It still was unusual compared to the many rockets that reach that speed and do not pop. Perhaps it was a perfect storm of shape, size, speed, altitude, and weather. So, do we know if it actually did reach the speed of sound?
-----Original Message------- ROC-Chat mailing list roc-chat@xxxxxxxxxxxxx http://www.freelists.org/list/roc-chat
From: Lakestake Rocketry
Sent: Jun 14, 2012 6:18 PM
Subject: [roc-chat] Re: Interested in Sonic Boom Sound
Kurt, Google "speed of sound". ;)
A pop heard half a second after burnout at an average temperature of 25 degrees C travels at approximately 346m/sec.
If the event occurred at a altitude of 340 meters the pop would have happened 1/2 second before burnout and been heard half a second after (give or take the spedd of light). If burnout was higher it happened even earlier.
On Jun 14, 2012 6:08 PM, "Kurt Gugisberg" <kurtgug@xxxxxxxxxxxxx> wrote:Richard, I heard it too. Seemed to me it was shortly after burnout which makes it even more mysterious. I was watching the flight and, as far as I can visualize it, the burn ended and and half second or more later, the pop.-- ROC-Chat mailing list roc-chat@xxxxxxxxxxxxx http://www.freelists.org/list/roc-chat
From: Richard Dierking
Sent: Jun 14, 2012 8:49 AM
Subject: [roc-chat] Re: Interested in Sonic Boom SoundOk, glad that someone else heard this Mike! And yes, this sounds like a very good explanation. I was a sharp pop and that's what surprised me. Do you know who's rocket it was? Just wondering if there's video out there.Thank you,RichardOn Thu, Jun 14, 2012 at 12:29 AM, Mike Riss <rockt_dude@xxxxxxxxxxxxx> wrote:
I think I heard the same thing, and IIRC, I was standing in the safety zone at the time. Seemed like it was towards the end of the motor burn. It sounded pretty sharp to me. I was thinking it was that "liner getting expelled" that usually gets thrown out as an explanation for that type of sound.
--- On Wed, 6/13/12, Richard Dierking <richard.dierking@xxxxxxxxx> wrote:
From: Richard Dierking <richard.dierking@xxxxxxxxx>
Subject: [roc-chat] Interested in Sonic Boom Sound
Date: Wednesday, June 13, 2012, 8:20 AMDuring ROCstock after I was doing some maintenance on one of the back pads and was walking away, a rocket was launched. It was about a 4" diameter, and had a large enough motor to get it going fast. During the flight, I definitely heard a "pop" but it didn't coincide with any event I saw on the rocket. I thought that a sonic boom could only be heard if the cone created by the disturbance passed by you. So, what could this have been? I was thinking perhaps a sound generated by turbulence at the base of the rocket?Anyway, this is the first time I've heard this kind of sound and I wonder if someone has video that includes this "pop."Richard Dierking