 When aeronautical engineers want to know how air will flow over one of their designs, they can build a model and test it in a wind tunnel. But thanks to today's supercomputers, like this Cray XMP, there's a less costly, less time-consuming way to evaluate their ideas. These ultra-fast machines, with incredibly large memories, make it possible to do timely, accurate simulations before committing to expensive hardware. And it's not just airflow that can be studied. Here, the flow of water around a submarine is being investigated. Even the flow of fuel through the shuttle's main engines can be examined. Recently, scientists producing these simulations at NASA's Ames Research Center in Mountain View, California began using a new supercomputer, the Cray II. Though much smaller than the previous generation Cray, it's faster than any computer in the world, performing 250 million calculations per second. It also has 10 times more memory than any existing machine. In fact, the Cray II is so powerful that its circuitry is continually immersed in a cooling solution to keep it from overheating. Putting this new supercomputer's capabilities into proper perspective is the manager of the numerical aerodynamic simulation program at Ames, Ron Bate. What you see in this small tank of liquid in the Cray II is equivalent to a warehouse of small home computers. The Cray II makes more comprehensive simulations possible. For example, the people at Ames have been able to simulate airflow around the shuttle orbiter itself. But the orbiter attached to the solid rocket boosters and a large external fuel tank has posed too great a problem for any computer today. Ames Research Scientist, N.E. Shosi. But with the Cray II becoming accessible to us, that will give us enough storage or memory where we can actually solve the flow around this whole configuration. And in some cases, it may be very important to see what that flow is in order to maybe be able to take the safer routes when the thing is going off the pad. The Cray II will also play a key role in technology development for the NASA DOD National Aerospace Plane Program, leading to an entire new family of aerospace vehicles in the next century. NASA's Cray II Supercomputer, a valuable new tool in air and spacecraft design.