B1 bomber breaking the sound barrier. I've seen & heard this in person numerous times... Sounds like the worlds largest cannon was just fired, but it's really cool to see. Smaller aircraft breaking the sound barrier are not as impressive as seeing & hearing this big girl doing it.
Real(Mislabeled) - Captioned as: "B-52 Breaking the Sound Barrier" - This is a B-52 Bomber flying thru a moisture/condensation barrier at subsonic speed.... another link: http://www.spacewar.com/reports/Boeing_B52_With_CONECT_Upgrade_Accomplishes_First_Test_Flight_999.html and discussion in comments: https://reposti.com/p/V7 (644 mph top speed for B-52(I don't know about secret versions.) vs 768 mph speed of sound.)