+/- G's - CoasterBuzz

Ok, I am sure this is a stupid topic, but what is a positive G and a negative G? I can feel the G's on coasters..just dont know the difference.

A positive g would be like if you're goin through a loop or at the bottom of a hill, you get pushed down or back into your seat. A negative g would be at the top of a hill, same thing as airtime.

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It's his turn to feast, when you ride the Son of Beast.

A positive G is where on the bottom of a drop of loop, you get pushed into your seat. A negitive G is where you fly out of your seat, or what we call it.. Airtime!

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Got Cheese?

"Floater" air is generally a longer duration of small negative g's. These are nice and fun. "Ejector" air is usually a sharp spike in negative g's, and are INTENSE and FUN! Sustained high positive g's, as in Goliath's "Centrifuge", are also very intense. Opinions may vary.....

Interestingly enough, my favorite G's are lateral. Mmmmmm, Legend is calling. ;)

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Coming Soon: Coasters "American" Style.

I am a huge fan of ejector negative G's and laterals, but I realize that a lot of people do not like laterals because they are often a tad uncomfortable and VERY unnerving (which is exactly why I love them). Positive G's are cool, but easily my least favorite of the G types.

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I get the feeling there's a conspiracy over at King's Island to remove anything that has "K" or "C" in its initials.

There are six different types of G's: negative vertical (ejector airtime), positive vertical (pushed into seat in loop or bottom fo hill), left lateral (right turn which pushes you left), right lateral (like left), positive acceleration G's (launch on a launched coaster), and negative acceleration G's (brake run). Of course, these vector quantities can be combined to form sharp forces in a direction, or cancel eachother out to result in "floating airtime."

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"Hello to Yogi, Hello to Booboo, Hello to Scooby Doo. Barney and Fred say hi..." --King's Dominion's Singing Mushrooms

Quote Roar "Laterals, you never feel the end of them"

Shipps...I am a positive G, you are a negative G ;)

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Ride the New England Bush!

astrosgp said:
negative acceleration G's (brake run).

hey! someone actually used the proper term. I always think back to physics class whenever I hear the word "deceleration."

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-Bob (formerly Coaster Jedi)
Knott's Berry Farm Cuba ~South Park
"Your proctologist called, he found your head!" ~Jerry "The King" Lawler

The descriptions given here have all been pretty good. Let me sum up...
G forces are merely accelerations expressed in terms of 'standard' Earth gravity: 1 G is equal to a force of 32 pounds per slug, or 9.8 Newtons per Kilogram. G gives us a means of expressing forces in conditions where the exact mass is unknown.
All forces can be expressed as vectors, that is, they specify both a magnitude and a direction. Generally speaking, forces pushing the rider down, left, or forward are considered "positive" and forces pushing upward, to the right, or backward are considered "negative."
It appears that the amusement industry has standardized on referring to the vertical axis (up/down) as "Z", the transverse axis (left/right) as "Y", and the longitudinal axis (forward/backward) as "X". Personally, I find that more than a little confusing, as I have always thought of those axes as Y, X, and Z respectively as you can see at the top of my page about coaster cars.
I suspect this has something to do with the measuring equipment used for measuring rides having been originally designed for use in the automotive industry, where the longitudinal and transverse axes will show larger displacements than the vertical axis, so to measure high readings in the vertical axis, the accelerometer would have to be rotated to line its largest displacement axis with the coaster's vertical axis. It's only speculation on my part, but it seems to make some sense.
At any rate, in enthusiast talk, we're almost always talking about forces along the vertical axis (no matter what you call it) where +G is a force that feels like it's pushing down, and a -G feels like it is lifting us from the seat.

--Dave Althoff, Jr.

ahhh, Dave (or anyone else who'd like to answer). I've been thinking about the difference between ejector air and floater air. My intuition, which is way better than my physics, tells me that in general terms, ejector air is usually on hills shped like an upside-down V, whereas flooater comes more on hills shaped like an upside-down U. Is this somewhere on target, or does it have to do more with the speed of the train, or something else entirely?

Floater air is when the g-forces are between 1 and 0.

Ejector is when the g-force is below 0.

Just think about it. Of course more negative G's are acheived on a sharp hill, which is why the air is usually ejector.

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AC?, RB?, MF?, DD?, PR? Who can keep track of it all?

Dave's I.Q. is in the giga coaster range.

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Dosn't G stand for Gangsta?

Chuck, the O,G, Nungester :)

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Charles Nungester

Americana is opening in 2002 and needs your support as many company picnics are already schedualed for someplace else, Indivdual visits are very improtant to the parks survival.

'Gator, you're really, really close.
Okay, so you have position, velocity, and acceleration as time rate of change for each other. There is something missing from that system and that something missing is going to be the difference between 'ejector' air and 'floater'air.
You are not likely to find a force on a coaster less than -0.5G as a matter of course. In general, you're going to see the accelerations controlled in such a way that an unrestrained rider isn't going to get too far away from the seat.
What you are looking for is the next element, something that can be controlled with the hill profile.
Now, take the measurements and extend it out. See how the position, velocity, and acceleration are related to one another? And remember we are now in an environment where the net acceleration is no longer constant. So what's next?

--Dave Althoff, Jr.

ok, now I think I understand a little better what I'm looking for...now if someone could tell me why I felt so "deceived" by those nice-looking hills on Steel Force...LOL. Thanks Dave!

But Gator, you didn't identify it! YOU might have it figured out, but why didn't you tell the rest of us? The word is "jerk". And it doesn't refer to the kid acting out three rows down from you in the queue house.

Ah, well.....

Remember that you have position.
Then you have velocity, which is the rate of change of position.
Then you have acceleration, which is the rate of change of velocity.
Jerk, then, is the rate of change of acceleration. When you go over a nicely curved hill, the jerk rate approaches zero: in a perfectly profiled hill peak, your upward acceleration will be -1G as the train's vertical motion slows, stops, and reverses to come down the other side. Jerk will be zero, and the hill peak will be parabolic. That would be the first three hills of Shivering Timbers.

On the other hand, you have Magnum XL-200. With its more angular hill peaks, as the train approaches the top of the hill the up-stop catches on the rail and abruptly pulls down on the train. The vertical acceleration which has been -1G all the way up the hill abruptly rises to some brief peak until the train's direction of travel reverses to go back down the other side, then it drops back down again. When that happens, you'll get a jerk...a change in the acceleration.

--Dave Althoff, Jr.

Dave, I would disagree with your assessment of the difference between floater and ejector air.

If I'm understanding you correctly, the only difference is the rate of onset (jerk) of the sub 1g acceleration.

However, I think that if you applied a total vertical acceleration of 0.9g very rapidly, you wouldn't call it ejector air. Additionally, if you slowly applied a acceleration of -0.5 g, it would have some nice pop to it.

Ejector air HAS to have at least 0 g acceleration. Otherwise, regardless of the jerk, you'll just be floating. Similarly, I don't think you could really call a -1g hill floaty, regardless of how slowly you got to the point where you were feeling like you were hanging upside down (because of the negative g).

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The legend lives!

*** This post was edited by ApolloAndy on 4/2/2002. ***

Bump...really wanna have rideman's response to this one...

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The legend lives!