Airtime Explained
"Airtime" is a well-known phrase within the world of roller coasters.
It's used by most members of the industry, from roller coaster manufacturers, to enthusiasts,
and even theme parks themselves.
Some attractions are even being marketed
based on the amount of airtime present throughout the ride experience.
This is a great selling point, but what actually is airtime?
In short, airtime is a sensation of weightlessness
which often occurs as riders crest the hill of a large drop at some speed.
This sensation could be linked with riders moving up and out of their seats.
The upward motion is directly linked to the amount of g-force the trains and riders experience.
G-Force, or the force due to gravity, is relatively constant around the globe.
This force causes everyone to accelerate towards the centre of the Earth
at a rate of 9.81 metres per second per second, known as 1g.
Therefore, a roller coaster which boasts a maximum g-force of 5,
means you'll experience five times the acceleration due to gravity at some point throughout the ride experience.
G-Forces can be placed into two categories: positive and negative.
Airtime generally occurs at g-forces less than 1,
but has significant effects at accelerations of 0g or less.
Forces below 0g are called negative g-forces
These result in large amounts of airtime.
Before we continue, we must understand the basic physics behind the airtime phenomenon.
The crest of an airtime hill can be roughly modelled as a circle.
Therefore, it is suitable to say that the trains undergo circular motion as they navigate this part of the track.
For circular motion to occur, there must be an acceleration towards the centre of rotation.
This acceleration is equal to the velocity of the train squared, divided by the radius of our circle.
Therefore, we know the speed of the trains and the size of the hill
will affect the amount of airtime riders experience.
When the acceleration towards the centre of the circle equals that of gravity,
the riders experience total weightlessness.
This is because there are no forces acting on them except for gravity.
Essentially, the guests are consistently falling.
At g-forces of -2 and below, riders experience more abrupt airtime.
This is because gravity can no longer provide all of the acceleration towards the centre of rotation.
As a result, riders quickly fly up in their seats and touch the restraint.
The restraint provides the additional force, and therefore acceleration, towards the centre.
These two type of airtime are known as floater airtime and ejector airtime.
There are no concrete definitions for the types of airtime.
However, floater generally occurs at g-forces between 1 and 0g, 0g being total weightlessness,
whereas ejector airtime often occurs at g-forces below -1g, as riders are quickly thrown out of their seats.
The reason airtime mainly occurs at negative g-forces is quite simple:
g-force is measured by the amount of force an object must provide for you to not fall through it.
For example, at 1g, the seat of the train will provide 1g of force upwards.
At negative Gs, the direction of the force is reversed.
Instead of the force being directed upwards, against the weight of the rider, it's now downwards.
This is because the restraint provides a force on the riders to stop them rising out of the train.
As a result, -2g means that the restraints provide 2g of force towards the centre of rotation.
Airtime is not only limited to roller coasters.
Drop towers often allow riders to experience weightlessness, or even ejector airtime.
Several examples of this can be found on the Tower Of Terror rides, located at the various Disney theme parks.
The attraction causes riders to fall at rates faster than gravity,
meaning they raise up and out of their seat.
Let me know if you enjoyed this video and would like to see more roller coaster terms explained in the future.
Thanks for watching, and I'll see you next time.