Further updates on W02 pushed diffuser development into a new step to cope better with new aerodynamic needs of the chassis . The new diffuser not only has a new shape but is also built differently allowing the abomination of the metallic cables which increased rear floor-diffuser stiffness , offering a cleaner path and less obstacles to airflow .
The crucial central zone of the diffuser is modified to the former boxy launch version .Nevertheless it is not identical to launch spec as changes took place especially on the engine starter holes. Additionally the longer fences which separate the central zone from the side tunnels now have a leaning inwards attachment on the diffuser roof to restrict as possible mixing of the flow coming from the centre with the one coming from the sides tunnels leading to wicker vortexes formations and thus less drag .
The power of the diffuser to pull air from under the floor is also strengthened by the higher square tab fence under the rear crash structure which extends up to the light .
As regards the exhaust pipes,they are placed since China a bit outwards combined also with new rear floor fences , both causing diffuser roof to regain back the side tabs but of a smaller width this time compared to launch spec . The side tabs prevent strong mixing of hot air from exhausts, which aim now closer to the wheels , with cool air coming from under the floor . Any interaction between the two flows will create powerful vortexes which will be affected further by the wheel rotation leading to serious drag increase . Finally the endplates are supported on additional pillars onto the diffuser , not only to increase stiffness decreasing vibrations but also to isolate airflow coming under the beam wing from that coming close to the wheels .
During early testing W02 showed poor performance , being unable to challenge top teams ,thus Mercedes launched major updates before season kick start in Melbourne including new bargeboards , exhaust layout , front and rear wing , nose vanes , sidepod panels and rear end major modifications among of which a new diffuser .
Barcelona test on March , used in Melbourne
Speaking for the new diffuser it features double small vertical fences now and a new less boxy central zone to extract air from under the floor more efficiently . The new central zone forced the team to put under change the little hole which permit mechanics to enter the engine starter . Moreover the tab fence across the diffuser edge was restricted in length being cut off thoroughly from the sides ,a change triggered by the new exhaust layout, the new nose vanes ,the revised sidepod panels and bargeboards which in total changed the way air flows around the car body and towards the diffuser . Finally the beam wing which had a raised lower section close to the endplates is now flat, a changed linked to the increase in number of the rear brake winglets (will be analyzed in another post) and an additional winglet is placed over the rear structure to generate more downforce (all changes in yellow color pointed with red arrows) .
All changes paid off as the pace was improved but yet could not match the top teams both in qualify and race conditions .
Mercedes revised THE sidepod inlets to improve cooling efficiency at last winter test , with the sidepods having now a circular inlet .
At Jerez testing on February Mercedes added thin and long spoilers on nose box sides . The spoiler is almost parallel to the ground level and act as air stabilizer .
To increase further frond stability Mercedes used at second Barcelona test a new front wing based on the previous design as regards the flaps . Apart from the flaps themselves, the rest components of the wing including camera winglets and nose pillars are all changed to a significant or lesser extend .
Starting from the camera winglets (No2) , they are now located higher onto the nose box sides (a traditional approach) leaving their former position behind the neutral central flap ( an idea springs from Red Bull RB6) . The nose pillars (No1) are wider close to their bottoms to increase the quantity of air passing through them towards the rear . The cascade winglets (No3) are now doubled to provide extra downforce , with the larger winglet to be significantly different from the old one, having now a steeper attack angle and an inner endplate . The wing’s endplate floor (No4) has a greater venturi channel to speed air under it , while the trailing edge of the endplate has a deep cut in its middle (No5) to create a strong vortex around the outer wheel profile aiming drag reduction. Finally the wing retains the slot on the main flap ( No6) , a slot that can easily be sealed by a solid piece in some occasions altering the wing’s characteristics according to each track needs .
To solve any cooling issues mechanics added extra gills located behind the Petronas logo just above the new exhaust layout . The gilled bodypart can be easily removed and replaced by a solid piece of bodywork in cooler conditions to favor aero efficiency .In an attempt to improve airflow above the sidepods the former openings close to the cockpit sides were replaced by gilled slots .
The new bargebords shown at Barcelona on March have a new saw-tooth upper profile towards the rear to cut turbulence and furthermore their leading edge now inclined outwards instead of inwards to divert more air towards the sidepod bottoms . The new bargeboards alongside with the new nose vanes and full size sidepod panels aim to feed the new diffuser, also launched on Barcelona, with upgraded flow of air and generate extra downforce .