Comment on 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...

noorbeast@lemmy.zip ⁨10⁩ ⁨months⁩ ago

• duckCityComplex@lemmy.world ⁨10⁩ ⁨months⁩ ago

  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.

  www.dictionary.com/…/hypersonic-vs-supersonic

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  • Eezyville@sh.itjust.works ⁨10⁩ ⁨months⁩ ago

    It means a little bit more than that. Mach 5 at sea level is usually when the properties of air changes into a plasma. The electrons are separated from their atoms creating an electrically charged plasma that the vehicle travels through. The speed where hypersonic is defined differs at higher altitude due to the composition of the fluid it travels through. I’ll have to dig up some old textbooks to get a more accurate definition though.

    Source: Aerospace engineer who worked on hypersonic projects for the Air Force

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    • Hadriscus@lemm.ee ⁨10⁩ ⁨months⁩ ago

      Thanks for delivering on that textbook, even though I don’t understand most of it, it sounds cool as hell

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