored vehicle first starts out in life. Or, to be more exact, it is where Pumas with even-numbered serial registrations are assembled.

Drive PowerPacks from MTU
Under the umbrella of the specially formed PSM organization (Projekt System & Management GmbH), production of the new armored vehicle is shared between defense technology concerns Rheinmetall and Kraus-Maffei Wegmann (KMW). The program foresees delivery of 350 Pumas to the Bundeswehr by 2020. Eight of the armored vehicles are projected as driver-training units. Vehicles with odd-numbered serial registrations are manufactured at KMW facilities in Munich and Kassel whilst the even-numbered units are produced at the Rheinmetall facility in Unterluess. However, no matter which production facility is involved, the powerpack for the Puma comes from MTU. At around 3.5 tonnes, the MTU drive PowerPack accounts for around a tenth of total vehicle weight (up to 43 tonnes). The PowerPack includes a 10-cylinder MTU Series 890 engine, a 6-gear Renk transmission unit, a starter-generator from Jenoptik and a cooling and air-filtration system. “This drive unit is more compact than any other previous defense drive system. Its power/mass ratio of 1 kW per 1.5 kg engine weight is unique for this application,” said Jürgen Schimmels, Director, Special-Purpose Engines & Propulsion Systems at MTU Friedrichshafen. With compactness of design playing a major role among the Puma’s development targets, these performance figures reflect an important aspect of the vehicle’s success.

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The MTU drive PowerPack is more compact than any other defense drive system has ever been before. It incorporates a 10-cylinder MTU Series 890 engine, a 6-gear Renk transmission unit, a starter-generator from Jenoptik and a cooling and air-filtration system.

Core aims: Compact design and power density
One of the Bundeswehr’s prime demands prior to the start of development was that the vehicle had to be suitable for airborne transfer with the Airbus A400M transport aircraft. That meant a maximum weight limit of 32 tonnes. Over years of development and trials, this target was also successfully achieved. After removal of a few components, the armored vehicle weighs in at 31.45 tonnes, making it air-transportable in the A400M. The vehicle’s compact character benefited significantly from the engine downsizing concept consistently applied by MTU engineers throughout development of the Puma PowerPack. Engineers also created additional space by integrating sub-assemblies like oil filters and oil coolers in the engine case.
Another target set for the Puma meant it had to provide operational support for the Leopard 2, delivering the same level of mobility as the main battle tank itself. The Puma’s high-performance MTU powerpack enables it to do just that – despite the fact that the Leopard 2 can call on a 48-liter engine while the Puma has a ‘mere’ 11 liters of engine capacity. “Its outstanding power/installation-space characteristics and its intelligent control and monitoring technology are what make that possible. The MTU PowerPack management system keeps the engine and all powerpack components within optimum performance parameters at all times to ensure that drive performance always ideally matches the vehicle’s current travel situation,” explained Jürgen Schimmels.

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A system of rails is used to install the MTU drive in its intended location before it is secured with just two bolts.


Puma: The Smartphone of the armored vehicle world
Puma vehicles start their careers at the Rheinmetall facility in Unterluess where they are assembled step-by-step at eleven workstations operating double-shift production. Starting with an empty armor-steel hull, the whole process from integrating the latest computer technology and installing the MTU powerpack to fitting the gun turret takes around 26 days. The MTU drive system is introduced into its installation position using a system of rails before being secured with just two bolts. Around twenty hoses and cables are then connected and installation of the MTU PowerPack is complete after around 15 minutes – a real ‘plug-and-play’ solution.

The really time-intensive part of the process is taken up with adjusting, fine-tuning and testing the various elements in the complex hi-tech configuration – that takes another 29 days or so. “Bundeswehr personnel compare the Marder with a telephone with a rotary dial and the Puma with a cutting-edge Smartphone,” said Anton Neuwirt, Deputy Leader of the Puma Project at Rheinmetall. “That gives an idea of how complex the process of systems calibration and testing is for this vehicle.” The Puma’s computer system communicates with five chassis cameras and two complex, turret-mounted external visual systems. The nine-strong crew no longer needs a hatch to see what is happening outside and is fully enclosed by protective armor during combat. They identify their surroundings solely with cameras, viewing screens and sensors. “At first, it all seems strange and runs counter to your natural sense of orientation. But the younger generation that has grown up with ‘Game Boys’ and video games has no problem with that at all,” said Neuwirt.

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Engineers freed up extra installation space by integrating sub-assemblies like oil filters and coolers in the engine case. Weighing around 3.5 tonnes, the drive system accounts for about one-tenth of total vehicle weight (up to 43 tonnes).

MTU PowerPack undergoes extreme testing
After assembly, running gear trials, turret tests, optical calibration and final inspection, the Puma undergoes thorough operational driving trials that put the MTU powerpack, including the brake and transmission systems, through extreme tests at the Rheinmetall proving grounds in Unterluess. “For example, the Puma is driven at top speed over the 18-kilometer vehicle trial course that is dotted with obstacles and rough terrain. The target-sighting systems and main weapons systems have to remain completely stable over the entire course. The vehicle also has to meet specific deceleration targets while braking from a speed of 50 kph,” explained Neuwirt. Travel performance and maneuvering are also tested on slopes with a 60% gradient – about the same slope angle as black-rated ski pistes. In this situation, the MTU PowerPack has to deliver its top performance level of 800 kW. “Finally, during the rough terrain trials the Puma has to demonstrate its capabilities under extreme conditions by traversing a 1.8-meter deep fording basin filled with water,” added Neuwirt.
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The MTU powerpack, including brake and transmission systems, are subjected to demanding tests during drive trials at the extensive Rheinmetall proving grounds at Unterluess. For example, this includes driving the Puma at full speed over the 18-kilometer vehicle test route that is dotted with numerous obstacles and rough terrain.

At this point, the armored vehicle and its drive PowerPack have already demonstrated their operational capabilities under extreme heat and cold during previous development-phase tests. In climate trials, the Puma proved its ability to reliably withstand Arctic cold as well as dust-laden desert heat. For missions in desert regions, MTU developed a 2-stage air filtration system that pre-cleans the combustion air before it is fed to the two turbochargers. Unrestricted mobility in extremely high ambient temperatures is further ensured by an intelligent thermal management system for the PowerPack that utilizes three separate cooling circuits.

Crew training
Following trials, the Puma is decked out in its green, brown and black camouflage livery before undergoing final quality inspection and leaving the Unterluess facility after a production process lasting 55-days. From the Rheinmetall facility, the vehicle transfers to the Bundeswehr training establishment just 25 kilometers away in Munster. This is where the crew, consisting of commander, driver, gunner and six mechanized infantry personnel, are trained to operate the Puma. By spring 2017, Rheinmetall and KMW supplied the Bundeswehr with around 120 out of the total order of 350 hi-tech infantry fighting vehicles – every one powered by a reliable, high-performance MTU drive system.

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