But that's just my take... I only made it through 5 semesters of engineering.
The centrifugal force (which isn't a real force, but we won't go into that) throws you to the "outside" of the roll while you're executing it - same theory as Music Express rides and Rotors that throw you to the outside of a spinning axis. So, when you're in the apex of the roll, theoretically, the centripital/fugal force throwing you "out" of the roll is strong enough that it counteracts gravity and you seem to "float" in the air, rather than be glued to your seat. The floating in the post-apex part of hte roll that olsor is talking about is just teh centripital/fugal letting go and gravity taking back its hold which is weird enough that it feels like you're still floating.
But there's also a difference in sensation depending on where you sit in a roll. Correct me if I'm wrong, but if you traverse a left-hand roll, as in this picture, the people sitting on the right-hand side of the train will feel more outward force entering the roll (since their turn radius is wider than the left's), and the people sitting on the left-hand side of the train will feel more outward force exiting the roll.
I might not have gotten that exactly right, but I noticed a huge difference in Alpengeist's zero-G roll when I sat on the left, then the right. On the right side, the roll felt like it would toss me, and on the left side I merely felt like I was rolling over. *** Edited 1/19/2004 9:54:08 PM UTC by Olsor***
I don't understand how people on the outside seats of the train have a slower direction change. The rows move as a whole. If anything, the outside seats travel further (being further from the axis of rotation) and therefore move faster.
My understanding of the zero-g roll is that, in the middle rows of the train, you're tracing the parabolic arc, creating a zero-g effect. The twist heightens the sensation because you're upside down when you're weightless.
Well, the zero-g roll or "revolution" as it is called by its creators is actually a 0,1 g roll. Unlike on the top of an airtime hill, there is always a slight pressure which "guides" the body through the inversion.
The forces go down to 0,9g on the incline, reach 0,1 on the apex and go up to 0,9 on the decline.
Nevertheless this is an remarkable feature, since the body is close to weighing nothing, while the lateral acceleration is just 0,6 g throughout the revolution.
The "heartline spin", found on the Intamin loopers, was initially designed to simulate a flipping car in an accident (go figure). The rider has to endure -1g and is practically falling out of his seat while inverted.
/solemnly closes the book with clouded stare, replaces book into vacuum globe, reciting obscure mantras while switching numerous levers with dreamlike sincerity, disposes gloves and puts oxygene level back to normal. Closes heavy door and goes upstairs where mother is preparing liver for dinner./
The row is all one fixed object. The angular acceleration around the axis of rotation (dw/dt) of the row is the same for all seats. Thus, the direction change is the same for all seats. However, since the inner seats have less distance to travel in the same amount of time, less linear force is applied in acceleration and deceleration (dx/dt).
Brett- Maybe I don't understand your point, but I don't see how the outside seats could ever have a slower direction change.
My thoughts exactly, AA. Impulsive, I don't buy it. Could you explain differently? I also only had about 5 semesters of Engr. (honestly not trying to be sarcastic), I'm not trying to be an expert, but if you're right on this I would like to understand why.
Ok, let's try this again (and I think we're all saying the same thing here).
The seats closest to the track spine in the roll have less distance to travel to accomplish the same roll around the "centerline" of the car than the seats furthest from the track spine. Correct? Ok, what I'm seeing in my head are two arrows pointing in the direction of the active force on the people in the train. The one coming out of the folks nearest the spine will really whip around the spine, faster than the one at the centerline of the train. Conversely, the arrow on the outside will move "slower" around the twist than the arrow at the centerline.
Make any more sense? I believe that its this difference in "speed" due to distance from the center of rotation that causes the different sensations depending on your seat in a zero-g roll.
btw tricktrack - nice one with the "holy writ of werner" ;)
Ok one last try then I give up. You and I are on a football field. Someone draws a B&M zero-G looking straight down the spine (so basically all you see is a box with a circle going around it representing the "rails"). Now, add in a circle for the approximate location of the center of the train as it executes that roll. Finally, add a circle for the outside seat, and one for the inside seat. Now, you and I run at the EXACT same speed, but I run around the outside "seat circle" and you run around the inside one. You're going to get back to your original starting point before I do. I have a longer distance to travel to get to the same point. Therefore, I have to move faster.
Get it? (If not, this is going nowhere and I give up ... my girlfriend's the teacher, not me ;) )
Here's an analogy. Look at a record player (remember those?) from above. Pretend its the zero-G roll looking dead on as Brett mentions above. Put a coin halfway across the turntable and one at the edge. Start the player. None gain or lose position in this little "race" but the outer coin is obviously covering more ground because the circumference is bigger there than the coin at the halfway. Now look at those 2 coins as the inside seats, and outside seats respectively; and the pin that would hold the record as the heartline as the train travels through a zero G. In relation to the inside seats, the outside seats cover more area than the inside seats in the same amount of time.
No - seriously I think you're probably right with your explanation:
In the direction of the train travelling, all seats have the same speed. But concerning the path travelled resulting from the rotation of the roll, the outside seat travels more distance.
Just like the length of a groove traveled by the stylus when playing back a record travels less and less length per revolution the deeper into the record.
I'm not sure where you're going with the deep forest and the fries, but hey, sign me up ... but yea, I think yinz gots the idea I was tryin to get across - but I think who gets whipped and who gets float is more a matter of opinion (either that or I'm burnt out thinking about this). Either you feel that more distance or more speed gives you the whip.
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