Hello folks! I was just watching a YouTube clip of the American MLRS system being used during Operation Desert Storm in 1991. I'm afraid I can't post a direct link to the video because of the 15 posts requirement, but if one does a search for "MLRS" it is the first video in the results. My question is, at around 2 seconds into the video, and again at about 38 seconds, one can hear a pipe organ type sound (similar to the sound made by Soviet "Stalin's Organs" rocket launchers during WW2). I'm wondering what phenomena is responsible for this noise; my best guess is that as the rocket leaves the barrel it is leaving an area of low pressure either in the launcher barrel or in air as the rocket travels, which is then vibrating like a resonant chamber. Any thoughts?