Optimizing for Fun: Engineering Amusements

by James Herzing 9 July 2016

The field of engineering design is quite vast and multi-faceted - from designing rockets and aircraft to household appliances to communications devices to bridges and roads.  Often overlooked, however, are those brave souls who devote their entire careers, not to lofty ideals such as  interplanetary exploration, time-savings or peace of mind, but to something much more personal (yet arguably, as lofty): fun.

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Of course, “fun” means something different to everyone; whether you enjoy the thrills of rocketing at 120+ miles per hour via linear induction motor towards a 450+ foot tall tower and down again, the spinning centrifugal forces of a tilt-a-whirl, the heights and views atop a Ferris wheel, the gentile ups and downs of a merry-go-round or just take pleasure in watching others have fun.

When looking to best interpret and design for these varying concepts of “fun” into amusement experiences, designers must understand the following concepts and optimize them based upon human tolerance within all appropriate safety factors:

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G-force - technically, not a force at all, but acceleration experienced by the ride-goer.  It can be vertical (roller-coaster) or horizontal (gravitron).  When a car on a roller coaster track reaches the apex of a “bunny hill”, its vertical acceleration goes to zero as it transitions from upwards to downwards and therefore the human body experiences a brief moment of “weightlessness” or “zero-gs”.  Alternatively, at the bottom of such a hill, riders will experience a higher g-force (>1).  G-force is also experienced in the horizontal direction as in a banked turn or a corkscrew inversion (as much as 3gs or over).

Shock - a short-term “excitation” or pulse, measured in magnitude and duration.  Typically, this is due to vibrational forces on the machinery of an amusement or to the quick-jerky motions of certain rides like the “cat and mouse” style roller-coaster.  While this is normally not a major concern, it is believed that those who are exposed to such vibrations for an extended period of time may be more prone to lower back problems.  Some people, however, due to their occupation, may already be exposed to such and may find riding for even a short period of time to be “irritating”. This is typically why certain rides will discourage riding if the person is pregnant or prone to lower-back pains.

Jerk - the rate of change of acceleration.  This can typically occur when the change in acceleration is considerable.  Such an example might include a head-on bumper car collision.  Just like with regular driving, such extreme cases can cause whiplash, especially if the rider is already prone to frequent neck pain.

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With such considerations, ride design is kind of like automotive and/or aeronautical design.  Rides are a lot like other vehicles, after all, but the major difference is the overall goal.  Traditional vehicles are designed to get from Point A to Point B while serving a myriad of purposes.  Amusement rides are all designed to be Point A to Point A...they’re all on a closed loop, and the accelerations, along with the sights and the sounds are there to create an overall “experience”.

And it’s around these experiences that design engineers build such wonderful mechanisms; from analyzing the structural components, hydraulics, electrical systems to even fluid dynamics.  When it comes down to it, most of the analysis is the same as any other engineering application - finite element analysis, modal analysis, thermal analysis, computational fluid dynamics and more will be used.

So the next time you consider taking a trip to your nearest water/amusement park or traveling carnival, think about the various teams of engineers and designers that are behind ensuring that you and your family have a thrilling, enjoyable and safe experience that will last a lifetime.