Toro Rosso: Radiator layout

Posted on May 19, 2011 by scarbsf1

Toro Rosso went aggressive with the design of the STR-06, by adopting a double floor sidepod design. Although the team refer to it as a deep undercut sidepod, the effect is very much aimed at removing the blockage of the sidepods from the flow passing low along the floor towards the diffuser. We have previously described the external design of the sidepod (http://scarbsf1.wordpress.com/category/toro-rosso-str06/). We can now see the radiator layout required to make this packaging work. Surprisingly the radiator layout is quite conventional with good sized coolers fitted within the smaller sidepod envelope.

Firstly we can see the sidepod is raised above the floor, the yellow areas is free for airflow to pass under the sidepod shape and reach the diffuser. Ex-BMW Sauber head of Aero Willem Toet pointed out that this design creates a large area of exposed floor surface for the air to pass over, which might create problems with increasing boundary layer and hence drag. Potentially the ducted exhaust solution speeds up the slowing airflow over the latter part of the floor before reaching the diffuser.

Within the sidepod the radiators are made up of several cores, each serving different cooling needs for engine oil, engine water and KERS water cooling. Hot water exits the engine from the cylinder heads and passes to the radiator (red) and then the core cools the liquid before passing back to the water pump and lower front of the engine. It’s interesting to note the water pipes exit the engine as a single hose, but spit to feed the radiator core in two places to ensure an even distribution of coolant across the relatively large cooler.

A small water cooler also serves to cool the battery pack for the KERS.

In this right-hand sidepod we can see the radiator follow a slightly different construction as the oil cooler is also place din this sidepod.

FIA: Ban on Aggressive off-throttle Engine maps

Posted on May 19, 2011 by scarbsf1

Teams have been adopting exhaust blown diffusers (EBD) since last year and in 2011 every team has exploited the exhaust to some extent to help drive airflow through the diffuser. As I have explained in previous posts on the subject (http://scarbsf1.wordpress.com/category/exhaust-driven-diffuser/), the problem with EBDs is that they create downforce dependant on throttle position, so as the driver lifts off the throttle pedal going into a turn, the exhaust flow slows down and reduced the downforce effect, just at the point the driver needs it for cornering.

If a team want to really exploit the benefits of an EBD then they need to resolve this off-throttle problem. Last year Red Bull exploited a different mapping of the engine when off throttle (see http://scarbsf1.wordpress.com/2010/07/10/red-bull-map-q-the-secret-to-the-teams-q3-pace/ ). By retarding the ignition when the driver lifts off, the fuel is no longer burnt inside a closed combustion chamber, but instead the fuel and air burn in the exhaust pipe, the expandign gasses blow out of the exhaust exit as though the engine is running . This creates a more constant flow of exhaust gasses between on and off throttle. The problem here is that the mapping uses more fuel and creates excessive heat in the exhaust pipe and at the exhaust valve. Renault reported that both Red Bull and Renault used 10% more fuel in Melbourne compared to last year, most likely due to these off-throttle mappings.

With these off throttle mappings the fuel burns in the exhaust pipe, not the cylinder

As the engine suppliers have become increasingly comfortable with the heating effect of these off throttle mappings, teams have been able to use more of this effect in the race. One of Red Bulls advantages this year according to McLaren is their use of aggressive engine maps for downforce. At the Turkish GP several people pointed out the engine note on the overrun on Alonso’s Ferrari during FP2. Teams have clearly started to drive the engine quite hard when off throttle, to keep the diffuser fed with a constant exhaust flow.

Now the FIA have stepped in to limit this effect. Although initially scheduled to be in effect from this weekends Spanish GP the change will now take effect after Canada. This clarification is based on Charlie Whitings changing opinion of how these mappings are used. At first some mapping was allowed, but these increasingly aggressive and fuel hungry mappings are changing the engines primary purpose. Effectively when off throttle the engine is being used purely to drive the aerodynamics, this contradicts the regulation on movable aerodynamic devices. Although this is a vague interpretation it can be justified.

What is now required is that the engines throttles (at the inlet manifold) must be closed to 10% of their maximum opening when the driver lifts off the throttle pedal. Unlike in most road cars, in an F1 car the engines throttles are not under the direct control of the driver via the pedal. The throttle pedal is instead the drivers method to request powertorque, the cars SECU then controls the level of throttle required to meet the drivers request. So as the driver lifts off the throttle pedal, he is no longer requesting powertorque and therefore the throttles should close. what happens with these EBD mappings is that the throttles remain open, Fuel continues to flow then the delayed spark from the plugs sends the burning charge down the exhaust pipe.

Now with the throttle closed to 10%, the amount of fuel that can be burnt will be limited and thus the blown effect will be reduced. so drivers see will a bigger variation in downforce as they modulate the throttle pedal, making the car less predictable to drive.

Blowing the exhaust under the 5cm of outer floor (yellow) will be most penalised by the ban

All teams will be affected to some extent, however the more aggressive that teams have been with the exhaust position relative to the floor, then the greater they will be affected. From the start of the season Red Bull, Ferrari and McLaren have blown the exhaust at the outer 5cm of diffuser. this area is allowed to to be open and bow the exhaust gas under the diffuser for greater downforce. these designs will be most greatly affected by the clarification. Renaults Front Exit exhaust is also likely to be a victim of the change. Many teams have been developing Red Bull Style outer-5cm EBDs, such as: Williams, Lotus, Virgin, Sauber, While Mercedes are rumoured to be adopting a front exit exhaust. These may to need be shelved after Canada, in order to employ a less aggressive EBD.

Red Bull: Front brake ducts and wheel design

Posted on May 19, 2011 by scarbsf1

Since the start of the season red Bull have been running these complex brakes ducts on the RB7. The design varies between the front and rear, where as the front bake ducts used to be the more complex, the Turkish update to the rear ducts probably balanced their complexity.

At the front, the heated flow exiting the brake disc passes through the drum shaped duct via 9 angled vanes. These help direct the flow out of the wheel. Additionally there is a secondary outlet made into the leading face of the drum.

Feeding the disc is a solution also employed by Renault, where the main inlet scoop is allied to another inlet on the inside of the protruding vane. This creates a large amount of inlet area, but only requires a small scoop sitting out on the airflow inbetween the wheel and chassis, which should create less drag.

Red Bull started a trend in 2009 with wheel with a much shallower offset between the spokes and the outer rim of the wheel. This was partly to bring the spokes closer to the airflow to provide some aerodynamic benefit. Also the change created more space inside the wheel for the upright and potentially longer wishbones.

The current wheel design features 11 solid spokes, which have a slight “H” section to them. As the side faces of each spoke are machined with a small pocket to reduce weight. Its visible that the outer face of each spoke has sharp right-angled edge. However less visible in the inside face of each wheel spoke, features a generous fillet radius to help the streamline the spoke to improve airflow out of the wheel.

New "Vaned" wheel for Spain via @slitz (http://twitter.com/#!/slitz)

It is expected that Red Bull will feature more complex wheel design this weekend. This could either be a revised spoke design to work in conjunction with the brake duct vanes, or an even shallower offset to move the spokes closer the wheel rim or a switch to wheel with radial vane, as used by Ferrari and McLaren.

As soon as the wheels are uncovered, this post will be updated.

Red Bull – Pull rod suspension detailed

Posted on April 7, 2011 by scarbsf1

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/

Red Bull – KERS installation detailed

Posted on April 7, 2011 by scarbsf1

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/

The Flying Lap

Posted on April 1, 2011 by scarbsf1

If you havent already started to watch this show, I suggest you really should. Theflyinglap.com, is a webcast and audio download going out every Wednesday at 6pm UK time. Peter Windsor runs this show from a studio in London. He’s had guests as varied as Frank Williams to John Surtees, Willem Toet and Sergio Rinland on the technical side. The show is an hour of live F1 chat with journalist and people within F1, often with aftershow chat continuing for upto an hour after the live show. the show is then available from smibs.tv, youtube and available as a free I-tunes download.

I dont know any other source for such a long and in depth insight into F1, that goes out every week. I’ve made three appearances talking about the new rules, testing and post race analysis. I’ve linked to the latest one below.

http://www.youtube.com/watch?v=WA4SHUbZZig

Renault – Front Exit Exhaust Details

Posted on March 24, 2011 by scarbsf1

Although we almost didn’t believe it when the rumours emerged at the launch of the Renault R31, The car does indeed have exhausts that exit at the front of the sidepods. We (@f1fanatic.co.uk and I) managed to see, understand and get the first pictures of the unique set up (http://scarbsf1.wordpress.com/2011/02/01/renault-r31-front-exit-exhausts-fee-explained/). Now the car can be seen stripped in the pit garage, we can see exactly how the Renault packages the exhaust.

The exhaust system routes the four pipes into a collector which then continues to point forwards and direct the secondary pipe low underneath the radiator to the front of the sidepods. As the exhaust routes gasses at up to 1000-degrees C, it needs insulating to protect the other equipment housed in the sidepods. Renault appear to have fitted an insulated jacket around the main length of pipe in the sidepods. What is clear from the set up is that Renault had to raise the radiators to allow the pipe to ass underneath. The R31 has unusually large sidepod inlets and this might to cope with the ducting of the cooling airflow to the laid down radiator.

From these pictures via Andrew Robertson (@Jarz) we can see the front detail around the sidepods. Although the exhaust outlets are not seen here, the problem of the final routing is apparent. Teams need to fit beams to the side of the monocoque for side impact protection. Known as Side Impact Tubes (SITs) there are two pairs to share the load, with one upper pair and a lower pair. As these SITs are heavy, the majority of the work is down by the lower pair, to keep the weight low in the car. Correspondingly the lower SITs are larger and the exhaust needs to pass over these and down to exit sideways.

Renault has packaged these lower SITs into a narrow front and wider rear Tube. The exhaust will angle down along the front tube to blow still pointing downwards across the lower leading edge of the floor. We can see the metallic heat protection on the SITs.

More info on Front Exit Exhausts and how they work – http://scarbsf1.wordpress.com/2011/03/22/trends-2011-exhausts-and-diffusers/

Williams – Lowline gearbox in detail

Posted on March 24, 2011 by scarbsf1

Having been obvious at its launch the Williams FW33 has a radical shrunken gearbox case. Now we can see how the case is actually configured, which is close to the diagram I posted back in February (http://scarbsf1.wordpress.com/2011/02/10/williams-fw33-lowline-gearbox/). As I explained Williams sought to remove as much blockage ahead of the beam wing as possible, to do this they lowered the top of the gearbox, switched to a Pull-Rod set up and repositioned the differential much lower. The revised layout has lead to a very neat gearcase.

Nico / Slideways @ Autosport.com

To get a reference point for what we see in this picture, it’s the lower wishbone that’s fitted. This is usually mounted halfway down the gearcase and the top wishbone mounts above it. So what we are seeing is the casing dropping downwards from its front face to create a low flat top. It’s this front face that also gives an idea of how high a conventional gearcase is. So clearly Williams have lowered the case dramatically (see below).

Equally the differential (the diff’ circled above) is very low too, normally its several centimeters above the lower wishbone, now the diff’ is below the wishbone. This is why when we see the car from behind; we can see the driveshaft’s angle upwards from the gearbox at an extreme angle. Above the diff’ is the bolt on wing mount, as explained in my previous article, this metal structure supports both the rear wing and the top wishbone. One curiosity of the diff’ and wing mount set up is how the diff’ is removed. Normally the gearcase is split to allow the differential to be removed from the back of the case. Perhaps with the new Williams set up, the case has a cover over the left hand side of the differential and the diff’ is removed sideways. This set up would create a slightly stiffer case, critical for its complex waisted shape.

Not seen in this picture is the top wishbone, it mounts to the top of the bolt-on metal pylon and also to the pick up on the front of the casing (circled above)

Williams have also switched to a pullrod suspension, this places the rocker linkage and the dampers low down at the front of the gearbox. The dampers heave spring and inerter have to pass horizontally across the front of the gearbox; they enter the gear case via the aperture seen at its lower front side.

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

McLaren rear end: Exhaust, cooling and suspension

Posted on March 23, 2011 by scarbsf1

A ScarbsF1 follower in the Melbourne pit lane sent me these exclusive pics. We can see the McLaren stripped in the garage. There’s a huge amount of detail to take in, The key details are the missing exhaust heat shielding, cooling ducts and suspension detail.

We can see the exhaust system is missing in the picture. However there’s a lot of grey heat shielding around the floor giving us some clue to where the flow is going. Notably at the side of the engine where the main exhausts will sit and beyond exit to the sidepod. I can also see heat shielding above the starter motor hole, which is a rounded profile further suggesting this will be subject to fast exhaust gas flow. There’s a curious bulge in the tail of the coke bottle shape. This would be next to the exhaust collector and unlikely to be a good place for sensors, so it’s a mystery why this shape is there. So we can see potentially an exhaust route blowing out of the back of the sidepods, some of this flow passing under the gearbox to the starter motor hole. This seems innocuous enough, as long as the gas finds its own way to these areas. Continued rumours around the pitlane suggest bodywork is used to duct flow to these areas, which would be a contraversial solution. Only when the car is fully built and scrutineered will we fully know what the solution is.

As already explained in this blog (http://scarbsf1.wordpress.com/2011/02/16/mclaren-roll-hoop-and-cooling-arrangement/) the roll hoop fulfils several function for engine air feed and cooling. We can see the main airbox, beneath it the KERS cooler and its exit duct wrapping around the airbox. At the rear of the airbox is the gearbox oil cooler. The oval exit duct for this cooler isn’t fitted in this picture.

Lastly the pullrod suspension can be seen, the rocker and some of the springdamping set up is down low on the gearbox. A small detail is the shaft and rocker merging vertically from the gearbox, (beneath the silver pipe with blue connector). This might either be the heave damper or inerter, placed higher up for better access, or it might be the pre-load adjuster for the torsion bar (if torsion bars are fitted).

Trends 2011 – Exhausts and Diffusers

Posted on March 22, 2011 by scarbsf1

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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Everything Technical in F1

Category Archives: F1 2011

Toro Rosso: Radiator layout

FIA: Ban on Aggressive off-throttle Engine maps

Red Bull: Front brake ducts and wheel design

Red Bull – Pull rod suspension detailed

Red Bull – KERS installation detailed

The Flying Lap

Renault – Front Exit Exhaust Details

Williams – Lowline gearbox in detail

McLaren rear end: Exhaust, cooling and suspension

Trends 2011 – Exhausts and Diffusers