Models that once required up to four days to complete are now finished in a few hours on the SGI solution. This has allowed Sikorsky engineers to meet aggressive delivery schedules, even as they run more iterations of design ideas than ever before.

The 48-core, 48GB Altix XE cluster was installed in October of 2006 to give the propulsion engineering group a dedicated resource for the CH-53K project. On earlier design projects, the team relied on Linux systems assigned to other Sikorsky departments, scheduling its computational fluid dynamics (CFD) studies when server time was available. But tight deadlines and larger data sets prompted the purchase of the Altix XE system. As a result, the team spends less time waiting and more time working.

"Previously, we had models that were 3 million cells in size, but today some models have more than 12 million cells", stated Mike Kazlauskas, propulsion engineer for the CH-53K programme at Sikorsky. "We're running larger, full-vehicle simulations that include complex interactions, like rotor downwash effects and heat transfer models. We simply needed total access to more memory and more processors, and that's what the Altix XE cluster provides."

The CFD studies are part of Sikorsky's $3.08 billion design and demonstration contract for the CH-53K, which will replace the Marine Corps' "Super Stallion" heavy-lift helicopter currently in use throughout the world. Sikorsky engineers face unique challenges with the CH-53K. The new aircraft must be able to carry a cargo load of 27,000 pounds for up to 110 nautical miles - all at an altitude of 3000 feet in temperatures surpassing 90 degrees Fahrenheit. Because these "hot and high" conditions can quickly erode a helicopter's ability to carry cargo for long distances, the aerodynamics of the aircraft itself become even more crucial.

"We're focusing on propulsion now", added Mike Kazlauskas, "but eventually we'll be looking at airflow throughout the entire aircraft." The propulsion engineering team is currently studying such vehicle design factors as exhaust gas reingestion, engine bay cooling, avionics cooling and environmental control systems. Those factors impact a range of variables, including reliability, capacity, and cargo and crew safety.

For Sikorsky, the new Altix XE cluster amounts to doing more - much more - in less time. "Where we may have previously done one or two design iterations, we can double or triple that now", explained Mike Kazlauskas. "For the first time, we can run multiple iterations concurrently, and we can run five or six flight conditions at the same time. This is a huge benefit that amounts to a lot of value."

Sikorsky's turnkey, factory-integrated SGI cluster uses a SGI Altix XE240 head node with two Dual-Core processors, to direct job submissions and administration, and a second storage node with approximately 2.5TB of disk capacity. Another 10 Altix XE210 nodes are reserved for computational work, dedicating 40 Intel Xeon processor cores and 40GB of memory to drive advanced CFD software. A 24-port InfiniBand switch enables high-performance MPI communications, and a 24-port Gigabit Ethernet switch streamlines NFS traffic. The system runs Novell SUSE Linux Enterprise Server 9.

"The CFD software we run is highly parallelized code, which means you need a large number of processors and a very fast interconnect to make it run quickly and efficiently", stated Mike Kazlauskas. "With the Altix XE cluster, we were able to acquire a large number of processors at the price point stipulated for this project. And the InfiniBand interconnect is extremely fast, and that has given us very good performance. As the CFD problems we run continue to grow larger in the coming years, we'll appreciate this system even more."