Paint probably isn't the first thing that comes to mind when you think of rocket science, but NASA's Ames Research Center has discovered it can use paint to identify the parts of rockets that are being overly buffeted by pressure as they zip toward supersonic speed. Specifically, it's "Unsteady Pressure Sensitive Paint" that reacts with oxygen to create light, causing the parts of the rocket under the most duress to shine bright red in simulations. By studying those points, they can refine their designs to minimize or eliminate those problem spots in order to keep the craft or rocket from breaking up.
The paint isn't actually used on real rockets. Instead, the pinkish substance is lightly painted over a scale model, which is then set up in a wind tunnel that mimics the intense atmospheric pressures on a real spacecraft or aircraft. NASA has used pressure sensitive paint in the past, but it wasn't effective as it could be as it only measured averages over time.
With the new "unsteady" paint, however, researchers can see the fluctuations from buffeting in far greater and faster detail when they're monitored under ultraviolet light with multiple high-speed cameras. When the resulting data are compiled, the areas enduring less pressure than average appear blue and the most affected parts shine red.
"We learned from this test that this method is what you need to study buffet," said Jim Ross, one of the two scientists at Ames heading the project, along with Jayanta Panda."There's a lot we don't understand about unsteady flow that this paint will help us figure out."
It doesn't even look much different than standard pressure sensitive paint, but up close it's filled with pores that allow the air flowing down the sides of the model to interact with a greater area of paint. The pores cause oxygen to react much more quickly with the paint, which produces more accurate images of the potentially damages forces.
For all the thought that went into creating it, it's a fairly simple procedure that could greatly minimize the costs of future testing. By contrast, the traditional method of measuring buffeting forces on rockets involves hooking up to 400 tiny microphones to a model and running it through a wind tunnel. Not only is this approach much more time-consuming and expensive, but it doesn't even cover the full surface of the model as the Unsteady pressure sensitive paint does.