It is good because the pressure gradient across the diffuser is lower so air will stay attached (in the vernacular) i.e., doesn’t become chaotic and turbulent. The pressure behind the diffuser will still be higher […]
Turbulence doesn’t *always* result in downforce destruction. Look at vortices which are turbulent but can energise the air in a positive way.
However, the reason why turbulence is often unwanted is that […]
Yes – I agree with this. I also get the sense that McLaren, in a desperate bid to catch Red Bull, and ride the wave of ‘trick innovation’ invested all its time on what the latest wheeze could be – F-duct, U side […]
Sure. The diffuser generates downforce through a process called the Venturi effect. To simplify a little when air flows through a constricted volume the pressure reduces. When it then expands the pressure […]
Monza and Spa demand the lowest downforce settings seen all season long. Particularly at Monza, where there are only a few fairly short corners to break up the straights, the cars are trimmed out to reduce drag to a minimum in order to maximise top speed.
The most obvious visual change is the rear wing, which tends to be far skinnier than at most grands prix. Ordinarily it is positioned to generate downforce, but at high-speed Spa and Monza this is sacrificed for pure speed.
The top teams create bespoke rear wings for Spa and Monza. But even between these there significant differences. The Mercedes-powered cars, revelling in the extra grunt of the three-pointed star, could afford to use a thicker rear wing than the likes of Red Bull.
To make up the shortcomings of their Renault engines Red Bull opted for a drastic low drag set-up. It was able to get away with this because the other surfaces of Adrian Newey’s RB10 generate so much downforce to begin with.
The illustration below shows the rear wing McLaren used on their MP4-29 at Spa:
In comparison, note the depth of the wing McLaren used in Hungary in the photograph. The angle of the Monza wing flap is shallower, reducing the cross-section area of the rear wing, which results in lower drag.
The most interesting feature of the MP4-29 rear wing is the ‘wave shaped’ leading edge on the upper flap. When DRS is de-activated it often takes a short while for downforce to build back up. The ‘waves’ create mini-vortices on the underside of the rear wing that help air attach more quickly after DRS is deployed.
As seen in the drawing the main plane has a gentle U-shape. This creates more consistent downforce, for better rear stability on cornering. McLaren felt that was important at Spa where there are a number of medium-to-high speed corners. McLaren altered the main plane for Monza making it straight thereby reducing its cross-section area and lowering drag.
The other notable feature of the rear wing is the end plate slots and also the slats on the lower aft part of the rear wing endplate. Both of these structures are designed to reduce drag. The rear wing flaps create a pressure gradient either side of the endplates. When the airflow has passed the rear wing this air collapses into a vortex, which creates a substantial amount of drag. The slots and slats allow air to bleed across this pressure gradient thereby reducing the strength of the vortex.
In sharp contrast, this weekend’s race is at Singapore, where we can expect teams to use wings closer in specification to those seen in Hungary. Singapore is a typical ‘point and squirt’ street circuit with a ton of corners, where teams will go to the opposite extreme and sacrifice straight-line speed for downforce.
Those Monza ‘tea trays’ will be left at the factory in favour of the Singapore ‘barn doors’.
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Images © Ferrari/Ercole Colombo, McLaren/LAT, John Beamer
There is no restriction on flaps. In fact there is a minimum surface area restriction, which if anything encourages proliferation of flaps. It is interesting to look at the top-most illustration and notice the […]
Yes – this is correct. When I said the Mercedes design was not legal this was in reference to the positioning of the nose relative to the front wing and not the fundamental concept, which as you point out is legit.
In modern Formula One there are only a few areas where designers have any aerodynamic freedom. The outer part of the front wing is one; the zone around the rear brake ducts and surrounding floor is another.
The regulations governing the location of aerodynamic parts around the rear wheels are complex and going listing each one will be a boring exercise, but it is worth running through the essence of what they say.
Article 3 of the FIA Technical Regulations governs bodywork dimension. Bodywork around the floor is permitted as long as it does not extend a certain height above the reference plane and meets certain (restrictive) cross-section area and curvature requirements. Furthermore the floor must form a solid structure – i.e., cannot contain holes, which was a particular area of dispute in 2012.
Article 11 describes the brake ducts. It defines a cube-shaped area within which aerodynamicists are free to have as much or as little bodywork as they like. The position of this area is 160mm above and below the wheel centre line, 120mm from the inner face of the wheel towards the car, and 330mm fore and aft of the rear wheel centreline. In this area we see a proliferation of carbon fibre which is clearly designed to enhance downforce rather than improve braking performance.
The first illustration below shows some the detail around the RB10:
First, note the detail around the brake ducts. In this configuration the duct opening is quite small and there are at least four winglets protruding from the ducts. The brake ducts contribute substantially to the downforce produced at the rear of the car. This downforce is generated very close to the rear wheel, which helps get heat into the tyres and reduce degradation.
In addition there a number of flicks and vanes attached to the floor of the car. These serve the purpose of manipulating the airflow around the rear wheels to optimise the wing-wheel interaction. The tyre creates a lot of drag — this can be reduced by diverting airflow either side of the rubber or by altering the flow the structure hitting the rubber.
Also note the slot in the floor. Although this looks like a hole there is a hairline gap from the edge of the floor to the slot so it complies with Article 3 in the Technical Regulations. Again, this slot is designed to bleed air below the floor to optimise the wing-wheel interaction. This slot can’t be too large or else it would create too much turbulence, which would increase drag.
The illustration below shows the brake ducts from a different perspective – again note the complexity of the device with brake cooling being a secondary objective!
The original intention of the regulations was to ensure teams could properly cool the brakes. This is a very important safety requirement as we have seen with some recent high profile brake failures. Canny F1 engineers have exploited the regulations for aerodynamic benefit.
But as with double diffusers, exhaust blown diffusers and other inadvertent aerodynamic loopholes, don’t be surprised if FIA decide to impose tighter control over brake duct design to reduce their aerodynamic benefit in the future.
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Images © John Beamer
This is chiefly thanks to the revised nose regulations, where designers have explored creative means of satisfying the FIA’s demand for lower and theoretically safer noses.
Good F1 car design starts with the front wing. This is because an F1 car works as an aerodynamic system – the rear of the car is designed with the front in mind.
The flicks, fins and vanes on the front wing manipulate the airflow in specific way to maximise air flow to the floor, around the sidepods and to the diffuser. Ferrari, who have tended to lag behind their rivals when it comes to aerodynamics, have some interesting approaches to this challenge.
What the rule book says
For 2014 the front wing width was reduced from 1,800mm to 1,650mm, chiefly to reduce the risk of carbon fibres slicing tyres open in the chase to the first corner.
Significant changes were also made to the nose, the tip of which must meet a minimum height. Further rules restrict what designers can do with the rest of this structure.
The area 50mm behind the tip must be centred at 185mm above the bottom of the stepped floor (which is known as the reference plane). This nose area must be contained between 135mm-300mm above the reference plane. In addition the cross-section must be exactly 9,000 square mm, but its shape is not restricted.
Furthermore, to prevent excessively arched noses, the FIA defined an exclusion zone which designers may not use. This zone is the area above the maximum nose tip height (300mm) and the front bulkhead height (650mm).
Finally, the length of the nose can not be shorter than front wing centre section and can extend forwards beyond the front wing.
Front wing workings
Besides meeting the technical regulations, designers aim for the following objectives when designing the front wing and nose: generating downforce, controlling the airflow to the rear of the car and balancing front and rear downforce.
In years past ensuring the rear of the car was properly fed with air was the main objective. As air works its way over the chassis to the diffuser the risk is that it stalls (similar to an aeroplane) because the air flow speed is too low. Raising the nose is one way to ensure that air ‘hits’ the car later and is easier to manipulate. This has been the dominant design trend in recent years.
One problem with high noses is that they don’t create downforce. But as long as the car isn’t saturated with rear downforce then it isn’t too much of a problem. Although exhaust blown diffusers previously resulted in a rapid increase in rear downforce, this was mostly in low speed corners where rear traction was limiting factor.
Many of the cars with ‘finger’ noses are trying to recreate the high nose philosophy. A look at the McLaren or Toro Rosso illustrates the concept nicely with the nose cone arched to maximise airflow underneath it.
Ferrari have gone in a different direction and have made the nose ‘downforce positive’. The nose and wing form a letter box shape (see (1) on the diagram), which expands behind the leading edge of the nose.
The nose tip is at minimum point (135mm) above the reference plane and its thickness conforms with FIA’s cross-section requirements. The area behind the nose acts as a venturi tunnel and it is this that creates downforce.
Air is forced through the letterbox nose at high speed and then expands in to the area behind it (2). It is similar to how a diffuser or ground-effect car works. Bodywork extends down from the nose section (below the Kaspersky Lab sponsorship) to enhance the diffuser effect and also to prevent air that is pushed over the top of the nose from spilling in to this area.
Given the mantra in recent years that higher noses are better, many ask what have Mercedes done to build a similar design but with a higher nose? The assumption is that Ferrari have messed up – but it isn’t necessarily the case.
Ferrari likely creates more downforce with its contraption than the W05. The W05 nose is slightly narrower and higher than Ferrari’s and is positioned at the FIA mandated 185mm above the reference plane. If you look closely you can see the shape of the front wing mounts change, which is to comply with the FIA’s cross-section requirements
Dealing with the wheels
The flaps and cascade obviously produce downforce. Depending on how you count, the Ferrari front wing has up to six flaps, but many of these are slots in a continuous structure. The slots allow air to bleed through to the underside of the wing which adds energy to this flow. This energises the air and prevents it from stalling, which harms downforce. The slots actually cut overall downforce but deliver more consistent performance, which is more important from a driver’s perspective.
A big factor in front wing design is managing the wheel-wing interaction. The tyre not only presents a large surface area, which increase drag, but also rotates ‘pushing’ air towards the front wing. Again careful design is needed to ensure the wake coming off the endplates and cascades interacts with the wheel in the right way to prevent this turbulent air hurting performance.
One technique is to shape the endplates and cascades to push the air outboard of the wheel. With the narrowing of the front wing for 2014 this has meant significant changes to shape of the cascade structure. The curled structure by the ‘V-Power’ insignia on the cascade (6) of the F14 T serves precisely this purpose. Before the season some thought it may make sense to direct airflow inside the tyres as was done before 2009 when the front wing was much narrower. However, none of the teams have gone this route.
The endplate itself contains some slots and a number of curved structures around the footplate. The slots (7) serve a similar purpose to those in the front wing and help air transition from outside the endplate to underneath the wing. This creates a vortex that helps pulls air around the outside of the tyre. The footplate curves (8), which are either side of the endplate, are also designed to create an capture vortices. If one were to look at the airflow CFD traces it would likely show that all these vortices roll up in to one larger, more powerful vortex.
The Y250 vortex
The outer part of the front wing is the most aerodynamically intricate part of a modern F1 car. The various cascades and flaps produce downforce but also set up the airflow regimen along the rest of the car. This is done by creating a series of vortices and ‘squirting’ them to areas of the car that are critical for performance.
A vortex is twisting mass of fluid – think a whirlpool – and is easily created by allowing high pressure air to ‘fall’ into a zone of lower pressure. This happens naturally at any flap. Typically air on the top side of the flap is at a higher pressure and when this spills over the flap it twists and creates a vortex.
It turns out that vortices are very robust fluid structures and once formed take a while to break down. Moreover smaller vortices and eddies in the air can be absorbed by a larger vortex cleaning up the airflow profile around the car. It is these features that make the vortex structure so useful.
The Y250 vortex is so-called because it is generated by the flap 250mm from the car centreline (4). All cars will create a Y250 vortex because the front wing regulations prevent bodywork from being any closer to the car centreline. Turning vanes (5) appended to the chassis will then steer this vortex to the bargeboards where it will funnel around the sidepods.
This will seal the side of the car and under nose area from any turbulent air. On a humid day it is sometimes possible to see the vortex and its progression along the length of the car.
The FIA also mandates the requirement and positioning of the nose cameras (3). The trend this year is to have the camera pods to sprout from the bodywork and look like ears protruding from the chassis. They are a micro version of the ‘elephant ear’ devices that adorned the McLaren MP4-23.
Although the FIA has written the regulations to try to negate any aerodynamic benefit from camera placement, the position on the Ferrari will condition airflow over the top of the sidepods, to a small benefit.
Interesting, Red Bull has dispensed of the camera pods altogether and has cleverly integrated the camera in to the chassis bodywork (pictured).
This is an elegant solution that minimises drag. The picture quality from the camera, which points through a narrow aperture in the nose, isn’t great – but that’s not a concern for Red Bull.
Developments in 2014 and beyond
But we are in the first year of a new rules package so it can’t be ruled out completely. The next race in Spain is often where such aggressive changes appear, as it marks the beginning of the ‘European season’ where teams are racing closer to their factories and can bring new parts at short notice.
Mercedes introduced a revised nose in China which sits as far back from the front wing as possible to ensure clean air over the central section. However its broad concept is unchanged.
For 2015 the FIA plans to alter the regulations again in the hopes of doing away with the unattractive designs which were produced this year. The regulations are yet to be published so it is not clear what the FIA has in mind but expect a stricter definition on the dimensions and positioning of the front cross-section.
Until then we can enjoy the variety that the the current regulations have brought, if not the aesthetic qualities of the current generation of noses.
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Images © John Beamer for F1 Fanatic, McLaren/LAT, Red Bull/Getty, Daimler/Hoch Zwei
Yes – I didn’t mention. Mostly because I focused this piece on aero — but you are right, Ferrari has some interesting innovations in the engine and gearbox. I’ll write about that in a future article.
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