X-33
The X-33 is an odd one, in that it was designed in the late 2000s for an idea that we’ve only begun to see the next stage of over the last few years. Lockheed Martin designed the wedge-shaped X-33 to be a reusable launch vehicle, one with commercial implications. (Sound familiar to any ideas you’ve heard floating around of late?) Though it never got far out of the conceptual stage (NASA did go as far as testing its thermal protection materials in 1998), the plan was for the X-33 to be an uncrewed spaceplane that launched vertically and landed back on Earth horizontally. The program was cancelled in the early 2000s after engineers couldn’t resolve technical problems with the aircraft’s liquid hydrogen fuel tank.
