Red Bull – Pull rod suspension detailed

Via Motorsport Magazin

From these images we can finally see some detail of the Red bull gearbox. Firstly the construction is carbon Fibre, which the team switched to mid way through 2009, in order to save weight over the old aluminium case.

Top wishbone location - via Motorsport Magazin

Then we can note the geometry of the wishbones, Red Bull followed high mounted wishbones since the RB5, the rear top wishbone (RTWB) being very high and near horizontal, being mounted to the ridge along to the top of the gearbox.

Differential - via Motorsport Magazin

Equally Red Bull have gone for a low differential, but the total effect is a very tall and bulky gearbox, albeit one that fits into the natural space created as the car tapers to the rear. But compared to Williams gearbox its clear to see where better airflow can be created at the tail of the car.

Pull Rod - via Motorsport Magazin

It’s rare to find pictures of the Red bull pull rod suspension. The low mounted mechanical parts normally covered by body panels and heat shielding. But here we can quite clearly see the pull rod leading down to the rocker. The pull rod is split to allow easy ride height changes by adding shims into the split and also allows the pull rod to be permanently mounted to the bearings on the rocker. When the rear wishbones are removed this lower part of the pullrod will remain with the gearbox. In turn the rocker operates the compliant elements of the rear suspension, the springs, dampers and heave elements.

Damper - Via Motorsport Magazin

The damper is clearly visible being mounted alongside the flanks of the gearbox case. The red anodized body and labels making it easy to spot. Note the rocker has a longer lever to operate the damper in comparison to the lever that the pull rod mounts to. This is to increase damper travel compared to wheel travel for greater wheel control.

rocker or Bell Crank - via Motorsport Magazin

Its not clear if the rocker works on a torsion bar t provide the rear springing, its believed Red Bull went away from torsion bars and individual wheel springs in 2009. Instead using the heave spring allied to the antiroll bar for a springless rear set up (read more at http://scarbsf1.wordpress.com/2010/12/03/spring-less-rear-suspension-a-quiet-revolution/). If a torsion bar is used it will need to run near vertically along the axis of the rocker.

Rocker to operate the Heave spring - via Motosport magazin

Not entirely visible is the heave control set up, this will consist of a Heave spring, damper andor bump rubbers, plus an inerter (not strictly for heave control but mounted in the same location). These run across the front of the gearbox, being mounted just above the clutch. We can see the splined end of the anti roll bar; the bar will have levers reaching forward to drop links that will provide the rear roll control.

Antiroll Bar location - via Motorsport Magazin

More on Pull Rods http://scarbsf1.wordpress.com/2010/10/10/red-bull-pull-rod-suspension-what-is-looks-like-how-it-benefits-aerodynamics/

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Red Bull – KERS installation detailed

via Motorsport Magazin

Having run KERS for Friday only in Melbourne, RBR will probably run the KERS system for the full weekend in Sepang. As RBR were not seen to use KERS on their qualifying laps, although they were unknown to be equipped with Renaults KERS raised rumours of a start only KERS. While a start only KERS is technically legal and has some technical advantages, it’s not thought such a system is planned for any team.
From images seen this in the team’s garage this morning we can see the KERS set up quite clearly. The actual set up is quite different to the image provided by Red bull in their Launch press pack. Which shows a far more conventional layout?

KERS control unit - Via Autosport.com

On the right hand side of the car, we can see a silver box with FIA anti-tamper seals; this is the KERS control unit (KCU). This controls the power exchange between the motor generator and the battery pack. The thick red cables carry the current in between these other devices. Running very hot from the current passing through it, the KCU will have a cool air feed from the sidepod ducting. Although not certain, the small radiator at the bottom of the other coolers is probably to cool the battery pack.

Possibly the KERS water cooling radiator - via Autosport.com

From the other side we can see the Battery pack, unusually this is mounted to the side of the gearbox. It is the rounded carbon fibre item, with the yellow warning sticker.

KERS Battery Pack - via Autosport.com

The other three KERS suppliers (Mercedes, Ferrari and Williams) all place this item beneath the fuel tank for better weight distribution and crash safety. Although McLaren did place theirs low down in the front of the sidepod in 2009. With the more rear biased mandatory weight distribution rule, this more rearwards location is not a handicap. It frees up fuel capacity and sits inside a dead area of space within the sidepod. You can see the same thick red cable emerging from the battery pack. Inside the carbon case will be an array of small lithium-Ion cells (Li-ion). These will run at high temperatures as the cells charge and discharge, as explained they will be cooled a dedicated water radiator and pump.

More on KERS: http://scarbsf1.wordpress.com/2010/10/20/kers-anatomy/

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Trends 2011 – Exhausts and Diffusers

This year the technical talk has largely been about exhausts.  How teams have adapted to the ban on double diffusers and the added restriction on Exhaust blown diffusers. Just to aid understanding going into the new season, I have explained how these solutions work and how they look from beneath.

Double Diffusers

Force India 2010 Double Deck Diffuser (DDD)

Since 2009 the regulations regarding the floor have been interpreted in a literal sense to allow the double deck diffuser (DDD). Indeed the very same rules were exploited to a lesser extent under the previous rules, but this only produced small extra channels in between the outer and middle diffuser tunnels. With the major cut in aerodynamic aids for 2009, several teams sought to find a way to gain more expansion ratio from the smaller diffusers. In essence the loophole exploited the definition of surfaces formed between the step and reference planes. Multiple surfaces allowed fully enclosed holes, which fed the upper diffuser deck that sat above the 175mm lower diffuser. This allowed diffuser to be significantly larger in order to create more downforce. Notably Brawn, Williams and Toyota launched 2009 cars with DDDs. Other teams soon followed suit in 2009 and last year every car exploited the same loophole. Over the winter the FIA acted to close the loophole, by enforcing a single continuous surface across a 90cm span under the floor. In a stroke this banned the double diffuser, there being no scope to create any openings in the floor to feed the upper deck.

Single Diffuser

Double Diffuser

 

Exhaust Blown Diffusers
Another approach to regain lost downforce was the re-invention in 2010 of the exhaust blown diffuser (EBD). This used high energy exhaust gasses to blow the diffuser, the faster throughput of flow under the floor increased downforce. Two methods of EBDs were used in 2010, one blowing over the diffuser and the second blowing inside the diffuser. This latter solution was more effective at driving flow through the diffuser and created more downforce. However this necessitated a hole made into the diffuser to allow the exhaust gas to enter, I‘ve termed this method an ‘open fronted diffuser‘.

2011: No openings allowed in the yellow 90cm zone, outside certain holes are permitted

A by product of the 2011 rules intended to ban the DDD, also stopped this open fronted diffuser solution. However the rules enforced the continuous surface only across a 90cm width of floor and the diffuser is allowed to be 100cm wide. Thus a 5cm window was allowed each side of the diffuser.

Outer Blown Diffuser – Solution

Red Bull Diffuser: Flow passes under the outer 5cm of floor into the diffuser

Red Bull and Ferrari appear to have found this loophole simultaneously. Recently Sam Michael pointed out this was probably the most efficient way to blow the diffuser under the new rules. As Red Bull appeared with this set up first, its often termed the Red Bull Blown diffuser.

What these teams have done is to open up the floor 5cm either side of the diffuser, then route the exhaust towards this opening. The exhaust gas gets collected by the coved section of floor and this directs the high energy gasses under the diffuser, to recover some of the losses from the more open diffuser allowed last year.

Front Exit Exhaust

Renault Front Exit Exhaust: Flow passes wide around the floor before entering the diffuser

Renault meanwhile turned the problem on its head. As the aim of the EBD is to increase flow under the car, they pointed their exhaust at the front of the floor. I’ve had it confirmed to me by two ex-Renault sources that the exhaust does indeed mainly flow under the floor.

The exhaust pipe outlet sits above the step plane just ahead of the leading edge of the floor. This is not simply blowing out horizontally and across the floor, but is ducted slightly to blow downwards and backwards, this is roughly in line the with the flow trailing off the “V” shape above the splitter. Along with the strong vortices set up by the splitter, vanes and bargeboards, this makes the floor appear wider than it is. The flow will go out beyond the floor and then curl back in and under the floor. Some flow will inevitably pass over the floor, but the most of the energy will be driving more flow under the floor to the diffuser.

McLarens Slit Exhaust

The slit above the floor is visible. Copyright: Liubomir Asenov

No conversation about exhausts this year, would be complete without some speculation about McLaren. Amongst the several exhaust systems run by McLaren over the pre-season tests was a “slit” exhaust. This appeared at the first Barcelona test, but did not seem to appear for the second Cataluña test. The exhaust collector could be seen to duct towards a double thickness section of floor ahead of the rear wheels. This section was also interesting for its longitudinal slot, this slot was not large enough to be the actual exhaust outlet, This might be a cooling slot, or to improve the flow from above to beneath the floor.  I beleive the Exhaust is actually below the floor.  As when the car ran the same floor with a conventional exhaust outlet, there appeared to be a removable section of floor ahead of the rear wheels. Being just outside of the 90mm opening rule, the floor ‘could’ be opened to allow an exhaust to blow through to underneath. If sculpted correctly, the exhaust could be ducted back inboard and blow towards the diffuser from under the floor. It’s possible that this could be in interpretation of a legal opening, assuming it met the maximum fillet radius rules.
I’d expect the resulting exhaust outlets to be a long wide slot, this wider outlet would be needed to meet the maximum radius rules and also reduce the back pressure from the tight curve of the exhaust outlet. As the exhaust would have a tortuous bend, to curl back under itself to direct the flow inboard, rather than out wide around the rear tyre.

Mac Slit: The exhaust might exit beneath the floor in a long narrow outlet

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Red Bull – Preseason front wing update

20110318-094109.jpg

In the last pre-season test at Barcelona, Red Bull introduced their updated front wing. Like the rest of the car, this is an evolution of what has gone before. Albeit based on the complex late-2010 set up, with 3-4 elements in differing areas across the wings span. It’s the endplate and cascade that have changed the most. While the flaps take some inspiration from Renaults early 2010 shape.

Firstly the shape of the main plane remains the largely the same, While the 2 flaps also retain their extra slot on the outermost span. This creates a four element wing nearest the endplate, this section gains a gurney to help keep flow attached. Meanwhile the inboard ends of the flaps follows Renaults idea from 2010, as they are feathered. This is visible by the space created in between the wing tips, Looking at the set up intuitively, the flaps remain loaded, but their tip vortex would be broken up into two smaller less powerful trails. Which still creates downforce, but may be less disruptive to the flow along the centre of the car.

20110318-094124.jpg

The cascade is slightly revised, again with the two conjoined winglets. Now the larger outboard winglet is curved near the join with the endplate, creating a deeper angle of attack and correspondingly a larger vortex spilling of the wingtip to direct airflow around the tyre.

20110318-094133.jpg

Mounting the new cascade is a revised endplate vane, Red Bull merge this organically into the rest of the outboard wing shape, but in principle this is the same as the vanedendplate-less set up of most other teams. The vane is slightly more outboard creating a wider cascade, probably for both more downforce potential and also to move the aforementioned vortex further outboard.



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Red Bull RB7 – Sidepods and Cooling

When the Red Bull RB7 was rolled out, it was clear the car was a neat development of the RB6, but was not an innovative car. As with well developed cars like this, its details are well thought through, a particular case is the sidepod design. If you look at the RB7s sidepods, from the radiators back they appear to slope away to nothing. This leaves the distinctive flat floor and open area ahead of the rear wheels. This creates an obvious aero gain, but how is cooling achieved with such a tight design?

Firstly the sidepod forms the main blockage to the rear wing and diffuser. We’ve seen several approaches this year to manage the airflow around the sidepods to the rear of the car. In each case the team are trying to get the best and most direct airflow to the top of the diffuser and beam wing. As the better flow these devices receive, the more downforce they produce and the less drag is required from a larger rear wing.

Since the 2009 aero rules sidepods are extremely limited in the openings they are allowed, so most of the flow has to exit between the rear wheels. Normally sidepods send the heated air from the radiators back through the tapered rear (known as the coke bottle, due to its shape). In a simple sidepod this means the coke bottle ends with an opening and the hot air passes out and over the diffuser. However this makes the tail of the coke bottle unduly wide, which creates a blockage between the rear wheels and blocks flow over the diffuser. Red Bull discovered with the RB5 that the radiator airflow can pass up towards the centre of the car and exit above the gearbox in a bulged opening. This keeps the tail of the coke bottle nice and narrow.

With the RB7 Red Bull have taken this a step further, there is no appreciable exits in the tail of the coke bottle, so nearly all the radiator airflow ends up passing through the bulged outlet. This means the coke bottle is the slimmest and simplest of all the cars on the grid. Clearly the huge floor area and exposed beam wing show how easily airflow can reach the rear of the car. The concession Red Bull has to make for this benefit is the increased blockage in front of the rear wing. But as they are aiming for downforce from the more efficient diffuser and beam wing, the rear wings effectiveness is not such a concern. Other teams have similar low swept coke bottle shapes, but each of them still exploits some cooling exit at the back of the sidepod. Given enough testing a fully enclosed sidepod with the central bulged outlet could be copied.

Red Bull RB7 – Open Fronted Exhaust Blown Diffuser

When the RB7 was launched the cars apparent lack of any innovation was surprising.  Yet the car ran in its launch guise during the first day of testing.  Then, in only the tests second day, the RB7 evolved with a new diffuser and exhaust system.  Despite rule changes Newey has found the loophole that allows exhausts to blow inside the diffuser for more downforce.  Although the rules were revised for 2011 to try to prevent double diffuser and openings to allow the exhaust to blow inside the diffuser.  The rules did permit openings in the outer 5cm of the diffuser, an area where teams have recently split the floor and created raised lip, coincidentally a practice first exploited by Newey on the RB5.

In my 2011 trends and solutions post (see http://scarbsf1.wordpress.com/2011/01/27/2011-trends-and-solutions/) I proposed this area could be exploited if the exhausts could be routed there:  “ The only openings in the diffuser are the starter motor hole and a 5cm area on the outer section of floor. Exhausts could be routed to this outer section of floor, but routing the large diameter exhausts across the floor could create their own blockage effect in-between the rear wheels. Offsetting the benefit they are supposed to provide.”

It appears Newey had the same idea and has presented the modified RB7 with flattened exhausts reaching rearwards under carbon overs (shown yellow in the above picture)  these reach towards the outer 5cm of floor and blow under the raised lip in the floor.  The fast moving exhaust gas then curves inside and blows out via the sidewall of the diffuser (shown below with the red arrow).  Blowing inside the  diffuser this way helps accelerate the airflow out of the diffuser and increases downforce.  As with last years EBDs they will be sensitive to throttle openings and Renault have assisted as much as possible in accommodating the aerodynamics with a special overrun strategy, to keep the exhausts gas velocity as high as possible without overheating the engine (see http://scarbsf1.wordpress.com/2010/07/10/red-bull-map-q-the-secret-to-the-teams-q3-pace/).  Renault were also understanding in developing an engine mapping that would work with far longer secondary exhaust pipes, without losing power or drivability.

In a strange coincidence with the Lotus Renault team, the exhausts has been extended by up to 1 meter and equally has a flattened oval exit, with the central separator (http://scarbsf1.wordpress.com/2011/02/01/renault-r31-front-exit-exhausts-fee-explained/).