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21 June 2012


I'd imagine it is difficult for the causual or none technical fan to understand why there is such a disparity in performance between the front runners and lower tier teams. If we were to take Red Bull Racing and Caterham as examples for this article we will see differentiators in performance. I have decided to use these teams as an example as the 2010/11 Champions Red Bull are a team at the top end of their game. Meanwhile Caterham joined the sport in 2010 (under the guise of Lotus Racing and ran 2011 as Team Lotus before finally settling on the Caterham marque). Caterham initially entered the sport using the Cosworth engine and although they weren't quite upto the speed of the established teams they did make their mark as the best of the 3 new teams.
The main reason I have decided to use these two teams as the reference points is due to their common use of the Renault engine but also because Caterham purchase their gearbox and parts of the rear suspension from the Red Bull Racing team (albeit the Caterham uses the previous seasons setup, so for this year the RB7's setup)

So why is there a performance difference between the two I hear you ask. Well that may not be as an easy answer as you would think. Firstly using last years suspension setup means that you are using a geometry/layout that was designed to cater for EBD (Exhaust Blown Diffusers) without the use of this, this year the teams lack rear end downforce. Red Bull utlised the quantity of air flow that could be generated through EBD to run much more rake. Something that the teams this year would need to start with much less of and as the season progresses and additional airflow is scavenged through upgrades they can increase the rake.
Rake for those that are unfamiliar is the pitch angle of the car over its longitudinal distance (ie higher at the rear than at the front, pointing downward) The reason for more rake is as you find a way to add downforce on top the car you need to balance this with creating more airflow under the car. Adding Rake or raising the rear end can give the diffuser a larger cavity to flow more air.
This obviously gives the Caterham designers something to work around and results in a compromise that will ultimately narrow the window in which the suspension can be adjusted. With EBD now banned next year should see Caterham take advantage of the RB8's design philosophy of which the RB9 will simply be an evolution.

Infrastructure

Aerodynamically the Red Bull team over recent years has had the jump on most of the field, lead by Adrian Newey the Red Bull aero team are at the forefront of F1 design. Red Bull embraced the transition from on track testing to a less restrictive ability to design their cars in the Wind Tunnel and CFD. They have also adopted the use of 3D printing in order to rapid prototype parts and test them in the Wind Tunnel environment, this speeds up a process that in the past may have taken much longer to produce parts for testing. Red Bull have many test rigs in order to analyse stress and performance of the car either in it's entirety or individually. By designing the car at this level it allows for a higher level of freedom in terms of design, allowing you to test many components in a short amount of time. As Caterham are a much younger team their level of infrastructure is much less than Red Bull and so it will take time in order for them to purchase and use the equipment and get the skilled staff required to operate them. Red Bull also had a head start by purchasing the pre existing Jaguar team and simply building on that pre existing setup. Caterham however have started from nothing and are working hard to replicate the infrastructure of teams like Red Bull.

The video below is a great watch as it goes around the Red Bull factory circa 08/09 to look at the ways in which the team approach the design of their F1 car. As an emerging team i'm sure they continue to push the envelope and add additional features to those shown but it gives a great idea of the processes involved:


Engine / KERS Performance

Red Bull Racing began using the Renault engine back in 2006 and has such has a fantastic understanding of how to extract the best from the powerplant. Adrian Newey's designs always centre around shrink wrapping the car and making the bodywork as tight as possible. This is part of a match made in heaven as the Renault engine is incredibly efficient and requires less cooling than it's counterparts. Number's touted around the paddock suggest that the Renault engine is down on overall power in comparison compared to the Mercedes & Ferrari engines by around 15bhp. This however is not a problem as the drive ability and much better fuel consumption the engine produces can outweigh this. It is said that the Renault uses around 15 Litres less of fuel over a race distance, this equates to around 10KG's which in a race car is essential weight that can be placed elsewhere.
Red Bull Racing's ongoing technical partnership with Renault has also allowed them to perhaps better understand the mapping requirements of the engine in comparison to Caterham who are only in their second year of supply from Renault.

KERS is something that both teams purchase from Renault Sport and can also affect the balance of the car whilst in both the harvesting and dispensing stages.  Red Bull have more experience using the KERS system and although they struggled initially with system failures they now seem to be on top of the system.  This being the first year that Caterham have used the system they not only had to find a way to package the system but also find a balance in order to gain additional lap time.  KERS also has an aerodynamic effect as additional cooling is required in order to keep the batteries cool.  (Imagine using a piece of electrical equipment for a while and then fetching the battery out, you will notice how warm it is.  As electricity is dispensed the chemical reaction taking place inside the battery heats up the chemicals and in turn the casing.  To give you an idea of the difference in a battery you use to the type installed in a KERS system: A small AA battery has a discharge rate of just less than 10,000 Joules or 1Kj, a KERS battery can store 400KJ's so that's 400 times the storage capacity.  Heatsoak can be a massive factor in the performance of both the batteries life and performance.  The more heat the battery is exposed to the faster the cells degrade and the less effective the cells produce optimum power.
Energy Harvesting is when the electrical motor connected to the crankshaft on the front of the engine withdraws power under braking (engine braking) which has an effect on the balance of the car.  This is why you see drivers adjusting their brake balance during the lap.  The team that can best manage the transition between harvesting, energy storage, battery cooling and energy release will attain the best system.  This I believe is why Red Bull now have Super Capacitors located at the rear of the floor.  These Super Capacitors help to store and release energy more quickly than the larger batteries housed under the drivers seat.  Cooling them will require a more intense level of airflow and that's why they have been situated near the starter hole as it almost sucks airflow into that region.


Mechanical & Aerodynamic Platform

If we take a look at the RB8 and CT-01's main features it's clear to see the disparity in both mechanical & aerodynamic performance between the two. This comes mainly from Red Bull's desire to win and clear determination to provide an effective aerodynamic platform.


Looking quickly at the 2 images above will leave you with very little to tell the differences between the two packages. However on closer inspection there are many details that differ here (Please bear in mind that the photo has been taken at different zoom levels and at different angles and so the 2 photos aren't a true 100% representation of the same thing. We also have to remember that we don't know what fuel loads are onboard either car which could also affect the way in which the cars look/operate):

Mechanical

Firstly the ride height, the Red Bull car is running closer to the tarmac as we can see by the distance the front wing and skid block are from the tarmac. This not only has an effect on the suspension but the aerodynamic platform, you'll note that all of the suspension elements are much more upright on the Caterham this invariably leads to less motion available and in turn less adjustability.  The CT-01 would also seem more softly sprung as you can see by the weight transference. The weight of the car is leaning over on the right of the car as the weight shifts under cornering load. Due to the softer suspension approach we can see the additional angle of attack that the Caterham driver is having to take in order to get around the same corner. Both the wheel angle and drivers hand position show the Caterhams deficiency to the Red Bull.

In order to attain more grip we can see that the CT-01 is also running with less air pressure in the tyres. This is shown as the tyre bulges off the rim. Lower tyre pressures help to squat the tyre on the rim giving a larger contact patch which in turn gives up more grip. The problem with less tyre pressure is it also dissolves some of the suspensions work. Due to the tyre having less inflation the weight of the car acts on the sidewalls creating squish. This squish acts as a form of suspension and counteracts some of the suspensions actions. I'm not saying running with massive tyre pressures is good either as that can create deflection and have the opposite also non desirable effect on the suspension. Finding a happy medium between the two will result in a much more responsive suspension.
One of the larger problems with more body roll is that you spend more time cornering than your opposition and as such will also have to run compromised gear ratio's in order to corner in the right rev range.

Aerodynamically

The front of the nose cone on the RB8 has a much more bulbous frontal area which is in stark contrast to the CT-01's almost pointed nose. The RB8's nose design is all about continued flow management in order to feed/push the airflow into the path of the next component. The CT-01's nose is a much more blunt design with perhaps the highest possible nose configuration available. This is done to try and drive more air under the car towards the floor and speed up the airflow to the diffuser beyond.



The step nose that features on most of the cars this season is a direct response to the teams wanting to get as much air under the nose to the floor as possible.  When EBD (Exhaust Blow Diffusers) were in use this wasn't such a huge requirement as the exhausts fed the diffuser with more than enough airflow.  This meant the air from the front of the car could be directed at both the underside and top side of the floor. 

Red Bull's nose slot in the step area helps to stop flow detachment that usually occurs when airflow meets with a sheer surface. The step or ramp of the nose design although minimally will create some drag. This disadvantage has been deemed acceptable by the teams to gain the air underneath.


The Front wing planes used by the two teams are very similar in design even with the top element sporting similar pointed ends at the inner edge of the element. The RB8's front wing however has additional pylons/vanes just infront of this area that combine with the top element in order to generate flow vortices. These vortices travel at a higher speed than a normal laminar flow. In the case of the RB8 these vortices are then targeted at the turning vanes behind (mounted below the nosecone) in order to direct the flow further down the car. As Caterham don't have these pylons/vanes the vortice(s) generated from the wing tip is much smaller and so the turning vanes are also designed more neutrally.


The picture above is a very crude explanation (in 2D) to explain what I mean by a votice or vortex, the two wing tips create airflow that act on one another sending the airflow into a spin and create a higher speed airflow we call a vortice.


The frontal entry point of the Sidepods of both cars are very similar dimensionally however where the top of the Sidepod on the RB8 slopes inward toward the cockpit the CT-01's lean away. The reason Red Bull follow that ethos is this helps to funnel the airflow towards the rear of the car creating a downwash towards the rear of the floor.  Caterham's version will allow the airflow to tumble off the sides towards the floor and so less flow is contained and sent towards the rear floor. Although both cars run the same engine due to mapping requirements their cooling methods may differ and so radiator size and layout will differ between the two cars. This leads to the difference in sidepod size and shape (packaging).

Due to the requirement to vent the exhaust in a specified way this year design and integration of the exhaust remains a key element of this years car designs. The exhaust gases can be used to manipulate airflow and generate additional downforce when used in the correct way. Red Bulls approach to this is to create a ramp at the rear end of the sidepod with a channel to direct the exhaust/exhaust plume. Positioning/Angling the ramp and channel is vital in helping to draw the airflow coming across the top of the sidepod and from around the sidepod toward the exhaust plume which in turn directs the flow toward the rear of the floor. Doing this helps to generate downforce. 

 
The CT-01's exhaust solution is higher on the body and deals more directly with the airflow from the top of the sidepod than the air travelling around the side. The Shark Gills that cover the exhaust are there to try and keep the airflow attached from the top and side of the sidepod and also reduce the boudary layer speeding up the flow heading toward the exhaust plume. (The Shark Gills are ejecting air that comes through the sidepod entry) The exhaust plume at this higher point on the car does not provide as much airflow toward the rear of the floor as it's Red Bull counterpart and so generates downforce on other area's including the beam wing.


The rear wing has become an area in which much more performance can be extracted than simply by adjusting the wings angle of attack. The beam or beam wing as most call it creates a level of downforce aswell as providing the wings attachment to the car. This area is now designed in order to achieve additional downforce shaped like a wing plane. Some designs are much more complex than others but it's design/usage is very much determined by the airflow presented to it by the components in front of it. 
Rear wing design has altered since the inception of DRS as teams try to balance the effects of using or not using the DRS system. Designing the heights of the two wing planes will effect not only the angle of attack that can be implemented in the closed position but also the effect of the effectiveness of DRS when active. This is a tuning decision made based upon the circuits characteristics.
The louvres that you see at the front edge of the wing endplates are used to reduce drag at the rear wing tips. Robbing airflow from one side of the endplate and sending it to the other thus affecting the airflow and reducing the drag.
To add additional downforce the rules permit a Gurney Flap on the trailing edge of the rear wing plane. If used it helps to stunt the flow and forces the air backwards causing the air to spiral against itself creating more downforce.
In the case of the two rear wing designs from Red Bull and Caterham there is nothing major in design philosophy between the two with very similar endplates except at the rear where the RB8 has trailing strakes that will manipulate the airflow and help guide any airflow exiting the rear of the car.


The diffuser is obviously a key area in extracting rear downforce from an F1 car. Over the last few years the teams have exposed loopholes within the regulations in order to better extract more downforce. Each year the FIA has to re clarify areas within the technical regulations to try and reduce the amount of downforce the teams can generate. The latest of these has been the removal of EBD (Exhaust Blow Diffusers) unlike the top exiting exhausts of this season the exhausts used to channel their airflow in a cavity in the floor of the car in order to speed up the diffuser process and seal the diffuser edges. (When we talk about sealing the diffuser this is achieved by creating a channel of airflow, the stronger & wider the airflow the better the effect. The term sealing is like creating a wall of airflow to which outside airflow doesn't affect the performance with the diffuser channel.) Without EBD this has become a much more difficult task and means the teams had to start with a much narrower sealed area. This is all intrinsically linked to Rake as we discussed earlier and depends heavily on how much air can be driven underneath and over the rear of the floor/diffuser.
Unlike when EBD blocked it's passage into the diffuser airflow, tyre squirt has become a factor for the teams to manage this season. Tyre Squirt is the air that is pushed laterally off the sides of the tyre as it rotates. This air, if not managed will push latterally into the diffuser flow and upset the balance of the car. 
We have to remember that although most of us can only visualise airflow in a uniform way (front to back over the car) as the car turns and travels on it's suspension the airflow is also moving. This means that managing an element like tyre squirt can greatly affect the level of downforce and in turn the balance of the car.


Just like the gurney flap I mentioned in the Rear Wing section the diffuser is also allowed a gurney flap in order to generate downforce.  As we can see from the pictures above both teams again have very different 
Philosophies in this area to attain better performance.  Red Bull's Gurney flap is slightly detached from the diffusers edge, this allows the flap to work as a wing in unison with the diffusers top edge. This bleeds airflow through the gap allowing an element of flex and allows more downforce to be applied to the gurney flap as the low pressure air goes beneath the flap.  Meanwhile the Gurney flap on the Caterham is a much more blunt approach with a sheer 90 degree surface at the maximum 20mm permissible surface area.

In Season Updates

This is perhaps one of the more important aspects of racing within a series like F1, as the season progresses and the team are able to find additional performance gains they are bought to each circuit to be evaluated.  Updates come in either Mechanical or Aerodynamic forms and sometimes utilise both in order to gain either additional balance for the driver and/or extra downforce.  For example this season has shown the depths and pure rate of development that Red Bull can achieve having produced at least 4 major different exhaust configurations in quick succession.  To say that the teams always get things right would be wrong though, Red Bull chased their Sidepod/Tunnel/Exhaust solution for a number of races only to abandon it in favour of a more neutral solution.  Sometimes the over complexity of a design can lead it impacting how it feels for the driver.  In terms of the Tunnel solution Caterham also briefly tested a version of the same type of idea at Mugello.  This is something that I intend to write an article on in the future but will briefly touch on it now: Aero Convergence is when a seemingly leading team has a key area of aerodynamic gain, other teams see this a way of extracting more performance from their own package and so develop their own iteration.  McLaren's exhaust system this season highlights this brilliantly, with the clear advantage at Melbourne the teams invested their development time chasing similar solutions to the McLaren style exhaust.

Red Bull's Exhaust / Sidepod / Tunnel solution featured a section that was missing from the bottom edge of the sidepod and in its first iteration exited at the rear of the sidepod.  The idea was that the airflow from around the side of sidepod would go through the tunnel and help produce an extremity of airflow above the diffuser to help seal itSeemingly this worked in both the Wind Tunnel and CFD but when placed on the car didn't have the desired effect.  Red Bull latterly exited the airflow inside the engine cover and presumably but abandoned this method too.  I'm still not sure this is the last we will see of this design as the team refine how the airflow pattern works.

Caterham CT-01 - Mugello: As we can see from this picture Caterham did test an alternative exhaust solution at MugelloThe design centres around the same ethos as the Red Bull Tunnel with the exhaust placed in the lower position in an attempt to draw airflow into the tunnel below.  The Caterham version exited the airflow into the engine cover and presumably out of the starter hole at the rear.

In Summary

Red Bull are no stranger to the world of FIA rule changes / clarifications as they push the boundaries and interpret the rules in a different way. Having perhaps without the DDD (Double Deck Diffuser) the best car of 09 and then using their facilities to rapidly catch and overtake the initially superior Brawn GP car of that year. This was a year I believe Red Bull learnt many lessons both on and off track in terms of strategy, car design and how to handle the FIA's ever changing rule book. In 2010 & 2011 they produced cars that leant on the side of illegality and prospered using 09 as a yard stick for future processes.  More recently they have fell to the wroth of the FIA's ever changing rule book and have had both their Floor and Front Brake housings banned under rule clarifications.  This won't stop the teams pushing ever closer to their interpretations of what is legal and illegal.

As we can see from the disparity between these two teams, having the same/similar engine/gearbox and ancillaries is not the only thing required to produce a winning car. It's a multi faceted design process that requires decisions on everything from engine mapping, exhaust tuning, gear ratio selection, suspension geometry, tyre pressures, aerodynamics to name a few. These processes are also reviewed and changed based on the particular circuit F1 are visiting at the time.

In terms of running an F1 team the costs are large, having invested a large sum of money in their team Red Bull have reaped the rewards with the constructor wins in 2010 & 2011 giving them a return on their investment through the prize money received at the end of the season. In stark contrast Caterham having been placed 10th since its inception will receive a much smaller prize fund. As the Caterham team continues to expand I expect their expectations will be met with much better race placings giving them the opportunity to shadow Red Bull Racing's success.
Tagged
Different Themes
Written by Matthew 'SomersF1' Somerfield

Formula One is a sport that pushes technological boundaries, with the pace of the changes to the cars as swift as the laptimes. This blog looks to keep you upto speed with these alterations.

3 comments:

  1. I barely have time to read what fellow bloggers are doiing, but this one is lovely detailed article, Matt, congratulations for that excellent writing.

    MY humble contribution to the Red Bull arsenal would be their partnership with Leica and in particular the laser system that is supposed to check the materials and parts for defects. That way, RB7 became the most reliable car in 2011 after the bad 2010 season, where reliability have stolen lots of points.

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  2. Hi Kiril

    Thanks for your positive comments, yes you are quite right about their Leica partnership being crucial in RBR's development. Trouble is how far you go with these blog posts as you can see this is a rather large one.

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  3. I now see why you did not want to rush this one. It has filled some gaps for me, it's a gem Matt. Will read it a few more times and try to glean more. My hopes of getting you on the big screen were scuppered by the WI they booked the room in the RB Legion. More interested in knitting..........I'll try again!

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