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# Automotive Aerodynamics: A Guide for Dummies (Part II)

By Harshita Singh Chauhan

Brief Recap

Hello there, budding engineer in the making! Now that you have finished the miniature crash course on aerodynamics (if you haven’t read the previous article, head down to “Automotive Aerodynamics Part I”). We will now be diving straight into the even more #interesting bits: the science behind F1 cars.

CAPTION(7.): F1 Car

VROOOMM… You can hear the cars coming from a distance. As this sound gets louder, the adrenaline of the audience in the stands starts to pump in, excited Hamilton fans stand and cheer. Australian patriots wave their flags excitedly as they await the arrival of their local hero, Ricciardo! Blink at the wrong time, and you won’t even spot these fast cars zoom past. Watching the 2018 Grand Prix in Singapore was really a really #exhilarating experience, but it really got me thinking: how on earth are these cars SO fast?! If you’ve wondered the same thing, but ended up being even more confused after a couple of Google searches, fret not my friend, The Scientific Teen’s got your back! Now buckle up, for one quick ride.

CAPTION: At the Grand Prix Stands!

Downforce!

Let’s get down(force) to business! Bad jokes apart, downforce is a really important force that F1 cars in particular make use of to keep them from essentially flying off when they turn. It’s a bit like when you tie a string to a rock and swing it in circles, without the string, the rock would be swung out of its circular path. Similarly, to keep the high-speed F1 cars on the race track whilst they make their turns along the circuit, downforce in a way acts as the string to the F1 cars. But hold up, what IS downforce? Before we find out, I’ll do a brief recap on the types of forces first.

CAPTION(5.): Four Types of Forces acting on any moving body

There are 4 main types of forces acting on any moving object, namely weight, drag (covered in depth in Part I), normal force, and thrust from the engine. Another force that is equally important is lift. Lift is a force that is generated through the pressure difference between upper and lower surfaces on a body. This phenomenon can be explained using Bernoulli’s principle, which states that velocity and pressure are inversely proportional, that is when speed decreases, the pressure exerted will be higher. As seen in the diagram below, the air is split into two streams, the one on top traveling a longer distance than the stream at the bottom. Using Bernoulli’s Principle, we can see that the pressure exerted by the surrounding air on top of the wing will hence be lower and since the pressure at the bottom is greater, the wing will be pushed upwards, and lift, a force that pushes objects upwards is generated. In scientific wording, fluids that flow past the surface of a body exert a force on it, with lift being the component perpendicular to the oncoming flow direction, and drag being the component that is parallel to the flow direction.

CAPTION (3.): Lift explained using Bernoulli’s Principle

Some of you might be wondering, why on earth would an F1 car be concerned with lift when it doesn’t need to fly? Let me give you a hint: consider what will happen to the aerofoil in the above picture if it is turned upside down. Since the pressure on top of the aerofoil is now greater, there will be a push force exerted by the air on the car, essentially pushing the car down on the track. This force, negative lift, is more commonly known as downforce!

The downforce created by F1 cars is so strong they can even overcome gravity and drive on ceilings! But that’s not why downforce was added to F1 cars. F1 cars need speed, and by making turns at high speeds, they save time and do not have to speed up again once they reach a straight line path. However, when cars turn, centrifugal force acts on them to throw them off their circular path. This force increases as velocity increases, and since F1 cars are traveling at very high speeds, this force could really bring the car off the race tracks. However, to counter this, F1 cars have been designed to produce large downforce to increase the “grip” that the wheels have on the racetrack, to prevent the car from going off track as it makes turns at high speeds.

CAPTION(6.): F1 Car Turning At High Speed

At this point you might be wondering, why create downforce when you can just increase the weight of the car to increase the “grip” of the wheels on the track? Increasing the downforce increases the apparent weight of the car, without actually increasing the mass. Since F=ma and the force created by the engine is constant, with a lower mass cars can achieve greater acceleration! #Smart, isn’t it?

However, a downside of downforce is that it produces a lot of friction, which results in a lot of wear and tear (which is why you see drivers getting their tires replaced during the race!) That’s why we don’t have F1 cars driving down neighborhood streets (imagine the number of tires we’d need!) #lit

Downforce vs Drag

As we discussed in Part I, another important factor that automobile engineers take into consideration is drag. For the car to be more aerodynamic, and hence go faster, we need a lower drag coefficient. However, downforce can only be created at the expense of increased aerodynamic drag. As such, engineers have to find a delicate balance between these two as they design their cars.

If you’re still reading this, then good job! You’ve just finished an #extensive crash course on the basic aerodynamics behind an F1 car, and now, as young scientists, you can appreciate the beauty of physics the next time you watch F1 cars racing.

PS: Who’s your favourite F1 driver? Mine’s Vettel, hands down!

CAPTION(8.): Meme of the day!

Sources:

“Aerodynamics.” Formula 1® - The Official F1® Website, www.formula1.com/en/championship/inside-f1/understanding-f1-racing/Aerodynamics.html

“Simple Tech: Aerodynamic Downforce.” Overdrive, overdrive.in/news-cars-auto/features/simple-tech-aerodynamic-downforce/.

“Explosions Mrs. Mattingly The Science Lady - Lessons - Tes Teach.” Tes Teach with Blendspace, www.tes.com/lessons/wbjchN5GG9z7IQ/explosions-mrs-mattingly-the-science-lady.

“Lift (Force).” Wikipedia, Wikimedia Foundation, 9 Apr. 2019, en.wikipedia.org/wiki/Lift_(force).

GCSE PHYSICS - What Are the Forces on a Moving Car? - How Do Wheels Move a Car Forwards? - GCSE SCIENCE., www.gcsescience.com/pfm26.htm.

Raulongo. “Best Tyres GIFs | Find the Top GIF on Gfycat.” Gfycat, gfycat.com/gifs/search/tyres.

Sky Sports. “What Would Premier League Kits Look like on Formula One Cars?” Sky Sports, Sky Sports, 20 Mar. 2018, www.skysports.com/football/news/11661/11296214/what-would-premier-league-kits-look-like-on-formula-one-cars.