Walking to my car yesterday and I heard a couple F22s go by in super cruise (they can fly supersonic without using afterburners). Weíve been hearing them fairly regularly; Lockheed is building them nearby and as itís too far to the Gulf of Mexico to do their testing, theyíve received permission to do it along the Tennessee valley area. What surprised me was that until now Iíve been inside and the building muffles the shock wave enough that itís more felt than heard; yesterday, however, I was outside with no buffering and I noticed that it was a double boom.
It was pretty cool, I stopped and listened to the echoes bouncing around the buildings trying to figure out if I had indeed heard a double boom when the second plane went by and sure enough it was a double. I didnít know the nose and tail were far enough apart to create a noticeable time lag between the shock waves.
I had given up hope of hearing one as Iíll probably never get around to being in the right place and time to watch a shuttle landing before theyíre retired.