T-10 seconds...
Liftoff...
6.4 miles from the pad, it takes sound about 30 seconds to travel from the rocket to the microphone
6.4 miles ~ 33, 800 ft
Speed of sound at sea level ~ 1100 fps
33,800 ft / 1100 fps = ~30 s
...about T+30 from ignition, the rumble reaches us
Lost the track due to footing charge around tripod
Thank goodness for entry burns.
Once again, sound takes time to travel...
