In aircraft designations, what does 'X' stand for?

In aircraft designations, the letter 'X' indicates that the aircraft is intended for research or experimental purposes. This designation is used to signify that the aircraft is being tested for new technologies, designs, or concepts that may not yet be ready for operational use. The use of the 'X' prefix helps differentiate these experimental aircraft from those that are fully developed and operational, highlighting their role in advancing aerospace technology.

In addition to the role of research and testing, these experimental aircraft often serve as platforms to validate potential future designs or enhancements, allowing engineers and designers to gather valuable data. This process is essential in the field of aviation, as it helps inform decisions about which technologies may transition to operational capabilities.