This is the crash I'm referring to:

https://www.youtube.com/watch?v=J9eUwJ79fvo

And the same crash from a second point of view:

https://www.youtube.com/watch?v=5quxhNEio_g

This doesn't even look real, but I can assure you it is. So, what happened here? Why is it that a car—especially one with such tremendous downforce—could do something so crazy as this? Well, first, I think it's important to take a closer look at how these aerodynamic systems work.

Think of what happens when you're skating on ice. You slide. You have less friction with the ground, so you can't grip it to walk like you normally would. Now, imagine that you're carrying a heavy weight over your head, and this weight pushes your shoes into the ice (without breaking it). The force of the weight would give you better grip and allow you to walk on the ice, right? Sure, that makes sense.

So, obviously, the better you can grip the ground, the faster and easier it is for you to walk. Race cars work by this same principle—the more weight there is pushing down against the ground, the more power can be applied without the wheels slipping.

Notice there how at around 35 seconds in, the wheels start to spin, but they slip on the ground. Now imagine that if there was a force pushing the car to the ground, the wheels wouldn't slip, and the motion would be transferred entirely to the car. Thus, the car would be faster.

This is where downforce comes in. Using wings, race cars generate a literal force pushing downward, and this helps the car stick to the ground. It does so without adding mass to the vehicle, so acceleration is largely unimpeded. This is why more downforce is generally better.

The rear wing of the car is what generates downforce. It works in the same way a plane's wing generates lift, just in reverse. The wing creates a pressure difference in the air around it, so that a force is generated on the wing itself. This force pushes the rear of the car downward. This force allows the tires to grip the road better, which, as I mentioned, allows for better cornering and more stability.

So, why is it that this one time, the downforce didn't work? You saw that car—it was literally flying. Something must have gone horribly wrong here, but what?

The answer is actually not that complicated. Notice that before the car takes off, it is coming up on a hill. Due to the car's speed, the front of the car comes off the ground a little at the top of the hill. When this happened, it reached a critical angle. It reached the angle at which the air flowing under the front of the car starts to push the front upward.

So, what we have is a car with a front end going upward, and a rear end going downward. This creates a moment, or a torque, or a spin, most informally. The back goes down, the front goes up, and voila! You're airborne. The car still has downforce, but it's all in the back of the car. The front of the car loses its downforce, and instead creates lift. Effectively, the whole thing acts like a wing, and up it goes.

Still don't believe me on this? Consider what would happen if you have a sheet of paper sitting on a desk. If there's no wind, the paper won't move. If there's a little wind, the paper still may not move. But if you lift the edge of the paper up slightly and into the wind, air will flow between the paper and the desk, and this will push the paper up, up, and away.

These cars work in a similar way; they're just heavier and we're talking about much stronger winds. Once that front end goes up, it's like that sheet of paper in the wind.

As crazy as it looks, the phenomenon is hardly as uncommon as you'd think. This isn't the only time race cars do this. This happened once to a Mercedes prototype in 1999, and again to a Porsche in 2008...

Notice how it always starts as the car rounds the peak of a hill. Notice how the back end still keeps pushing downward, even when the front of the car is high in the air. That's the combination of downforce and lift at work, simultaneously.

There is one crash that doesn't involve the car first going over a hill, though. It's this one.

So what happened in this case? When the Ferrari hit the prototype, the left rear wheel came off. You can see it rolling along the track. This impact made the left rear corner of the car go down, and by extension, the right front corner of the car came up. It's the same problem, just a different cause. The motion, in principle, allowed too much air to flow under the car, and again, the whole thing acted like a wing. Up, up, and away!

And to think some people say flying cars are infeasible. Nonsense!