Williams – Rear wing mount and reports of lateral movement

Williams have a unique rear end set up, with the rear wishbone and rear wing mounting to the same pylon. In early tests other drivers and media suggested the rear wing moving laterally and this was related to the lack of stiffness in this pylon. However Sam Michael has refuted these claims and looking at the rear wing set up, you can see where the movement came from.

Due to its low gearbox casing, the rear leg of the top rear wishbone mounts to a vertical metal extension of the gearbox. The structure then continues vertically in the form of a carbon fibre strut, which mounts the top rear wing. Normally teams will also support the beam wing with sizeable mount to the top of the rear impact structure. As part of Williams ‘waisted’ approach to structures at the back of the car, the beam wing ‘floats’ above the impact structure. Thus aero loads from this device pass upwards through the endplates into the top rear wing and consequently into the vertical pylon back to the chassis. In early tests the endplates were not able resist the lateral loads the beam wing exerted on the assembly and as a result the lower of the wing moved laterally. Williams had already accounted for this with a small metal stay (illustrated – yellow) between the vertical pylon and the beam wing. Such were the cornering loads around Valencia, this was unable to steady the wing. So Williams added links from the endplate to the diffuser. This greatly reduced the movement and no negative comments have merged about the structure around the back of the car since.

Renault R31 – Cooling solution and diffuser performance

Renault are not only unique in their exhaust location, but also their sidepod cooling set up. Its possible that the two solutions are related.

Teams have to find the most efficient way to vent hot air from within the sidepods. This air has to pass through the radiators and coolers, as it passes from the sidepod inlet to the tail of the coke-bottle shape. In order to keep the car as slim as possible for reduced and drag and better airflow to the diffuser and beam wing, teams adopt different cooling outlet solutions to work with the other aero flow structures around the car. In Renaults case the majority of the outlet area is in three places: a tall narrow outlet above the gearbox and two low and wide vents either side of the gearbox. We can see the gearbox oil cooler within the upper outlet, so some of its volume is used for venting this heat. Reducing its ability to vent air from the sidepods.

Renault appear to have chosen the two lowwide outlets in order to boost airflow to the beam wing. The compromise in doing this, is the airflow over the diffuser. Airflow over diffusers might be considered as unimportant, as its the flow underneath creates the low pressure and hence downforce. But with a restricted diffuser height , the use of directing high energy airflow over the top of the diffuser and its trailing edge gurneys, helps the airflow beneath. Effectively making the diffuser act like its larger than it is. With other teams, they use the exhaust gasses or very narrow sidepods to direct as much high energy flow as possible over the diffuser. In Renaults case, the airflow running along the floor does not flow directly over the top surface of the diffuser, as these wide vents are in the way. Some people have suggested the teams are directing the heated airflow from within the sidepods out of these vents and over the diffuser for greater aerodynamic effect. However the reality is different, the air coming out of these vents will be of low energy, having passed through the various cooler matrices. Thus its effect in aiding the diffuser is much reduced.

So why have Renault thrown away some aero gains in this area? Probably because of the exhaust solution, As the flow under the diffuser is accelerated by the exhaust gasses passing under the floor, the diffuser does not need the effect of airflow blowing over the top. Thus they moved to the sidepod outlets to this area and played better airflow over the beam wing.

So far no other team have gone for low wide cooling outlets, but equally contrary to the rumour mils no teams has adopted front exit exhausts either. It will be interesting if any team follows Renaults solution in either of these areas.

HRT F111 – Launch & Analysis

With just a day and half of pre season testing left to go, HRT finally unveiled their 2011 car, the F111. Possibly the team with the least budget and smallest technical resources, their efforts to find a chassis partner in the past year have failed to deliver. Thus its been left to the teams Technical Director Geoff Willis to build up a design team to rework the 2010 F110 chassis into a 2011 legal car. Willis worked with Paul White, a designer with long F1 experience in both teams such as Jordan and Honda, as well a stints as a freelancer at Super Aguri. Construction of the car has been sub contracted to the usual range of F1 industry specialists. Then the cars then assembled at Kolles workshops in Germany (Greding, near Ingolstadt).

I had already been told by Colin Kolles that the car is based on the 2010 car, with the only major structure carried over being the top half of the monocoque. But visually the the car is a mix of new details and shapes from the old car.

Certainly the nose appears different at first. But the strakes, camera pods and the revised wing mounting pylons do a lot to disguise the overall shape, but the nose cone shape itself seems to have been carried over. Beneath is a front wing that is all new, the main plane is larger and the flaps are simpler being a pair of elements stacked above each other. The cascades are also new, which along with the endplates appear to be inspired by the Brawn BGP001, Paul White being a long time Honda designer, perhaps brought these ideas to the team.

In general monocoque shape and with it the roll hoop and front suspension are visually inseparable from the 2010 cars design. Equally the front brake duct design appears to be carried over. Aside the tub, the bargeboards are new, being quite tall pointed designs taking over from the smaller serrated versions. Then the sidepods are largely new, albeit with inlets similar to the F110, possibly due to the crash structures being in largely the same places. But the sidepods undercut is far more pronounced and the coke bottle shape, now much lower and sporting a low exit for the exhaust pipe. HRT maintained their periscope top exit pipes through out last year and never developed a blown diffuser.

Allowing the sidepods to be slimmer is a Red Bull style bulged exit above the gearbox. This also highlights the vestigial shark fin on the top of the engine cover.

At the tail a new rear wing is complete with new endplates and a central mounting pylon. This in turn shows that the rear impact structure has been redesigned to both accommodate the Williams 2010 gearbox, the wing mounting pylon and also the differing needs of a single diffuser over the 2010 double diffuser. No detail of the diffuser is clear as yet, but as the exhaust appears to be simply a set up to blow over the diffuser, the floor is not expected to hold any surprises.

As the car sports Williams gearbox technology and the gear case from 2010, the car is duty bound to have similar inboard suspension geometry and pushrod springdamper actuation. In order to package the new gearbox, HRT will have had to alter the rear suspension linkages and possibly the uprights. Being a well developed and contemporary aluminium cased gearbox, the Williams rear is likely to be lighter than the outgoing Xtrac gearbox. Although HRT did not specifically suffer with hydraulics unreliability last year. The Williams set up is also likely to be far more reliable and well package compared to the 2010 set up. This weight and design resource saving fro the Williams rear end will no doubt aid HRT in designing the rest of the car and getting down to the right weight distribution and still have the small amount of ballast to play with.

As with the Virgin who also run the Cosworth engine, no KERS is to be installed in the car. Thus these two teams use a slightly different spec of engine to Williams, whose engine is reconfigured slightly for the KERS installation.

In summary the upgrade to the car appears to be a logical and quite far ranging upgrade, possibly no less different year to year than other budget limited teams. it’s a surprising fact that although teams make th ePR headline that the car is all new and only something mundane like the wheel nuts are carried over. Most teams do in fact re-use a lot of componentry from older cars. Looking at their parts list for the current car will see model numbers for some parts dating back ten years.
In 2010 the HRT car kept pace with Lotus and Virgin through out the year, albeit still slower but the gap never increased significantly. While their rivals had many updates through the year, with big steps at Silverstone, HRT were able to develop the set up of the car to maintain the gap. Notwithstanding the discontinuity of drivers. A big update from a pair of respected engineers should allow HRT to keep up to the tail of the pack. However, testing suggests Lotus have made a larger step up the grid in pace than Virgin. It may be that HRT only have one team to fight with this year.

McLaren MP4-26 exhaust – is the “U” bend a Front Exit?

 

MP4-26 - the "U" bend is visible between the diffuser and suspension

McLaren lead the way with innovations in 2010 with the F-duct, but they were late to debut their double diffuser and blown diffuser. In 2011 McLaren appear to be right on the tail of this year’s novelty the front exit exhaust.
So far in testing, the MP4-26 has been seen completing a diligent aero programme with the car appearing with two different format exhausts. One conventional set up which blows over the diffuser and another which appears to have a “U” bend in the system. This latter solution is believed to be a front exit exhaust as used by Renault (http://scarbsf1.wordpress.com/2011/02/01/renault-r31-front-exit-exhausts-fee-explained/).

But as yet there is no sighting of the actual exhaust outlet.

Last year teams started to blow the exhaust over or through the diffuser to produce more downforce. With the method of opening the front of the diffuser up and letting the fast moving exhaust blow inside the diffuser, being the most effective route for more aero grip. Rule changes for 2011 prevented teams opening the front of the diffuser up (aside from a 5cm outer section of floor). So teams are faced with either blowing less efficiently over the floor or finding a new way. Renault have exploited another way, by leading the exhaust forward and pointing it under the front of the floor. Blowing the exhaust at the leading edge of the floor effectively creates more flow under the floor, which in turn creates more downforce. This front exit is a good aero solution, but packaging the duct from the main exhaust to the front of the sidepod is difficult due to the space constraints within the sidepod and heat rejected from the exhaust duct itself.

MP4-26 the conventional exhaust exits at the rear and blows over the diffuser

With McLaren’s conventional exhaust the four pipes merge into the collector and the secondary exhaust pipe points backwards to blow flow over the ramped outer section of diffuser. This set up has been used on and off consistently through the test. It also appears to the baseline configuration. As a lot of the aero tests using pressure rakes, flow-viz and long runs, are being completed with the conventional exhaust.

MP4-26 with the conventional exhaust exposed, the "U"bends crease in the floor can be seen

However other tests have been completed where the sidepod is revised. The sidepod features a bulge at the rear of the coke bottle, the bulged section appearing to house a revised exhaust system. Looking from the rear where the normal exhaust outlet can be seen is instead a “U” bend of exhaust tubing. With this set up the exhaust exit cannot be seen. Although several photos of sensors and cabling around the sidepodsplitter have prompted some fans and media to propose they are exhausts. In my opinion no photo as yet exposed the real exhaust outlet. With both systems, the rear of the floor and diffuser are the same.

MP4-26: This is how the "U" bend exhaust might look

Knowing the “U” bend system exists, I’ve tried to find proof for a front exit. One bit of evidence is on the launch car, which was initially unveiled without bodywork. Clearly a lot on the car was missing, but the floor appears definitive enough and just below the normal exhaust collector was a crease in the floor. This niche moulded into the floor is in the same location as the bulge in the sidepod when the “U” bend is run. Looking at its shape, I’d suggest this is where the collector and secondary pipe sit when the “U” bend exhaust is fitted. We can roughly predict that the collector sits further outboard and a little lower. The secondary pipe then curves inboard and then forward under the branch of four primary pipes (see illustration). Of course from here we don’t know where the exhaust routes, so we can’t confirm if it does blow back under the floor.

MP4-26: this is the aero rake used to measure flow accross the floor

Amongst the various aero rake tests McLaren have run, some tests features a huge array of pressure sensors in a rig mounted behind the diffuser. A later test had a simpler rig, which passes the floor ahead of the rear wheels. Initially this system ran with a conventional exhaust, and then later the rake was run with the “U” bend. I believe the rake was used to look at the pressure distribution under the floor. The two runs were used to map the different between the conventional exhaust and the improved flow of the front exit. So this suggests they are running some form of front exit.

MP4-26: the aero rake and "U" bend being run simultaneously

So where is the exit? I’ve looked at every picture I can find of the MP4-26 and I have yet to see any evidence of the front exit. I do believe its there, hidden behind the bargeboards somewhere below the sidepod inlet, or routed inside the splitter and blowing backwards. Other journalists at the Jerez test have confirmed some form of exhaust exit appears to be in there, kept out of sight both by other bodywork and the huddle of mechanics around the front of the car with the portable blowers to keep things cool when it returns to the pits. Also I’ve heard that the switch for one system to another takes 2 hours, which has reduced the McLarens track time.

But until we see a photo of the exit we can only speculate.

Notes:

This is not an exhaust

 

This is not an exhaust

 

This is not an exhaust

Red Bull RB7 – Sidepods and Cooling

When the Red Bull RB7 was rolled out, it was clear the car was a neat development of the RB6, but was not an innovative car. As with well developed cars like this, its details are well thought through, a particular case is the sidepod design. If you look at the RB7s sidepods, from the radiators back they appear to slope away to nothing. This leaves the distinctive flat floor and open area ahead of the rear wheels. This creates an obvious aero gain, but how is cooling achieved with such a tight design?

Firstly the sidepod forms the main blockage to the rear wing and diffuser. We’ve seen several approaches this year to manage the airflow around the sidepods to the rear of the car. In each case the team are trying to get the best and most direct airflow to the top of the diffuser and beam wing. As the better flow these devices receive, the more downforce they produce and the less drag is required from a larger rear wing.

Since the 2009 aero rules sidepods are extremely limited in the openings they are allowed, so most of the flow has to exit between the rear wheels. Normally sidepods send the heated air from the radiators back through the tapered rear (known as the coke bottle, due to its shape). In a simple sidepod this means the coke bottle ends with an opening and the hot air passes out and over the diffuser. However this makes the tail of the coke bottle unduly wide, which creates a blockage between the rear wheels and blocks flow over the diffuser. Red Bull discovered with the RB5 that the radiator airflow can pass up towards the centre of the car and exit above the gearbox in a bulged opening. This keeps the tail of the coke bottle nice and narrow.

With the RB7 Red Bull have taken this a step further, there is no appreciable exits in the tail of the coke bottle, so nearly all the radiator airflow ends up passing through the bulged outlet. This means the coke bottle is the slimmest and simplest of all the cars on the grid. Clearly the huge floor area and exposed beam wing show how easily airflow can reach the rear of the car. The concession Red Bull has to make for this benefit is the increased blockage in front of the rear wing. But as they are aiming for downforce from the more efficient diffuser and beam wing, the rear wings effectiveness is not such a concern. Other teams have similar low swept coke bottle shapes, but each of them still exploits some cooling exit at the back of the sidepod. Given enough testing a fully enclosed sidepod with the central bulged outlet could be copied.

McLaren Roll Hoop and Cooling Arrangement

 

McLaren have adopted ideas from other teams with the cooling set up for their MP4-26. With the return of KERS, having to package all the hardware and its cooling requirements is a challenge. McLaren want to reduce the volume within the sidepods for aero benefit, so anything the team can do to resite cooling to other areas of the car will be an advantage. Thus the team have developed a car with three inlets around the roll hoop.

Typically all the cars coolers are fitted within the sidepod and fed by air from the sidepods inlet. An F1 car needs to cool the engines water and oil, as well as the gearbox oil and the hydraulic fluid. KERS places an additional load as the MGU and batteries each need to be cooled (via oil and water). With the 2010 move to no refuelling, the fuel tank had to be increased in size. The bigger fuel tanks robbed the sidepod of space and the recent emphasis on airflow to the diffuserrear wing also creates a demand for smaller sidepods. Over recent years teams have fed the gearbox and hydraulics coolers above the gearbox and fed via different methods from the roll hoop. Typically this is either a dedicated inlet (as per the Williams FW32, Force India VJM03) or by splitting the main inlet snorkel above the drivers head (Ferrari F60-F10).

McLarens 2011 solution is to provide a dedicated feed for each of the different cooling requirements. The engines main coolers reside within the sidepod, fed by the “L” shaped inlets. These vent partly through the rear of the sidepod and partly through the bulge in the tail of the upper engine cover. Equally the engines induction system if fed by the snorkel formed by the roll hoop, which leads into the airbox above the engine.

McLaren MP4-26 airbox inlet flow

Then McLaren feed the gearbox cooler with an inlet moulded behind the roll hoop, this leads down to the cooler behind the airbox and vents via a dedicated tube out the back of the car.

McLaren MP4-26 gearbox cooler flow

Lastly the KERS system is mounted beneath the fuel tank as one component. The entire KERS is cooled by a dedicated cooler mounted behind the roll hoop and under the airbox snorkel. This gets fed from air passing just above the drivers helmet and under the snorkel. From straight ahead the coolers aluminium matrix can be seen through the hole. Heat rejected from the KERS cooler then vents out the back of the engine cover.

McLaren MP4-26 KERS cooling flow

With all of these inlets McLarens reduced sidepod shape, has lead to some compromises. Which is has been to adversely affect the airflow approaching the centre of the top rear wing. Equally inlets create drag and McLaren have two additional inlets to account for. I doubt the cooling set up is a major differentiator between teams. But the different approaches do create some welcome variances in appearance between the cars.

Footnote:

Those little inlets inside the main ones are for cooling the electronics and hydraulics within the sidepods.  Most teams have inlets positioned just inside the main sidepod inlet.

Blade Roll Structures – Legality (Lotus & Force India)

Last year Mercedes GP surprised many with their blade style roll hoop. Rather than the rounded hoop with the engine air inlet snorkel formed in the centre, the structure was a single thin blade and the inlet split into two either side of the blade. There are several benefits to such a solution, the primary one being better airflow to the rear wing, but also weight and inlet tract length are likely secondary benefits.

Although meeting the various load and impact tests, many thought the set up was marginal on safety, primarily thought the narrow structure being likely to dig into soft surfaces such as gravel traps, reducing the effective height of the structure, with obvious consequences for the drivers head. When the new rules for 2011 were introduced, I immediately thought the regulation 15.2.4 intended to ban these structures, but the wording does not go as far as that. What the rule requires is that there is a minimum cross section for the structure. It transpires that the rules intent was not to outright ban these blades, but to ensure they had a reasonable cross section, to allay fears of a ‘digging in’ problem.

15.2.4 “The principal roll structure must have a minimum enclosed structural cross section of 10000mm², in vertical projection, across a horizontal plane 50mm below its highest point. The area thus established must not exceed 200mm in length or width and may not be less than 10000mm2 below this point.”

The rules mean when looking from above (vertical projection) a horizontal projection 50mm below the top of roll hoop must have a cross sectional area of 10000mm2. Which for a rectangular cross section, the blade would to be a minimum of 50mm wide, which isn’t too difficult to achieve. The effect of this rule is that the long very thin blade of the Mercedes is outlawed, but shorter and wider structures are still allowed.

Roll hoops have a series of load and impact tests to ensure they are strong enough to survive an accident. Historically a roll hoop has been a metal tubular fabrication, boltedriveted to the top of the fuel tank area of the tub. As carbon fibre became the choice for monocoques teams started to simplify the roll hoops, making a point or blade structures moulded into the top of the tank. Gordon Murray’s BT53 is the first example I can recall. Over subsequent years, Arrows and Benetton have tried pointed hoops, but since the advent of normally aspirated engines the roll structure has also formed the inlet snorkel for the engine, making blades less desirable. Rules initially mandated a maximum cross section to prevent huge inlets seen in the seventies. These rules appear to have been dropped from the regulations and there have been few regulatory requirements for size and shape of the structure. Aside from the demand for a slot to pass a sling through, should the car need to be craned away. As Monocoques are now homologated, the structural shape of the roll hoop cannot be altered during the season. Mercedes achieved this last year, by homologating the blade and later adding non structural bodywork to form the inlet snorkel. This add-on section being later removed to expose the blade. The blade used to be visible inside the inlet snorkel, even at its launch. A point to note is that although the roll protection has to absorb massive loads to pass the crash tests, it is not in itself an initial part of the monocoque. The carbon fibre tub is made up of several major parts, the top and bottom of the main shape, bulkheads and cockpit surround. But the roll structure is a separate bonded on part. Laid up separately and attached at the later part of the monocoques completion.

This year Both Lotus and Force India have adopted blade style roll over protection, both adopting similar layouts albeit different structural solutions. Mike Gascoyne was clear that the benefit on aero was marginal, but he insisted the prime benefit is also CofG height. Lotus have engineered their structure from composites, this in itself is quite unique, as even conventional roll hoops are made of metal to create the slim undercut shapes to meet the impactload tests. Albeit they are subsequently wrapped in carbon fibre, acting as both streamlining and structural reinforcement. As the blade shape is simpler, Lotus have been able to make the protection from carbon, this saving a weight and significantly removing weight from about the highest point on the car. Force India meanwhile went a similar route but their structure is a metal part, clad with carbon, although the weight comparison to the lotus is impossible, it would be fair to assume it is slightly heavier.

As Mercedes have moved away from this solution, it will remain to be seen if the blade will be a more permanent solution in F1 or just a passing fad.

Williams FW33 – Lowline gearbox

Williams said their new car would be aggressive, but at first look the FW33 seemed quite conventional.  Until the area above the gearbox is looked at.  In order to gain the maximum flow towards the lower beam wing, Williams have removed a large part of the gearbox case (as described in the below illustration shaded yellow) ,lowered the differential and reworked the rear suspension.

In fact Williams Design team have completely rethought the rear suspension and gear case. By going to a Pullrod set up, the rockers, torsion bars and dampers that normally occupy the space above the gearbox are sited low down at the side of the gearbox (see http://scarbsf1.wordpress.com/2010/10/10/red-bull-pull-rod-suspension-what-is-looks-like-how-it-benefits-aerodynamics/).  Without this hardware mounted so high up,  the area above the gearbox is just a void. So although it serves a structural purpose the stiffen the suspension mounting points.  If they can be sufficiently stiff, then this area can be removed. Thus with the Williams the air flows over the upper body and around the engine cover, the bodywork then curves in behind the engine and airbox in a sharp “V”.   There is then no structure to hinder the airflow, until the air passes around the rear wing support, which now doubles up as the top rear wishbone mounting.

To remove other elements in the air steam, Williams have removed the toe link from behind the driveshaft and replaced it with a “Z” link upper wishbone. The slim carbon fibre moulding acting as both suspension members.
Further lowering the rear end the differential is lowered as far as possible. The differential is driven from the cross shaft between the diff and the main gear cluster. The differential can effectively be at any angle pivoted around the centreline of the cross shaft. What Williams have done is to lower it as far as possible while still allowing the CV joints some consideration and the starter shaft to be accessed.  This does effectively make the gearbox slightly longer.

One fear from the outsiders point of view would be the structural efficiency of such a waisted design, especially the vertical spar, that supports the wishbones leg above the differential. Williams would either have to compromise weight or stiffness to make the design efficient. So despite the loss of a large proportion of the gear case, the gain may be offset by the penalty of added weight to make the remaining structure stiff enough.

This gearbox has been a long lead time project, Sam Michael told me the new case was planned as early as March last year and the hard worked CV joints and driveshafts are designed and made by Pankl. They have no worries about the set ups reliability, although the joints are installed with such an extreme angularity, that they would either rob power or reliability with a normal design joint.

So complex is this set up, it would be near impossible to copy during the season.  As this would require new rear crash structures which are now homologated.  Not to mention the lead time and cost involved in developing a new gearcase and driveshaft solution.

Toro Rosso STR06 – Double Floor

Scuderia Toro Rosso (STR) launched their car on the first day of the Valencia test. It’s significance has been somewhat lost amongst the fanfare of the front running teams cars and the innovation of the midfield runners. However the new STR06 deserves more attention, as it has some unique aerodynamic concepts that are drawing praise from other teams engineers. STR have been able to reduce the cooling and packaging demands placed on the sidepods. Thus with a smaller sidepod envelope, the team have revived an old concept from Ferrari, the double floor. This separates the sidepod from the flat floor of the car to improve airflow towards the rear. Pioneered by the Jean Claude Migeot while at Ferrari, the twin floor concept came about in 1992 for the teams F92A. Although not a success, mainly due to mechanical reasons, the car did exploit clever sidepods to improve flow over the diffuser.

Diffusers are limited in length and exit height, as such there is little that can be done with their internal geometry to create a greater volume for more expansion-ratio and hence more downforce. Teams realise that driving more airflow over the diffuser not only creates higher pressure above, but can also drive airflow within the diffuser with aids such as gurneys on the trailing edge of the diffuser opening. The problem is getting airflow with enough energy to pass over the diffuser. To reach the diffuser, the air has a tortuous journey. Starting with passing over the front wing, under the nose and raised chassis, then over the splitter and around the sidepods, before sweeping in between the rear wheels and through the rear suspension. We’ve seen other solutions aimed at improving this path, such as the extreme raised nose, tight coke bottle shape and recently the undercut sidepod. It is the sidepods that create the biggest obstacle to the airflow, sidepods span some 30-40cm beyond the sides of the chassis and in order to package large enough radiators they tend to need the full width across a significant height, making the sidepods effectively a rectangular block to the airflow. If you could remove some of this blockage, especially low down then the airflow can head unimpeded to the diffuser. This is exactly what Migeot did with the Ferrari F92A and Ascanelli has done with the STR06. The Toro Rosso’s sidepods curl in backwards towards the monocoque along their full length, this space is evidenced by the large area of flat floor beneath the sidepods. Air passes under the sidepods directly to the diffuser with little to sap energy from the airflow.
With any advantage comes compromises, as it is the case with the double floor. These compromises being the space available within the sidepod and centre of gravity height. Space within the sidepod is already taken up by extra wide fuel tanks and various electronic boxes, not to mention in STRs case the rounded sidepod profile which further robs space. STR must have somehow been able to package large enough radiators to meet the Ferrari engine and KERS heat rejection requirements. Indeed at the first test the team soon blocked up the sidepod openings with moulded panels to reduce the inlet size.
Centre of Gravity height is clearly compromised, as the sidepods sit some 10-15cm higher than normal, This weight needs to be offset with ballast placed low down in the car. The increased minimum weight limit this year (640kg) will help, but conversely running KERS will not help in this regard. As with many of this years concepts, the double floor can be copied. As it does not impact on the homologated monocoque, although the teams side impact crash structures may not be optimised for this sidepod shape. Just as with McLarens “L” shape sidepod, any switch to this format would be a major undertaking. Which would also only be possible if the engine can cope with the downsized radiators.

Other details on the STR06 were the ducted exhaust outlets. On the cars initial runs the exhausts exited low and along the floor, contained within box like covers and blowing through long rectangular outlets. In later tests the car was tried with conventional periscope style exhausts, protruding through the upper part of the sidepod exit.

At the rear, the diffuser in interesting, STR have created a slotted gurney flap, air passes under and over the gurney for a greater effect in drawing air from within the sidepod. Perhaps a sign of the more powerful airflow now reaching the top of the diffuser. They have also exploited the middle 15cm behind the diffuser, this area does allow extra channels to be created, so STR have added a simple “U shaped diffuser trailing the main underbody.

Virgin MVR-02 – Exhaust Positioning

As the round of 2011 car launches nears it end, Virgin were the next team to unveil their new car today. Outwardly the MVR-02 is a simple evolution of the VR01, with every detail improved upon and developments that weren’t readied for last year have been applied (namely the EBD). In order to improve from last years reliability problems the cars hydraulic system has been subject to a lot of development and simulation. However this years must-have aid, KERS, is absent from the car.
One detail of note on the car was the exhaust system. Already the buzz word at every launch, the exhaust mates the simpler diffuser to help produce downforce. In Virgins case they have extended the exhausts to blow over the diffuser. Nick Wirth did confirm a Renault style front exit was simulated, but the more conventional approach has been adopted on the launch car at least.

Slim tapered sidepods allow the low-line exhaust the leave at the exit of the coke bottle shape and extend into the boat-tail formed by the underbody step. This is similar to Saubers idea, but instead Virgins exhausts diverge and blow over the mid part of the diffuser. To aid their airflow, fairings have been added the top of the diffuser; these direct the airflow onto a specific region of the diffuser, just above the inner pair of fences. These fences sit 50cm apart and thus can reach down to the reference plane, some 5cm below the floor of the sidepods. Blowing above these fences would pull air from the underfloor and also from along the underbodies step.

However the other design aspects of the MVR-02 suggest the exhaust outlets might be shifted once the car runs. Firstly the car has a well-shaped and detailed starter hole and secondly the inner face of the wings endplates are coated with heat shielding. Neither of these areas would directly benefit from the current exhaust positioning. So either Virgin will move the inlets inwards to blow partly through the starter hole or move the exits outwards to blow along side the wing endplates. As with most teams the exhaust positions will change and may even form a circuit specific set up, some exhaust exits being used for high downforce tracks and other for lower drag tracks.