Sauber: Rear Inboard Pull Rod Suspension

Sauber_suspension_module

With the shift toward pull rod rear suspension, the teams’ mechanics are faced with a maintenance issue.  As the pull rod reaches down into the gearbox casing, access to the transmission is hindered by the inboard suspension inside the gear casing.  Most teams maintain their transmission by first having to remove parts of the inboard suspension.  However the Ferrari engined teams have each found a neater solution to this problem.  Sauber use the Ferrari gearbox and also follow a similar practice of using a separate module to mount the entire inboard suspension in between the engine and gearbox.

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Monza: Rear End Analysis

One of the most insightful views of an F1 car is from the rear. From this angle we can easily assess the amount of rear wing, cooling, exhaust position\effect, suspension geometry and important elements of aero\diffuser design. At Monza this weekend XPB images kindly allowed us to show these images, which clearly show different elements of some of the cars running this weekend.

Ferrari


The F2012 has followed its own aero philosophy, so it looks different to many other cars from the rear. For Monza specifically we can see the low drag rear wing, much shallower than the usual rear wing and with the “V” cut outs on the trailing edge. Also for Monza Ferrari cut down the beam wing, the small amount of drag the beam wing creates is reduced by slimming the outer spans of the wing, to reduce the tip vortices.
Ferrari’s sidepods are laid out differently to other cars, most of the cooling outlet area is on the flanks of the sidepods, through the Acer ducts and in the area of the tail of the coke bottle shape. So when we look at the car from the rear, the central tail funnel cooling exit is not present. This design may hinder flow in the coke bottle area, but does leave far more airflow to reach the rear wing. Additionally several cooling vents are made in the narrow bodywork around the gearbox.
Around the diffuser Ferrari have gone further than other teams, with the aero parts around the perimeter. Teams often fit gurney flaps or flaps at the diffusers trailing edge to lower the pressure behind the diffuser and encourage more air to pass through the diffuser for more downforce. In Ferrari’s case the diffuser now sports two flaps above the diffuser, one lower down and the larger one above. This larger one is clearly visible, the lower one is mainly visible through the arched shaping. Having a two element design to this flap means it can be angled more aggressively to have a greater aero effect.


Along with trailing edge the flap the tall flap formed under the crash structure has also gained a two element design. Evident in this picture is the starter motor hole, the end of the shaft that the starter motor engages with is clearly visible through it, but although the starter motor shaft is round the resulting hole is far from circular. Teams exploit the ruling for this opening, by making the hole a blow slot to improve airflow through the middle of the diffuser. Rules dictate only one hole must be used and of a maximum surface area. In Ferrari’s case their two holes are joined by a small slit to make them effectively one hole. Most teams exploit this area in one form or another.

Lotus


In comparison to the Ferrari the Lotus is a more conventional shape with the sidepods, although the exhaust position is evidently different. As Lotus are one of the most successful teams to race this year without a downwashed exhaust solution blowing the diffuser. In the case of Lotus the exhaust blows into the duct formed by the rear wing. Cooling for the E20 is largely exited through the middle tail funnel.
For Monza this wing is very small indeed, the reduced drag helping the Renault powered Lotus reach higher top speeds on the long straights of Monza. Unlike other cars described here, the Lotus beam wing is not waisted away and also retains the taller flap exploiting free bodywork zone the middle 15cm of wing span. Also interesting to note with the tidy rear end of the Lotus is the extreme convergence of the wishbones where they meet the gearbox.


There are two distinct features on the E20 diffuser exit; the side exits and the trailing edge flap. Lotus expands the diffuser not only upwards but also outwards, such that the diffusers exit passes sideways out of the maximum 1000mm width allowed for the diffuser. This increases the diffusers expansion ratio, for more downforce, the trick being keeping the airflow attached to the aggressively shaped diffuser walls. Above the trailing edge Lotus fit a flap in-between the rear wing endplates.

McLaren


McLaren is very similar to Lotus with the conventional sidepod and cooling arrangements, of course McLaren exploit different exhaust positions, with the side exiting exhaust being downwashed to blow the side of the diffuser. The central cooling funnel has been augmented by two small outlets near the cockpit. These sit just inside the free area for sidepod bodywork, any further outboard and they would be subject to the strict rules on openings and curvature in the sidepod bodywork.


McLaren run a low incidence Monza spec wing, but this is not as slim as some other teams. Likewise their beam wing is slightly revised with the outer tips eased off to reduce drag they create. Below this the diffusers trailing edge is treated to a flap around most of its perimeter and inside the diffuser large single opening for the starter motor is apparent.

Red Bull


The unique shape of the RB8 is apparent in this image, the sidepods blend into the gearbox and rear structure freeing up airflow to the diffuser and beam wing. This is possible because so much cooling flow is ducted out of the central tail funnel. Although for the heat of Monza extra openings are created in the lower flanks of the sidepod. Drag reduction is aided by the beam wing being shorn of its central peak. Resulting in a “V” shape dip in the beam wing. Below the tail light a small electronic device with cabling emerging from it is visible. This is the back up timing transponder. The primary transponder to signal to the timing system sits under the nose of the car. Being mounted in the position, the transponder is exposed to potential damage, so teams fit covers over the device to protect it.

Timing transponder position as described in the Appendix to the FIA Technical Regulations

The exhaust position is clear in this image, the exhaust outlets despite pointing upwards, is actually diverted downwards by the downwash over the sidepods and the coanda effect of the sloping tail of the sidepods. These effects deliver the exhaust gas to the edge of the diffuser for a greater sealing effect. This sealing effect is critical as the Red Bull runs the car with a high rake angle, which is a low front ride height compared to the rear ride height. We can see the edge of the diffuser is nearly as high as the rear wheel rim; this rim is about 15cm high, so with the 5cm under floor step the rear ride height must be near 10cm.


Similar to other diffusers, the RB8 also sports an arched diffuser with a trailing edge flap. However, Red Bull curves the flap downwards over the arched sections, this results in a small flat edge on the flap above the arch. Due to the way the carbon fibre is finished around these flats, they appear like openings from some angles and have been mistaken for blown outlets. Lastly Red Bull continues to use extended rear wing end plates that form vanes behind the diffuser. While other teams have used this design, they have raised the bottom of the vanes to only sit in the wake coming over the top of the diffuser, not coming out from under it.

Williams


Aside from their waisted gearbox creating nothing but open space ahead of the beam wing, Williams follow many of the principles seen on the other cars in this article. The rear suspension geometry can be clearly seen with the near horizontal top wishbone and far less convergence in the top\bottom wishbones compared the Lotus. While the steep angle of the driveshaft’s shows just how low the differential is placed. In this picture the lack of cooling outlets on the Williams is apparent and very different to the Red bull & Lotus who run the same Renault engine.


For Monza the beam wing has been dramatically slimed down to reduce drag on the straights. While the diffuser sports a trailing edge flap and tall curved vertical gurney under the rear crash structure. Like many teams William paint the cover of the rear timing transponder in fluorescent paint to make is clear to the rear Jack man to avoid it during hurried race pitstop.

Analysis: Scoop-less brake ducts


For a few years now, teams have been extending the inner face of their brake ducts to reach forward towards the tyres forward edge. Up until recently teams placed the protruding vane as close to the tyre as possible, but latest solution offsets the vane from the tyres sidewall to allow airflow to pass in-between the tyre and vane. An inlet formed in the brake drum duct catches some of this air and redirects it towards the brakes for cooling. This year Williams went even further and removed the usual brake cooling scoop and have the brakes entirely cooled by an inlet between the tyre and vane.

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Ferrari: Canadian GP Updates

Having revised their exhaust position throughout the opening races, Ferrari had found some stability with their Mugello package. However, for the Canadian GP the team brought what will probably be their definitive set up for the year. Like most teams Ferrari have followed McLaren’s practice of a exiting the exhaust pipe out of the side and housing it within a duct to help the flow to be redirected inwards and downwards towards the diffuser footplate. This solution diffusers from McLaren’s in several areas, but like other teams who have followed the McLaren exhaust set up, the differences are a pragmatic approach to save having to redesign the entire sidepod package. The team have also brought revised brake ducts, turning vanes and a Canada specific wing package to Montreal.

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Red Bull: Floor Hole Legality

Its been announced today that the FIA have issued a Technical Directive clarifying the issue that emerged over the Monaco weekend around the Red Bull floor hole. This TD-13 outlines that the area 650mm outboard of the cars centreline cannot now exploit fully enclosed holes. As a result Red Bull will have to change the floor design before the next race, the Canadian GP. Although their design has now been deemed to be illegal retrospectively, so they are allowed to keep their results from the three races in which the design has been raced, including the win in Monaco.
Having introduced a “tyre squirt” slot into the floor ahead of the rear tyres at the Bahrain GP, Red Bull had completed two complete GPs before rival teams raised questions about its legality. On the morning of the Monaco GP, several teams started a discussion regarding the slots legality, as it did not follow the practice of Sauber or Ferrari in linking the hole to the edge of the floor. No formal protest was made, but the Technical Working Group (TWG) wanted the rules around holes in the floor clarified.

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First sight: Ferrari Revised Mugello Exhaust

Picture Via Russell Batchelor

On Day3 of today’s Mugello test, Ferrari appeared with a major update to their sidepodexhaust configuration.  Although at this stage it’s not clear if this set up is Ferraris definitive exhaust solution going forwards, or merely another interim set up.

What’s clear is Ferrari continue to follow their own path for exhaust and cooling flow.  With the main cooling outlets being via chimneys exiting from the flank of the sidepod, a solution popularly termed the “Acer ducts”, due to the presence of the sponsor’s logo on the launch spec bodywork.  With the launch car the exhaust exited through the rear exit of the ducts, and latterly the exhaust was moved to prevent overheating rear tyres and the duct cut away to allow more inboard location of the exhausts tailpipe.

Now the “Acer” ducts are brought more inwards and the exhaust exits over the top of the duct, periscope style.  This suggests the exhaust is not being aimed at the floor at all, simply along the centre of the top bodywork towards the beam wing and the winglet mounted atop it.  This would be less effective at creating downforce, but would be less sensitive to throttle position and have less of an effect on the rear tyre temperatures.

The floor and top body mouldings appear to new and quite large sections.  This also suggests that the bodywork is going to change. Often with interim bodywork the panels are smaller to allow different shaped sections to be added.  However the black heat shield panel around the exhaust is removable and may allow a switch to a McLaren style open-topped duct exit.

The continued presence of the vortex generator near the mirrors suggests some downwash effect is still being created, although the current spec is not really making use of it.

I will update this post as the test develops

Launch Analysis: Ferrari F2012

Car: Ferrari F2012
Concept
Having followed a very similar concept since the 2009 F60, Ferrari found in 2011 that the conservative route was not making up the ground to their rivals. The F150 was a fast car, but lacked that final ounce of pace to beat the Red Bulls and McLarens. This was exacerbated by the car being easy on its tyres, to the point where it had tyre warm up issues. This showed itself in qualifying were the car would not make the most of a tyre around a single lap and also in cooler weather, or where the harder Pirelli tyre was used. The team recruited Pat Fry in a major reshuffle of engineering staff. Fry spent the year assessing Ferrari problems and set about a recruitment programme of new staff and a more adventurous design programme. The resulting car is clearly very different from its predecessors.
Externally very little remains the same on the new car, it does perhaps shares Ferraris favour for a long wheelbase and clearly is set up to run a fairly steep rake angle. But only the front wing, which is derived from the late 2011 wing appears to be carried over. Even this detail was a development in preparation for 2012, Fry leading the team to follow Red Bulls format of front wing in both shape and aero elasticity.

Layout
With a similar wheelbase, the revised seating position is perhaps the only change to the cars layout. The seating position was altered for Fernando Alonso last year and has been altered once more for a lower position.

Nose

Of all the 2012 front ends Ferrari has one of the most striking, the nose being very wide and square in cross section. The width is part of philosophy to use the extended wing mounting pylons, as a pair of turning vanes cascaded with the normal undernose turning vanes. By making the nose as wide as possible within the space allowed within the regulations, more undernose surface can be used to accelerate air through the duct formed by the nose and vanes. As a result the edges are tightly radiussed and cannot be rounded as with other teams. The aesthetics of the nose being also worse for the rectangular cross section front bulkhead. Ferrari opting not to make a “V” shape of the bulkhead, in order to make the area under the raised chassis uncluttered to make the vane set up work most effectively.


The flow through this vane set up starts with the wing mounting pylons, these are wide spaced at their leading edges and they then converge to end inboard of the main turning vanes. The main turning vanes then pick up the flow accelerating between the pylons and sweep out to direct the flow towards the lower leading edge of the underfloor.
Curiously Ferrari has yet to fit a driver cooling vent into the nose. This hole is not mandatory and clearly not a requirement for a chilly Spanish pre season test.

Front wing
As previously mentioned, the front wing is a derivative of the late 2011 wing. This was extensively detailed in a previous post. The wing is a three element set up, the main plane being slotted to create the leading two elements, and then the flap trails this. An extra slot in the down-turned corner of the flap helps keep flow attached in the steepest section of wing. The footplate is formed by the wing curving down on itself, while the upper section of endplate is a separate vane, albeit joined along a lot of its length to the foot plate. Front wings are now subject to a doubling of the deflection test used by the FIA 2011. So far the Ferrari wing has not exhibited the flutter seen last year, which is not to say it is not flexing.

Front Suspension

A mention of front suspension in the cars launch analysis will be unique to Ferrari this year, as they have revisited an old direction with its layout. Every other car for well over ten years has had pushrod front suspension, but Ferrari has revived the pullrod set up for the front of the car.


This effectively turns the pushrod set up upside down, now the rod passes down from the upper wishbone and connects with the rocker, which is now mounted at the bottom of the chassis. According to Fry, this set up is a little lighter and has a slightly lower Centre of Gravity. These gains alone will not pay for the systems inclusion on the car, so the team claim to have found an aero benefit. The pullrod can be thinner, but the real gain is the pullrod is mounted near horizontal across the front suspension. This places it in line with the upwash from the front wing. Just as with the wishbones, its profile can be subtly altered within the rules to help control the wake from the wing and improve the airflow over the rear of the car. Despite appearances the pullrod is as effective in moving the rocker for a given wheel travel as a pushrod. The important factor is the angle between the rod and the wishbone is connected to, rather than the rods angle to the chassis. I’ll explain a lot more pull rod suspension in a subsequent article.


Roll hoop

Although not a performance differentiator, the new roll hoop is very different concept to that seen in previous Ferraris. A far curvier pair of inlets are formed by the structure, this shaping being at odds with the ungainly nose. It is strange Ferrari have not undercut this area and exposed the structure supporting the roll hoop, which is the common practice to achieve more airflow to the rear wing. The main inlet feeds the engines airbox, while the smaller inlet piggy-backed behind it, most likely feeds the gearbox and hydraulic oil coolers mounted above the gearbox. The lifting point for the trackside cranes is formed by beneath the main inlet and enclosed by a simple bar connecting it to the top of the chassis.

SidepodsCooling

It’s perhaps the sidepods that are the big performance area for the car this year.
Starting at their leading edge, the car sports a new format Side Impact Spar (SIPS) design inside the bodywork. Since 2009 Ferrari had a staggered SIPS arrangement, with a narrower spar sat ahead of a wider spar, creating the distinctive peaked sidepod inlet. Now it spears a single spar spans the sidepod and protrudes through to form the mount for the sidepod vane. This allows the spar to be wider, which creates an easier job to absorb the impact. Viewed from above the sidepod inlet lean inwards. This makes them more efficient at meeting the diverging flow that passes around chassis to enter the sidepod.


Much smaller and far more undercut, the sidepods now feature radiators mounted upright and splaying outwards from the rear of the car. Their new placement allows the flow through the cores to be directed outboard, rather than in towards the central tail funnel. This heated flow from the radiators passes out through the downswept chimney-fairings that differentiate the car from its rivals. This design keeps the centre of the car as slim as possible, with there being no tail funnel to obstruct the rear wing. Airflow passing through the undercut in the sidepod, still enters a coke bottle shape below the chimney-fairings and is passed over the diffuser. But these chimney-fairings also have a more important secondary use, for housing the exhaust outlets.


Additional cooling outlet area is provided in the tail of the sidepods, in between the rounded end of the chimney-fairings and the gearbox fairing. This gearbox fairing is nearly round in cross section also forms an outlet for hot air to exit from the engine bay.

Exhausts
With floor level exhausts no longer allowed, the teams have had to find different ways to make use of the powerful exhaust plume. Most teams have directed it over the sidepods towards the centre of the beam wing, but Ferrari have purposely placed the exits as far outboard as allowed (on the launch spec car at least). When viewed from above its clear these are aimed outboard of the rear wing endplate.


Sat inside the downswept chimney-fairings, the exhaust at first might be thought to be pointing downwards. But the rules state the exhaust outlets have to point upwards by at least ten degrees. Although not visible inside the chimney-fairings, the last 10cm of exhaust do indeed point upwards.


But the cleverly the down sweep of the chimney-fairings creates a downwash effect over the exhaust plume and this directs the combined flow downwards between the rear brake ducts and rear wing endplate. This set up will potentially reach the floor and act to seal the diffuser from the ground as with the 2011 EBD.

In testing the set up has gone through several iterations, firstly the exhausts exits were in line with the end of the chimney-fairings, but soon the exhaust tail pipes were shortened and the chimney-fairings above had to be cut back to maintain legality and also the allow the downwash flow to reach the shorter tailpipe.


At the Barcelona test the exhausts were again altered, this time being brought further inboard, approximately in line with the channel formed between the chimney-fairings and the engine cover. Now the exhausts appear to point inboard of the rear wing endplate. It’s not clear if this is an aerodynamic decision or a request for a less obviously aerodynamic solution from the FIA. Should the exhaust outlet stay in this position the sidepod and the chimney-fairings will need to be altered to optimise the downwashed airflow around the tail pipes.

Rear suspension
Almost unspoken of amidst the talk of the front pullrod set up, Ferrari also switched their rear suspension on its head and gone for pullrod on the rear of the F2012. Last year we saw the Ferrari had a very complex setup around the rear suspension rockers and placing this hardware lower down around the clutch and engine drive shaft, will be a tough task package.


Mounted to the revised gearbox, the rear top wishbone has been repositioned this year. It appears to be nearly horizontal; this places it in line with the beam wing, so the wishbone can act as a flow conditioner ahead of the wing. Even if the new gearbox is not as low as the Williams, the wishbone needs to mount to a vertical extension above the gearbox. This wishbone mounting hard point also forms the mounting for the beam wing. At first this appears to be a duct, but is just the thick swan-neck mounting similar to that used by Marussia for the past two years.

Diffuserrear impact structure
Within the bodywork rules, there is not a lot of scope for a very different diffuser. So Ferrari have now added a full width flap around the diffuser on the new car.
Unusually Ferrari have not fully exposed the underside of the beam wing above the rear crash structure. Looking at the crash structure itself its clear it is shallow enough to allow this. Instead the crash structure has additional bodywork above and below it, which merges it with the beam wing.

Gearbox
As already mentioned the gearbox is a new design. The hybrid carbon and titanium case now has to mount a very different rear suspension system, with the switch to pull rod springdamper operation and the raised upper wishbone.
Last year Ferrari were notable for having a single selector drum for their seamless shift set up. Most teams use two selectors; each one operating alternate gears, so that the phasing from one gear engaging and the other disengaging can be adjusted. Ferrari with a single selector must be confident that their system can always shift with the same aggressive phasing, without the option to go for a longer overlap.

KERS
Ferrari develop their KERS with Marelli, the system retains the same layout as in 2011 with the MGU mounted to the front of the engine and the Batteries placed under the fuel tank. The power electronics reside in the right hand sidepod.

Engine
With the engine freeze, not much can be said of the engine. Ferrari have usefully provided a high resolution image of the 056 engine, complete with integral oil tank, but lacking the KERS MGU.