Are you looking at the video John posted with the school bus in the image? It's a little more than 1 and less than 2 seconds from the time of the flash to the sound.Trying to stay out of this but I have a technical questions. That video looks much closer than 1/2 mile. 1/2 mile is far enough away to barely see anything unless a good camera lens is used. Also the sound would take approximately 2 seconds to reach the observer at that distance. I could not detect much sound delay in the video but it is hard to tell. Can you provide any details or confirmation on how far that video is from?
It's 11 seconds between the time of the flash and the time the burning propellant hits the roof of the quonset hut so it got some altitude.