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.

McLaren MP4-26 – “L” shaped sidepods

Airflow passes over the sidepod to the beam wing (yellow), while an undercut still directs flow the sidepod

With a lot of expectation around McLarens new car, the newly unveiled MP4-26 did indeed surprise with its sidepods. Termed “U” shaped by Technical Director Paddy Lowe, as the two “L” shaped individual inlets together form a “U”. As with other design elements on the McLaren these are almost directly opposite to what the rest of the grid is doing.

What the team have done is to shift the inlet for the radiators at the front of the sidepod as far outboard as possible, to allow a freer flow of air to the rear beam wing (the lower element between the tail lamp and the top rear wing). Typically teams place the inlet for the radiators as close inboard a possible, as this airflow is the cleanest and with the most energy. This allows the sidepods to cool efficiently and hence have smaller inlets for less drag. By placing them outboard the vertical inlet catches the turbulent airflow from the front wheel wakes. Its this messy airflow teams try to keep away from the car with the pod fins. While McLaren may have to have a slightly larger inlet to cope with the poorer airflow, the benefit is that the better airflow closer the centre of the car can now be directed at the beam wing. With the double diffuser banned, a larger proportion of rear downforce will have to come the from the rear wing.

Also by creating this shape inlet it means McLaren cannot have the deep undercuts in the sidepods, which other teams use to direct the airflow around the sidepod and over the diffuser. McLaren have still managed to keep an undercut, but this is much smaller and lower, at about the same as the bottom of the raised nose.

Packaging radiators and ducting into this shape is far more complex than a simple inlet. The radiators themselves have a stepped upper edge, the protruding section reaching up inside the higher “L” shape section of sidepod. This makes the duct that directs air from the inlet to the radiator much simpler.

It remains to be seen if this set up works better than conventional undercut sidepods for creating rear downforce. Others team would be able to recreate the McLaren “L” shaped sidepod inlets. Although it would require a significant change the radiators and bodywork, making it a major package upgrade and not a quick test. For those teams that have not already tried this idea in the past, they will certainly being giving it some simulation time over the next few weeks.

Ferrari F150 – Starter Motor Hole – Blown Diffuser

Picture co F1Fanatic.co.uk

Ferrari are amongst many teams that have placed their exhausts down low close the cars centreline. In doing this they are passing some of the exhaust gas through the starter motor hole in the diffuser to create more downforce. This solution was likely given the cars exhaust and diffuser layout, but was proven when Felipe Massa’s fire on the third day of testing showed the flames passing not only over, but also through diffuser via the starter hole. Given the rule changes this year, this solution is surprisingly legal.

Teams were using this legal opening in the diffuser last year for aiding their double diffusers. Using the opening as an extra slot to make the diffuser more aggressive, just as rear wings use more slots to allow them more angle-of-attack. Mid season in 2010 the FIA issued a clarification to reduce the size of the slot. This formally made it into the technical regulations for 2011 as article 3.12.7.

3.12.7 An aperture for the purpose of allowing access for the device referred to in Article 5.16 is permitted in this surface. However, no such aperture may have an area greater than 3500mm2 when projected onto the surface itself and no point on the aperture may be more than 100mm from any other point on the aperture.

It doesn’t state or prohibit what else the aperture can be used for, just its maximum surface area and width can be. A rectangular slot would be 10cm wide and 3.5 cm tall, a simple round hole would be a 66mm in diameter.

As the FIA moved to prevent double diffuser, the loophole allowing opening the floor was also closed to the kind of open fronted diffuser as used by Red bull and latterly many of the top teams. With this change in the rules teams are limited in how they can blow the exhaust into the diffuser. Aside from Red Bulls exploitation of the outer 5cm of floor, the only other option is to blow some of the gas through the starter motor hole.
By pointing the exhausts along the sides of the gearbox the fast moving gas flow will pass over the top of the diffuser, when it hits the trailing edge and gurney flap it will help draw more flow underneath the diffuser.

Red Bull RB7 – Open Fronted Exhaust Blown Diffuser

When the RB7 was launched the cars apparent lack of any innovation was surprising.  Yet the car ran in its launch guise during the first day of testing.  Then, in only the tests second day, the RB7 evolved with a new diffuser and exhaust system.  Despite rule changes Newey has found the loophole that allows exhausts to blow inside the diffuser for more downforce.  Although the rules were revised for 2011 to try to prevent double diffuser and openings to allow the exhaust to blow inside the diffuser.  The rules did permit openings in the outer 5cm of the diffuser, an area where teams have recently split the floor and created raised lip, coincidentally a practice first exploited by Newey on the RB5.

In my 2011 trends and solutions post (see http://scarbsf1.wordpress.com/2011/01/27/2011-trends-and-solutions/) I proposed this area could be exploited if the exhausts could be routed there:  “ The only openings in the diffuser are the starter motor hole and a 5cm area on the outer section of floor. Exhausts could be routed to this outer section of floor, but routing the large diameter exhausts across the floor could create their own blockage effect in-between the rear wheels. Offsetting the benefit they are supposed to provide.”

It appears Newey had the same idea and has presented the modified RB7 with flattened exhausts reaching rearwards under carbon overs (shown yellow in the above picture)  these reach towards the outer 5cm of floor and blow under the raised lip in the floor.  The fast moving exhaust gas then curves inside and blows out via the sidewall of the diffuser (shown below with the red arrow).  Blowing inside the  diffuser this way helps accelerate the airflow out of the diffuser and increases downforce.  As with last years EBDs they will be sensitive to throttle openings and Renault have assisted as much as possible in accommodating the aerodynamics with a special overrun strategy, to keep the exhausts gas velocity as high as possible without overheating the engine (see http://scarbsf1.wordpress.com/2010/07/10/red-bull-map-q-the-secret-to-the-teams-q3-pace/).  Renault were also understanding in developing an engine mapping that would work with far longer secondary exhaust pipes, without losing power or drivability.

In a strange coincidence with the Lotus Renault team, the exhausts has been extended by up to 1 meter and equally has a flattened oval exit, with the central separator (http://scarbsf1.wordpress.com/2011/02/01/renault-r31-front-exit-exhausts-fee-explained/).

Renault R31 Front Exit Exhausts (FEE) – Explained



Renault have found a new solution to the blown diffuser concept. In fact they’ve turned it on its head. With an exhaust that exits at the front of the sidepods.

Last years teams reintroduced the blown diffuser concept, either by blowing exhaust gasses over the top of the diffuser, or by creating an opening into the diffuser to blow inside the diffuser. Both solutions created more downforce. With the latter solution now banned, it seemed the less effective over-blown solutions are all that’s left to race. However LRGP have found another way, blowing the front edge of the floor.

For a diffuser to create downforce it needs as much flow to pass through the venturi as possible. Teams arrange bargeboards and other aero devices to build up a high pressure region ahead of the floor to ensure the greatest mass flow underneath. Its then down to the expansion ratio of the diffuser to pull that flow through. Last years blown diffusers improved the expansion ratio, but not the flow ahead of the floor. What Renault have done in to lead the exhausts forward through the sidepods (about 1 meter) in-between the chassis and the radiators, then turn the exhaust 90-degrees to point it down towards the leading edge of the floor. The exhausts gasses follow the curved leading edge and round underneath the floor. This accelerates the flow under the floor for more mass flow and hence more downforce.


Problems with this solution are mainly to do with heat and engine mapping. With exhaust temperatures of 6-800c some clever insulation solutions are needed to keep hits heat from the fuel tank, radiators and a electronics. Then the Renault engine team lead by Rob White need to design exhaust tuning to deal with a far longer secondary pipe. typically longer pipes are better for low revs, somewhat contrary to the needs of an engine running at 18000rpm. Renault placed their KERS MGU and Battery underneath eh fuel tank, this was clearly to allow the packaging of the FEE. Unlike the McLaren F-duct, it is possible for this solution to be copied as no monocoque alterations are required.

Renault R31 – Launch Details and Analysis

What was formerly the Renault F1 Team and now Lotus Renault GP (I’ll use the term LRGP for this article) have unveiled their new car the R31. It seems some critical details are not fitted to the car for its unveiling, indeed the car was shown only briefly to the press before it was covered back up and returned to the garage. Despite the mystery surrounding the cars exhaust exit location, its clear this is a very new design for the team. In creating this the team were given a mandate to take risks, which probably explains the very different front and rear end treatments. But in packaging the chassis to take KERS and meet the new weight distribution rules, the car has altered only 50mm (longer) and the major masses remain in largely the same locations.

The Raised "V" nose and undersut sidepods are apparent

While James Allison talked up the risks taken with the car, parts which I’m told are yet to be seen on the car, the basic R31 is a step change from the designs of the R29 and R30. Firstly the low straight nose, complete with integral turning vanes has gone. This is replaced by a more contemporary highly raised “V” nose, with the underside of the “V” being particularly rounded and the concave upper surface continues all the way to the nose tip. Only a simple set of turning vanes are fitted amongst the front suspension, but there’s now a lot more space to place additional vanes under the nose. As with most launch cars the front wing is a variation of last years wing and will not remain as it is for the whole of testing. As with last year the steering rack has been placed low in line with the bottom wishbone.

A simple roll structure, albeit with a strange stepped bodywork line

Around the cockpit the be-winged mirror mounts seen on the wind tunnel model are not present, but LRGPs usual large pointed mirror pods are carried over. The sidepod fronts are highly unusual, the inlet shape has gone towards a “U” shaped inlet, rather the “P” shape used by LRGP for several seasons. Additionally the inlet features two peeks, similar to those used by Ferrari. The resulting shape is highly undercut and the sidepods lead back to a exit the tapers outwards to meet the floor, the bulbous coke bottle exit of the past two cars has gone.

The lowline rear end features downward tapered sidepods

Although small cooling outlets next to the cockpit are evident, there were no other apertures made into the sidepods at all. Their unusual tapered exit, created a wide low duct exiting across the top of the diffuser. This low line effect is further accentuated by the move to Pull Rod rear suspension, the engine cover being wider at the bottom and very low around the gearbox. A simple tall cooling exit vents at the end of the tail, with in this is the oil cooler fed by the F-duct-like inlets aside the airbox. For the wing endplates, LRGP appear to have followed a red Bull solution by joining the endplate to the top of the diffuser. Curiously LRGP have not used a rear wing mounting pylon, the exposed beam wing, sits on two supports to mount to the rear crash structure. Around this area the Titanium of the gearbox is exposed to the airflow. It appears as though the differential is lower this year, although Allison couldn’t confirm this. Compared to the simplistic Ferrari diffuser, the Renault under tray is far more developed. Starting narrow and sweeping out to the maximum width, the diffuser is complemented by several fences.

Amongst all of this detail no exhaust pipe is apparent, This is clearly one of LRGPs trump cards. I understand the exhaust does not exit at the rear of the car. This leaves few reasonable option for the pipes location. Either above the gearbox or increasingly rumoured the exhaust routes forward and exits in front of the sidepods. I presume the aim if this were the case, would be to pull airflow from under the nose to create some front downforce and speed the flow up back towards the diffuser. We are being told to expect new parts on the car for its first tests. These are apparently both the exhaust and some parts at the rear of the car.


Aside from the Pullrod rear suspension the main mechanical changes are to accommodate KERS, the Renault engine again having the nose of the crank coupled to spur gears to drive the MGU. The MGU and power control unit PCU are all mad ein cooperation with Marrelli.  While the Battery pack is mounted beneath the fuel tank area. The Renault engine has not had any dispensations this year to increase power. Only the normal changes to package KERS and resolve any reliability issues are allowed.

Sauber C30 – Launch Detail and Analysis

Now simply known as Sauber Motorsport the Team are embarking on their second as a born-again independent. Their new car, the C30 has been completed under the technical leadership of Ex-Force India TD James Key. James bring his experience from the budget conscious FIF1 team and its forebears JordanMidlandSpyker.  Aiding key are two Long term Sauber staff, as Christoph Zimmerman as Chief Designer and Seamus Mullarkey leading the aero dept.

Development was held back last year as the team focussed its resources on the new car, which first hit the wing tunnel in May. This switch in resource was partly the reason the exhaust blown diffuser was not developed in 2010. Their new car sports just such a device, with an interesting twist. Otherwise the car is largely a logical evolution of the already quite advance concept of the C29. With Key having sorted the Ferrari engine installation problems and the cars ride height sensitivity which blighted the teams early season last year, Now the team can expect a strong run in the midfield for 2011.

A slightly higher and "V" sectioned nose for the C30

Sauber went the right direction with the front of the chassis last year. So this C30 doesn’t look too different in this regard. The front end is slightly higher, with eh slight “V” section, while the nose cone is slightly wider. Current the turning vanes and front wing are carried over from the C29, so we can expect Sauber to also adopt some more typical concepts for these parts, especially the turning vanes which currently differ to the conventional shaped vaned adopted by most teams. Also the philosophy of evolving the monocoque extends the roll structure, the roll hoop is now supported by four pylons, creating an exaggerated undercut for better airflow to the rear wing.

New roll hoop now supported by four pylons

Either side of the tub, the sidepods now sport a slightly squarer profile, the inlets being “U” shaped rather than triangular as they were last year. Yet this bulkier shape still allows for a huge undercut, leading back to a slimmed coke bottle shape, which now ends with a vertical slit to allow cooling air to escape early, and also allowed the exhaust to exit close the floor and the cars centreline. Also aiding cooling is the enlarged exit above the gearbox.  While the top body exhibits no form of shark fin. Routing hot air out through here, keeps the tail of the coke bottle shape slim, for greater airflow over the diffuser.

Cooling exit over the gearbox keeps the sidepods slimmer

In fact the diffuser is not quite as simple as the first pictures suggest and during the unveiling the diffuser was covered with a tarpaulin. However, I was able to look down onto the top of the diffuser. Sauber have kept the gearbox and sidepods so narrow that they have created a channel between the outer tunnels, which the exhaust blows through. This would work the centre section of diffuser, which is typical struggling for airflow, by the lower ride height of the step beneath the car.

Saubers EBD points the exhaust into a channel and partly through the starter hole (yellow)

Exhausts close the cars centreline blow into a channel in the middle of the diffuser

 

Blowing the gurney flap on the edge of the diffuser and starter hole aid downfroce

Above this the on-trend exposed beam wing has been created by shaping the crash structure within the rules to bend underneath the wing. Currently the beam wing is a simple straight slot-less affair. This could be made work harder in conjunction with the blown diffuser, by adding a longer section in the middle 15cm of the wing.

Exposed beam wing is a big trend this year

Another rear wing aid to the diffuser is the addition of a series of vanes hanging below the endplates. These sit within a legal loophole in the rules, and effectively make the diffuser longer than the rules envisaged.

These vanes on the RW endplate help flow out of the diffuser

The upper rear wing, is adjustable and this system is known with the technical F1 staff as the ‘Drag Reduction System’ DCS. Saubers is a elegant solution to making the flap hinge about its trailing edge. A simple metal lever moves to open the slot gap up, reducing drag and boosting top speed.

The Driver Adjustable Rear Wing is known as 'DCS' Drag Control System within the sport

Mechanically the car retains the Ferrari drive train. So again the car will sport the Ferrari gearbox, which is a hybrid Titanium and Carbon fibre construction. Therefore Sauber will adopt Ferrari KERS and their inboard rear suspension geometry. Technical Director James Keys explained the pushrod mountings, place the hardware at the very front of the gearbox, this keeps the parts accessible, but does not affect rear aerodynamic volume. Key also confirmed Sauber have designed and built the suspension that attaches to the Ferrari gear case, while the Hydraulics and Electronics are all Sauber designed too.

Sauber continue to use OZ Racing wheels with hollow spokes

 

Drivers brake bias adjuster

 

Splitter detail

2011 Winter Launch and Test Schedule

Team Engine Car Date Location
         
Red Bull Renault RB7 Feb 1st  Valencia
Ferrari Ferrari F150 Jan 28th Maranello 
McLaren Mercedes MP4-26  Feb 4th Berlin 
Mercedes Mercedes W02  Feb 1st Valencia 
Renault Renault R31 Monday 31st Jan (12.00 CET) Valencia 
Williams Cosworth FW33  Feb 1st Valencia 
Force India Mercedes VJM04  Not until Jerez test  
Sauber Ferrari C30 Monday 31st Jan (11.15 CET) Valencia
Scuderia Toro Rosso Ferrari STR6 Tuesday 1st Feb Valencia
Team Lotus Renault TL11  Monday 31st Jan (06.00 CET) Online 
Hispania Racing Team  Cosworth  F111  Current car in Valencia & interim car at Jerez & F111 in Bahrain  
Virgin Racing Cosworth MVR02 Feb 7th London  
         
Testing        
Valencia February 1-3    Debut: Ferrari, Red bull, Renault, Mercedes, Sauber, Toro Rosso, Williams  
Jerez February 10-13    Debut: McLaren, Force India, Virgin  
Barcelona  February 18-21      
Bahrain  March 3-6