Posted on 05/22/2010 7:02:04 PM PDT by Malone LaVeigh
The pressure suit won’t protect him from the forces of the air applied to his body during the fall, and if he succeeds, while breaking the sound barrier.
I think you've reached the next level of the "tree falling in the forest" philosophical endeavor.
Bill does not have enough money to entice you even with all of it?
Joe Kittenger, Capt, USAF - one ballsy guy....
LOL...I remember our black hat (Airborne Instructor) at Ft. Benning telling us when we'd stand in the door for our first jump, "Your pucker factor will be so high you couldn't drive a needle up your a$$ with a 10 lb. sledge."
A real simple much smaller scale is what we see in a elevator. As it is dropping, it's probably go what maybe 20 mph? Notice the sensation as the elevator stops. Well now multiply it times 20.
There is basically NO air at 100,000 feet or above.
The air pressure at sea level is about 14.7 psi (or barometric pressure is 29.92” Hg)
The air pressure at 25,000 ft is about 5.5 psi (11.12” Hg). Almost 2/3rds lower.
At 50,000 ft - - 1.7 psi (3.44” Hg).
At 75,000 ft - - 0.5 psi (1.00” Hg)
At 100,000 ft — 0.16 psi (0.33” Hg)
At 100,000 feet your are in a strong vacuum - only 1.1% of the air remains - 98.9% less air means MUCH less air friction / drag.
That is why they MIGHT be able to break the speed of sound in freefall - there is almost NO force exerted by the air as drag. He will fall and continually accelerate, almost completely unhindered by drag.
(Thus aerodynamics isn’t really a factor. If one WERE to drop a P-51 from 120,000’ (with it’s prop featherd and engine NOT running) I can almost guarantee it would break the local speed of sound. I cannot guarantee it would make the transition to denser air as it falls without shedding its wings.)
As the air pressure increase, drag will increase and his speed will slow naturally.
I am not sure at what altitude and speed he will reach maximum dynamic force (product of increasing drag and decreasing speed).
The extra altitude he starts at WILL give him a better chance of reaching a terminal velocity that IS faster than the speed of sound at that altitude.
One possibly BIG issue with breaking the sound barrier will be if some dynamic factor caused by fluid dynamics of the air around him causes some sort of flutter (high-speed vortex shedding from his hands for example).
If something like that occurs, he might experience tremendous force variations and be seriously injured.
BUT that is normally more a problem with rigid structures. The body being soft / compliant, I think this is unlikely.
For HIS sake I hope it is unlikely...
One thing in his favor is that as he drops, the atmosphere increases and his speed will naturally slow down (more atmosphere means more air friction). I think there is a terminal velocity at 1 atmospheric pressure unit that is about 125 mph if I remember correctly from HS physics. He will therefore go from 600 mph to 125 mph in a gradual manner. His parachute will open as it normally would -- provided he does not pull the rip cord too soon.
If a shockwave forms on his ass, he might get a little behind in his research.
Thanks for the answer. So the jump will give him enough time to deaccelerate from 600 mph to terminal velocity? I didn’t you could slow down in free fall.
He’s going to burn up.
I want that certificate witnessed and notarized as well!
The big problem even a small amount of drag can cause him is rotation. As soon as there is enough air to have even "negligible" effects on his radial velocity, he will start to turn, and he will spin very quickly without stabilizers.
Ignoring air resistance completely, the best case calculation says he can hit the local speed of sound (around 300 m/s) when he gets slightly over 116,000 feet. I think 120,000 is more like what he needs, but even there I'm not sure it's quite high enough.
I don't work in the field any longer, but most of my research was done at 10^-6 - 10^-9 atmosphere, so I laughed at 10^-2 as a "strong vacuum." I suppose in some applications it is. "Strong Vacuum" is not a term-of-art in my old field (low energy physics.)
The problem is that he isn't really in free fall. There is a resistive force proportional to his velocity, which also increases exponentially (by the Law of Atmospheres) as he falls from near vaccuum to one atmosphere of pressure.
It’s vacuum, dumbass.
Under certain conditions, the speed of sound is exceeded by the speed of smell.
Reminds me of what my dad said when I had the opportunity to attend jump school at Ft. Benning before I reported to flight school; “Why would you go to school to learn how to do something you have to do right the first time anyhow?”
I don't agree. At very high altitude, there's little air and therefore little air resistance; terminal velocity is much faster than the 120 mph attained down here. Above some altitude, terminal velocity for a human will exceed the local speed of sound. He's jumping above that altitude.
You can slow down in free fall if the air density increases - which is what happens when you descend to lower altitudes.
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