© Getty Images

Bulls’ Guide To: AerodynamicsThe RB16B at Monza is very different to the RB16B at Zandvoort. Welcome to the wonderful world of aerodynamics…

It’saniceco-incidence–ordeliberatelyplayful–tohaveMonzafollowZandvoortonthisyear’scalendar,giventhatitallowseveryonetoshowoffthetwoextremesoftheiraerodynamicoptionsinthespaceoffivedays.

Zandvoort was a maximum downforce circuit (maximum and a bit – but more on that below), whereas Monza is a maximum efficiency circuit, with much of that downforce removed. The easiest way to spot the differences is in the size of the rear wing elements: skinny, shallow razors of carbon composites at Monza, versus the proverbial barn door at Zandvoort – though there are plenty of other differences around the car too.

TheScience-yBit

The core tenet of F1 aerodynamics resides within Bernoulli’s Principal, developed by Dutch mathematician Daniel Bernoulli during the powdered wig era of scientific discovery. Bernoulli’s principal states that increase in the speed of a fluid occurs simultaneously with a decrease in static pressure.

While this led to comparatively trivial inventions like the aeroplane and carburettor, its crucial relevance is to the motor racing industry, where it is applied to generate downforce. Moving airflow faster beneath a surface, compared with the speed of the airflow over the top of it – for example by using shaped aerofoils – generates a low pressure zone under the surface which sucks the car down to the track. The greater the pressure differential, the more powerful the effect, and the more aerodynamic grip the car will have.

Bigger wings, however, also generate more drag, which slow the car down, limiting acceleration (a bit) and top speed (a lot), so there is always a trade-off to be made between downforce and drag. On at track that’s all corners (Zandvoort) the trade-off prioritises downforce; on a track that’s all straights (Monza) the priority is to reduce drag – hence the very different shapes on display.

Wings Are Key To Performance© Getty Images

Not every team will bother to build a Monza-spec rear wing. It’s an expensive activity, and with few reasons to run it elsewhere, teams with limited resources might consider it an extravagance. Instead, they’ll make do with the wing that sees action at other (but not quite so extreme) low downforce venues such as Spa, Circuit Gilles Villeneuve, or Baku. These things come as a package, however, and ideally you’d want options for low downforce (though it’s generally called low drag, or maximum efficiency), medium-low, medium-high and maximum downforce to cover the full range of circuits.

MaximumDoesn’tMeanMaximum…UnlessItDoes.

It’s confusing to many that F1 teams often add more downforce to the maximum downforce car. The classic example of this can be seen whenever the Spanish and Monaco Grands Prix are paired.

The Circuit de Catalunya is a maximum downforce track, at which teams run their biggest wings to cope with the many loops and dips around the circuit. It’s usually followed by Monaco, which is also a maximum downforce circuit – but more maximum. Leaving aside the insult to grammar, there is method in the madness.

For Monaco, the team will take the maximum downforce package that ran in Spain and add extra downforce-generating whistles and bells: if the car didn’t have a mid-wing (T-wing, coat-hangar, call it what you will) in Spain, it will likely gain one for Monaco. Likewise, the wings will start spouting Gurney flaps (stick-on spoilers) to generate more downforce. What you finish up with is a car that has maximum downforce… but more.

Many weeks the downforce package the team opts for is a no-brainer: one look at the Monaco layout tells a team everything it needs to know. Other weeks the decision is more nuanced, and even though simulations are pretty good, it’s not uncommon to see a team experimenting during free practice with several different downforce levels – either adding or removing gurney flaps from the wings or swapping between wings altogether.

Downforce Plays An Important Factor© Getty Images

DRS

One way in which choice comes into play in the modern era is with DRS (Drag Reduction System). DRS works by raising the flap on the rear wing and thereby reducing drag for temporary access to higher top speeds.

At a track like the Red Bull Ring, which has DRS zones on each of the three straights, this allows the team to both have its cake, and eat it. They’ll run more downforce than the circuit layout suggests, because of an all-important qualifying lap. It can gain the benefit of the extra downforce through the corners but activate the DRS to avoid paying the drag penalty on the straights. It may suffer more in the race on laps when the DRS isn’t available – but that’s often a price worth paying, given the higher downforce car slides less and thus protects its tyres better.

The Need For Speed With DRS© Getty Images

EOSvsSOS

Somewhere like Monza, you’ll hear a lot of talk about EOS – End of Straight – speed but top speed tends to be more indicative of set-up choices rather than a guide to performance, and it can be the case that the fastest cars on the straight will also be the slowest around a lap: they’re quick in a straight line because they simply aren’t generating as much downforce as their rivals, and thus have less drag. Of course, the opposite can also be true.

Monza is nicely illustrative of that. When we won here in 2011 with Sebastian Vettel taking pole position and victory. The interesting thing about Vettel’s pole position lap is that he was the slowest car – 24th from 24 – through the speed trap. The trap at Monza is towards the end of the main straight, just before the braking point for the first chicane, and the fastest part of the circuit. Seb was clocked at 327.7km/h. In contrast, the fastest driver, a young Mexican pup by the name of Sergio Pérez driving for Sauber, hit 349.2km/h – but lined up P15.

However, those speeds aren’t related to engine performance. The Renault RS27 V8 in the back of the RB7 was the same as that used by the Renault works team, for whom Bruno Senna (347.3km/h) and Vitaly Petrov (344.8km/h) were second- and third-quickest through the trap.

Gliding Through The Corners© Getty Images

Rather, it’s a deliberate aerodynamic set-up choice with Vettel’s car top speed is important at Monza – which is why the car features the skinniest of the skinny wings here – but it isn’t everything. In the case of that 2011 race, the team believed there was a faster lap time to be had by running a package that was a little less extreme. It gives the car better and more stable performance under braking, but it also makes it quicker through the corners. While EOS speed makes the headlines – because it’s impossible to be a fan of motorsport and not get a thrill from seeing something going really, really fast – it’s often speed at the start of the straight that makes the bigger impact.

Consider it this way. The car with slightly more downforce can go through the final Parabolica corner one gear higher. It exits Parabolica travelling 10km/h quicker than a rival and maintains most of that speed advantage all the way down the first part of the straight, pulling away from the other car as they both accelerate. Drag will eventually get the better of it and, hitting its maximum speed earlier, it will start to lose ground to its more slippery rival which continues to accelerate for longer – but it may still reach the breaking point with an overall gain.

RacingvsDriving

The thing which makes these decisions a choice rather than an obligation is that lap time – may we be forgiven for saying this – isn’t the only thing that matters. Driving and racing are often different things and optimising your car for the quickest lap time isn’t very useful if you can’t get into clean air to use that pace.

Spa might be more illustrative than Monza in this regard. The first and third sectors at Spa, with their long, full-throttle sections are best served by having a low drag car with skinny, Monza-style aerodynamics. The middle sector, in contrast, with its chicanes at Les Combes and Fagnes, the hairpin at Bruxelles, the ultra high-speed Pouhon, would, taken in isolation, demand maximum downforce of the type seen at Monaco or Zandvoort.

Optimisation Is Vital Over The Race Weekend© Getty Images

For a qualifying lap, it may be that the best aerodynamic package is the one which favours sector two over sectors one and three – but that doesn’t mean the team automatically reaches for the box of bigger wings.

The problem is that you’re not lapping the circuit in isolation. Add more downforce – and thus more drag – and the car will be slower on the straights. It will make it difficult to pass other cars, and it will make it difficult to defend against anyone with a sizeable top speed advantage. Under those circumstances, you don’t get to use those higher downforce advantages through the chicanes and Pouhon because by that point you’re tucked up under the rear wing of the slower car and forced to proceed at whatever pace it can manage.

All of this makes choosing a wing level as much about understanding what rivals are likely to do, as it is about finding the fastest way around the circuit. That makes the sprint race at Monza, as was the case at Silverstone, particularly interesting, as the team don’t have time to study what rivals are doing and respond to it.

ThePresentAndTheFuture

One criticism of these high downforce cars is that they really don’t play nicely with others. The ideal race for an aerodynamicist is one which takes place on a very still day with a good gap between the cars – preferable an entire continent or, failing that, at least a time zone.

Circuit racing is a particularly vicious sort of circle for these cars in the sense that the aerodynamic surfaces work best when driving into undisturbed airflow, but the act of driving the car into that airflow creates a substantial wake. The turbulent air in this wake severely disrupts the airflow being used by the following car, and thus, the closer it gets to the car in front, the less well it works.

This makes overtaking very difficult. More difficult, the general consensus says, than is conducive to a dynamic racing environment. Single-maker series can tune their cars to limit the wake, or push the worst of the turbulence out of the path on the chasing car, but F1 doesn’t have that luxury. Aerodynamicists want to move the turbulent air generated by the interaction of the front of the car with the airflow out and away, so that smoother airflow can be sucked in under the floor to work more effectively with the diffuser.

The sport over the last few years has experimented with ways to combat this, introducing rules to temper the turbulent wake and move it out of the path of a following car but wholesale change is coming next year, when F1 moves to a ground effect car, redesigned from first principals to allow closer racing.

But that’s a different Bulls’ Guide.

Aerodynamics Is All-Important In Formula 1© Getty Images