[dlcarrier]

The military selected early pilots based on how close they were to average dimensions. They measured dozens of attributes and designed airplanes around the median of each attribute, assuming it would be easy to find people that fit into that design. It turned out that it's really easy to find people that fit into one or two median measurements, but effectively impossible to find someone that fits into even half a dozen median measurements.

Also, averages change over time, as the environment we are raised in changes, so what was designed around an average height in the 1920's required shorter than average pilots by the 1940's.

Here's an article on the topic: https://www.thestar.com/news/insight/when-u-s-air-force-disc...

Here's a book with several chapters going even more in depth: https://www.goodreads.com/book/show/24186666-the-end-of-aver...