SRB separation

"In absolute silence we watched huge glowing chunks of debris shoot out."

I wrote this story as I remembered it happening, but a reader recently emailed me with a question:

"Was there a loud sound when the Challenger exploded?"

He said that he was in Melbourne, Florida and though he wasn't watching the launch he thought he heard a louder-than-normal rumble. He had a friend in Cocoa Beach who swore there was no explosive sound. When he asked me to remember about the sound that day I could only remember the silence.

I went in search of Challenger-related websites and sent emails to several places explaining my curiosity and asking:

"Was I in shock and just not registering the sound, or could it have been some trick of altitude, distance, wind, etc. that would have made the sound more audible at a distance than close up?"

Mostly I got auto-replies telling me that such and such organization was unable to give a personal response, but one individual did reply:

Dear Peb:

I believe the reason you didn't hear any sound from the Challenger disaster is because it was not an explosion like everyone thinks. Yes, there was a huge fireball but it was the result of a deflagration that is a very rapid burning of volatile fuel. At most, this type of event causes a whooshing sound and not a loud bang. It's like spreading a gallon of gas on a street and lighting it. It doesn't explode, it just burns rapidly with a whooshing sound. In the case of Challenger the amount of fuel was so large it created enough pressure to break up the orbitor into its major component parts that all fell to the ocean and then were crushed by the hitting at over 200 miles per hour. Hope this helps.

Best Regards,

Roger M. Boisjoly

I wrote back to thank Mr. Boisjoly for his clear explanation and to ask for permission to reprint his letter (which he graciously gave). Then I started looking for the original website that had caused me to write to him and found that he is much more of an expert on the subject than I had thought:

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