With the extra downward force, the only way for the forces to add up to zero is if the normal force increases. This means the frictional force is greater, so the new acceleration is greater.
Now instead of getting a maximum acceleration of 6 to 7 meters per second squared, it’s possible to get much higher values—maybe 15 or even 20 m/s2. The McMurtry Spéirling in the video went from 0 to 60 mph in … wait for it … 1.4 seconds. Just thinking about that will pin your ears back.
The fan idea isn’t new. In 1978, the Brabham BT46B used it to win the Formula 1 Swedish Grand Prix, but it was quickly banned. The idea of increasing downward force lives on, however. F1 cars today channel airflow through the body in clever ways to achieve some of the same “ground effect”—justified by saying their purpose is to cool the engine.
While these airflow systems do help cool the engine, everyone knows the real purpose is to generate low pressure under the car to suction it closer to the road. In fact, the new McLaren W1 that we recently reviewed is a road car that makes this the sales pitch. (You can buy one for $2.6 million—or you could have if you’d signed up in time. McLaren is making only 399.)
The cool part is that this higher acceleration isn’t just for increasing your speed. It also allows the car to slow down faster and even make sharper turns, since these are also types of acceleration. The downward thrust can turn a fast car into a crazy fast car—if that’s what you want. For me, I’m happy as long as it’s a red car and it drives.