Have you ever noticed that roller coaster loopings are not shaped like a perfect circle but rather like a reverse rain drop? Ofcourse there are perfectly circular loopings (like Typhoon at Bobbejaanland, for example), but they’re a minority. Why exactly is that?
Roller coasters are exciting because of the speed, the height and the combination of forces that your body is subjected to during the ride. There’s positive G-forces (being pushed in your seat), negative G’s (being lifted out of your chair, which we enthusiasts call air time) and lateral G’s (like when you slide to the side of your seat and crush the friend that’s sitting next to you). For roller coaster designers, however, it’s a daunting task to find the balance between super exciting elements and painful, uncomfortable forces. That’s the reason why most loopings are shaped like a rain drop as well.
Imagine that you’re riding your car on the highway and you want to take an exit. You’re going fast and you can’t slow down nor break. Let’s say you’re going 100 km/h (62 mph). Would you rather choose a long turn, allowing you to exit the highway in a safe and comfortable way? Or would you rather have a really short turn that would put unacceptable forces on your body and car, probably resulting in you flying off the road? If you chose the second option, you must have some kind of death wish. It’s easy though: the faster you’re going, the bigger the radius of your turn must be!
The same goes for loopings. When you’re entering the loop, your speed is high in order to make it through the element. When going up the loop, that kinetic energy gets transformed into potential energy, slowing the roller coaster train down. So when your speed gets lower, the radius of the loop should get shorter as well. In other words: the part of the looping when you’re going the fastest is actually the ‘longest’ (for lack of a better word). The top part of a looping is considerably ‘shorter’ because your speed will be the lowest. Get it? This results in a more enjoyable ride and will put less stress on both you and the train.
So there you have it! Another fun fact you can annoy your friends with from now on.