Breaking the sound barrier... in freefall.
- Thread starter Data Holmes
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The speed of sound also changes with altitude, because the air pressure and temperature vary.
One of the effects of this is seen in seen in supersonic wind tunnels: As the air is moved to higher velocity, the pressure reduces causing the speed of sound to reduce.
Once it passes Mach one the aerodynamics changes, and the air will accelerate as it expands, which reduces the pressure further. And you can theoretically take the Mach number up to infinity by expanding a supersonic flow.
You'll notice on the exhaust of rocket engines the cup shaped nozzles. These bits control how the supersonic fluid is expanding.
One of the effects of this is seen in seen in supersonic wind tunnels: As the air is moved to higher velocity, the pressure reduces causing the speed of sound to reduce.
Once it passes Mach one the aerodynamics changes, and the air will accelerate as it expands, which reduces the pressure further. And you can theoretically take the Mach number up to infinity by expanding a supersonic flow.
You'll notice on the exhaust of rocket engines the cup shaped nozzles. These bits control how the supersonic fluid is expanding.
He'll have to top out pretty early in the jump, as the required airspeed for Mach 1 gets higher as he drops into warmer air.
Once he gets below 35,000 feet (Below 35,000? skydiving? WTFO???), Mach 1 increases steadily from 659 mph to 761 below 5,000 feet or so.
That dude better double insulate his berries. Above 35,000 feet, the temperature is a not quite balmy -56 degrees C!!!!
See this link to observe the effect temperature has on Mach 1.
Calculations like this get a little funky. Many online calcs use the 1976 Standard Atmosphere model, which incorporates pressure and temp differences.
Once he gets below 35,000 feet (Below 35,000? skydiving? WTFO???), Mach 1 increases steadily from 659 mph to 761 below 5,000 feet or so.
That dude better double insulate his berries. Above 35,000 feet, the temperature is a not quite balmy -56 degrees C!!!!
See this link to observe the effect temperature has on Mach 1.
Calculations like this get a little funky. Many online calcs use the 1976 Standard Atmosphere model, which incorporates pressure and temp differences.
His terminal velocity should also be higher at higher altitudes because of the lower air density. The lower density will result in less resistance, and therefore a higher terminal velocity than at lower altitudes. I guess that, along with the lower speed of sound, is why he's jumping from 23 miles.
Consider the wind chill factor:
http://www.nws.noaa.gov/om/windchill/images/windchill.gif
He'll be down in that purple corner, and off the chart.
Agreed... deep purple... I'm talking berries, not the chart! BRRRRR!!!!!! LOL
BBC and National Geographic are co-producing a documentary about the attempt...
Given the extreme conditions he must endure, what happens if he passes out on the way down? Or his limbs become unresponsive because of the cold? Would there be some parachute opening fail-safe, or is it totally up to him to pull the string?
Also wondering what a sonic boom would do to the body (if anything?), should he hit that magic speed.
Also wondering what a sonic boom would do to the body (if anything?), should he hit that magic speed.
Sonic booms are simply the result of hearing sounds in the wrong order. Since the object is traveling faster than the sound it is making, the observer hears nothing until all the sound reaches him at once, hence the "boom".
The quieter the moving object is to begin with, the less pronounced the boom, and there wouldn't be much of a notable effect at the source anyway.
The quieter the moving object is to begin with, the less pronounced the boom, and there wouldn't be much of a notable effect at the source anyway.
Sound is a pressure distortion. An object moving through air also creates a pressure distortion. Usually it is so low frequency that you can't hear the sound of things moving through air. But as you cross the sound barrier, the air becomes squashed to a high density, and generates a discontinuity in the air pressure, known as the Prandtl–Glauert singularity. (Although in reality it is just a very steep and sudden drop in pressure.)
This produces a shock wave, not unlike an explosion. This is what you hear as the boom.
[yt]http://www.youtube.com/watch?v=-d9A2oq1N38[/yt]
This produces a shock wave, not unlike an explosion. This is what you hear as the boom.
[yt]http://www.youtube.com/watch?v=-d9A2oq1N38[/yt]
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Yep, you're hearing the compression wave, then the sound trailing the object.
Fine he breaks the sound barrier. But as his elevation decreases and the required speed to maintain his position in front of the "sound waves" becomes inadequate, the stress on his upper body as pressure tries to slow him down. Add in "turbulence" similar to what's experienced by aircraft, except he's not made of steel. I guess this idea also applies to breaking the sound barrier in the first place.
I'm not an arm chair physicist or doctor, but my money is on his brain shutting down due to blood being squeezed out of his head -- possibly even serious injury from the "turbulence."
I'm not an arm chair physicist or doctor, but my money is on his brain shutting down due to blood being squeezed out of his head -- possibly even serious injury from the "turbulence."
Felix Baumgartner has some very BIG balls!!
[yt]http://www.youtube.com/watch?v=8Oq2Xl7oiws[/yt]
So would/could this be considered the 1st orbital Sky Dive?
[yt]http://www.youtube.com/watch?v=8Oq2Xl7oiws[/yt]
So would/could this be considered the 1st orbital Sky Dive?
Good thing you weren't actually betting real money.
Incredible and impressive. Huge congrats to this guy and this achievement. (It's "good" his attempt(s) were delayed till to day where it's the anniversary of Yeager breaking the sound barrier in a jet.)
Thanks for that info.
I suspect there's only so high he can get in an aircraft (be it a plane or balloon) before rockets or more aggressive propulsion is needed and even then you'd need a way to do it and then "park" in a spot in the air in order to be able to jump out and make it to your desired landing spot. This may not have been a jump from true Earth orbit but it was still a damn high-jump that required him to wear a pressure suit that still had complications in it.
Baby steps.
I suspect the guy right now is already trying to figure out a way to go higher.
Baby steps.
I suspect the guy right now is already trying to figure out a way to go higher.
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