You hear it all the time – Formula 1 commentators talking about slipstream.
“Oh look, he’s going to duck into his slipstream” or “The driver in front is trying to break slipstream” or “This should be an easy overtake with slipstream and DRS”.
Photo : SimScale
And yet, most casual F1 fans haven’t a clue what slipstream is. One guy I talked to said there’s a “slipstream button” in the cockpit for overtaking. Kill me now.
In this edition of Bhat on Wheels Tech Talk, I shall attempt to explain to you exactly how slipstreaming works, keeping it as Layman as possible.
The way aerodynamics works in Formula 1, air passing over an F1 car leaves a pocket of low pressure air in its wake i.e punches a hole in the air and leaves a pocket of low pressure air behind itself.
This air coming off the car in front is turbulent i.e dirty air. If another car is following behind in this pocket of low pressure air, it gets induced with this dirty air causing low downforce and low drag.
Now, we know that F1 cars are heavily reliant on aerodynamics for their performance. Downforce gives the cars grip to turn into the corners later and sharper, increasing lap time. Drag is an evil byproduct of downforce because it provides resistance and reduces top speed on the straights.
When you’re in the slipstream of the car in front, both your downforce and drag are reduced. However, when you’re chasing the car on a long straight part of the track, the induced lowered drag is actually good for you because low drag = low air resistance = higher top speed, and lowered downforce is irrelevant because you need downforce around corners, not on the straight.
So by ducking into a slipstream, your drag reduces and therefore top speed increases, giving you a better chance at overtaking.
Photo : Tag the World via YouTube
Now, a relevant question to ask would be : Hang on, so are you saying dirty air is good? Surely not?
You’re right. Dirty air isn’t good. Formula 1 car aerodynamics are designed to work in laminar flow i.e clean air.
But, slipstreaming is basically dirty air used to your advantage on the straights.
It is easy to work out. From what I said, if you try to “duck into a slipstream” around corners, your drag and downforce are still lowered.
But in the corners, downforce is everything. The pocket of low pressure air left behind for you by the car in front will affect your downforce so much that your car will be a nightmare to drive.
Simply put, slipstreaming is an advantage on the straights. Everywhere else, massive disadvantage.
Another question you may ask – Given a 20 car race, considering the fact that apart from the race leader, 19 cars are always behind a car, why can’t F1 aerodynamics be optimised for turbulent flow instead of laminar flow?
My answer to that is you try and do it!
Turbulent air flow is extremely unpredictable, unpredictable and ever changing. Basing your entire aerodynamic design on it is basically impossible. Also by trying to design for turbulent flow, you’re risking peak downforce offered by the laminar flow design as well as variable downforce throughout. It’s a mess, don’t do it.
Credit : Tag the world via YouTube
Watch this video to see the power of slipstream as the McLaren gets consumed on the Kemmel straight at Circuit de Spa Francorchamps in Belgium.
I hope I have been successful in explaining to you what slipstreaming is and how it works. If you’ve got any questions or if you want me to cover another topic in the next edition of Bhat on Wheels Tech Talk, leave it in the comments below and I’ll be sure to address them.
Feature image : Chain Bear F1 via YouTube
– Aditya Bhat.