For years I watched with a certain amount of envy as model coaster builders such as John Hunt displayed their creations at Coaster Cons and get-togethers. I wanted badly to design and build my own coaster. The problem for me was mainly one of space. I certainly don't have a yard big enough to build a full-sized ride. I live in a tiny apartment and short of bolting a model flat against the wall or onto the ceiling, I have no place to put even a scale version, at least not one on the scale I'd seen others work in. Perhaps I could have built it to sell it, but I wanted one I could admire during the long New England winters. In 1993, I began an enormous project: to build an exact scale working replica of the Crystal Beach Cyclone. After more than a year of research, including scrutinizing the original blueprint groundplan, I built a 2-foot by 4-foot platform and drilled holes for all the footings. And that's where I stopped. Again, I couldn't imagine where I'd put such a huge creation. Plus, I had never built a model coaster before, and I thought that perhaps I was getting in over my head. Perhaps it was better to begin with something a little simpler. And so, one year later the Shooting Star was born.
I found what appeared to be an ideal substrate: a block of corrugated cardboard, 11" long by 4" wide by 1" thick. I glued the cardboard to a plywood base, glued a strip of fake grass on top of it. Then I began sketching. I originally thought of constructing a Figure-8 coaster in the tiny space I had to work with, but I didn't want to get too complicated with track sections criss-crossing and requiring special bracings. I wanted a simpler design. Given the small plot of land, I went with a double out-and-back configuration.
I've sketched out over a hundred fantasy coasters. I began them all with an overhead view and then added the elevations. For this project, I started with a simple profile view, drawn to the size of my working area. I drew it on graph paper, with each 1/4" square the equivalent of 10 feet. This was my first mistake. I was drawing a three-dimensional object on a two-dimensional grid. I took all my height measurements from this drawing, not quite grasping the fact that in a three-dimensional world, structures in the foreground would appear taller than larger structures in the background.
On graph paper, I then layed out an overhead view of the footings, placing bents (the vertical members) at equal spacings of one set every ten feet. I numbered the bent sections beginning at the bottom of the lift hill. The turnarounds were wonderfully symmetrical, but in retrospect much too tight. This stemmed from that same problem of drawing it out in two dimensions instead of three. I couldn't visualize the depth required for the turnarounds. As they stand now, the track (and probably structure as well) would most likely be a maintenance nightmare at those spots. Laying out the bents in the turnarounds is tricky business. On try after try, the inside edges of the bents would end up colliding with each other, while the outside edges were too widely spaced. The solution would have been to extend the radii of the turnaround curves. However, the small plot of land I had restricted myself to didn't allow for that. As it stands now, the turnarounds would slam you against the side of the car and probably snap your neck. (No problem -- my imaginary amusement park has great liability coverage.) I chalked another mistake up to experience and pressed forward.
I next dealt with the practical problem of how to actually construct the model. Balsa wood seemed to be a popular choice for many model builders, so I went with that material. There was a nearby model railroad store that sold 1/16" square strips of balsa in 3-foot lengths. I bought out their entire stock (30 pieces) after roughly calculating the number of inches I'd need (adding up the lengths of all the bents and allowing for ledgers and ribbon bracing).
In order to assemble the bents, I needed some sort of guide or blueprint. Once again on graph paper, I drew out each numbered bent section as if looking flat onto it. Since the drawings were the actual size of the model, I could use them as templates for assembling. Those drawings included all cross-bracing, plus some interesting (if impractical) truss work. Based on the coaster's profile at various points on the graph paper, I guesstimated the height of each bent along the course and how much superelevation each section would need.
Once all these preliminary steps were completed, I became pre-occupied with other projects and the model base gathered dust. Months later I was talking with Rich Boehmer, a coaster friend who had created an interesting computer program that could take an entire coaster, "unwind" it and print up an accurate profile view of the entire course. The advantage of this is that any rough transitions along the track become immediately obvious. He offered to enter the stats for my model coaster. The results were enlightening and amusing. Although there appeared a few nicely-rounded parabolic hills in the computer's profile, many stretches of track featured hills that appeared buckled or that formed a very ominous "V" shape. Rich notated a few spots with the understatement "great air," where the hills came to a sharp point. One rule of coaster design that he impressed upon me is the importance of the ratio of change in elevation -- that is, the vertical distance from bent to bent. Throughout most of my track, there would be an increase of 4 feet from one bent to the next for thirty feet. Then there would be a drop of 2 feet each bent the next fifty feet of track. This practice led to the "V"-shaped troughs and hills. Rich stressed how the change in elevation should not be a constant; the increments should rise and fall smoothly, without "flat" spots.
Another point he made was how short my track length was in relation to its height: it was only 1600 feet long, and had a lift hill of 90 feet. The Great Escape Comet, my favorite coaster, has a length-to-height ratio of 43:1. The Steel Phantom, one of the more severe and intense coasters around, has a ratio of 18:1. The Shooting Star works out to a ratio of 17:1. It had better have a lonnnnnnnnng break run. Rich figured out that if I had created a standard lift rise of 3.5 feet per bent (instead of my 5.5' rise), that would have given the ride a 56-foot-high lift and a ratio of 29:1, the same as Knoebel's Phoenix!
The last bit of wisdom he imparted to me was how to judge the heights of the hills along the length of a coaster. Due to frictional losses, each succeeding hill along the length of a coaster track can be only so high. The hills need not get progressively smaller, but their height cannot exceed a certain point. Rich revealed a simple way to determine that point: on a scale representing the "unwound" view of your coaster track, draw a line from the point equivalent to the top of the lift hill to the point equivalent to the end of the ride. The resulting line displays at any given point the maximum height for hills along that track. If you create a hill that touches the line or goes beyond it, the train will lose momentum before cresting that hill and will stall. I had created two hills near the end of the run that exceeded the line by quite a bit. I had assumed wrongly that since most of the hills on the Shooting Star were significantly lower than the lift hill, the train would acquire extra speed to easily leap over the larger hills that followed. Frictional losses, however, don't change with varying hill heights; losses are a constant. The train's energy would dissipate whether I chose to put large hills first or not. The only difference is that with lower hills, the train would have more constant speed. The higher the hill, the slower the train moves over it; the sensation produced is more of a "stop-and-go" type of ride.
Armed with all this new information, I set about revising my design and a few weeks later sent a new version off to Rich, which he in turn input into his computer. The ride had improved at the roughest spots, but there were still many refinements to be made. This coaster design business was a little trickier than I had anticipated....
Another year and a half went by before I resumed work on the model. The impetus was e-mail correspondence with other coasterholics who were working on their own models. I really didn't have time to work on a coaster model, with all my other projects going on, but I figured if I didn't start something soon it would never get done. So on Thanksgiving day of last year I set up shop on our kitchen table and began bringing the drawings to life.
I still had all the balsa wood strips, which had been lying around so long they had begun to curl. In order to ease assembly, I made copies of the bent-section pages and laminated them with plastic. That would allow me to lay the balsa pieces right over the drawing and glue them in place. When the wood glue dried, I could simply pry the pieces up off the page and place them onto the base. I allowed 1" of balsa to stick "beneath the ground." That assured all pieces would line up properly. The first thing I noticed when I began assembly was that my bents were too detailed. On the scale I was working, there was no practical way to insert all the tiny crosspieces that would have been required on a real coaster. So I opted to leave them out. Work progressed quite rapidly afterwards. I found it most efficient to place a small piece of masking tape across the bents to hold them in place before attaching the ledgers. I averaged about 6 bent sections completely assembled every hour. I highly recommend that method of assembly. It's a little more work to draw out each bent section, but it saves so much time and aggravation afterward. I would work on the model for an hour before I went to bed each night. It was a lot of fun to watch the progress. As more and more track went into place, the model looked more and more authentic.
One other difficulty I discovered was with the material I had chosen for my base. When I made holes in the base for the footings, the point of my tool was often deflected by the corrugation in the cardboard. A variance of a fraction of an inch offset the bents enough to be noticeable. For the next model I build, I'll use a foam core base instead.
I often got impatient,wanting to finish the model as quickly as possible. Every time I rushed the project, the still slightly-wet pieces would come apart in my hands and I'd have to re-set them. I learned the hard way what model builders have said for years: be patient. Let the pieces dry.
When all the bents were in place, I began puzzling over how to apply the ribbon bracing. I had assumed I could simply use the leftover balsa wood, but it proved horribly out-of-scale. I needed thinner wood -- paper thin, in fact! Paper was too white. We had lots of old grocery bags lying around.... I cut very thin strips out of a bag and glued then in place at every twenty feet of vertical height (about half as many as on a real coaster). That material proved perfect -- easy to glue and very flexible for wrapping around those tight turns.
I had planned to lay strands of bus wire (very thin silver wire) along the course to simulate the track. But even bus wire was too large. I puzzled about this one for a long time. One night I happened to see some rolls of 3mm ribbon my wife had bought. Just for laughs I placed it on the ledgers and found that it fit perfectly! It was a light pink, though. So I went to the local craft store and got the same ribbon in brown. I thought about silver, grey and black ribbons, but brown seemed to call the least attention to itself.
I layed the ribbon out along the course in one (long) evening. Corners were very tricky. I had to make small slits in the ribbon in order to bend it without kinking. It was also quite a challenge to snake the ribbon through the bents where the track crossed under itself. The brown turned out to be too dark to look like authentic track and catwalks. It resembles more the sections of grease-catching wood on some newer coasters (such as the Georgia Cyclone). It does make it easy to follow the track direction though.
The last structural pieces were the three sections of side bracing and the Cobb-style guy wire bracing on the turns. The "wire" is grey thread. The side braces are pieces of balsa positioned to create nice "capo-del-fine" effects. I hadn't thought of side bracing when I designed the coaster. Construction of them would have been greatly simplified had I first drawn them out.
The finishing touches were the paper sign glued onto the lift hill and the station, which is a piece of paper bag on balsa wood legs. White enamel paint was used for the queue line.
I learned quite a bit about real coasters working on my first coaster model: the importance of the length-to-height ratio, the trick to figuring out hill heights, the need to have smooth transitions into and out of hills, what materials to use for a base, how elaborate preparation can cut down on construction time.... Most of all I learned how fun and relaxing a hobby model building can be. Over three months of this cold New England winter, I created a little bit of summer in our home.
Karen and Jay's Amusement Page