Part 4: Rolling Over

Alright, unfortunately I'm fresh out of dynamics material to cover so from here on out it's all history, technique, and my own philosophy on design. First, I'll explore the rest of the basic inversion types, starting with corkscrews. Corkscrews were the first inversion that was actually ridable (barely). They beat modern loops by a single year (1975 at Knott's Berry Farm).The first company to make corkscrews was Arrow Dynamics, and they became a staple inversion on almost all of their rides through the 1990s. Corkscrews are named for a ride path that resembles the wine-cork removing implement of the same name, and are naturally shorter than loops. Originally corkscrews were perfectly circular, sort of like moving at constant speed and rotation around the outside of a barrel.
Old school:

This led to some funky transitions into and out of the corkscrew, and made for lateral forces in the bottom half of the inversion (not so fun). Modern corkscrews are a bit fancier, and generally involve rotating mostly around the apex and have very slightly banked entrances. This ensures the lateral gs are minimized. Here's the new fanciness:

Look at the banking of the last car in the train, half-way up the corkscrew. It's only about 45 degrees from the horizontal. If you look at the cars half-way up the old-style corkscrew, you can see they are already on their side, banked at 90 degrees. At this point, however, the ride path is still curving upwards and thus to eliminate lateral force the train needs to be banked at less than 90 degrees. It's a strange concept to get, but think of how uncomfortable it would be to begin curving vertically upwards from a sideways position. Due to the complex assortment of roll variations available today, corkscrews are now more generally defined as a rotating inversion with positive g force. There are so many manufacturers making so many sizes and shapes of corkscrews that it's kinda hard to keep things straight, especially when they start giving them different names (wing-overs, flat spins). I just call them all corkscrews to save myself the trouble. I'll be putting one on our ride, here it is.

Next, the roll! This is really as simple as it sounds. It was first made in 1985 (on this bizarre thing) and wasn't terribly exciting then. They're easy to make and require the least speed of all of the inversions, but I've never really liked them much. Moving on to something more worthwhile, the zero-g roll! This type of roll gets its name because, simply enough, it's a zero g hill that's warped into a roll. This gives riders a sensation of floating while rotating, a really cool inversion. They were first done well by Bolliger and Mabillard (who, to me, really began the modern design era in 1993 with Batman: The Ride at Six Flags Great America). Here's a side view of a sample zero-g roll.

Note how the yellow heartline follows a basic parabola to create the zero-g while the track rotates around it to create the roll. Here's a real-life version, on Scream at Six Flags Magic Mountain.

I'll put a slightly tweaked version of this into our ride, right after the loop and a turnaround. The turnaround was made 'by hand' meaning I placed each track node individually. This isn't very precise, but I'm on a steep time budget here. I've made the turn ascending, so we end up high in the air in the middle of the loop.

Now, Since we're already so high in the air, I'll skip the first half of the parabola and do a flat roll through the loop into a zero-g finish. This'll give us a distinctive element which is still within ridable limits and that seems feasible. This sort of cautious innovation is what I base most of my designs on. I like to see what a manufacturer does, then move to the next logical extreme. This gives my rides unique elements that push the envelope of technology, something that's always fun.

Anyway, now that we've covered the basic elements we can start to get into combos. Most compound elements consist of some combination of corkscrews, zero g rolls and loops. I'll give 4 of the most popular here. First, the dive loop. This consists of a zero-g roll that stops rolling at the apex and drops into a half-loop all the way to the ground. Bolliger and Mabillard do this really well, here's a good example on Mantis at Cedar Point.

I've decided to feature a dive loop on our ride, right after the complex roll. Our dive loop soars over the final brake run. I'm always a fan of tying a coaster in knots. Here it is in it's final placement.

An 'Immelman' is the exact reverse of the dive loop, starting with a half loop but then rolling over into a descent. Here's 'Dive Coaster' and its stupidly huge Immelman at Chimelong paradise in China.

The next inversion type is kinda like an Immelman and a dive loop combined. The 'Cobra Roll' features a half loop then a sort-of half corkscrew. Next, a half-corkscrew throws rides back upside down until a second half-loop points them back in the direction from which they came. This is kinda hard to illustrate with words so here's The Incredible Hulk at Universal Studios Florida to do it for me.

This element is supremely useful for turning a ride around, and is a great feature to play with pacing a bit. Next, the batwing was a favorite of Arrow Dynamics for a long while. Almost the opposite of a cobra roll, the batwing consists of a half-corkscrew into a half-loop, then a second half-loop leading into a second half-corkscrew sending riders, again, out the way they came. Here's Viper's batwing at Darien Lake.

Many other inversion types exist, but most are possible only in certain train configurations (some more bizarre than others). Others are simple changes on the ones listed above, and aren't really that important.

Now that we've got our inversions straight, let's move back to our coaster. Originally I had thought that, after the dive loop, 2 corkscrews over the launch would occur. This brings me to the next important part of coaster design, pacing. Pacing really amounts to the intensity of elements and the speed at which they are taken. While strong forces are good, it's not really fun to spend an entire ride squashed in your seat at 4 gs. It's important to give riders a break, both to allow time to enjoy the experience and because the human body can only enjoy so much disorientation. With this in mind, I scrapped my original plan to create 2 corkscrews in a row after the dive loop. After riding a rough version, I felt that there was far too much rotation going on over this small section. I based this largely on my experiences in coaster design and what I would theoretically enjoy most on a coaster. I thought there was simply too much rotation and not enough time for the passengers to reidentify what was up and what was down. Therefore, I made the first corkscrew into a simple airtime hill. Again, it suited the style of ride and kept up the speed while still allowing a little break from all the spinning. The hill is also thrilling in its own right, giving riders a bit of a head-chopper effect underneath the first airtime hill. A 'head-chopper' is a percieved near miss above the track. Fortunately, at high speeds it's difficult for the human brain to differentiate between what is dangerously close and what if just out of the way. Therefore while the track above the riders is quite safely out of reach, it appears to be dangerously near. I love making extremely cramped coasters simply to create such crossovers and near misses, raising excitement levels greatly.
Here's an overview of most of the layout of our ride. You can see the launch (in the closest tunnel), the airtime hill, the loop, the turnaround, the zero-g drop, the dive loop, the second airtime hill, and the corkscrew.

Anyway, now that we've got all of the inversions out of the way, I'll wait explore the miscellaneous other important info next time. Until then.