My Technical review is now online at Automoto365.com. With the latest updates across the grid.
My Technical review is now Racecar Engineering Magazines Website. With News on the Ferrari, Renault and Mercedes blown diffusers, Red Bulls and williams Vaned double diffusers, Everyones f-ducts and all the new bits on the cars including Ferrari, McLaren, Renault and Williams.
My work also gets published along with other technical motorsport articles in each months Racecar Engineering Magazine…
At the start of the Monaco Race, McLaren had a rare engine failure. This was not a problem with the engine itself, but caused by a procedural problem on the grid.
Before setting off for the grid the car is warmed up in the garage and the driver often completes several laps, cutting through the pit lane before finally parking on the grid. By this time the car is fully up to temperature and needs fans to keep the car cool. In the case of the engines radiators and oil coolers, this takes the form of fans inserted into the sidepod inlets. Fans pass cooling air through the radiator cores to cool the engines fluids.
For McLaren their sidepod fans comprise several parts, an external fan which feeds into convoluted tubing to a carbon fibre duct, this has the option of a tray of frozen nitrogen being inserted into it to further reduce temperatures. This then is inserted into a rigid foam block that is squeezed tightly into the sidepod inlet itself. Other teams have electrical fans fitted into similar carbon mouldings, these are all in one piece and when removed nothing can be left behind.
What happened to McLaren in Monaco, and this was partly shown by the FIA TV feed, that the mechanics withdrew the ducts and tubing, but on one side the foam black was left stuffed in the sidepod inlet. This was obviously missed by the mechanics, but was brought to their attention by the BBC TV pit lane reporter Ted Kravitz. By then it was too late and the car had to complete the formation lap and start the race with the block still in. The team were obviously anxious, but the block does have a hole through it, so some cooling airflow was getting through. With the safety car deployed on the opening lap and the pit lane closed, Button had no choice but to circulate a low speed, with the engines temperature slowly rising until steam could be seen spewing from the sidepod.
Although this was a rare error, as the car has these fans fitted when it pits during testing and free practice. One still wonders if McLaren will revert to a one piece design or tighten up the grid procedure to prevent another similar situation arising at future races.
It’s rare to see the paperwork that the engineers or drivers look at in their pit garage. We can see Hamilton in Friday practice reading two traces from similar laps with different tyres (Used prime and new prime). What is interesting is that the print out states the fuel weight is 140kg for both laps. This must be near the race-fuel weight and the car is reset with the same weight of fuel for each practice lap to allow for direct comparisons.
How they work, by Racecar Engineering magazine with my illustrations
As McLaren set the car up for first practice, they appear to have new pod wings complete with mirrors. This is an aerodynamically benefical location for the mirror, McLAren have been late to try this set up out. Drivers do say the rearwards visibility is compromised, although there is a FIA static test for the quality of the drivers rear view. Both types of mirrors are mounted with infrared tyre temperature cameras, so we can expect to see the team to alternate between the options in free practice.
Although some aero devices were deemed legal in Bahrain, the FIA scrutineers did take a different view of some teams starter holes. This hole is allowed with in the rule to be in the diffuser in order to alow the starter mechanism to be inserted. Normally this is a simple round hole, but some teams have expanded the hole into a much wider ellipse shape. This effectively makes the starter hole an extra slot to alow the diffuser to be steeper and create more downforce. The Scrutineers have asked for these designs to be changed before the Australian GP.
It has now emerged from comments by Martin Whitmarsh to Autosport.com that McLaren do indeed have a link between their rear wing and the snorkel on the top of the chassis. While a link between the two parts emerged during testing as they were both fitted with the same aero testing set up, it is only now that the full picture has emerged. Using the driver to interact with the snorkel feeding the rear wing and its attendant slot, the wing can ‘stall’ increasing straightline speed when the driver needs it.
How its done…
The snorkel on the top of the chassis feeds a duct passing down inside the footwell, its position is some where around the pedals, most probably it runs down alongside the brake pedalfootrest so as to avoid the mandatory padding inside the cockpit. This duct has a ‘hole’ in it to ‘cool’ the driver inside the cockpit. However the duct continues inside the chassis, past the fuel tank and up and over the airbox (probably passing by the hatch fitted high up on the engine cover), then through the shark fin and into the rear wing flap.
When the driver places his footleg over the ‘hole’ the flow is diverted into the rest of the duct and this feeds the slot on the rear wing flap. There is enough airflow through the convoluted duct to disrupt the airflow under the rear of the wing, effectively breaking up the flow around the wing. This is what F1 aerodynamicists term a ’stalled’ condition, although this is different to the term ‘stall’ used in aeronautical aerodynamics. In this ‘stalled’ state, the strong spiralling flows coming off the wing, that lead to the huge drag penalty a highly loaded F1 wing incurs, break up. With out these flows and their resulting drag penalty, the car is able to get to a higher top speed, by around 3-4kph.
When the driver is ready to brake for the next corner, he releases footleg and the airflow passes back into the cockpit and the rear wing flow reattaches, creating downforce and its attendant drag. In this format the car can lap normally with its wings delivering maximum downforce.
This set up is legal as the rear wing slot in itself is legal (used by McLaren, BMW Sauber last year). There is no specific working to prevent wing stalling in the rules. There are no moving aerodynamic parts, except perhaps for the drivers footleg. It’s a piece of interpretive genius, but perhaps as far removed from the spirit of the rules as you can get.
Of course now its deemed legal, teams can either formally protest it or adopt it themselves. Doing the the latter is possible for most teams, as they have apertures in the footwell area to fit a snorkel, while the shark fin and rear wing are easily created. But, finding a route for the duct out of the tub might prove the headache, as the monocoque may not have any openings sufficiently large enough. This year the monocoque is also is subject to homologation and hence cannot be altered until the 2011 season. Of course ‘where there’s a will, there’s a way’, teams will not want to lose a straight line speed advantage.
Correction the diffuser has again appeared in its full guise in FP1, we all make mistakes…!
Incidentally McLaren arrived with major revisions around the rear of their car. firstly the diffuser shown in the pitlane for scrutineering was devoid of the upper deck bodywork that extended to the beam wing. this slotted panel effectively stretched the diffuser into a longer and higher device for more dowforce. While the diffuser below this panel is the same version as McLaren ran late in their testing programme. above the diffuser the crash structure and slotted beam wing remain the same, but the added duct to vent the oil cooler has gone.
McLaren ran a variety of new details on the MP4-25 in Barcelona, which included this new duct in the floor. Sitting just ahead of the tyre, this lets air pass from above to below the floor, which then passes the coved section of florr beside the diffuser. The coved (ridged) section was first used on the RB5 and has been copied by several teams. However so far no one has gone as far as McLaren in makign the top deck of the diffuser reach up as far the full width of the beam wing. McLaren have even added a slot to this section to keep the flow attached.
Additionally the team ran with different cooling outlets by the cockpit, some of these featured both an rear facing outlet and louvers along its top and side surfaces.