Okay kiddo, the Rockwell X-30 is a really cool airplane that scientists and engineers were working on a long time ago. It was going to be a super-fast airplane that could fly really high and go faster than any other airplane had gone before.
The X-30 had some really neat things about it that made it special. For one thing, it was designed to fly very high up in the sky, higher than airplanes normally go. This would let it travel faster because there's less air up there to slow it down.
Another thing that was special about the X-30 is that it was going to use something called "scramjet" engines. These engines are different from regular airplane engines because they don't need to carry any fuel. Instead, they can take in air from outside the plane and use that to move forward really fast. This means that the X-30 could go way faster than any other plane!
Unfortunately, the X-30 never actually got off the ground. Scientists and engineers worked really hard on it, but they ran into a lot of problems trying to get the scramjet engines to work right. In the end, they decided to cancel the project.
But even though we never got to see the X-30 in action, it was still really cool to think about what it could have done. Who knows, maybe someday we'll have an even cooler airplane that can fly even faster and higher than the X-30!