what does terminal velocity feel like?

February 19, 2009 5:07 AM

what does terminal velocity feel like?

when I'm in a lift or a plane, that falls suddenly i feel my stomach 'float'.
I guess what I'm feeling is, in addition to what my inner ear senses, that my internal organs which normally weigh down on whatever is supporting them, stop pressing down because my whole body is accelerating under gravity.

Which has got me wondering about terminal velocity, if you jump out of a plane and free fall to terminal velocity, what does it feel like?

I figure once you reach terminal velocity the air must be putting a force on your body equivalent to the force from the ground when your lying down. Do you stop feeling weightless?

Do you notice the moment when you reach terminal velocity?

posted by compound eye to science & nature (21 comments total)

You reach terminal velocity pretty quickly when you skydive. I was surprised at how short the "woah my stomach is in my throat" feeling was. 3 or 4 seconds? And then it's just very windy, but you don't feel like you're falling anymore. Then the parachute opens, and you've got a nice relaxing trip down, to enjoy the scenery.
posted by Grither at 5:19 AM on February 19

the first few seconds after you jump out of a plane, you have that floaty-stomach feeling, but as you pick up speed it goes away and you more or less feel like you're laying face-down on the floor, only there's no floor, just wind blowing up at you. but you don't notice "reaching" terminal velocity because you never (technically) get there; you just asymptotically approach it.
posted by sergeant sandwich at 5:20 AM on February 19

Mathematically, no, you can't reach terminal velocity. Practically, however, you reach it pretty quickly, as in, once that falling sensation goes away, you've pretty much reached your terminal velocity.
posted by Grither at 5:26 AM on February 19

right, i just meant that it's not a well-defined transition from "feels like falling" to "doesn't feel like falling".
posted by sergeant sandwich at 5:30 AM on February 19

Agreed. And compound eye, you can never really know how it feels until you go skydiving yourself. Which I highly recommend!
posted by Grither at 5:38 AM on February 19

When I bungi jumped at Victoria Falls (111 meters) I was shocked that I didn't feel like I was falling, I felt like I was floating. I thought, "oh, this is why free fall equals weightlessness." It only lasted a few seconds before the bungi cord started slowing me down, but it was a very cool feeling.
posted by alms at 6:36 AM on February 19

To answer your question in a word: weightlessness. It feels like you're floating in space, and it's wonderful.

As for that "bottom falling out from under you" feeling, it can mostly be avoided by getting into a good position, facing into the relative wind, as you exit the aircraft. If you think about it, you're already close to terminal velocity as you exit; your speed equals that of the aircraft. All that happens in the first few seconds is that your velocity translates from horizontal to vertical. If you were leaving a smoke trail as you exited, people on the ground would see a nice, graceful arc. If you're in a good freefall body position during this translation, it doesn't feel like you're falling.

Seconding Grither: go try it yourself.
posted by dinger at 6:47 AM on February 19

I didn't really think about much of anything on the way up, I was just in a zone, and then we were at the door all of a sudden having just watched my buddy disappear into the green ground in the distance below us.

And then the tap on the shoulder, and then you whoosh for a second into the propblast and I somewhat intentionally twisted around to get a look at the plane flying away from me. I suppose in doing that I was more focused on spinning than the feeling, but I suppose there was a second or two of weightlessness.

By the time I was able to right myself (4-5 seconds out of the plane?) and get my belly button pointing at the ground, all I was noticing was how fast the air was coming at you. Kind of like in high school when you're in a friend's truck or car with a sun roof and you stick your head up into the wind, except that was hitting the whole body, not just my face. You know how its kind of hard to breath if you don't really focus on it when all that wind is whipping at your face and down your throat? Yeah, like that, at first.

The next thing I really noticed was the curvature of the planet, which was awesome. For the first time, the horizon was no longer a straight line. I don't know why I've never been able to experience this in the thousands of hours I've spent in planes of all types, but it was something of a soul-grasping realization that I existed on a large ball, floating in space, and for the first time I was not on that ball, I was looking down at it, in its place. It was cool.

For the rest of the freefall I was pretty much just watching the ground get closer and checking my altimeter, but I would generally say it felt more like "flying" than it did "falling" or "floating." I mean, I knew I was falling but at those heights the ground doesn't seem to really be approaching all that fast, and you don't exactly have many points of reference zinging by you when you're way up there (like you would if you jumped off a building, per se). Definitely more like flying than anything else.

I highly recommend it, the only thing I've done in my life that was more acutely thrilling that skydiving was cage diving with the Great Whites.
posted by allkindsoftime at 7:09 AM on February 19 [4 favorites]

when I'm in a lift or a plane, that falls suddenly i feel my stomach 'float'.

I don't feel at all certain about this, but I attribute the floaty sensation to a mismatch between what your eyes are telling you (in a plane or an elevator your eyes are telling you you are at rest with respect to the rest of the world) and your inner ear is saying (hey! the little stones aren't pressing on the tiny hairs anymore -- we're falling!).

I base this partly on the way I remember jumping on a trampoline: I only got the floaty feeling at the apex of the jump, when the world stopped for just that moment, even though the forces on the inner ear and other bodily organs are essentially the same throughout the jump.

I figure once you reach terminal velocity the air must be putting a force on your body equivalent to the force from the ground when your lying down.

Thank you for that 'of course! why didn't I see this before?' moment.
posted by jamjam at 8:49 AM on February 19

I don't feel at all certain about this, but I attribute the floaty sensation to a mismatch between what your eyes are telling you (in a plane or an elevator your eyes are telling you you are at rest with respect to the rest of the world) and your inner ear is saying (hey! the little stones aren't pressing on the tiny hairs anymore -- we're falling!).

No.

I've never gone skydiving, but I have done lots of other things where the floor drops out on me. That sensation is a "real" result of your inner ear. It works just as well (even worse sometimes) with your eyes closed.
posted by Netzapper at 8:57 AM on February 19

Freefall does feel like flying. It's LOUD -- the wind is screaming by you. And it doesn't really feel like falling (at least, it didn't to me) because you're at such a distance. It felt like being buoyed up on a column of onrushing air. For a whole minute. A minute is a looooooong time.

Skydiving is one of those completely frivolous, why-would-I-ever-want-to-do-that things that, yeah, everyone should try once. It's fucking awesome.

And I'm so NOT an adrenaline junkie.
posted by BitterOldPunk at 9:31 AM on February 19

What dinger said. When I've been skydiving, I haven't noticed any 'falling' feeling at all - my momentum simply changes axis. All I felt was floaty. Floaty and loud as hell. You can't hear anything except the rush of wind.

I also found it a bit hard to breathe - but your mileage may vary on that. I tend to breathe through my diaphragm a lot, and the force of wind pushing up on it probably acted as a bit of an impediment. Plus, I imagine that there's that 'remember to breathe' adrenaline factor at play, too.
posted by kaseijin at 9:39 AM on February 19

I should note that by 'floaty', I don't mean that 'floor dropping out' feeling. I mean just a peaceful sort of cushiony feeling. Just like standing or sitting except there's nothing under you, so you have this crazy extra range of potential movement.

I am terrified of heights, and did not once feel like i was falling.
posted by kaseijin at 9:44 AM on February 19

It feels exactly like being in space. JPL has a Basics of Space Flight section: How Orbits Work. An orbiting spacecraft/person/whatever is basically something that is falling towards Earth but happens to be going fast enough in a specific direction to keep missing the planet as it falls. It isn't the absence of gravity like most people assume. The orbiting object is moving much faster than terminal velocity but the feeling should be identical, minus the whole "If my chutes fail and I land on something soft there's a slim chance I could live" bit, and the wind.
posted by jwells at 9:59 AM on February 19

Nthing being very loud and very, very windy. I am not sure why I didn't expect that but it was very loud. Also the sensation of speed is completely nonexistant since you have no easy fixed frame of reference while you are falling. So while you are pushing 100MPH+ towards the earth you really don't get that sensation at all.

The other major thought that was going trough my head (besides hoping that the freaky hippie guy I had just met 20 minutes ago packed the chute right) was "man if my goggles fall off this is going to be hella painful on the eyes".
posted by mmascolino at 10:46 AM on February 19

jwells, you've been in space??

The "feeling" of falling is generated in the inner ear. Wikipedia tells me that linear accelerations are sensed by the two "otolithic organs"; I only knew about the vestibular canals. But the principle of all three is the same: you have a semi-rigid sensory organ that interacts with some fluid. Sitting on the ground, the fluids are free to accelerate towards the ground, while the rigid bits are held in place by the rest of your body. In free fall (including orbit), the rigid bits and the fluids are always accelerating at the same rate. Terminal velocity should produce more of a sitting-on-the-ground sensation, since the rigid parts of the inner ear are not accelerating. Interesting that the skydivers all seem to agree.

If the terminal velocity is 200 km/h, if you accelerated at a constant rate g you'd reach terminal velocity in about six seconds. You'd have to pay attention to notice the transition.

I'd never considered the idea that the feeling in the stomach might be because of actual pressures and motions in the abdomen. Hmmm.

(I have never been skydiving. I have also never been to space. I did the free-fall haunted elevator at disney world fifteen years ago, if that counts.)

posted by fantabulous timewaster at 1:19 PM on February 19

Thanks fantabulous,

I think you actually managed to refine what I was wondering for me,

how does the feeling of acceleration at constant rate g
differ from
(almost) reaching terminal velocity

I think all your answers have probably painted as good a picture as I will get prior to jumping out of a plane, but just to thorough:

is there anyone listening who has both been in space and skydived?

I realise this is a big ask but it is Metafilter, there's probably six of you here right?
posted by compound eye at 5:09 PM on February 19

As far as your body's internal ability to detect acceleration is concerned, terminal velocity does not feel like being in orbit. The time you spend falling well before you reach terminal velocity feels like being in orbit.

As far as your body's internal ability to detect acceleration is concerned, terminal velocity feels just like being in elevator that is descending steadily, which in turn feels just like being on the ground.

As for your body's internal ability to detect velocities, none is possible.
posted by hAndrew at 2:13 AM on February 20

Mathematically, no, you can't reach terminal velocity. Practically, however, …

(almost) reaching terminal velocity

For the record, you do reach the terminal velocity. Exactly what the terminal velocity is depends in a complicated way on whether your limbs are extended or together, whether you're belly-down or feet-down or head-down, how much of your kinetic energy is being used to flap your clothes, the local density and viscosity and water content of the air, which way the wind is blowing, and so on. As you fall, all of these things change, and so your mathematical terminal velocity will fluctuate around some average value. When your fall speed gets closer to the average than these fluctuations, the fluctuations change whether you're speeding up or slowing down. So your terminal velocity is something like 200 kph ± 10%, and you reach it in a finite amount of time.

Mathematically, a spherical cow falling in a perfect laminar fluid never reaches its terminal velocity. Mathematically, a skydiver does.
posted by fantabulous timewaster at 2:00 PM on February 20

Reaching TV takes about 10 seconds IIRC. You don't notice acceleration, as the previous poster mentioned, you just notice the angle of the descent change. Then it's just incredibly noisy and overwhelming.

If you really wanted to hit max you would need to change your body position, dropping head to earth in a dive rather than adopting a 'frog' position.

In any case it takes (IIRC) about 20 seconds to fall through the first 1000 feet and about 10 seconds/1000ft thereafter. This is really just because of the parabola that you describe on exit, your speed doesn't actually change much.
posted by fingerbang at 2:08 PM on February 20

thanks for the answers,
good answers,

but deep down just a smidgen disappointed that buzz aldrin
didn't have anything to contribute on the matter
posted by compound eye at 7:46 PM on February 20