McLaren added these floor details (yellow) as part of the Barcelona update
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.
McLaren ran this vent with both a rear facing outlet and louvers
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.
try a simplified front wing and deeper sidpod fins, not visible in this pic, but they have new exhaust outlets too
NOTE: Update on McLarens SnorkelRear wing here http://wp.me/sNdA9-235
As McLaren continue to use testing rigs to map their cars aerodynamics, the importance of the snorkel on the top of the chassis is becoming apparent. On Friday The car lapped with an array of sensors attached to the rear wing. However, there was an additional sensor mounted inside the snorkel. Raising the question why would you want to test rear wing and driver cooling simultaneously?
This Snorkel, is an apparently innocuous looking part, which was at first believed to be solely an inlet to cool the cockpit. Several teams add similar inlets in this area to supplement the inlet in the tip of the nose. The cockpit houses the power steering rack, hydraulic lines and electronics boxes, so cooling is often required. However the initially simple inlet has been superceded by at least two more shapely snorkel-like derivatives each with an apparently unnecessarily complex double wall construction creating smooth narrow inlet and a streamlined outer surface. This snorkel has been present ont he car through out all the cold and wet testing sessions, suggestion its purpose goes beyond a simple primary purpose of cooling.
One rumour around the internet suggests the inlet is linked by a duct to the shark finblown rear wing. At first appearing to be simply a wild rumour, that the snorkel is blocked by the drivers knee to alter the rear wing airflow. However the presence of the airflow sensor along with the rear wing test rig, suggests there might be a link after all. The rumours suggest the drivers left braking leg, which sits unused on long straights could be used to alter the flow from the snorkel to the rear wing duct, where a valve alters flow through the blown slot to stall the rear wing. This would reduce downforce and also drag, which would allow a higher top speed. Then the driver moves his leg to start to brake for the next turn the valve switches airflow back to normal, the wings airflow reattaches and provides the downforce needed for the turns. This sounds both feasible and far-fetched at the same time.
It would be hard to link the rear wing and snorkel with any certainty, but any input from the driver that would alter the cars aerodynamics as the rumours suggest would certainly be an area of greyness in the rules and liable to protest come Bahrain.
McLaren again started the test with a aero test rig attached to the car. This time the array of pressure taps were affixed to the rear of the car, taking readings from the flow off the trailing edge of the rear wing. Flow Viz paint was also applied to the rear wing endplate to assess the surface around the vents on the upper front section of the endplate
In later tests Button ran the car without the snow plough device fitted under the nose.
Continuing their fight back from the MP4-24, McLaren are working hard with the aggressive looking MP4-25. Several aero tests were run during the last test, with some new details becoming apparent.
Their 2009 public testing of flow vis, the fluorescent paint used for surface flow visualisation, was unheard by the average fan before last year. Although this is in fact a common practice for teams. Used mainly in straight-line testing, but it has even been used in public testing.
Also using arrays of pressure taps is another common aero testing tool made public by McLaren last year. Again this year McLaren have used these tools in recent tests, the flow-vis being tried several times and the pressure taps early one morning in last weeks tests.
These are not necessarily the sign of a problem, as the tests are aimed at proving the simulation results (wind tunnel or CFD) are borne out on track.
Another tool commonly used and rarely seen are the tyre temperature sensors used in testing and often in Friday practice. McLaren have long since used tiny infrared cameras to measure the temperature signature across the full width of the tyre. In previous years these have been fitted in pods to the side of the cockpit or to the rear floor of the car. Now the cameras are so small land their range sufficient that McLaren fit theirs inside the wing mirror shells, pointing to each front tyre.
Small infrared cameras in the mirrors measure the temperature accross the full tread of the tyre
Details of IR cameras used in motorsport can be found at thermoteknix.co.uk
McLaren blown rear wing: The black line is fed by air fed through the airbox inlet and sharkfin
Still at the ‘unproven theory’ stage is the potential function of the supplementary air intake above the drivers head. This had been presumed to be purely to feed an oil cooler, but closer inspection suggests there may be another primary function for this inlet. Allied with the shark fin, the inlet appears to provide airflow to inside the rear wing. Creating a ‘blown slot’ to make the rear wing more effective. Similar to a concept used by BMW Sauber last year.
It looks like McLaren have opened up a slot in the back of the rear wing, this is visible as a blackline above the normal slot between the wing and flap. This slot is fed with air from the inlet and routed inside the shark fin and rear wing flap. The high pressure air exits through the slot and effectively makes the two element rear wing into a three element device. This allows the rear wing to angled more steeply without fear of stalling, thus creating more downforce.
Clues to support this theory is the way McLaren have closed off the inlet, an access hatch inside the shark fin, as well as the bulbous shape of the fin leading towards the rear wing.
As BMW Sauber set a precedent last year with a flap blown by an inlet in the front of the wing, this is a legal approach to circumventing the restriction on the number of elements allowed in the rear wing.