Mercedes GP W02 – Further diffuser changes at Spain

       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 .  

 

 pre Spain

  Spain , (all changes in yellow)

      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 .

  flow visualizing 

       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 .

Mercedes GP W02 -First major diffuser upgrade taking place before Melbourne

  Launch

 

    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 W02 – New sidepod inlets

 

Mercedes revised THE sidepod inlets to improve cooling efficiency at last winter test , with the sidepods having now a  circular inlet  .

 

 

Mercedes W02 – nose spoiler addition

 

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 .

 

 

 

 

Mercedes W02 – New front wing for second Barcelona test on March

 

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 .

Mercedes W02 – Refined car cooling configuration for Barcelona test

extra gills

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  .

Mercedes W02 – New set of Bargeboards for Barcelona test

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  .

Mercedes W02 – Modified exhaust layout at Barcelona March test

 

The new exhaust pipes are now shifted much forward from their former position, which was below the suspension elements . Later and during the testing a vertical fence ( in yellow arrow ) was added to guide better  the hot emissions towards the diffuser outer section , but not so direct like they did before .

The new exhaust layout is possibly connected to the way the new diffuser works and helped the team to build a bit slimmer rear zone .

Mercedes W02 – New sidepod Panels for Barcelona test on March

 

Part of the major upgrade package launched for Barcelona test on March was the full sized sidepod panels which replaced the previous very short ones . The new panels have a middle section leaning inwards to direct more air around the outer panel surface but retain the inclined outwards bottom section to divert as much air as possible inside the panel and around the sidepod bottoms towards the rear .

A comparison between the new panels of W02 and the latest spec of the W01 , which have an outward leaning middle section , reveals a shift in aerodynamic philosophy between the two cars .  A possible explanation is given by the fact that KERS reinstallation increased significantly the volume of W02 sidepods  making favorable airflow passing around the panels

 

W01

Mercedes W02 – New rear wing for Barchelona test on February

A new rear wing was tested at Barcelona on February  , with four horizontal endplate slits (No1) instead of three and triple flap separators instead of two (No2 arrow shows the central one while the two others are at the sides of the endplates). The central separator now has no role on moving the second flap like happened before .

The second flap , which is now smaller ,  has a boxy part close to the endplates (No3) which I suspect to house part of the flap angle adjuster mechanism and also to play  role on moving the flap .

 

Mercedes W02 – Rear wing (Launch spec)

 

W02 movable rear wing looks simple but effective at the same time .  The team exploits the two flap separators ( No1 ) to adjust the attack angle of the second flap enjoying a low drag configuration  .The  separators push the flap upwards , a motion helped by a rotation axis marked with No2 arrows . Housing the flap adjuster inside the endplates with the help of the flap separators to reduce the attack angle  and also making the main plane rigid enough made the mechanics to abolish any need of a wing centre pillar .

Mercedes W02 – Updated front wing for Barcelona February testing

 

W02 since now struggles for speed especially when cornering revealing lack of grip . To ease the problem , in the wait of major updates for the 2011 season debut , Mercedes tested a revised front wing at last day in Barcelona February testing . The revised wing had a slotted main plane to prevent wing stalling keeping downforce production high enough . Wing stalling  can cause sudden oversteer resulting time loss or even excessive  tyre ware . Pirelli tyres are proved to be  more susceptible to graining  than Bridgestone and teams have to pay special attention on keeping them in good shape .

Mercedes W02 – Technical specifications

Chassis

Construction: Moulded carbon fibre and honeycomb composite structure
Suspension: Wishbone and pushrod activated torsion springs and rockers
Dampers: Penske
Wheels: BBS forged magnesium
Tyres: Pirelli
Brakes: Brembo calipers
Brake discs/pads: Carbon/Carbon
Steering Power: assisted rack and pinion
Steering wheel: Carbon fibre construction
Electronics:   FIA standard ECU and FIA homologated electronic and electrical system

Transmission

Gearbox: Seven speed unit with cast aluminium maincase
Gear selection: Sequential, semi-automatic, hydraulic activation
Clutch: Carbon plate

Dimensions

Overall length: 4800mm
Overall height: 950mm
Overall width: 1800mm

Engine

Type: Mercedes-Benz FO108Y
Capacity: 2.4 litres
Cylinders: 8
Maximum: rpm 18,000 (maximum FIA regulation)
Bank angle: 90°
Piston bore: 98mm (maximum FIA regulation)
Number of valves: 32
Weight: 95kg (minimum FIA regulation weight)

 

 

credit: Mercedes GP

Mercedes W02 – Rear Zone & cooling options

1.Floor exhausts

2.Differential

3.Gills to aid cooling

The new regulations forced teams to ban multiple deck diffuser and put under rethink any diffuser exhaust blown configuration .  All teams including Mercedes to decrease the downforce loss caused by the previous mentioned changes put  all their efforts on slimming significantly the car end  to offer a cleaner airflow towards the rear . Mercedes even had to revert from push rod to pull rod rear suspension   . The exhausts are placed close to the floor and pointing outwards to blow the hot emissions towards the outer diffuser section , a solution might help also to heat the rear tyres  . Sauber instead exploits the engine starter hole to blow through the emissions to energize diffuser .

The body cover wraps so tightly around the internal mechanical parts , just like skin , making the team to open gills at the back to prevent overheating , as the single oval hot air outlet above the rear light was found insufficient to meet the cooling needs .  However some heat oxidized spots were observed at the back of the car , a sign to alert  mechanics to refine cooling treatment of the car .  Thus for the second pre season test at Jerez the team tried two alternative extra options seen below

Large slots above the radiators

small outlets at both  cockpit sides

An asymmetric configuration of the two options was also tested with the right sidepod featuring the larger slot above the radiators and the left one the small hole close to the cockpit , revealing that the oil radiator should be housed inside the right sidepod tunnel .

Mercedes W02 – Launch spec diffuser details

All 2011 diffusers must be single decked and look alike to the designs raced back in 2009 before the arrival of the multiple deck  diffusers .  Mercedes  W02 diffuser  has  two sets of vertical fences of different height  , which act like splitters dividing  the structure into two side tunnels  and a central section .  The central section is built wider so as to extract stronger the air flowing under the floor and close to the plank sides  to increase downforce production . The diffuser roof is surrounded by a high tab fence to pseudo increase the dimensions  of the diffuser opening  . I said “pseudo” because the actual size of the diffuser remains the same but airflow with the tab presence feels  the diffuser to be larger than actually is .

Finally the engine starter (in yellow) is reachable to mechanics via a rectangular hole in the centre also defined in size by 2011 rules .