When doing head-down, why don't skydivers/tunnel fliers get the blood to rush to their heads?

[craddock 0]

I have spent a fair amount of time upside down on earth and never had many issues with blood going to my head. I used to walk down hill on my hands for a challenge all the time and have walked around on the flat for exercise upside down for most my life although most those days are over. Certainly for longer than a simple skydive.

I even in attempt to prove I was sober enough to stay out many years ago, showed it by walking down a steep set of stairs from the deck of the bar to the parking lot(girlfriend held ice on my eye and head later as I was "sleeping". I didn't pass the test. S&TA's got me messed up as punishment for swooping stunts I pulled when I thought no one was looking)

Anyway. Point is that I am not effected by the time of a skydive to be upside down on earth. Now standing on head? That is not comfortable. I only spent seconds in a head stand and then pushed to a handstand. Or go into one briefly the other way around. I had a major dislocation to shoulder thought 6 months ago so those days are probably over.

How many people are really on their head in that room next to the tunnel

That spot isn't bad at all, the winds were strong and that was the issue! It was just on the downwind side.

[mattjw916 2]

Reminds me of this bad joke: Two blondes were flying to Miami from Cleveland. Fifteen minutes into the flight, the captain announced "One of the engines has failed and the flight will be an hour longer. But don't worry we have three engines left".Thirty minutes later, the captain announced "One more engine has failed and the flight will be two hours longer. But don't worry we have two engines left". An hour later the capain announced "One more engine has failed and the flight will be three hours longer. But don't worry we have one engine left". One blonde looked at the other the other blonde and said "If we lose one more engine, we'll be up here all day"

NSCR-2376, SCR-15080

[billvon 2,391]

>It’s unfortunate that your ignorance to the natural world impedes your ability to grasp such a concept.

He's right. No zero-G.

[ianyapxw 0]

I don't agree with the direct styles of the above two posters, so let me explain it to you
You don't feel weightless in freefall because you have gravity (1G of forces) pushing downwards but you have 1G of wind resistance pushing upwards. Your wiki article states "absence of stress and strain". This is not true in freefall, because you have two sets of forces pushing on you.

If freefall was really a zero G environment, nobody would have problems holding sitfly or head down.

[evan85 0]

Please understand that basic SAT problems, like the other basic physics concepts you linked to earlier, rely on motion in a vacuum for the purpose of being easier to understand. We do not skydive in a vacuum, but rather in an atmosphere where aerodynamic drag forces act upon us. You cite to wikipedia to support your position; let's see what wikipedia says about freefall:

http://en.wikipedia.org/wiki/Free_fall

In Newtonian physics, free fall is any motion of a body where its weight is the only force acting upon it.
. . .
The term "free fall" is often used more loosely than in the strict sense defined above. Thus, falling through an atmosphere without a deployed parachute, or lifting device, is also often referred to as free fall. The aerodynamic drag forces in such situations prevent them from producing full weightlessness, and thus a skydiver's "free fall" after reaching terminal velocity produces the sensation of the body's weight being supported on a cushion of air.

[Bufobufo 0]

The only time a skydiver experience true zero G is then the pilot decide to have some fun and set the plane in a dive at ~9,82m/s^2 allowing you to float around in the cabin.

I assume you get more zero g when jumping up and down on the ground then when you exit an air plane as the speed forward will be like jumping with a huge growing pillow around you, restricting your acceleration as early as the exit.

Guess a hot air balloon exit would be zero g also just as you jump out and your trajectory starts to travel downwards, but as soon as your speed picks up, so will air resistance up to a point where you finally find yourself at 1g again.

[potatoman 0]

Experiment to try.

Next time you jump, take a Plastic bottle with, fill it 1/4 with coloured water.

Fall as stable as possible, holding the bottle upright.

Will the fluid be in the middle of the bottle(Floating in Zero G), the bottom, or the top?

If it went to the top, you are still accelerating, faster than the water.

In Zero G, it is like the plane dropping with you inside, but equally to your acceleration.

BUT, the true word here is terminal. This is the speed you fall at with DRAG. Now, the water would keep on accelerating, because the water has no drag, and hence, it will go to the bottom.

Now just to confuse some..... Why does a balloon move forward when accelerating in a vehicle, backwards when braking? Just vica versa

You have the right to your opinion, and I have the right to tell you how Fu***** stupid it is.
Davelepka - "This isn't an x-box, or a Chevy truck forum"
Whatever you do, don't listen to ChrisD.

[Bufobufo 0]

potatoman

Experiment to try.

Now just to confuse some..... Why does a balloon move forward when accelerating in a vehicle, backwards when braking? Just vica versa

As long as the balloon is filled with any gas lighter then air I can see why that would work, but if it was filled with air, co2 or whatever makes the balloon+content heavier then any same volume air around it id assume it would move forward when you brake and backwards when you accelerate, just like a football would in the same car.

The water bottle experiment you mentioned seems kinda awesome, and would describe what is happening in a very visual way:P

[potatoman 0]

Indeed, did not mention helium filled balloon. Now even more confusing.

You have the right to your opinion, and I have the right to tell you how Fu***** stupid it is.
Davelepka - "This isn't an x-box, or a Chevy truck forum"
Whatever you do, don't listen to ChrisD.

[Arvoitus 1]

Bufobufo

The only time a skydiver experience true zero G is then the pilot decide to have some fun and set the plane in a dive at ~9,82m/s^2 allowing you to float around in the cabin.

I assume you get more zero g when jumping up and down on the ground then when you exit an air plane as the speed forward will be like jumping with a huge growing pillow around you, restricting your acceleration as early as the exit.

Guess a hot air balloon exit would be zero g also just as you jump out and your trajectory starts to travel downwards, but as soon as your speed picks up, so will air resistance up to a point where you finally find yourself at 1g again.

I wouldn't call it true zero G as it is an illusion created by the fact that the jumper is not falling, in relation to the hull of the plane, yet they're still falling towards the ground. They're just falling with the plane and the hull protects the jumper from the free fall airflow creating the illusion of zero G.

Your rights end where my feelings begin.

[billvon 2,391]

>I wouldn't call it true zero G as it is an illusion created by the fact that the jumper
>is not falling, in relation to the hull of the plane, yet they're still falling towards the
>ground.

That's true of everything in zero-G, including astronauts in the ISS (the space station.) Earth's gravity is almost the same at the altitude the ISS orbits at as it is at sea level. They are always falling towards Earth - but are going fast enough to always "miss."

[craddock 0]

I like it.. The blond joke above that is

That spot isn't bad at all, the winds were strong and that was the issue! It was just on the downwind side.

[JohnMitchell 14]

Here's an explanation to the "No zero-G" we're talking about.

If you were to jump from a hovering helicopter, stationary balloon or, of course, base jump, you will indeed get a few seconds of weightlessness. Once you accelerate to terminal, the wind pushes on your body just as much as the floor does on the ground (or perhaps visualize laying face down on a mattress, same concept). Therefore you're experiencing the force of 1G.

We speak of freefalling as jumping with no static line.

Physicists speak of freefalling as falling with no resistance., as in a vacuum.

[ianyapxw 0]

No, the forward speed does not restrict acceleration.

In vector addition, there are two components, horizontal and vertical, and both components are independent. You would accelerate downwards as fast jumping out of an otter, 182 and baloon (assuming you have the same position)

[ianyapxw 0]

What do you mean, you get weightlessness whatever you're jumping out of, whether it's a 182, otter or balloon.

Relative wind is a horizontal component, and is independent of the vertical acceleration and velocity.

[billvon 2,391]

>What do you mean, you get weightlessness whatever you're jumping out of,
>whether it's a 182, otter or balloon.

Not really. If you jump out of a King Air (for example) doing 110 knots, then you experience no real change in force on your body during the transition. (You actually slow down a bit in terms of your net velocity before you accelerate again.) This is different than, say, a balloon exit, during which you have zero force on your body during the first instants of freefall. In that case you are truly close to "zero G."

[ianyapxw 0]

Ahh I get what you mean.

It's true that there's always forces on your body, it's just the direction that changes.

Also, the other thing is that Zero-G isn't defined well. If it's truly weightless feeling (floating), you won't even experience it on a balloon jump as there's a force acting downwards the moment you jump out.

edit: Well if you define weightlessness by force of support, you're technically weightless the moment you jump out of an otter, 182 or balloon. http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/hump.html

[wolfriverjoe 1,340]

Feeling "Zero G" is when you are accelerating at the same speed gravity is pulling you down.

When you jump from a balloon or helicopter, the initial part of the jump is with little or no forward speed, so there isn't any air resistance acting on your body.
So you accelerate at nearly the same as gravity.

If you jump from a moving plane, you are already moving at or near terminal (depends on the plane). The horizontal deceleration occurs simultaneously with the vertical acceleration.
And your body doesn't feel like it's at zero g at any time.

Have you made a jump yet?

"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo

[ianyapxw 0]

Yes.

I have made 5 jumps from a caravan, and I do feel Zero G when I exit the door, very similar to the top of a roller coaster.

Have you considered the components of vectors that I mentioned earlier yet?

[wolfriverjoe 1,340]

Yes. We've had this discussion before. The physics of it are pretty basic. But the actual sensations and perceptions are different than the physics would dictate.

Most jumpers don't feel the "stomach drop" like on a roller coaster, unless they are going out of a balloon or helicopter.

"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo

[ianyapxw 0]

Actually I agree with you, because jumping out of a turbine aircraft, one is much more likely to focus on the relatively wind.

I personally also felt the stomach drop has gone away significantly over the course of 5 jumps.

[craddock 0]

wolfriverjoe

Yes. We've had this discussion before. The physics of it are pretty basic. But the actual sensations and perceptions are different than the physics would dictate.

Most jumpers don't feel the "stomach drop" like on a roller coaster, unless they are going out of a balloon or helicopter.

Oh my god I am getting a headache. I need to get off my head again!!!!

I hate the way my stomach feels on roller coasters and when cowboy pilots putting passengers in a less than 1g environment zigzagging through supposed holes in the clouds. OPEN THE DOOR! Let me out before i get sick! I have never ever felt this though with the pure positive g's jumping from anything, including Helicopters and fixed objects.

This thread is bizarre to me. And I mean no disrespect

That spot isn't bad at all, the winds were strong and that was the issue! It was just on the downwind side.

[JohnMitchell 14]

ianyapxw

Ahh I get what you mean.

It's true that there's always forces on your body, it's just the direction that changes.

Bingo. Your gravity vector is towards the forward horizon on exit, due to the acceleration of the wind force on your body. We perceive that as the relative wind. You are weightless momentarily on the vertical vector.

Now, the slower the exit speed, the less wind force, the lower the G load. Jumping from a Cessna doing 55 mph (extremely slow) would have .25 G load, assuming you had a terminal belly velocity of 110 mph. That's why slow hop and pops feel a little weightless.

Quote

Also, the other thing is that Zero-G isn't defined well. If it's truly weightless feeling (floating), you won't even experience it on a balloon jump as there's a force acting downwards the moment you jump out.

Nope, no force except for air resistance upwards.

Gravity, you say? Naw, I prefer to think of gravity as a curvature of space-time that we perceive as a force, simply because we're usually resisting it. Quit resisting and you feel nothing, including weight.

[Pablo.Moreno 0]

Lol, I guess you really cant believed everything the internet says...

I guess the only time you could feel zero G, it would be the half a second you spend after you leave the airplane, on the transition of going up and then down/forward (same feeling you get if you do a jump right now on the ground on the moment where you are changing direction from going up to go down) If you for any reason decided to jump up while exiting the plane.

Reason why blood doesn't rush to your head, is because your blood is falling at the same speed as your skin. It also accelerates at more or less the same speed.

Why your blood rushes to your feet when you spiral on your canopy?? Because in this case scenario your blood is rushing to your feet but your skin is not moving.

[manseman 0]

Pablo.Moreno

Reason why blood doesn't rush to your head, is because your blood is falling at the same speed as your skin. It also accelerates at more or less the same speed.

Sounds simple enough, but it doesn't really explain anything about flying hd in the tunnel, right? Your "skin" is being pushed away from the ground but your blood will still be pulled towards the ground just as if you were outside of the tunnel.

Also, people inside an aircraft falling out of the sky don't seem to automatically fall at the same speed as the aircraft they are inside, so maybe your explanation is a bit too simplistic.