F1: why no overtaking and are bigger wings the answer?
Why do modern f1 cars struggle to overtake? its to do with highly loaded wings & aero surfaces forced by years restrictive rules, is there an answer?
F1’s new rules have certainly made the cars look exciting, their pace around a single lap is exciting, but in the first race the battle was far short of exciting, with little overtaking. While we shouldn’t get too carried away with just one race completed, the writing was on the wall over a year ago, that the new rules wouldn’t provide for on track battles. What’s the problem with overtaking and what can be done to fix it?
It’s certainly not the case that overtaking is as bad as ever in F1, but there’s clearly an endemic problem with the cars being able to pass each other.
Overtakes are typically created by a better exit from a corner, giving better acceleration/top speed and if the overtake is not completed along the straight, then under braking to the next turn. Sometimes the process makes several corners, so that the leading car is wrong footed defending through preceding corners.
Thus, the ingredients for a maneuver are; better exit, better top speed, better braking, along with a track that provides the corners and space to give these opportunities. With the current design of the cars, evolving from the past decade’s designs to meet the current 2017 rule set, creating this perfect overtaking recipe is off the menu for several reasons.
Aero is of course the defining factor, every driver comes out with the cliché “once I was behind him, I lost all front-end grip”, this is a truism, albeit slightly inaccurate. F1 cars create downforce from the front wing, rear wing and underbody, these are designed to work in clear air and the flow then coming out the back of the car is then a swirling mess. When the following car hits this wake, the air is going in all sorts of different directions, not the steady uniform flows the car’s surfaces were designed for. To some extent this is unavoidable, it’s just the physics of one car following another, the air will always be being kicked up by a car and the following car has to pass through it.
These flows are formed by pairs of powerful vortices being spun up by the diffuser and rear wing, plus the wider turbulence created by the front and rear tyres. Contrarotating vortices formed at the diffuser and rear wing tips create an upwash. This means the following car does not see still air, but a wake revolving upwards, the opposite to what the wings would rather see to produce downforce.
It’s the same with aircraft queued up around an airport, a large aircraft creates a wake and if a following aircraft hits it then it will be spun into the same direction as the wake is rotating. Larger aircraft try to reduce this wake, by altering the flow at the wing tips, such that even a huge A380 can produce a smaller wake than lesser aircraft.
Just such approaches were promoted in F1 back in the mid-2000s, the centerline downwash generating (CDG) twin rear wing, which was never brought to reality, then the more analytical results of the 2008 Overtaking Working Group (OWG). This study involved wind tunnel runs and then tests with two contemporary cars run on track together. The findings were complex, but simplified they found the following car was less sensitive if the front wings downforce generating surfaces were spaced out wide ahead of the front tyres and leading car had less aero addenda, a smaller diffuser and the rear wing was higher and narrower. This created the 2009 aero package, although some compromises were made to still allow small areas for aero freedom around the sidepod fronts. The immediate impact of these rules were diminished by the unplanned introduction of the double diffuser and also the disparity between the power units with the newly introduced KERS.
No further development was put in after the findings from the OWG were published. In the following seasons, aero development accelerated, with diffusers, rear wings being worked ever harder. Also in this intervening years, another aero development has further made following a car even harder, front wing complexity.
Modern F1 front wings are not hugely complex to create front downforce, in fact the front wing is oversized for the load it needs to produce. Remember that the front wing is only there to balance the downforce produced at the rear, no more, no less. So, it merely needs to match what the designers can create at the rear with the diffuser and rear wing, at a drag level that meets their top speed target. From the early 2000s front wings were relatively simple as the wing was purely used as a downforce producing device. This made them less sensitive when in the wake of a leading car.
But over the past ten years, the front wings function has become more about pushing the front tyre wake away from the car. F1’s open wheels create huge amounts of drag and turbulence, this turbulent wake trails down the car and wants to be drawn in to the coke bottle area, upsetting the airflow to the rear wing and diffuser, making them less efficient. Teams realised if you can keep this wake away from the rear, then the wing/diffuser will be more efficient, so the car can either have more downforce or less drag to boost lap time.
This front tyre wake management has gone to extremes with nine element wings and ten part cascades. So now when in the wake of another car, not only does the front wing lose downforce, the tyre wake control is diminished which wrecks the airflow to the rear of the car too. So not only is front downforce is lost, but also that at the rear. This both costs grip and unbalances the car, making it hard to follow another closely through corners.
As the cars continued to get faster through the 2000s the governing body sought to reduce their speed. With aero the target, wings and diffusers were made smaller and smaller. Of course, the teams battled to regain the lost grip, so the approach was to make the smaller devices work even harder. Back in the 90s, we saw huge rear wings, the airflow over these was relatively inefficient, they created downforce in a lazy way, the surfaces weren’t hard worked, so the car had downforce, but not sensitivity. Then into the 2000s much smaller wings were worked far harder, rear wings now just 30cm long, kicked up to a near vertical rear flap. What happens in this situation is known as an adverse pressure gradient, the airflow wants to pull away from the wing surface and create a separation in the surface and airflow, which will eventually cause the wing to stall. To keep the air attached to such a hard-worked surface, the air approaching needed to be directed carefully; turning vanes, flaps, winglets and monkey seats all work to condition the airflow, making for a very sensitive set up. Should one part in this cascade of aero devices fail to do its job because it’s in dirty air, then the entire flow breaks down.
Top speed to for overtaking along the straight is a factor of drag, engine power and traction out of the previous corner. With the fuel flow formula drivers, don’t have the push to pass boost of the 80s-turbo era. We now have DRS, which provides an unlimited number of uses through a weekend, subject to the session, track design and following a car in the race. While a boost in top speed is a great means to implement an overtake, this is a not a meritous means to provide for it.
When we look at the 2017 rules, the results of the 2008 were overlooked and nearly every idea has been reversed, so we have low and wide rear wings, larger diffusers, more aero add-ons and still maintain hugely complex front wings. In the rush and compromises to get a rule set through for 2017, that gave the arbitrary aim of a 5s a lap time reduction and no target to improve overtaking, common sense was lost. The plans for the rules went through various iterations, but throughout the same sort of solution was promoted and teams knew even that overtaking would not be improved, if not even deteriorated by the resulting aero set ups. Oddly the impact of F1’s rules are rarely investigated, so we often see unexpected results, such as pointy noses and shark fins.
So, sadly despite warnings F1 has walked into a set of regulations that will intrinsically hurt overtaking, but its doesn’t stop with aero, there are knock on effects that weren’t anticipated. Key amongst these is braking, the other key ingredient over the overtaking recipe. Superficially the new F1 cars being heavier were predicted to be harder to brake. But the aero impact was not considered, with more downforce and drag, the delta between speed on the straight and corners is smaller, so there will be less braking needed to go from top speed to the apex speed. Then the added downforce means corners that used to need a lift are now taken flat, corners with dab of brake are now taken with a lift etc. Then with the downforce, the braking event can be even more aggressive, as its downforce that makes for F1 super short brake distances, not the carbon brakes. So now with the added grip, the braking can be later and harder, reducing braking distances, by some six car lengths from the super high speed Barcelona straight into the tight turn1.
Then we have the new tyres, these are 25% wider, suggesting much faster cornering by up to 1g. This added mechanical grip allied to the extra downforce, is not matched by a greater power output from the PU. This means the cars are less grip limited, again the cars can be flat more of the time, less chance to get the car out of shape out of a turn, to give an opportunity to a following driver, less overtaking chances.
Furthermore, the new tyres have purposely been made more durable, after years of high degradation tyres. In some respects, this suggested better racing, drivers not having to manage the tyres, being able get them hot when sliding and not finding a drop off in performance. The pendulum may have swung the other way, in Melbourne the Ultra softs, a compound supposed to be a qualifying/short stint tyre, could be pushed far longer than expected, then the super soft also able run a long stint. The upshot of this is that the options for tyre strategy to mix up the race, that has worked so well in the past year, is gone. With the drivers Q2 tyres able last a third race distance, then the next softest able to finish the race, a one stop strategy is inevitable, there being no means to mix this up and less chance to find a race winning strategy as everybody is doing it too. Ironically the tyres may be too hard and in doing that, they aren’t delivering the 5s per lap target the FIA set.
So, with less chance to follow into a corner, then less time to brake and no options on tyre strategy, how can overtaking be improved with these new cars?
Many fans and media have made suggestions to improve overtaking, wider tyres has always a popular one, but we have them now and alone it’s not helping. Get rid of all wings is another kneejerk reaction, but this will drop lap times to F3 levels and its clear F1 fans want the cars to be FAST. Banning carbon brakes to lengthen braking distances is another myth, but as explained it’s not the brake material, but the downforce that allows such hard braking. Going back to ground effect underbodies with long tunnels is a more realistic plan and one initially mooted for the 2009 rules. But this would give both fast cornering and straight line speed, when F1’s thinking was to slow top speed, to manage lap times and try to make the cars corner harder for a greater spectacle.
Unhelpfully the answer is there’s no easy answer. There are two themes that need to be resolved in this quandary, how fast do F1 cars need to go? Corner speed or top speed, how easy should overtaking be? Then the trickier question how do we achieve that?
With F1’s recent change in ownership comes not only Liberty, but a new approach in how to run the sport. This brings Ross Brawn back into the sport. These questions will be researched and resolved by a new Overtaking working group, along with other relevant technical and sporting matters. Perhaps this will lead to some joined up thinking, not only for F1, but the ladder of junior categories leading to it.
I agree that corner speed is the route to go for target lap times, at the cost of top speed. So, we need downforce, but not at the cost of sensitivity when following. Drag needs to be kept high relative to downforce, but managing tyre wake still needs to be achieved, to prevent the rear wing needing to be too powerful overcome running in the turbulence.
So, I’d propose a rule set that seeks to reduce the wake creating elements, reduce the sensitive devices needed to support hard worked wings and diffuser, matched to stickier tyres that while durable have a finite life as they wear and lastly a reduction in braking torque.
Primarily this will see larger front/rear wings and diffuser underbody. It’s believed that downforce produce by the underbody is less sensitive to following I the wake of another car, although this really needs to be categorically proven in the wind tunnel. So, the car should feature longer ground effect tunnels under the floor. While the front and rear wings are longer and a little wider, but shallower than the current wings.
But the increase in these areas is countered by reducing their complexity, with the number of elements and curvature. With the wings and tunnels being much longer, but just 2-3 elements on the front wings and a shallow maximum angle of attack on both the wings and underbody. In this format, we get the downforce, but not the sensitivity and extra drag to slow top speeds.
Throughout the car simpler bodywork, to rid the cars of the sharp multiple aerodynamic edges. Perhaps with a non-overlapping rule allied to minimum radius enforcement, similar what we have on sidepods now. In my view the car shape should be formed only of the monocoque, crash structures and sidepod bodywork. Nothing added on and no ducted aero tricks to circumvent the outer surface rule, to prevent things like MotoGP ducted vanes etc. While these detail parts often reduce, total drag, which goes against the fundamentals of this overtaking concept, they add greatly to sensitivity and with the blunter wings, they should b=not be required so much. Equally they should not disrupt the wake for the following as much as they do now.
This simplification needs to be added to the wings, but there needs to be some small allowance at the rear wing tip and diffuser outlet to prevent strong tip vortices forming. Its these that create the upwash that wrecks the following car’s performance. Already rear wings have twisted profiles and drag reducing slots in the endplate. It would be advantageous to keep some of these, more for the upwash management than drag reduction. A solution for diffuser vortices and upwash, would also need to be considered by the OWG.
To further reduce drag in the light of the loss of the all the flow conditioners, there will be a simple turning vane added behind the front tyre. Like those used in the nineties, this will manage the front tyre wake, allowing more efficient rear wings, as they’ll run in clean air. It’s even OK if this part can be used for some downforce generation, as it’s behind the front tyre is should be less sensitive to running in another’s wake. In turn making the front wing smaller further improving wake sensitivity.
I’m a fan of active aerodynamics, this could help with overtaking, but I see this much more as an efficiency tool, so tied more closely to the power unit and environmental regulations. Still it would be good to consider, bodywork that adapts around the lap. Wins that flatten for straight, steepen on braking and corners, sidepods that morph shape to reduce cooling to suit the conditions, brake ducts open only in under braking. There’s a huge performance and efficiency potential here, but outside the boundaries of a simple overtaking rule set.
Tyres are hard to regulate as the science is not a fully predictable one. Single stop races seem restrictive in terms of strategy and tyre choice. I think two stops should be target, but the choice of tyres between one, two, three or even any compound can be debated. Again, going with big tyres add lots of drag to maintain the target top speed.
Braking zones need to be lengthened, as we have seen brake material is not factor, but the rest of this rule set provides lots of mechanical and aero grip, so to stretch the braking zone we need worse brakes! This is a tricky concept to sell, brakes equal safety for most of us, so reducing braking power is not going to be popular and the approach will need research. Perhaps a limit of caliper pistons, pad size or brake line pressure. Also, this might suit a single supplier solution, such as Brembo spec-brake package. But then there’s no competitive advantage a team or driver can bring, but equally we don’t want a brake development war to shorten brake distances again. This idea is a work in progress, one for the OWG.
A push to pass solution is an option might need to be considered, but one that must come with a cost to the driver’s weekend. Either a fuel flow boost for the power unit or an adaptive aero solution to cut drag could be used, as a magic bullet performance boost. Rather than tied to the session or following another car, there should be a number of deployments over the weekend. The driver can use it freely on specific straights throughout the weekend, but once the number of uses is emptied, that’s it. Use it in free practice or quali, then there’s less for the race. Mid field drivers can save their up for more race overtakes. Drivers can use it in the race to attack, defend or even just to close a gap, as its not tied to following another car. TV graphics should match the video game’ concept’ of the magic bullet. I don’t want to go too far with this concept as I see as an add-on, but drivers could be awarded or deducted uses over a weekend for good or bad behavior.
With this package, I think the aims of overtaking can be achieved, with good lap times, beautiful cars and without fake or expensive solutions. There remains lots of other regulatory areas to be considered in addition to overtaking, costs, power units.
Nothing discussed here is new or ground breaking in either understanding the process of overtaking, the problems in overtaking and solutions to improve things. A number of these points have come from F1 engineers I’ve talked to on the subject. What’s needed is an open and heathy debate, a clear target and some research into the problem/solutions. With the resources and skills in F1 this shouldn’t be such an insurmountable problem to overcome.