Forums: Skydiving: General Skydiving Discussions:
What is Zero G's, Negative G's, and some examples?

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BravestDog

Sep 1, 2012, 12:44 PM
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 What is Zero G's, Negative G's, and some examples? Can't Post
Trying to figure out what Zero G's and Negative G's are, in simple terms. I looked it up on Google, Wikipedia...and am still confused. I don't want mathematical formulas, looking for simple, understandable examples.

0.165 G standing on the moon
1 G standing on earth.
0 G in the vomit comet when you are airborne above the floor and not on the ceiling.
3 G's on Space Shuttle Take Off and Landing.

Is a Negative G, what you would feel if you were to fall inside a chamber where there is no air (don't think that exists) or what you would feel if you fell faster than 120mph while skydiving, like if you had rockets attached to yourself and you were accelerating as you were falling by rocket power?

I've seen videos of Mike Mullins King Air where I assume he makes the plane dive and it assists the jumpers to the standing position. I've seen videos of the Vomit Comet airplane that is used to train astronauts and have seen it's parabolic flight curve on paper. Is that a Negative G? If you feel weightless and rise inside the airplane without hitting the ceiling, is that 1 Negative G? If you hit the ceiling of the airplane, is that more than 1 Negative G? How fast does the airplane have to fall in order to make you rise off the floor and not hit the ceiling, so you are floating inside the airplane?

Is a Negative G a constant? Does it vary from whether you are inside an airplane or whether you are skydiving?

When would a Negative G occur in Skydiving, never? How fast would you have to fall to experience a Negative G while skydiving?

Somebody help me with this concept please?

(This post was edited by BravestDog on Sep 1, 2012, 4:42 PM)

freeflyer58D  (B 32456)

Sep 1, 2012, 1:02 PM
Post #2 of 49 (2285 views)
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 Re: [BravestDog] What is a Negative G and some examples? [In reply to] Can't Post
this is a difficult one to describe, but im sure you already have experienced both positive and negative G's plenty in life. a G is just a measurement of the force of gravity... i know you dont want the physics, but it is physics, so i need to explain just a bit... 1 G is what we live in all day everyday. that is 1 unit of earths gravity. if it is a positive G, then it is going to be pulling you down toward the floor and you feel like 170 pounds. 2 G's would simply be twice the earths gravity, and you would feel like you weigh 340 pounds. generally if you feel like your lifting out of your seat, that is a reduction in the gravitational force. when you crest a hill in your car going fast, that weight less feeling is typically somewhere around .3 or .5 G's. when you see a person floating in the vomit comit, they are at 0 G's, or no gravity. one time you would experience negative G's would be if you flew an airplane upside down. when flying right side up, you have +1G, when your inverted your -1G. any time your heavier than your normal weight (towards the floor its more than +1G. the +/- stuff is really more dependent on the reference being used than anything else. you might experience a negative G while skydiving in rough air. but this would occur in the plane... and it is why you get tossed out of you seat towards the ceiling. ok, let me know if that helps at all! i have been rambling

Sep 1, 2012, 1:10 PM
Post #3 of 49 (2275 views)
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 Re: [BravestDog] What is a Negative G and some examples? [In reply to] Can't Post
The terminology is often misused. A 0g exit is often mistakenly called a negative g exit.

Being in freefall with constant acceleration is 0g. The vomit comet does that (accelerating descent). Being in orbit around the earth is 0g (always falling toward the earth as you are orbiting it). Negative g in an airplane would be pressed against the ceiling, or your seatbelt, or flying inverted, or doing an inverted loop would be more than 1 negative g. After you've reached terminal velocity while skydiving (no more acceleration), you are at 1g, even though you're falling, because it is the same situation as being in an airplane at a fast but constant descent - you'd still feel your normal weight.

(This post was edited by sundevil777 on Sep 1, 2012, 1:11 PM)

BravestDog

Sep 1, 2012, 3:01 PM
Post #4 of 49 (2240 views)
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 Re: [sundevil777] What is a Negative G and some examples? [In reply to] Can't Post
Less than 1G is what you feel if you are in a car, and it quickly descends down a hill. You feel that the car is falling faster than your body and your body feels as though it is lifting out of the seat. At the point of you lifting completely out of your seat, but not thrown into the ceiling, you are at 0G's, correct?

Anytime you feel less than 1G, you are at Negative G's, correct? And Negative G's begin at .999999....of 1G and less, correct?

When does all this begin?

(This post was edited by BravestDog on Sep 1, 2012, 3:18 PM)

BravestDog

Sep 1, 2012, 3:08 PM
Post #5 of 49 (2236 views)
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 Re: [BravestDog] What is a Negative G and some examples? [In reply to] Can't Post
If you were to build a device, say the size of a 10x10 room, and toss it out of an airplane/balloon... and you wanted to remain inside the device not touching the floor and not touching the ceiling, what would be the vertical speed of your fall?

And if you could do this, that would be 0G, yes?

Sep 1, 2012, 3:18 PM
Post #6 of 49 (2228 views)
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 Re: [BravestDog] What is a Negative G and some examples? [In reply to] Can't Post
Less than 1G is what you feel if you are in a car, and it quickly descends down a hill. You feel that the car is falling faster than your body and your body feels as though it is lifting out of the seat. At the point of you lifting completely out of your seat, but not thrown into the ceiling, you are at 0G's, correct?

Correct.

It is not just that you're descending, you get the feeling because you're accelerating. Driving down a steep hill at constant descent rate gives no unusual feeling.

(This post was edited by sundevil777 on Sep 1, 2012, 3:23 PM)

Sep 1, 2012, 3:20 PM
Post #7 of 49 (2227 views)
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 Re: [BravestDog] What is a Negative G and some examples? [In reply to] Can't Post
If you were to build a device, say the size of a 10x10 room, and toss it out of an airplane/balloon... and you wanted to remain inside the device not touching the floor and not touching the ceiling, what would be the vertical speed of your fall?

And if you could do this, that would be 0G, yes?

The speed would need to be constantly increasing (not steady - accelerating) in order for you to feel weightless - at a 0 g condition.

Being in freefall is not 0g unless there is no drag from the air, because your acceleration is less than 1g.

It is important to realize that the acceleration of gravity is an acceleration (change of velocity per unit time), not a constant speed, as that is no acceleration at all.

(This post was edited by sundevil777 on Sep 1, 2012, 3:22 PM)

muff528  (D 17609)

Sep 1, 2012, 3:31 PM
Post #8 of 49 (2215 views)
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 Re: [BravestDog] What is a Negative G and some examples? [In reply to] Can't Post
If you were to build a device, say the size of a 10x10 room, and toss it out of an airplane/balloon... and you wanted to remain inside the device not touching the floor and not touching the ceiling, what would be the vertical speed of your fall?

And if you could do this, that would be 0G, yes?

Well, tossing the room from a balloon or airplane implies that the room will be descending through "air". A person inside the room will remain on the "floor" throughout the descent. Even if the room does not reach v(t) it is still impeded by the air. The passenger is not.

ETA - that is, if the room is not a screen room.

(This post was edited by muff528 on Sep 1, 2012, 3:33 PM)

billvon  (D 16479)
Moderator
Sep 1, 2012, 9:52 PM
Post #9 of 49 (2161 views)
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 Re: [BravestDog] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
>Is a Negative G, what you would feel if you were to fall inside a chamber where there
>is no air (don't think that exists) or what you would feel if you fell faster than 120mph
>while skydiving, like if you had rockets attached to yourself and you were accelerating
>as you were falling by rocket power?

Sort of. If you accelerated towards the earth at 64fps^2 (say inside a space shuttle performing an RTLS abort maneuver) you'd feel -1G. To you it would feel just like 1G but the Earth would be above you and the "floor" of the vehicle you were in would be towards the sky.

>If you feel weightless and rise inside the airplane without hitting the ceiling, is that 1 Negative G?

No, that's zero G. If you were at -1G you'd be sitting on the ceiling of the plane weighing your usual amount.

>How fast does the airplane have to fall in order to make you rise off the floor and not
>hit the ceiling, so you are floating inside the airplane?

It has to descend 20mph faster every second for that to happen. So after 10 seconds you'd be heading downwards at 200mph.

To hit -1G you'd have to descend 40mph faster every second.

>When would a Negative G occur in Skydiving, never?

The only time most skydivers experience negative G is when the pilot screws up and people hit the ceiling.

davelepka  (D 21448)

Sep 2, 2012, 5:47 AM
Post #10 of 49 (2111 views)
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 Re: [BravestDog] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post

Let's not reply to this post any further until the OP fills out his profile.

Diverdriver was keen enough to recall the OP from awhile back, where again he was asking some loaded quesitons about jumping. To date, the OP has had zero forum activity, until now where again he appears to be mining for info. Reporter? Lawyer? Could be either one, but until he comes clean, let's not indulge him either way.

pchapman  (D 1014)

Sep 2, 2012, 6:10 AM
Post #11 of 49 (2100 views)
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 Re: [BravestDog] What is a Negative G and some examples? [In reply to] Can't Post
Anytime you feel less than 1G, you are at Negative G's, correct? And Negative G's begin at .999999....of 1G and less, correct?

No, it is done just mathematically: Below 0 is negative g. So -0.01g is negative g. Between 0 and 1 one might say one is in a low g environment, but that's just a general term.

Sep 2, 2012, 6:28 AM
Post #12 of 49 (2091 views)
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 Re: [pchapman] What is a Negative G and some examples? [In reply to] Can't Post
Don't feed the troll.

BravestDog

Sep 2, 2012, 11:30 PM
Post #13 of 49 (2002 views)
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 Re: [davelepka] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
davelepka, DougH

I was hoping to ask some simple questions regarding Skydiving and want people to stay on topic without making False Accusations, Speculation and Comments that are Off Topic especially if it involves me, which it has. I'm not here to be your friend or to be popular. I don't need to know and have no desire to know who you are. I'm interested in asking some questions and learning something. My questions are on topic and relative to the forum.

Would you politely remove your off topic posts to my questions before I contact the website administrator and have them do it for you? If that is necessary, then you will be wasting their time and my time because of YOUR inappropriate public behavior.

If I wish to remain anonymous, guess what, it's NONE OF YOUR BUSINESS and it's probably a good idea. Ever hear of Identity Theft, Psychopaths, Sociopaths, Cyber Bullies, Mentally Ill Violent people who want to harm you etc? Guess what, they exist everywhere.

Your responses are Off Topic, Accusatory, Speculatory and you are saying this in a public forum. Amounts to inappropriate behavior.

If you feel the need to Speculate, Investigate, whatever...Use Private Messaging, your telephone and leave your responses out of my posts. I do not want you to post your responses to my questions if they are going to be off topic, accusatory and speculative

Let's not reply to this post any further until the OP fills out his profile.

Diverdriver was keen enough to recall the OP from awhile back, where again he was asking some loaded quesitons about jumping. To date, the OP has had zero forum activity, until now where again he appears to be mining for info. Reporter? Lawyer? Could be either one, but until he comes clean, let's not indulge him either way.

Sep 3, 2012, 3:12 AM
Post #14 of 49 (1969 views)
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 Re: [BravestDog] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
Some one is off their meds!

nickfrey

Sep 3, 2012, 3:29 AM
Post #15 of 49 (1961 views)
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 Re: [BravestDog] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
Yep, lawyer. And likely not a very good one, somebody got bumped around on an observer ride and is trying to make a quick buck.

Sep 3, 2012, 3:34 AM
Post #16 of 49 (1960 views)
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 Re: [BravestDog] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
Would you politely remove your off topic posts to my questions before I contact the website administrator and have them do it for you?

They'll do that for you?

You must be very important - people, be nice!

Sep 3, 2012, 3:43 AM
Post #17 of 49 (1954 views)
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 Re: [jakee] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
Apparently were not the only website he has pulled this on:

http://www.thedieselstop.com/forums/f10/forum-name-change-suggestion-e-series-bravestdog-forum-20456/

JackC1

Sep 3, 2012, 5:05 AM
Post #18 of 49 (1914 views)
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 Re: [BravestDog] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
You wouldn't be Fred Martin Feller, the lawyer from Alameda would you? Who are you suing?

Sep 3, 2012, 5:19 AM
Post #19 of 49 (1900 views)
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 Re: [JackC1] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
Who are you suing?

Not like there's anything wrong with that.

<runs>

davelepka  (D 21448)

Sep 3, 2012, 5:23 AM
Post #20 of 49 (1895 views)
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 Re: [BravestDog] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
Quote:
Would you politely remove your off topic posts to my questions before I contact the website administrator and have them do it for you? If that is necessary, then you will be wasting their time and my time because of YOUR inappropriate public behavior.

Show me where I've broken the forum rules, or more appropriately show an admin where I've done so, and I'm sure they'll pull my post.

However, you'll find that I did not break the rules, unless you consider being called a lawyer a 'personal attack'?

The simple fact is that lawyers have driven many DZs into bankrupcy with frivilous lawsuits over the years where the DZO spent all their money defending themselves against cases that ultimately went nowhere. The plantiffs did not prevail, the DZO went broke defending themselves, but guess what? Big surprise, the lawyers all made out like bandtis.

So go ahead and report me to whoever you want, and write me a stern post (I'm guessing it's the same 'cease and desist' you posted in all the threads where I called you out), but in the end you're not going to get anywhere.

I see Doug found that you some problems on another webstie, one for deisel trucks, more specifically E-series vans. What happened, did a 15 passenger van roll over and you're trying to sue Ford?

Quote:
I'm not here to be your friend or to be popular. I don't need to know and have no desire to know who you are. I'm interested in asking some questions and learning something. My questions are on topic and relative to the forum.

Well, tough shit. Many of these people are my friends, and the ones I haven't met I would certainly welcome as friends if I ever did. Again, this includes DZOs, instructors, and gear manufacturers (and their employees) who all stand to lose when lawyers get involved in things they shouldn't. So despite what you 'want' (information), this is what you're going to get (a hard time).

News flash, skydiving is dangerous, and it says so on the liability waiver that your client signed and that I'm sure you requested a copy of in discovery.

Now fuck off, and go mine for information somewhere else.

(This post was edited by davelepka on Sep 3, 2012, 5:25 AM)

muff528  (D 17609)

Sep 3, 2012, 5:44 AM
Post #21 of 49 (1883 views)
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 Re: [DougH] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
Apparently were not the only website he has pulled this on:

http://www.thedieselstop.com/forums/f10/forum-name-change-suggestion-e-series-bravestdog-forum-20456/

This can't possibly be the same guy ...unless he is so tangled up in superstrings and black holes that he has completely forgotten Newton. (maybe his real name is "Sheldon".)
Attachments: bdprofile.jpg (64.4 KB)

Shelbyrlff

Sep 3, 2012, 8:33 AM
Post #22 of 49 (1824 views)
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 Re: [BravestDog] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
Physiologically, doesn't a positive G force the blood flow to your feet while a negative G forces the blood flow to your brain due to the direction of the gravitational pull? I believe G's in skydiving is usually only referenced under canopy. Positive G's are the cool roller coaster feeling you get spiraling under canopy. However, I've heard of folks achieving negative G's under a malfunctioning canopy, but can't quite wrap my brain around how that could happen. Anyone know?

CSpenceFLY  (D 25252)

Sep 3, 2012, 1:03 PM
Post #23 of 49 (1763 views)
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 Re: [DougH] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
Apparently were not the only website he has pulled this on:

http://http://www.thedieselstop.com/...vestdog-forum-20456/

Sep 3, 2012, 2:19 PM
Post #24 of 49 (1699 views)
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 Re: [CSpenceFLY] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
there are some excellent pics of swoopers achieving negative g's for a very short period of time, followed by some very high g's..... some good examples here :

hillson  (C 40438)

Sep 3, 2012, 3:41 PM
Post #25 of 49 (1657 views)
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 Re: [BravestDog] What is Zero G's, Negative G's, and some examples? [In reply to] Can't Post
Zero G is how I feel at the DZ bar on Saturday night. Negative G is how I feel when I drag my carcass out of bed on Sunday morning.

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