This was my Tech Desk scheduled to be published after the British GP. For various reasons it was not published and I have copied here…
Round10 of this year’s championship, see’s an unplanned return to Silverstone after the developments at Donnington the intended venue failed to progress. Even with the short notice the famous Silverstone layout saw a major revision with a new in-field stadium section. Despite the new section being another fiddly low speed section, much like the complex of turns ending the lap, the fast turns remain a key feature of the track. As a result the track demands high downforce, but also a high level of aero efficiency as the teams cannot afford to lose too much speed on the straights. With the demand on a mix of low speed grip and higher speed turns, the race saw the debut and return of several F-duct and blown diffuser solutions. Additionally several teams brought major development steps to their cars for this weekend, in expectation they will also provide gains at the forthcoming races. Being an aero dominated track usually demands a stiff suspension set up, but the transition between the old track and the new section produced some tricky bumps and steps in the surface, especially affecting the braking areas.
Caption: McLarens blown diffuser placed the exhaust low and wide, making the sidepods extremely small.
McLaren brought forward their developments originally scheduled for the German GP; this consisted of a new front wing and the Exhaust blown diffuser package. Both cars were equipped with the comprehensive package of parts that make up the blown diffuser, floor, sidepods, exhausts and heat shields were all specific to this set up. McLaren’s iteration of the blown diffuser is similar to Ferrari and Renault solution, repackaged exhaust blow low down over the diffuser. The effect at the diffuser exit as the exhaust passes over the gurney flap is to help extract air form under the diffuser, effectively making the diffuser think it’s bigger than it is. In McLarens case the exhaust is placed quite far outboard from the cars centreline, this probably allows the flow to pass into the low pressure area behind the rear wheels for a reduction in drag. With the exhaust exits now low down the large fairing that wrapped around the exhaust to aid cooling no longer exists. With the unusually warm British weather the fitted new optional cooling outlet sin the similar position to the old exhaust outlets. These used the Ferrari trick of slotting the louvers together to create the regulatory single exit. Coping with the heat of the exhausts the lower wishbone was fitted with a carbon heat shield and this along with large parts of the diffuser were given a silver heat reflective Zirconium coating.
In practice the blown diffuser set up complicated what appears to be stability problems for the MP4-25′s, in the corners where the old track met the new. The car was unsettled by the bumps and steps in the road, frequently running wide on the exit of these turns. This instability is probably not caused by the blown diffuser, but rather the stiff set up McLaren have preferred to run this year. Regardless the blown diffuser was removed from both cars after second free practice and replaced with the normal top bodywork.
Although the diffuser was dropped the new front wing was retained for the whole weekend, it was a completely new wing and a very different philosophy from that seen before. The wing is effectively split into two sections each side, the outer section sitting n front of the front wheel, which is split from the inner part of the wing via a fence. Presumably McLaren are trying to boost the efficiency of the inner wing whose wake is unaffected by the front tyres, then leaving the less efficient outer portion separate.
A number of updates to the RB6 were tried over the weekend. Grabbing the headlines for non technical reasons was the revised front wing, but there was a revised diffuser and a new f-duct set up was also tried on Friday. The new front wing consisted of revised nosecone, wing mounting pylons, wing elements and endplate. While the wing itself was a similar three element to recent iterations of Red bull wings, the endplate now sported larger slot in its side to expose the two slots formed between the main plane and the flaps, this aids the airflow being directed around the front tyre. also new was the position of the FOM camera pods, having been mounted hammer head style since the cars launch, they are now mounted almost siamesed between the front wing mounting pylons. This places them above and behind the wings neutral centre section. Force India tried this set up briefly but has never progressed with the idea. What the camera position is trying to do is the negate some of the lift the neutral wing section creates, but mounting the equally neutrally shaped camera pods in a cascade with the wing; they may actually act more like a wing. Although the nose cone is a primary crash structure and thus its design homologated for the year, team ‘skin’ retain areas of the wing allow small shape changes without having to request re-homologation. So red bull were able to alter the camera mounts without any legality issues.
However of the two wing assemblies that were manufactured, the set up on Vettels car failed in final practice. It appears that the pins that locate and secure the nose cone to the front of the chassis failed, allowing the wing to droop and scrape along the track. With only one spare nose cone there became the political issue of which drivers uses the set up for qualifying.
Other developments on the car were the diffuser. This has now gained a second slot. This is in addition the vertical slot that allows the exhaust to blow into the upper deck of the diffuser. This new slot is horizontal and outboard of the first one and feeds directly into the side channel of the diffuser. By blowing more of the exhaust inside the diffuser, there is greater scope to create more downforce. However this could possibly come at the cost of sensitivty to throttle position, so Red bull must have judged the design carefully to ensure is does not upset the balance of the car.
Also for Silverstone was a revised high pressure feed for the F-duct. In its initial form the F-duct used a section of the main inlet snorkel above the drivers head. This would have stolen some airflow intended for the engine, potentially costing some power on the open throttle sections of track. so the team tried a separate inlet taken the right hand side of the roll structure, this scoops feeds the fluid switch inside the ducting, sending its flow either to the slot in the wing or the outlets placed in the tail of the engine cover, depending if the driver has the control duct covered. In testing this new inlet, the team sprayed flow viz paint on the bodywork to track the surface airflows.
Caption: All new top bodywork brought a blown diffuser and revised F-duct, while the roll hoop oil cooler was closed off
Following on from the major front end updates seen at recent races, for Silverstone Williams brought their next batch of upgrades mainly focussed on the rear end of the car, although new front suspension geometry was also fitted. Primarily the change has been to fit a blown diffuser, but the team have also made change to the F-duct, brake ducts and some drag reducing changes.
Of all the teams adopting the blown diffuser, Williams have been the only team to closely follow Red Bulls design. The shape and position of the low exhaust exits closely mimic the RB6 design, admit technical director Sam Michael “Ours is most like the Red Bull when you look at the exhaust exits and how we are working the diffuser”. However what’s not clear so far is if the exhaust flow enters the diffuser via the small window or simply flows over the diffuser. unlike McLaren Williams retained their low exhausts fro the race, the team having to make some changes to the car to keep parts cool and in position, the additional heat shielding and bodywork stays cost the team a half a tenth in pace according to Sam Michael, but he felt this would recouped by the time the car was revised for Germany. The team also hope that cosworth will be able to develop a reliable Q-mapping, again similar to the Red Bull solution, where the engine mapping alters under braking to keep exhaust gasses flowing over the diffuser.
Along with the new top bodywork to accommodate the low exhausts, the F-duct was altered, unlike other teams this is a low pressure solution, there being no high pressure feed from the airbox inlet. Also the airbox area has been tidied up, with the distinctive secondary inlet for the oil cooler, being closed off for this race, as a drag reduction measure.
Returning with their exhaust blown diffuser in slightly revised form, Ferrari’s major development was a new front wing. This new wing sports three profiles, over the two favoured by Ferrari all season. Additionally the profile of the main plane kicks upwards far more aggressively where it meets the endplate, although the endplate philosophy remained the conventional endplate and vane arrangement first seen on 2009. As Alonso has completed his fourth GP with the same gearbox, he was able to upgrade tot he same specification as Massa first used in Valencia. This new casing repositions the lower wishbones to suit the lower exhaust position. Both the exhaust outlet and the heat shielding were subtly revised for Silverstone, the exhaust outlet being chamfered slightly and the Heat shield on the floor directly behind it now being a separate item to allow some protective cooling flow between the floor and the shielding.
Caption: Lightweight bodywork, was both slimmer and covered a package of lightweight internal parts
As announced by the team, Lotus arrived with a major update package to the T127. Visually this largely consists of new sidepods, although more importantly it also incorporated a new diffuser and a host of weight saving measures. Firstly the new sidepod package keeps the same internals, but the top body has been considerably slimmed, especially to the coke bottle shape near the exhaust outlets. Also benefiting the more aerodynamically efficient bodywork the top bodywork section is now in one piece and lighter than the multi piece solution used up until this point. Mike Gascoyne also confirmed that further weight savings’ come from the radiators “The same rad’s can be fitted but we are also running a lightweight radiator package this weekend” adding “We are running lightweight bodywork, rad’s, uprights, chin etc”. This weight saving is critical as it allows the car to run more ballast to tune the mechanical set up of the car. This weight saving is in itself difficult as the team run a fixed specification; engine and gearbox, as well as homologated monocoque and crash structures. Looking forward the team have already stated their focus will be on the 2011 car now, but there remain some updates in the pipeline, as outlined by Gascoyne “we still have Titanium wishbones, composite ones will come in 2 races” then “There will be final aero updates for Spa and further lightweight parts”.
Caption: virgin brought an all new front wing, with Red Bull-like endplates and low mounted camera pods
Having had to devote time earlier in the season to resolving the fuel tank issue, Virgin have taken some time to reach their first major performance developments to the car. For the British GP, the team brought lightweight parts, a new front wing and turning vane changes. Much like Lotus, the parts designed to go on the car for the early part of the season, have now been reviewed and lightened. Creating more opportunity to lower the centre of Gravity and weight distribution, via the addition of ballast. Their front wing is a very different solution to their launch wing, being vaguely Red Bull-like, with a full size endplate aided by two slots. Even the inner edge of the endplate gains a tiny aerofoil as Red Bull has run for two years.
Then taking a cue from Mercedes, the team have placed their FOM camera pods low down behind the front wing to gain additional aero effect.