

NASA shuttle launch video from the perspective of a solid rocket booster - bhousel
http://www.pbs.org/wgbh/nova/insidenova/2010/08/what-were-watching-nasas-accidental-video-art.html

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avar
Interesting that the parachutes are deployed 32 seconds before landing, and
only fully expand 22 seconds before landing (as far as I can tell from the
video).

Anyone know what the margins for a skydiving human are by comparison?

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Gibbon
The minimum "safe" height for skydiving is 2000ft with most jumps between
2000-5000ft depending on the type of jump and experience of the skydiver.

In emergency situations it's possible to deploy at 200-300ft. and survive.

Basejumpers deploy way below 2000ft. with 200 or 300ft. not being uncommon but
they have gear and techniques designed to open the chute very quickly.

Skydivers can fall at a rate of ~160 ft/sec. So in a worst case scenario
you've got 2 seconds before impact.

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spacejunkie
at 4:28 is that the launch plume on the left, the moon in the middle and the
spent rocket on the right?

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avar
Yes.

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sasvari
pretty amazing video indeed! the sound is kind of spooky during the space
flight :-)

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jballanc
Yes! I love how the sound actually gets "quiet" as they reach the upper
atmosphere. ("quiet" in quotes because I don't know that it's really correct
to say that when all that's really happening is the sound-carrying medium is
becoming less...)

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MrRage
The site says they used a "contact microphone," so I assume what we're hearing
is vibrations in the rocket not so much the air.

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yread
I wonder when does it break the sound barrier when falling. It must fall
pretty quickly - 7 minutes from start to landing.

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Marticus
Typically something in the far-upper atmosphere breaks the sound barrier by
just falling - not as many molecules to produce drag - but I don't think the
sound barrier "breaks" at that altitude for the same reason terminal velocity
is greater than the speed of sound up there.

I may be mistaken in this, but I don't think without propulsion or an absurdly
stable / aerodynamic falling that you can actually "break" the sound barrier
in the traditional sense at the point in the air where density is high enough
to produce the shockwave effect.

Edit: That second paragraph was entirely too convoluted on my first go at it.

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mchouza
It's not very difficult: the Tallboy Bomb was free-falling and exceeded Mach 3
at impact.

<http://en.wikipedia.org/wiki/Tallboy_bomb>

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Marticus
I guess what I'm now wondering is whether or not something requires a certain
drag coefficient to, upon achieving trans-sonic speeds, create a shock wave in
the air.

Obviously they probably didn't produce a shock wave at absurdly high
altitudes, but were also probably falling at trans-sonic speeds.

What I was trying to mull over was for how long and at which point could
something like that achieve enough drag to presumably both travel at trans-
sonic speeds AND produce an audible shock wave as per an aircraft achieving
the same speeds.

But that is also why I put in the disclaimer about high aerodynamic
capability, because obviously the terminal velocity would be enough to surpass
that pretty easily. I didn't know it would be Mach-3-easy, though.

Edit: That is pretty awesome though - traveling that fast would mean you
wouldn't hear it coming...

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yread
Does it even produce a shockwave when there's nobody to hear it?

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Marticus
Not if they're already dead.

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TotlolRon
The part where he lost his brother was heart breaking.

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sliverstorm
Is there something I don't know here?

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Retric
There are 2 SRB's, one on each side.

