- cross-posted to:
- futurology@futurology.today
- cross-posted to:
- futurology@futurology.today
SR-72: US secret hypersonic jet to allegedly break sound barrier in 2025 | Believed to be a top-secret project of the US Air Force, the SR-72 is touted to reach over 4,000 mph (6,437 kph), making i…::undefined
Right! They used to have a commercial airliner that broke the sound barrier.
I was confused about how the article kept saying “hypersonic” without defining it. Looks like hypersonic means 5x the speed of sound.
https://www.dictionary.com/compare-words/hypersonic-vs-supersonic